What a year! Jesus. This year has really sucked for a lot of folks, and given how stressed I've been and how much effort it has taken to do even a minimal amount of research - and still be very, very backlogged on reading new papers (I am about five months behind for the first time in my life) - I imagine that this year's summary of new research may be more useful to most folks than prior years. One thing I can thank 2020 for is the time stuck at home, giving me an opportunity to reflect - and realize I probably should get back to blogging. So, 2020 has been better for blogging than prior years (and this post is going up on time instead of like... May). As per usual - please let me know if I have forgotten something. However, please double check the 2019 post to make sure that it wasn't actually published 'online early' in 2019 with a formal publication date of 2020, in which case I probably already covered it last year. Also, don't you dare suggest I try to standardize formatting... on a blog post. Don't be daft.

Bell et al. 2020 - First fossil manatees in Texas, USA: Trichechus manatus bakerorum from Pleistocene beach deposists along the Gulf of Mexico. Palaeontologia Electronica.
Link: https://palaeo-electronica.org/content/2020/3178-pleistocene-manatees-in-texas
Extant manatees were documented on the Texas coastline as early as 1853,
but their reported occurrence in Texas waters has been sporadic and
poorly documented until relatively recently. We report eight specimens
that document the first occurrence of fossil manatees in Texas, and the
westernmost fossil occurrence of manatees in the United States. Seven of
the specimens were collected along McFaddin and Caplen beaches on the
northwest coast of the Gulf of Mexico; one was recovered from Corpus
Christi Bay. The fossil specimens reported here include a mandibular
symphysis fragment diagnosable as the extinct morphotype denoted by the
trinomial Trichechus manatus bakerorum Domning, 2005. Other specimens are diagnosed as Trichechus manatus
or as Sirenia. They were found on beaches that are known to produce
mammalian taxa characteristic of Pleistocene faunas, and our age
assessment is based on that association, and the comparable
preservation, color, and density of the manatee bones and bones of
extinct taxa of Pleistocene age from the beaches. It is not clear
whether the fossils represent remains of a resident population, or the
fortuitous preservation of vagrant individuals. However, assuming that
the ecological tolerances of manatees in the Pleistocene were comparable
to the tolerances of extant populations, the presence of manatees in
the northwest Gulf of Mexico in the Pleistocene adds an interesting, if
enigmatic, data point for paleoenvironmental reconstructions of the
region.

Benites-Palomino et al. 2020. Miocene freshwater odontocetes from La Venta, Huila, Colombia suggest independent invasions of riverine environments in tropical South America. Journal of Vertebrate Paleontology.
Link: https://www.tandfonline.com/doi/full/10.1080/02724634.2020.1812078
The two extant genera of strictly freshwater dolphins Inia and Platanista
are the result of convergent evolution to freshwater environments with
reduced visibility. Characterized by their long snout and small melon,
these extant taxa are clustered into two clades, Iniidae in South
America and Platanistidae in Southern Asia. Their evolutionary history
leading to freshwater environments remains mostly unknown, because many
of their related fossil species have been found in marine environments.
Here, we report riverine dolphin remains (two rostral fragments and a
periotic) from two stratigraphic levels of the late middle Miocene (ca.
12.5 Ma) from La Venta, Colombia. The periotic has a reduced cochlear
aqueduct mediodorsally oriented, the anterior process is relatively
thin, and the dorsal opening of the facial canal is located lateral to
the spiral cribriform tract. The rostral fragments are dorsoventrally
flattened; the mandible features two longitudinal ventral grooves, and
the premaxilla-maxilla suture of the rostrum is located in a deep
lateral groove. These characteristics indicate that the specimens belong
to Platanistidae, the lineage of the Ganges river dolphin Platanista.
Platanistids had also been recorded on coeval strata from the
Fitzcarrald arch, Peru. The occurrence of middle Miocene platanistids in
both the La Venta and Fiztcarrald localities suggests that members of
this lineage moved into freshwater environments in South America earlier
than the ancestors of the modern Amazon river dolphin Inia. The
subsequent collapse of the Pebas ecosystem could have played a role in
the extinction of non-marine Platanistoidea in South America.

Benites-Palomino et al. 2020. Scaphokogia totajpe, sp. nov., a new bulky-faced pygmy sperm whale (Kogiidae) from the late Miocene of Peru. Journal of Vertebrate Paleontology.
Link: https://www.tandfonline.com/doi/full/10.1080/02724634.2019.1728538
The modern pygmy and dwarf sperm whales (Physeteroidea, Kogiidae) are
remnants of a highly diverse group, which flourished in the Miocene
oceans. Unlike their modern suction-feeding, deep-diving relatives, the
past diversity of this family includes animals with disparate ecological
habits. Here, we describe Scaphokogia totajpe, sp. nov., a new
species of kogiid based on a well-preserved skull from the upper Miocene
strata of the Pisco Formation, Peru. A phylogenetic analysis places S. totajpe as sister taxon of S. cochlearis and divides Kogiidae into two clades: the first including both species of Scaphokogia and the second including Kogia, Koristocetus, Praekogia, and Nanokogia. Similar to S. cochlearis, S. totajpe
has a tubular rostrum with a hypertrophied mesorostral canal, a large
supracranial basin, and a leftward deviated facial sagittal crest, but
it differs by possessing a proportionately shorter rostrum, a reduced
projection of the lacrimojugal between the frontal and the maxilla, and a
flat occipital shield. The cranial morphology of Scaphokogia
indicates that the extent of the nasal complex was greater than in
modern kogiids. Furthermore, the overall rostrum shape and the
reconstructed muscle insertion sites indicate that Scaphokogia retained some plesiomorphic features related to a more generalist ecology. Inclusion of S. totajpe
into the context of the Pisco Formation indicates that during the late
Miocene, the Peruvian coastal system was a hot spot for the
diversification of physeteroids, with at least four species coexisting.
Finally, Scaphokogia totajpe highlights a late Miocene diversity peak for sperm whales in the global oceans, before the Pliocene odontocete turnover.

Benites-Palomino and Urbina, 2020. Physeteroidea (Cetacea: Mammalia) hyper-diversification from the late Miocene of South Pacific, new fossils from the Sacaco area, Arequipa, Peru. Revista Peruana de Biologia.
Link: https://revistasinvestigacion.unmsm.edu.pe/index.php/rpb/article/view/16507
Sperm whales (Physeteroidea) are a group of cetaceans with a restricted modern ecology. The three extant species are a remnant of a group that reached its diversity peak during the Miocene, including five already-described species from the Pisco Formation, Ica-Arequipa, Peru. We report two isolated teeth from the upper Miocene localities of Sacaco and Sud-Sacaco, which correspond with the typical morphology of Physeteridae. This morphology is similar to the one present in northern hemisphere taxa as Orycterocetus or Aulophyseter. Because of this the remains could be related to physeterids with piscivorous habits, so there would not be a niche overlap with other coeval sperm whales. This new registry expands the fossil cetacean community of Sacaco, which was favored by the great diversity of shallow environments that dominated the Peruvian coast until the final establishment of the Humboldt System.
Berta, 2020. Art revealing science: marine mammal palaeoart. Historical Biology.
Link: https://www.tandfonline.com/doi/full/10.1080/08912963.2020.1834541
Apart from mythological drawings (e.g. unicorns and mermaids), some
appearing during classical times, marine mammals have been the subject
of palaeoart since the seventeenth century. Whales were the first marine
mammals to be portrayed in detailed pencil and ink scientific
illustrations printed as woodcuts and copper engravings. The early and
mid twentieth century witnessed an increase in number of paleoartists,
such as ZdenĂȘk Burian and Charles Knight painting in rich, vibrant
colours. Later, more attention was focused on portraying the ecologies
and environments inhabited by fossil marine mammals based on analogies
with living species resulting in restorations of entire animal and plant
communities. In the late twentieth and twenty-first centuries,
traditional illustrations were complemented by digital art with an
emphasis on accurate, realistic portrayals of fossil marine mammals
based on new interpretations of their anatomy, ecology, behaviour and
habitat. Apart from the inextricable connection of palaeontology and
art, palaeoart also serves a vital role in visually communicating
science and evolution to the public as portrayed in museum exhibitions
and other venues.

Berta and Lanzetti, 2020. Feeding in marine mammals: an integration of evolution and ecology through time. Palaeontologia Electronica.
Link: https://palaeo-electronica.org/content/2020/3136-feeding-in-marine-mammals
Marine mammals are key components of aquatic ecosystems.
Feeding strategies identified in extant cetaceans, pinnipeds,
sirenians, marine otters, and polar bears are associated with anatomical
specializations of the head (rostrum, palate, temporomandibular joint,
teeth/baleen, mandible). Genetic and ontogenetic evidence of skull and
tooth morphology provide the mechanisms that underlie patterns of
feeding diversity. Based on a comprehensive diversity data set derived
from the Paleobiology Database, we considered feeding strategies
(suction, biting, filter feeding, grazing), prey type (squid, fish,
benthic invertebrates, zooplankton, tetrapods, sea grasses), tooth
pattern and cusp shape (homodont, heterodont, pointed, rounded,
edentulous), and habitat (marine, riverine, estuarine) in fossil and
extant marine mammals. These variables were then tested for correlation
and their changes through time examined in relation to productivity and
climate variables.
We provide an integrated analysis of the evolution of
feeding and trophic structure in marine mammals and explore the origin
and timing of particular feeding strategies over the last 50 million
years. In agreement with earlier reports, updated generic counts reveal
that the greatest diversity of pinnipedimorphs and cetaceans occurred
during the late Miocene (Tortonian), following the Mid-Miocene Climatic
Optimum. These historical data are used as a framework to inform past
and present structure and trophic interactions and enable predictions
about future marine ecosystems.The drivers of diet and feeding patterns
are both environmental (sea level fluctuations, climate change) and
biotic (anatomical specializations, competition, predator-prey). The
influence of these processes on paleodiversity varies depending on
taxonomic group, timing, and geographic scale.

Bianucci et al. 2020. Extensive diversity and disparity of the early Miocene platanistoids (Cetacea, Odontoceti) in the southeastern Pacific (Chilcatay Formation, Peru). Life.
Link: https://www.mdpi.com/2075-1729/10/3/27
Several aspects of the fascinating evolutionary history of toothed and
baleen whales (Cetacea) are still to be clarified due to the
fragmentation and discontinuity (in space and time) of the fossil
record. Here we open a window on the past, describing a part of the
extraordinary cetacean fossil assemblage deposited in a restricted
interval of time (19–18 Ma) in the Chilcatay Formation (Peru). All the
fossils here examined belong to the Platanistoidea clade as here
redefined, a toothed whale group nowadays represented only by the Asian
river dolphin Platanista gangetica. Two new genera and species, the hyper-longirostrine Ensidelphis riveroi and the squalodelphinid Furcacetus flexirostrum, are described together with new material referred to the squalodelphinid Notocetus vanbenedeni and fragmentary remains showing affinities with the platanistid Araeodelphis. Our cladistic analysis defines the new clade Platanidelphidi, sister-group to Allodelphinidae and including E. riveroi
and the clade Squalodelphinidae + Platanistidae. The fossils here
examined further confirm the high diversity and disparity of
platanistoids during the early Miocene. Finally, morphofunctional
considerations on the entire platanistoid assemblage of the Chilcatay
Formation suggest a high trophic partitioning of this peculiar cetacean
paleocommunity.

Biewer et al. 2020. Insights on the dental evolution of walruses based on new fossil specimens from California. Journal of Vertebrate Paleontology.
Link: https://www.tandfonline.com/doi/full/10.1080/02724634.2020.1833896
Twelve new specimens of fossil walruses are described from four Miocene
units in California. The new material represents five taxa: (1) a
specimen from the Santa Margarita Formation referred to Imagotaria downsi; (2) a specimen from the Valmonte Diatomite Member of the Monterey Formation referred to cf. Pontolis magnus; (3) six specimens from the Monterey Formation referred to a new species of Pontolis (Pontolis barroni, sp. nov.); (4) one specimen from the Oso Member of the Capistrano Formation referred to a new species of Pontolis (Pontolis kohnoi, sp. nov.); (5) three specimens from the Oso Member referred to a new genus and species (Osodobenus eodon, gen. et sp. nov.). A phylogenetic analysis suggests that both the Dusignathinae and an expanded concept of the genus Pontolis
represent monophyletic groups. We provide phylogenetic definitions for
clade names of odobenids. Two of the new species are represented by
specimens of males, females, and juveniles. Analysis of these specimens
shows that the dental anatomy of later diverging basal odobenids is more
variable than previously considered. The specific pattern of variation
is lineage specific and likely corresponds to the intermediate dental
morphology of late Miocene odobenids. Osodobenus eodon, gen. et
sp. nov., is the first basal odobenid with tusk-like canines, a
longitudinally arched palate, and an enlarged infraorbital foramen.
These features are plausibly correlated with benthic suction feeding in
the odobenins (Pliocene to Recent) and so Os. eodon may represent a case of convergent evolution of benthic feeding in the late Miocene.
Comments: I still need to read this in detail (long backlog and all) but this is a pretty exciting paper and fills a lot of holes in the walrus fossil record. I saw some of this material back in 2013 (like the Osodobenus skull above). This paper is extremely dense, so it will take some time to digest. These were all specimens in Larry Barnes' 'vault', so to speak, that few researchers ever got a chance to look at. Prior to Barnes' retirement, visiting marine mammal paleontologists were not allowed to peruse collections: you were asked to provide a list of specimens numbers (which you would only know about from published papers) and museum staff would go off and retrieve them for you while you waited at the long wooden table near the prep lab. This system ensured that pesky students and competitors wouldn't happen across one of however many new genera were hiding in LACM collections. Fortunately, it's a new day there, the vault has been cracked open, and new papers like this are finally being published on an incredible 'backlogged' collection.

Bisconti et al., 2020. Marzanoptera tersillae, a new balaenopterid genus and species from the Pliocene of Piedmont, north-west Italy. Zoological Journal of the Linnean Society.
Link: https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlaa131/5999660?redirectedFrom=fulltext
Marzanoptera tersillae gen. & sp. nov., a
new balaenopterid from the Pliocene of the Piedmont in north-west Italy,
is described based on a partial skeleton and compared with other living
and fossil baleen whales. Marzanoptera tersillae shares
characters, such as the shape of the supraoccipital, glenoid fossa of
the squamosal and zygomatic process of the squamosal, with ‘Balaenoptera’ bertae.
We used a computed tomography scan to view parts of the skull that were
otherwise impossible to observe, such as the periotic. A phylogenetic
analysis based on 355 character states scored from 87 taxa revealed a
well-resolved hypothesis of relationships for Balaenopteridae and a
general phylogenetic hypothesis for chaeomysticetes. The monophyly of
all superfamily- and family-rank clades and of crown balaenopterid
species was confirmed. In addition, a monophyletic group including most
basal thalassotherian taxa was recovered. The mollusc fauna associated
with the specimen was autochtonous and constituted a residual fossil
assemblage indicative of an environmental context located below the base
of the storm wave, characterized by a low-energy hydrodynamic regimen.
Many shark teeth have been found in close association or embedded within
the bones, suggesting a possible scavenging action by two shark species
on the whale carcass.
Comments: This is an interesting paper, but there's no way that Balaenoptera bertae is a species of Marzanoptera: the two taxa admittedly share some features of the occipital shield, but B. bertae has short zygomatic processes that are aligned anteroposteriorly (a feature fairly unique to Balaenoptera spp.) and also bears a squamosal crease (a feature certainly unique to, and a probable synapomorphy of Balaenoptera). I'm certain that the species I described was properly placed into the extant genus Balaenoptera, and most cladistic analyses by myself and Felix Marx support that.
Bisconti et al. 2020. The earliest baleen whale from the Mediterranean: large-scale implications of an early Miocene thalassotherian mysticete from Piedmont, Italy. Papers in Palaeontology.
Link: https://onlinelibrary.wiley.com/doi/abs/10.1002/spp2.1336
The discovery of an early Miocene chaeomysticete from the Pietra da
Cantoni Group in Piedmont (north‐western Italy) allowed for the
establishment of Atlanticetus lavei gen. et sp. nov. The new
species is represented by a partial skeleton including the periotic and
tympanic bullae and has an anatomical resemblance to Atlanticetus patulus
(comb. nov.) from the western North Atlantic. The early Miocene age of
the new specimen supports the view that it represents the oldest record
of Chaeomysticeti from the Mediterranean. A new phylogenetic analysis
showed that both A. patulus and A. lavei belong to a
radiation of basal thalassotherian taxa. The basal thalassotherians are
monophyletic to the exclusion of Cetotheriidae and Balaenopteroidea. The
reconstruction of ancestral characters at selected nodes indicates that
the group including Atlanticetus and living balaenopterid taxa
independently evolved rostra wide at the base, an anterolateral
expansion in the tympanic bulla, and a peculiar arrangement of the
endocranial foramina of the periotic, exhibiting a noteworthy phenomenon
of convergent evolution in feeding and hearing functions with
Balaenopteridae. Palaeobiogeographical analysis shows that the North
Pacific was the centre of origin of Balaenomorpha (crown mysticetes),
Thalassotherii and Balaenoidea. The recurrent invasion of the
Mediterranean by balaenomorph mysticetes occurred from both the North
Atlantic and North Pacific.

Bisconti et al. 2020. A new species of rorqual whale (Cetacea, Mysticeti, Balaenopteridae) from the late Miocene of the southern North Sea basin and the role of the North Atlantic in the paleobiogeography of Archaebalaenoptera. PeerJ.
Link: https://peerj.com/articles/8315/
The rich fossil record of rorqual and humpback
whales (Cetacea, Mysticeti, Balaenopteridae) is mainly characterized by
monotypic genera since genera including more than one species are
extremely rare. The discovery of new species belonging to known genera
would be of great importance in order to better understand
ancestor-descendant relationships and paleobiogeographic patterns in
this diverse group. Recent discoveries in the southern North Sea Basin
yielded a number of reasonably well preserved fossil balaenopterids from
the Late Miocene; this sample includes a balaenopterid skull from
Liessel, The Netherlands, which shares key characters with Archaebalaenoptera castriarquati
from the Pliocene of Mediterranean. This skull is permanently held by
Oertijdmuseum, Boxtel, The Netherlands, with the number MAB002286 and is
investigated here.
A detailed comparative anatomical analysis of the
skull MAB002286 is performed in order to understand its relationships.
The age of the skull is determined by dinocyst analysis of the
associated sediment. A paleobiogeographic analysis is performed to
understand paleobiogeographic patterns within the balaenopterid clade
the new skull belongs to.
Our work resulted in the description of Archaebalaenoptera liesselensis
new species. The geological age of the holotype skull is between 8.1
and 7.5 Ma. The phylogenetic relationships of this species reveals that
it is monophyletic with Archaebalaenoptera castriarquati from the Italian Pliocene. Moreover, in combination with a more basal species of Archaebalaenoptera
from the late Miocene of Peru, our paleobiogeographic analysis suggests
that the North Atlantic ocean played a major role as a center of origin
of a number of balaenopterid clades including Protororqualus, Archaebalaenoptera
and more advanced balaenopterid taxa. From a North Atlantic center of
origin, two dispersal events are inferred that led to the origins of Archaebalaenoptera species in the South Pacific and Mediterranean. The distribution of Archaebalaenoptera was antitropical in the late Miocene. The role played by the Mediterranean salinity crisis is also investigated and discussed.

Bisconti et al. 2020. A natural endocast of an early Miocene odontocete and its implications in cetacean brain evolution. Journal of Comparative Neurology.
Link: https://onlinelibrary.wiley.com/doi/abs/10.1002/cne.25015
The natural endocast Museo di Geologia e Paleontologia of the UniversitĂ
degli Studi di Torino (MGPT)‐PU 13873 is described and analyzed in
order to interpret its taxonomic affinities and its potential
significance on our understanding of cetacean brain evolution. The
endocast is from the early Miocene of Piedmont (between ca. 19 and 16
million years ago), Northwestern Italy, and shows a number of
plesiomorphic characters. These include: scarcely rounded cerebral
hemispheres, cerebellum exposed in dorsal view with little
superimposition by the cerebral hemispheres, short temporal lobe, and
long sylvian fissure. The distance between the hypophysis and the
rostral pons is particularly high, as it was determined by the calculus
of the hypothalamus quotient, suggesting that the development of a deep
interpeduncular fossa was not as advanced as in living odontocetes. The
encephalization quotient (EQ) of MGPT‐PU 13873 is ~1.81; therefore, this
specimen shows an EQ in line with other fossil whales of the same
geological age (early Miocene). Comparative analysis shows that there is
a critical lack of data from the late Miocene and Pliocene that
prevents us to fully understand the recent evolution of the EQ diversity
in whales. Moreover, the past diversity of brain size and shape in
mysticetes is virtually unknown. All these observations point to the
need of additional efforts to uncover evolutionary patterns and
processes on cetacean brain evolution.

Bisconti and Bosselaers 2020. A new balaenopterid species from the Southern North Sea Basin informs about phylogeny and taxonomy of Burtinopsis and Protororqualus (Cetacea, Mysticeti, Balaenopteridae). PeerJ.
Link: https://peerj.com/articles/9570/
An extensive radiation can be
inferred among balaenopterid mysticetes in the last 10 million years based on a
rich fossil record. Many extinct genera and species have been established in
the past by the study of fossil rorquals from northern and southern hemispheres.
In many cases, the new fossils are used to create new genera. However, in very
recent times, new species of known genera have been described that help our
understanding of the speciation processes and the biogeography of these whales.
Here, a new species of balaenopterid whales is described in order to better
understand the past diversity of Balaenopteridae and to analyze its
paleobiogeographical implications. As the new species closely resembles a taxon
established in the 19th century (i.e., Burtinopsis), a detailed
analysis of this taxon was necessary to support the new taxonomic statements of
this article.
A new partial skeleton including
skull and earbones is described and compared to an extended sample of living
and fossil mysticete species. A phylogenetic analysis including 355 character
states scored in 88 taxa was performed to understand its relationships within
the genus Protororqualus, to allow paleobiogeographic inferences
and to better understand the relationships of Protororqualus within
Balaenopteridae. Maximum parsimony analyses of character evolution were
performed to understand morphological transformations within Balaenopteridae.
The revision of Burtinopsis was carried out based on detailed
descriptions and comparisons of the type materials that were figured and
measured.
Protororqualus wilfriedneesi sp.
nov. was established based on a comparative analysis of the skull and earbone
morphology. The specimen is dated back to the Zanclean (Lower Pliocene,
between c. 5.3 and 3.6 Ma). A taphonomical study of the holotype
skeleton revealed evidence of interactions with sharks and fishes before the
definitive burial of the carcass. Based on the phylogenetic analysis, the
monophyly of the genus Protororqualus was confirmed. Protororqualus
wilfriedneesi sp. nov. was more derived than Protororqualus
cuvieri suggesting that it resulted from an invasion of the North Sea
Basin (and the North Atlantic ocean) from the Mediterranean basin. Several
specimens from western and eastern sides of the Atlantic Ocean are described
that suggest that Protororqualus wilfriedneesi had a
trans-Atlantic distribution in the Pliocene.
Comments: This is a pretty interesting paper as it reports specimens of this new species from both sides of the Atlantic. We've got these funky bullae with a triangular-ish anterior margin from the Pliocene of the Lee Creek Mine (and beyond) that I did not know how to identify - and they were referred to this new species of Protororqualus.

Boessenecker et al. 2020. Convergent evolution of swimming adaptations in modern whales revealed by a large macrophagous dolphin from the Oligocene of South Carolina. Current Biology.
Link: https://www.cell.com/current-biology/fulltext/S0960-9822(20)30828-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982220308289%3Fshowall%3Dtrue
Modern whales and dolphins are superbly adapted for marine life, with tail flukes
being a key innovation shared by all extant species. Some dolphins can exceed speeds
of 50 km/h, a feat accomplished by thrusting the flukes while adjusting attack angle
with their flippers
. These movements are driven by robust axial musculature anchored to a relatively
rigid torso consisting of numerous short vertebrae, and controlled by hydrofoil-like
flippers. Eocene skeletons of whales illustrate the transition from semiaquatic to aquatic
locomotion, including development of a fusiform body and reduction of hindlimbs, but the rarity of Oligocene whale skeletons has hampered efforts to understand the evolution of fluke-powered, but forelimb-controlled,
locomotion. We report a nearly complete skeleton of the extinct large dolphin
Ankylorhiza tiedemani comb. n. from the Oligocene of South Carolina, previously known only from a partial
rostrum. Its forelimb is intermediate in morphology between stem cetaceans and extant
taxa, whereas its axial skeleton displays incipient rigidity at the base of the tail
with a flexible lumbar region. The position of
Ankylorhiza near the base of the odontocete radiation implies that several postcranial specializations
of extant cetaceans, including a shortened humerus, narrow peduncle, and loss of radial
tuberosity, evolved convergently in odontocetes and mysticetes. Craniodental morphology,
tooth wear, torso vertebral morphology, and body size all suggest that
Ankylorhiza was a macrophagous predator that could swim relatively fast, indicating that it was
one of the few extinct cetaceans to occupy a niche similar to that of killer whales.
Comments: Arguably my biggest accomplishment of 2020, and only first-authored research this year. This paper took three years of hard work to get finished, and I don't think I'll be submitting anything for a high profile journal again for some time. To read more about it on coastal paleo, read here and here.
Bosio et al. 2020. Mineralogical and geochemical characterization of fossil bones from a Miocene marine Konservat-Lagerstatte. Journal of South American Earth Sciences.
Link: https://www.sciencedirect.com/science/article/abs/pii/S0895981120304673
Fossil bones, together with teeth, are the most common remains of
vertebrates that could manage to get preserved over geological times,
providing information on the diagenetic and fossilization processes that
occurred in the depositional paleoenvironment. Fossil bones from the
marine vertebrate Konservat-LagerstÀtte in the East Pisco Basin and
Sacaco area (Peru) show a high variety of different textural and
chemical features, suggestive of different processes variably
contributing to the fossilization path. At the macroscopic scale, bone
samples can be grouped into six different categories on the basis of the
color (red to gray to white) and hardness (which relates to the
mineralization degree); a variety of case studies can be found between
these categories. Microscopically, the original microstructure of the
bone tissue, both compact and cancellous, is well preserved in all the
studied samples, with differences in cavity fillings, distribution of
microcracks, and presence of Fe oxides in the diverse bone types. The
bone composition and mineralogy correspond to fluorapatite. Differences
in color, mineralization degree and geochemistry can be interpreted in
terms of different fossilization paths, from burial at the seafloor to
exposure in the present-day desert environment. The fossilization paths
are strongly conditioned by the factors controlling the interplay of the
mechanisms of apatite dissolution-recrystallization and dolomite
precipitation (formation of carbonate concretions) as well as the
fixation of iron in finely disseminated sulfides in the very early
stages of fossilization.

Carone and Rizzo 2020. A new record of fossil sirenians from the Miocene of Sardinia (Italy). Bollettino della Societa Paleontologica Italiana.
Link: http://paleoitalia.org/archives/bollettino-spi/104/vol-59-2-2020/
The first diagnostic sirenian material from Sardinia is reported and the fossil record of Miocene Sardinian sirenians is
reviewed through an updated geological and stratigraphic framework. The new specimens are referred to Metaxytherium cf. M. krahuletzi
Deperet, 1895, indicating the diffusion of the species into the
mid-southern Tethys. We also state that the other specimens from the
earlymiddle
Miocene previously found on the island should be assigned to the same
species. We regard the holotype of Metaxytherium lovisati
Capellini, 1886 as not diagnostic and consider it a nomen dubium. This
conclusion is consistent with the taxonomic analysis given by Sorbi
(2008) which winnowed the nominal taxa into four Miocene and Pliocene
species.
Collareta et al. 2020. A new physteroid from the late Micoene of Peru expands the diversity of extinct dwarf and pygmy sperm whales (Cetacea: Odontoceti: Kogiidae). Comptes Rendus Palevol.
Link: https://sciencepress.mnhn.fr/fr/periodiques/comptes-rendus-palevol/19/5
Nowadays, the odontocete family Kogiidae is monotypic and only includes
two species of diminutive relatives of the great sperm whale Physeter Linnaeus,
1758. Conversely, a growing body of extinct species indicates that
kogiids were diverse and disparate during the late Neogene. The fossil
record of Kogiidae is, to date, represented by several cranial specimens
from Mio-Pliocene localities of the Northern Hemisphere, with the
significant Southern Hemisphere exception of the Pisco Formation of
Peru, from which two genera were known so far, including Scaphokogia Muizon,
1988, a highly idiosyncratic form characterised by a distinctly
spoon-shaped dorsal surface of the neurocranium and a downturned
semicylindrical rostrum, which is even placed in its own subfamily
Scaphokogiinae. Here, we report on two skulls of Kogiidae from the
Messinian (upper Miocene) portion of the Pisco Formation exposed in the
East Pisco Basin. These two skulls are referred to the new taxon Platyscaphokogia landinii n. gen., n. sp., which our phylogenetic analysis recovers as sister group of Scaphokogia, within the subfamily Scaphokogiinae. Although Platyscaphokogia n. gen. shares with Scaphokogia
a remarkably spoon-like dorsal aspect of the neurocranium, it retains a
non-pachyostotic, dorsoventrally thin rostrum that distinctly points
anteriorly; as such, Platyscaphokogia n. gen. might be regarded
as testifying an early stage in the evolution of the scaphokogiine
cranial anatomy. Morphofunctional and palaeoecological considerations
allow for hypothesising that Platyscaphokogia n. gen. was a
raptorial physeteroid that foraged along the water column in relatively
open-sea palaeoenvironments. In conclusion, our finds expand the
palaeodiversity of Kogiidae, as well as our knowledge on the late
Miocene sperm whales of the southeastern Pacific, and further suggest
that the fossil content of the East Pisco Basin is crucial for
reconstructing the Neogene evolutionary history of physeteroids.

Collareta et al. 2020. The shark-toothed dolphin Squalodon (Cetacea: Odontoceti) from the remarkable Montagna della Majella marine vertebrate assemblage (Bolognano Formation, central Italy). Carnets Geology.
Link: http://paleopolis.rediris.es/cg/20/02/index.html
The extinct
family Squalodontidae consists of heterodont, medium-sized odontocetes,
featuring a long rostrum that houses large, procumbent incisors and
heavily ornamented postcanine teeth carrying accessory denticles, hence
their
vernacular name, "shark-toothed dolphins". These longirostrine toothed
whales are often seen as bridging the anatomical gap between archaic
Oligocene
odontocetes and their late Miocene to Holocene relatives. Possibly among
the
major marine predators of their time, the shark-toothed dolphins are
important components of several lower Miocene marine-mammal assemblages
from the
North Atlantic and Mediterranean/Paratethysian realms. In the present
work, a
partial skull of Squalodontidae is described from the strata of the
Bolognano
Formation cropping out in the northeastern sector of the Montagna della
Majella
massif (Abruzzo, central Italy), which has previously yielded a rich
lower
Miocene marine-vertebrate assemblage, including eleven taxa of
elasmobranchs as
well as subordinate teleosts and very
fragmentary remains of marine reptiles and mammals. The specimen
consists of the
anterodorsal portion of a rostrum, preserving parts of both premaxillae
and left
maxilla, and the anteriormost seven upper left teeth. This partial skull
is here
identified as belonging to the genus Squalodon, whose presence in the Montagna
della Majella vertebrate assemblage had already been tentatively proposed on the
basis of two fragmentary teeth. The paleontological significance of this find is
discussed in the broader framework of the Euromediterranean record of Squalodon.

Collaerta et al. 2020. On Leonardo and a fossil whale: a reappraisal with implications for the early history of palaeontology. Historical Biology.
Link: https://www.tandfonline.com/doi/abs/10.1080/08912963.2020.1787403?scroll=top&needAccess=true&journalCode=ghbi20
A recent reappraisal of two passages in Leonardo da Vinci’s Codex
Arundel, in which the then young Leonardo reports on visiting a cave and
on some sort of Êœmarine monster’, has led to the proposition that
Leonardo observed and wrote on fossil remains of a whale preserved in a
cave. Whereas this hypothesis appears reasonable overall, some problems
persist in accepting the purported location in which Leonardo would have
observed the fossil. Here we provide a new analysis of the
aforementioned passages by Leonardo which allows us to confirm that
Leonardo saw a fossil whale and recognised it as such. However, his
observation did not occur in a cave, but likely along the flank of a
hill, as relatively common for Tuscan Pliocene fossil cetaceans.
Leonardo seemingly made taphonomic observations on the fossil whale and
inferred that a considerable amount of time must have passed from the
death of the whale in the sea to allow for its eventual discovery on
land – an observation that likely contributed to shaping Leonardo’s
later thoughts on sedimentation and fossilisation. This might represent
Leonardo’s earliest text devoted to a palaeontological theme. Moreover,
it comprises the first known description of a cetacean fossil.

Coombs et al. 2020. Wonky whales: the evolution of cranial asymmetry in cetaceans. BMC Biology.
Link: https://bmcbiol.biomedcentral.com/articles/10.1186/s12915-020-00805-4
Unlike most mammals, toothed whale (Odontoceti) skulls lack symmetry in the
nasal and facial (nasofacial) region. This asymmetry is hypothesised to relate
to echolocation, which may have evolved in the earliest diverging odontocetes.
Early cetaceans (whales, dolphins, and porpoises) such as archaeocetes, namely
the protocetids and basilosaurids, have asymmetric rostra, but it is unclear
when nasofacial asymmetry evolved during the transition from archaeocetes to
modern whales. We used three-dimensional geometric morphometrics and
phylogenetic comparative methods to reconstruct the evolution of asymmetry in
the skulls of 162 living and extinct cetaceans over 50 million years.
In archaeocetes, we found asymmetry is prevalent in the rostrum and also in
the squamosal, jugal, and orbit, possibly reflecting preservational
deformation. Asymmetry in odontocetes is predominant in the nasofacial region.
Mysticetes (baleen whales) show symmetry similar to terrestrial artiodactyls
such as bovines. The first significant shift in asymmetry occurred in the stem
odontocete family Xenorophidae during the Early Oligocene. Further increases in
asymmetry occur in the physeteroids in the Late Oligocene, Squalodelphinidae
and Platanistidae in the Late Oligocene/Early Miocene, and in the Monodontidae
in the Late Miocene/Early Pliocene. Additional episodes of rapid change in
odontocete skull asymmetry were found in the Mid-Late Oligocene, a period of
rapid evolution and diversification. No high-probability increases or jumps in
asymmetry were found in mysticetes or archaeocetes. Unexpectedly, no increases
in asymmetry were recovered within the highly asymmetric ziphiids, which may
result from the extreme, asymmetric shape of premaxillary crests in these taxa
not being captured by landmarks alone.
Early ancestors of living whales had little cranial asymmetry and likely
were not able to echolocate. Archaeocetes display high levels of asymmetry in
the rostrum, potentially related to directional hearing, which is lost in early
neocetes—the taxon including the most recent common ancestor of living
cetaceans. Nasofacial asymmetry becomes a significant feature of Odontoceti
skulls in the Early Oligocene, reaching its highest levels in extant taxa.
Separate evolutionary regimes are reconstructed for odontocetes living in
acoustically complex environments, suggesting that these niches impose strong
selective pressure on echolocation ability and thus increased cranial asymmetry.
Davydenko et al. 2020. A small whale reveals diversity of the Eocene cetacean fauna of Antarctica. Antarctic Science.
Link: https://www.cambridge.org/core/journals/antarctic-science/article/small-whale-reveals-diversity-of-the-eocene-cetacean-fauna-of-antarctica/60762DFF372D829534013A54D4BEF066
Cetacean fossils have been recorded from middle and late Eocene deposits
on Seymour Island since the beginning of the twentieth century and
include fully aquatic Basilosauridae and stem Neoceti. Here, we report a
small cetacean vertebra tentatively referred to as Neoceti from the
late Eocene of Seymour Island. It shows a mosaic of traits, some of
which are characteristic of early Neoceti (anteroposteriorly long
transverse processes; a ventral keel on the ventral side of the centrum;
thin pedicles of the neural arch), whereas others are shared with
Basilosauridae (low-placed bases of the transverse processes). However,
some traits are unique and may be autapomorphic: presence of separate
prezygapophyses on the vertebra at the thoracic/lumbar boundary and a
proportionally short centrum. Both traits imply a fast swimming style,
which is characteristic of modern dolphins rather than Eocene cetaceans.
Thus, this specimen can be identified as Neoceti indet., with some
hypothetical odontocete affinities. Along with a few other Eocene whale
taxa, it seems to be among the earliest known members of Neoceti on
Earth. The finding of small and fast-swimming Neoceti in Antarctica also
demonstrates early diversification of cetaceans and ecological niche
partitioning by them dating back as early as the late Eocene.
Comments: Interesting paper that speculates perhaps beyond the bounds of the fossils. The ventral keel observation is a new one, but I might not be surprised if a small basilosaurid with this condition was discovered. A tantalizing find - but we'd need much more than this to confirm the existence of odontocetes in the Eocene. Ironically, this paper came just about a month or so after I updated my post on the Eocene origin of Neoceti and speculated that there is likely more to be found in Antarctica. I'll have to update it again...
Diaz-Berenguer et al. 2020. The hind limbs of Sobrarbesiren cardieli (Eocene, Northeastern Spain) and new insights into the locomotion capabilities of the quadrupedal sirenians. Journal of Mammalian Evolution.
Link: https://link.springer.com/article/10.1007/s10914-019-09482-9
In the transition from a terrestrial to an aquatic environment, sirenian
marine mammals reduced and lost their hind limbs and developed a
horizontal caudal fin, the main propulsive organ in extant sirenians.
Quadrupedal forms are only known from the Eocene and are represented by
three different clades: the amphibious “prorastomids,” the aquatic
quadrupedal protosirenids, and Sobrarbesiren cardieli, a
four-legged sirenian from the middle Eocene of Spain, considered the
sister taxon of the fully aquatic Dugongidae. This ecological shift from
terrestrial to an aquatic environment was naturally associated with
adaptations, among others, of the skeleton. However, sirenian hind limb
bones have been poorly studied because of the scarce material available
in the fossil record. Here, we describe in detail the hind limb bones of
Sobrarbesiren, analyzing their functional morphology and
comparing them with other basal sirenians and cetaceans, and with
related terrestrial mammals such as proboscideans and hyracoids. The
hind limbs of Sobrarbesiren were capable of a great variety of
movements. Based on the presence of a strong sacroiliac articulation, we
propose that it swam by dorsoventral pelvic undulation combined with
pelvic paddling analogous to extant otters and the “prorastomid” Pezosiren.
We also conduct the first microanatomical analysis of hind limb bones
of an Eocene sirenian. Data reveal extreme inner compactness in the Sobrarbesiren
innominate and femur, with the first description of osteosclerosis in
an amniote innominate combined with the highest degree of osteosclerosis
observed in amniote femora. The results confirm that the
microanatomical changes precede the external morphological changes in
such ecological transitions. The process of adaptation of sirenians to
an aquatic life was thus a more complex process than previously thought.

Gavazzi et al. 2020. Carpal morphology and function in the earliest cetaceans. Journal of Vertebrate Paleontology.
Link: https://www.tandfonline.com/doi/full/10.1080/02724634.2020.1833019
During the land-to-water transition in the Eocene epoch, the cetacean
skeleton underwent modifications to accommodate life in the seas. These
changes are well-documented in the fossil record. The forelimb
transformed from a weight-bearing limb with mobile joints to a flipper
with an immobile carpus. We used micro-CT imaging to assess evolutionary
changes in carpal size, orientation, and articulation within Eocene
cetacean taxa associated with the transition from a terrestrial to
amphibious niche. We compared Ambulocetus natans, a
well-preserved amphibious archaeocete, with other archaeocetes, and with
Eocene terrestrial artiodactyls, the sister group to Cetacea. A
cylindrical carpus in terrestrial taxa evolved into a mediolaterally
flattened, cambered carpus in the semi-aquatic and fully aquatic
cetaceans. Specifically, the pisiform bone shifted from a ventral
orientation in terrestrial taxa to a lateral orientation, in plane with
the carpus, within semi-aquatic and fully aquatic taxa. Flattening of
the carpus, including lateral rotation of the pisiform, likely relates
to functional shifts from weight-bearing terrestrial locomotion to
aquatic locomotion. This laterally projecting pisiform morphology is
retained in all extant cetaceans. Our results suggest this shift, along
with other modifications to the carpus, predominantly occurred during
the middle Eocene and facilitated an obligatorily aquatic lifestyle in
late Eocene cetaceans.

Gol'din et al. 2020. The Volhynian (late middle Miocene) marine fishs and mammals as proxies for the onset of the eastern Paratethys recolonization by vertebrate fauna. Palaeontologia Electronica.
Link: https://palaeo-electronica.org/content/2020/3152-the-volhynian-late-middle-miocene
The late Middle Miocene of South-Eastern Europe was the time of major
basin-wide physical and biogeographic transformations of marine
environments with mass extinction and faunal replacement. We examined
new material comprising marine fishes and mammals, re-examined earlier
finds, and analysed previously published data on the marine vertebrate
assemblage that lived along the western and northern edges of the
Eastern Paratethys. The studied materials represent marine fishes that
belong to at least four families (Clupeidae, Sparidae, Bothidae, and
Scombridae), including Sarmatella doljeana, Sparus brusinai, Bothus parvulus, and
indeterminate scombroids; true seals (Phocinae), the earliest seal
record in the area; small toothed whales of the family Kentriodontidae,
including Kentriodon fuchsii, whose presence in the Volhynian is confirmed here, and two other dwarf forms; a bizarre toothed whale Pachyacanthus,
the first record in the area between the Vienna Basin and Central Asia;
baleen whales, including an indeterminate member of the family
Cetotheriidae, and “Archaeocetus fockii”. The material found so
far hints to a low taxonomic diversity and biogeographical connections
to both the synchronous Sarmatian fauna of the Central Paratethys and
the later Bessarabian Eastern Paratethyan fauna. The taxonomic
composition of the faunal assemblage and its biogeographical connections
indicate that it has Central Paratethyan origin and shows an overall
west to east direction of gradual dispersal, from the Central Paratethys
through the Fore-Carpathian Basin and further east. The taxonomic
composition of described Volhynian fish and mammal assemblages supports
the idea of faunal connection and transition between the Central and
Eastern Paratethys.

Hafed et al. 2020. Current status of pinnipeds phylogeny based on molecular and morphological data. Historical Biology.
Link: https://www.tandfonline.com/doi/full/10.1080/08912963.2020.1795649
The disagreement surrounding the relationship within pinnipeds as
well as their phylogenetic affinities still remains unresolved.
Molecular-based studies neglect significant morphological data and
ignore the entire fossil record, which demonstrates why there are such
contradicting results from morphology-based studies. There still remains
a difference of opinion about the origin of pinnipeds, with research
supporting origination from either Ursid (bear-like) or Mustelid
(weasel-like) ancestors, even extending down to familial and subfamilial
levels.
This study examines certain morphological characters in
the three pinniped families: Otariidae (sea lions and fur seals),
Odobenidae (walruses), and Phocidae (true seals), with extra emphasis on
the four phocid subfamilies: Phocinae, Monachinae, Cystophorinae, and
Devinophocinae. Morphological characters of the cranium (skull,
dentition and mandible) and post cranium (humerus and femur) are the
basis for understanding pinnipeds’ movement, body size, and sexual
dimorphism, and all are ignored when only molecular analyses are used.
Biomolecular based studies involve larger sample sizes and incorporate
more phylogenetic characters, but ignore the significant data from the
fossil record (which can only be examined through morphology).
Therefore, the origin of pinnipeds cannot be resolved by depending only
on molecular (genetic) or morphological approaches independently and
future studies need to integrate both morphology and molecular data.

Hernandez Cisneros and Velez-Juarbe 2020. Palaeobiogeography of the North Pacific toothed mysticetes (Cetacea, Aetiocetidae): a key to Oligocene cetacean distributional patterns. Palaeontology.
Link: https://onlinelibrary.wiley.com/doi/abs/10.1111/pala.12507
Biogeographical distributional patterns of cetaceans reflect dispersal
events and colonization of the oceans from their ancestral area in the
ancient Sea of Tethys ̃53 Ma. Likewise, they reveal several vicariance
events throughout the evolutionary history of this group. However, our
understanding of how these processes took place and what biogeographical
scenarios occurred among the different groups of cetaceans through time
is limited. Consequently, this work focuses on explaining the
distributional patterns of the well‐known North Pacific toothed
mysticetes, Aetiocetidae, through the power of retrodiction offered by
track analysis (panbiogeography) and cladistic biogeography, using the
approach of evolutionary biogeography. Our results show that the
distributional patterns of Aetiocetidae explain their endemism in the
North Pacific, as well as indicating that their hypothetical ancestor
probably colonized the Pacific from the Atlantic Ocean by a dispersal
event (founder effect) via the Central American Seaway. Furthermore,
their biogeographical history shows that the adaptive radiation
(cladogenesis) of Aetiocetidae is result of peripatric speciation
followed by sympatric speciation within a heterogeneous environment.
Finally, the biogeographical framework of Aetiocetidae further supports
the relevant role that the Pacific Ocean has played in the evolution of
Oligocene cetaceans as a geographical area that promoted endemism,
dispersal and colonization. At more local scales, environmental
conditions further promoted increased diversity and disparity amongst
Mysticeti.
Comments: A very interesting paper from our colleague Ehecatl Hernandez Cisneros, who stayed with our lab for a couple of months in New Zealand. My inability to learn Spanish severely hampered our discussions. I'm very glad to see another great article come out - and I expect more on his work with El Cien Formation Oligocene cetaceans in the future. This paper interprets the controversial toothed mysticete family Aetiocetidae as being biogeographically restricted to the North Pacific - which I believe based on the published fossil record. I've seen some unpublished things that might make me question this, but they don't count yet and besides, that's for someone else to demonstrate.
Kimura and Hasegawa 2020. Norisdelphis annakaensis, a new Miocene delphinid from Japan. Journal of Vertebrate Paleontology.
Link: https://www.tandfonline.com/doi/full/10.1080/02724634.2020.1762628
Two well-preserved delphinid crania have been recovered from the
Haraichi Formation, Annaka Group, Gunma Prefecture, Japan (earliest late
Miocene, Tortonian; 11.29–11.25 Ma). The specimens represent a new
genus and species of delphinid, Norisdelphis annakaensis. The new
species is characterized by transversely narrow and anteroposteriorly
elongated external bony nares, and a wider proximal extremity of the
left premaxilla. Phylogenetic analysis suggests that Norisdelphis is the most basal member of the Delphinidae. The previous oldest known described delphinid, Eodelphinus kabatensis,
is from the upper Miocene (ca. 9 Ma), and other reliably dated and
described fossil delphinids are no older than Pliocene; thus, N. annakaensis is the oldest convincingly dated and well-diagnosed fossil delphinid species yet described. Norisdelphis annakaensis expands the geological range of the family Delphinidae.
Comments: There's a well-preserved skull at LACM that was discovered in the Monterey Formation, and Larry Barnes published a couple of conference abstracts about it being the oldest known delphinid in the world. It's now on display upstairs in the mammal hall, and when I saw it in 2012, photographed it - it is indeed very similar, but has a less asymmetrical facial region - and may be congeneric with Norisdelphis.
Kimura et al. 2020. Fossil allodelphinids from the early Miocene Tomikusa Group, Arakida Formation, Nagano Prefecture, Japan. Bulletin of the Gunma Museum of Natural History.
Link: http://www.gmnh.pref.gunma.jp/research_no24
We describe four individuals of the fossil odontocetes from the lower Miocene Tomikusa Group, Nagano Prefecture, Japan. All the specimens were from the Arakida Formation. The geologic age of the upper part of Tomikusa Group (i.e., Arakida and Awano Formations) has been estimated as ca 18.1~17.2 Ma by magnetostratigraphy. The specimens represent the following combination of morphological characters and here we identify the specimens as Allodelphinidae gen. et sp. indet.: atlas vertebra bearing separate dorsal and ventral transverse process, and the vertebra is compressed dorsoventrally; the occipital condyles are large and they protrude prominently posteriorly.
Lambert et al. 2020. A new longirostrine sperm whale (Cetacea, Physeteroidea) from the lower Miocene of the Pisco Basin (southern coast of Peru). Journal of Systematic Palaeontology.
Link: https://www.tandfonline.com/doi/full/10.1080/14772019.2020.1805520
The modern sperm whales Kogia and Physeter (superfamily
Physeteroidea) represent highly disparate, relict members of a group of
odontocetes that peaked in diversity during the middle to late Miocene.
Based on a highly informative specimen (including the cranium with ear
bones, mandibles, teeth and some postcranial elements) from the lower
Miocene (early Burdigalian, 19–18 Ma) of the Chilcatay Formation (Pisco
Basin, Peru), we describe here a new genus and species of physeteroid, Rhaphicetus valenciae
gen. et sp. nov. The latter is one of the geologically oldest
physeteroids. This medium-sized species (estimated body length between
4.7 and 5.7 m) differs from all other physeteroids by the following,
probably autapomorphic, features: a narrow, cylindrical rostrum
comprising nearly 75% of the condylobasal length; the two main dorsal
infraorbital foramina located posterior to the antorbital notch; an
upper tooth count of at least 36 teeth per quadrant; and anterior-most
upper alveoli filled by thick bony pads. Our phylogenetic analysis
recovers R. valenciae as one of the earliest branching stem
physeteroids. The highly unusual filling of the anterior upper alveoli
by bony pads is interpreted as part of a mechanism leading to the loss
of apical and subapical upper teeth. By comparison with other
odontocetes displaying some degree of anterior reduction of the
dentition, this condition may have corresponded to the rostrum being
anteriorly longer than the mandible. The elongated rostrum with a
circular cross-section, the long temporal fossa, and the high number of
slender, pointed upper and lower teeth all suggest that R. valenciae
used its dentition to grasp relatively small prey, possibly via rapid
movements of the head. On the one hand, this new Peruvian record
increases our knowledge of the morphological disparity of sperm whales
during the Miocene. On the other hand, it may provide clues to the
ancestral morphotype for all physeteroids.

Lambert et al. 2020. A new small, mesorostrine inioid (Cetacea, Odontoceti, Delphinida) from four upper Miocene localities in the Pisco Basin, Peru. Papers in Palaeontology.
Link: https://onlinelibrary.wiley.com/doi/abs/10.1002/spp2.1332
The moderately rich past diversity of the superfamily Inioidea (Cetacea,
Odontoceti) in both the Atlantic and Pacific oceans contrasts with the
present survival of a single genus (Inia, Amazon river dolphin, family Iniidae) in freshwater deposits of South America and of a single species (Pontoporia blainvillei,
franciscana, family Pontoporiidae) along the eastern coast of that
continent. However, part of the late Miocene – Pliocene inioid fossil
record consists of relatively fragmentarily known species, for which
systematic affinities remain poorly understood. Based on a sample of six
cranial specimens from lower upper Miocene (Tortonian, 9.5–8.6 Ma)
marine deposits of the Pisco Formation exposed at four localities of the
East Pisco Basin (southern coast of Peru), we describe a new genus and
species of inioid, Samaydelphis chacaltanae. This mesorostrine, small‐sized species is characterized by an upper tooth count of c. 30
teeth per row, a moderately elevated vertex of the cranium displaying a
long anteromedial projection of the frontals and interparietal, and the
plesiomorphic retention of a premaxilla–nasal contact. Recovered as a
member of the family Pontoporiidae in our phylogenetic analysis, S. chacaltanae falls as sister group to Meherrinia isoni,
from the upper Miocene of North Carolina (USA), which has previously
been tentatively referred to the Iniidae or regarded as a stem Inioidea.
Originating from the P1 allomember of the Pisco Formation, the
mesorostrine S. chacaltanae was contemporaneous and sympatric with two other inioids, the brevirostrine pontoporiid Brachydelphis mazeasi and the longirostrine iniid Brujadelphis ankylorostris.

de Lavigerie et al. 2020. New Pliocene right whale from Belgium informs balaenid phylogeny and function. Journal of Systematic Palaeontology.
Link: https://www.tandfonline.com/doi/abs/10.1080/14772019.2020.1746422
Right whales (Balaenidae) are the most distinctive family of extant baleen whales, thanks to their highly arched rostrum, tall lips and robust body shape. They are also the oldest, originating as much as 20 million years ago (Ma). Nevertheless, their fossil record is patchy and frequently understudied, obscuring their evolution. Here, we describe a new stem balaenid, Antwerpibalaena liberatlas, from northern Belgium, adding to the rich but historically problematic baleen whale assemblage of the Pliocene North Sea. Within right whales, Antwerpibalaena forms a clade with two previously described extinct genera, Balaenella and Balaenula. The holotype preserves much of the postcranial skeleton, and informs the emergence of typical balaenid traits like fused neck vertebrae and paddle-shaped flippers. Its size is intermediate between that of extant right whales and most of their extinct forebears revealing a more complex pattern of balaenid size evolution than previously thought.
Comments: This is one of two papers fundamentally altering the state of balaenid (right whale) paleontology. Antwerpibalaena, five years ago, would've just been called Balaenula - the monophyly of which some folks have rightly been skeptical of. Interestingly is that this taxon has a free atlas - most balaenids have fused all seven cervicals together, but the atlas is still free here - a bit like a sperm whale. This further indicates that the six v. seven rule is no longer useful for identifying fragmentary, poorly preserved syncervical specimens. This was published within 24 hours of the paper on Archaeobalaena, which felt like a Twilight Zone episode.
Montanez-Rivera and Hampe. 2020. An unfamiliar physeteroid periotic (Cetacea: Odontoceti from the German middle-late Miocene North Sea basin at GroĂ Pampau. Fossil Record.
Link: https://fr.copernicus.org/articles/23/151/2020/
The Miocene mica clay locality of GroĂ Pampau, known for
numerous and partly spectacular finds of marine mammals is becoming more and
more a prominent site that bears the potential to resolve questions
regarding taphonomic relationships and to interpret life communities of the
ancient North Sea because of its rich faunal assemblage including
invertebrates and other remains of various vertebrate organisms. In the
present work we describe a right periotic of Physeteroidea with
morphological characters so far unknown from other sperm whales. The
periotics of the middle Miocene Aulophyseter morricei demonstrate the closest resemblance to the
GroĂ Pampau specimen in their overall appearance and in the general
arrangement and proportions of single structures, particularly of the
anterior process and pars cochlearis. A great similarity is also documented
with periotics of the living sperm whale, Physeter macrocephalus, especially regarding the shape and
disposition of the anterior process and the bony element located dorsally to
the accessory ossicle. Kogiid periotics differ strongly from that of the
GroĂ Pampau specimen by having an inflated and short anterior process
and, typically, three well-defined spines on it. A new taxonomic naming of
the GroĂ Pampau periotic is not appropriate at this stage, although it
might demonstrate the existence of a so-far undescribed physeteroid species.
Additionally, its systematic position remains yet unclear and it is unknown
at this point if it could belong to Hoplocetus ritzi, another physeterid, whose fragments
were discovered in the same locality, or to another, already-described taxon,
of which the periotic is still unknown.

Nelson et al. 2020. A new platanistoid, Perditicetus yaconensis gen et sp. nov. (Cetacea, Odontoceti) from the Chattian-Aquitanian Nye Formation of Oregon. Journal of Systematic Palaeontology.
Link: https://www.tandfonline.com/doi/full/10.1080/14772019.2020.1783379
The Platanistoidea is a large superfamily of odontocetes whose sole surviving member is Platanista gangetica,
the Ganges river dolphin. Despite the diversity of the Platanistoidea,
it remains poorly understood and in need of revision. As one of the
earliest-diverging clade of crown odontocetes, understanding their
distribution, morphology, and phylogeny is crucial to understanding the
radiation of archaic odontocetes in the late Oligocene to the middle
Miocene. Here we describe an archaic odontocete, named Perditicetus yaconensis, gen. et. sp. nov., from the latest Oligocene–earliest Miocene Nye Formation in Oregon. Perditicetus yaconensis,
represented by the holotype USNM 335224, possesses several
synapomorphies of the Platanistoidea. Intriguingly, strong morphological
similarities exist between P. yaconensis and other archaic odontocetes in the ‘Chilcacetus
clade’ especially in the vertex and pterygoid region. However, the
results of our phylogenetic analyses failed to capture any phylogenetic
relationships between Perditicetus and Chilcacetus. In this analysis, P. yaconensis is sister taxon to the clade Allodelphinidae + Squalodelphinidae + Platanistidae and we consider that P. yaconensis
is one of the basal-most derived platanistoids. The type locality of
the holotype specimen, in the Nye Formation, provides a window into the
diversity of archaic odontocetes, especially platanistoids, during the
latest Oligocene to earliest Miocene.

Paterson et al. 2020. A total evidence phylogenetic analysis of pinniped phylogeny and the possibility of parallel evolution within a monophyletic framework. Frontiers in Ecology and Evolution.
Link: https://www.frontiersin.org/articles/10.3389/fevo.2019.00457/full
In the present study, a series of phylogenetic analyses of
morphological, molecular, and combined morphological-molecular datasets
were conducted to investigate the relationships of 23 extant and 44
fossil caniforme genera, in order to test the phylogenetic position of
putative stem pinniped Puijila within a comprehensive evolutionary framework. With Canis
as an outgroup, a Bayesian Inference analysis employing tip-dating of a
combined molecular-morphological (i.e., Total Evidence) dataset
recovered a topology in which musteloids are the sister group to a
monophyletic pinniped clade, to the exclusion of ursids, and recovered Puijila and Potamotherium
along the stem of Pinnipedia. A similar topology was recovered in a
parsimony analysis of the same dataset. These results suggest the
pinniped stem may be expanded to include additional fossil arctoid taxa,
including Puijila, Potamotherium, and Kolponomos. The
tip-dating analysis suggested a divergence time between pinnipeds and
musteloids of ~45.16 million years ago (Ma), though a basal split
between otarioids and phocids is not estimated to occur until ~26.52 Ma.
These results provide further support for prolonged freshwater and
nearshore phases in the evolution of pinnipeds, prior to the evolution
of the extreme level of aquatic adaptation displayed by extant taxa.
Ancestral character state reconstruction was used to investigate
character evolution, to determine the frequency of reversals and
parallelisms characterizing the three extant clades within Pinnipedia.
Although the phylogenetic analyses did not directly provide any evidence
of parallel evolution within the pinniped extant families, it is
apparent from the inspection of previously-proposed pinniped
synapomorphies, within the context of a molecular-based phylogenetic
framework, that many traits shared between extant pinnipeds have arisen
independently in the three clades. Notably, those traits relating to
homodonty and limb-bone specialization for aquatic locomotion appear to
have multiple origins within the crown group, as suggested by the
retention of the plesiomorphic conditions in early-diverging fossil
members of the three extant families. Thus, while the present analysis
identifies a new suite of morphological synapomorphies for Pinnipedia,
the frequency of reversals and other homoplasies within the clade limit
their diagnostic value.
Comments: I've been waiting for this paper for a couple years - and a paper like it for nearly a decade. The most critical thing is that this paper does support the idea that Puijila - the "walking seal" - is related to pinnipeds, and Potamotherium with it. It also supports a similar relationship with Kolponomos - the "oyster bear". However, in the analysis, Kolponomos is reconstructed as nested within Enaliarctos - which can't be right. Species of Enaliarctos are remarkably consistent in skull morphology and mostly distinguished from each other by minor changes in dental features. I think some of the details are a bit muddled, and likely would benefit from some double checking of character codings in the matrix, but on the whole I think it really moves pinniped paleontology forward. I'm also particularly smug about the findings with Kolponomos as an early pinniped relative or sister taxon as I predicted that it would be recovered there if Puijila and Potamotherium were found to be early pinnipeds, since they share some of the same pinniped-like features.

Paolucci et al. 2020. 'Aulophyseter' rionegrensis (Cetacea: Odontoceti: Physeteroidea) from the Miocene of Patagona (Argentina): a reappraisal. Zoological Journal of the Linnean Society.
Link: https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlaa137/6030877
The giant sperm whale (Physeter macrocephalus) and the dwarf (Kogia sima) and pygmy (Kogia breviceps)
sperm whales represent the only three extant species of physeteroids.
This group has diversified during the Miocene, and the Miocene marine
sediments of Patagonia (Argentina) hold one of the most important fossil
records of physeteroids. In particular, ‘Aulophyseter’ rionegrensis
(Gran Bajo del Gualicho Formation, Miocene), described based on two
subcomplete skulls nearly a century ago, has been a problematic taxon
because its generic assignation has been questioned in different works.
Besides, recent phylogenetic analyses have also failed to recover the
putative congeneric sister-group relationship between ‘A.’ rionegrensis and A. morricei (the type species). In this contribution, we re-describe ‘A.’ rionegrensis, evaluate its phylogenetic position and provide a taxonomic review of Aulophyseter. A detailed morphological comparison between ‘A.’ rionegrensis and A. morricei reveals several anatomical differences between them. Phylogenetic analyses recover ‘A.’ rionegrensis as a crown physeteroid, nested within Physeteridae, but not closely related to A. morricei. We provide the new generic name Cozzuoliphyseter gen. nov. for its reception. A preliminary re-assessment of material previously referred to Aulophyseter indicates that A. mediatlanticus, and also historical material of A. morricei, need to be reviewed.

Peri et al. 2020. A new record of Physeteroidea from the upper Miocene of the Pietra Leccese (Southern Italy): systematics, paleoecology, and taphonomy of a fossil macroraptorial sperm whale. Rivista Italiana di Paleontologia e Stratigrafia.
Link: https://riviste.unimi.it/index.php/RIPS/article/view/14284
We report on a partial skeleton of sperm whale (Cetacea, Odontoceti,
Physeteroidea) from the Pietra leccese, a Miocene limestone widely
exposed in the Salento Peninsula (southern Italy). This specimen was
found in Tortonian strata cropping out at the Cisterna quarry, not far
from the holotype of the stem physeteroid Zygophyster varolai.
The presence of a deep and rectilinear groove medial to the
tympanosquamosal recess of the squamosal, the bowed mandibles, and some
dental features suggest that this specimen belongs to a still
undescribed new genus and species of macroraptorial sperm whale that
displays some affinities with the late Miocene Acrophyseter from
Peru. Nevertheless, due to the incompleteness and poor preservation
state of the skull, we abstain from creating a new taxon. The teeth
exhibit both apical wear and deep occlusal facets, and three teeth even
lost their crowns. These dental modifications suggest that the studied
specimen used a raptorial feeding strategy for preying upon food items
such as large-sized bony fishes or diminutive marine mammals. The bones
are mostly disarticulated and broken, and some of them preserve traces
hinting at the action of macro-scavengers, possibly including both
sharks and bony fishes. Furthermore, the skull is pervasively encrusted
by oysters, which suggests that it laid on the seafloor for a long time
before being buried. This find provides new clues about the composition
of the Miocene vertebrate assemblage of the Pietra leccese and indicates
that various macroraptorial sperm whale species inhabited the
Mediterranean Basin during the Tortonian.

Perini et al. 2020. A new species of Trichechus Linnaeus, 1758 (Sirenia, Trichechidae), from the upper Pleistocene of southwestern Amazonia, and the evolution of Amazonian manatees. Journal of Vertebrate Paleontology.
Link: https://www.tandfonline.com/doi/full/10.1080/02724634.2019.1697882
The genus Trichechus (Mammalia, Sirenia, Trichechidae) harbors a
modest diversity, comprising only three living species of manatees, and
no species currently recognized as fossil. Herein, we report a new
extinct species of manatee from the late Pleistocene of the Brazilian
Amazonia, Trichechus hesperamazonicus, sp. nov. It comes from the
alluvial deposits of the Rio Madeira Formation along the Madeira River,
state of RondĂŽnia, western Brazil, and is represented by a partial
palate with both molar series and two partial right dentaries. The new
taxon shows a mosaic of characteristics resembling those of other
manatee species, as well as some unique characters. It differs from all
other Trichechus species by possessing a wide space between the
posterior lower tooth row and ascending ramus of dentary, and by having
the anterior border of the ascending ramus covering the posterior end of
the tooth row in lateral view. The results of morphometric analyses
(principal component analysis and discriminant analysis) further support
the distinctiveness of the new species. A phylogenetic analysis
recovers the new species in a polytomy with T. inunguis and the clade formed by T. senegalensis and T. manatus.
The levels from which the remains were recovered produced a radiocarbon
date of 44,710 ± 880 years before present; together with molecular
clock estimates, this date suggests that until recently at least two
species of manatees coexisted in the fluvial systems of western
Amazonia.

Rule et al. 2020. First monk seal from the southern hemisphere rewrites the evolutionary history of true seals. Proceedings B.
Link: https://royalsocietypublishing.org/doi/10.1098/rspb.2020.2318
Living true seals (phocids) are the most widely dispersed semi-aquatic
marine mammals, and comprise geographically separate northern (phocine)
and southern (monachine) groups. Both are thought to have evolved in the
North Atlantic, with only two monachine lineages—elephant seals and
lobodontins—subsequently crossing the equator. The third and most basal
monachine tribe, the monk seals, have hitherto been interpreted as
exclusively northern and (sub)tropical throughout their entire history.
Here, we describe a new species of extinct monk seal from the Pliocene
of New Zealand, the first of its kind from the Southern Hemisphere,
based on one of the best-preserved and richest samples of seal fossils
worldwide. This unanticipated discovery reveals that all three monachine
tribes once coexisted south of the equator, and forces a profound
revision of their evolutionary history: rather than primarily
diversifying in the North Atlantic, monachines largely evolved in the
Southern Hemisphere, and from this southern cradle later reinvaded the
north. Our results suggest that true seals crossed the equator over
eight times in their history. Overall, they more than double the age of
the north–south dichotomy characterizing living true seals and confirms a
surprisingly recent major change in southern phocid diversity.
Comments: I actually saw some of these specimens while they remained in private collections in New Zealand. These are all found in concretions - and one of the only phocid-bearing fossil assemblages in the world to be preserved in nodules. We have a serious problem with headless phocid taxa in the fossil record - very few fossil phocids are known from skulls, and most are known either only from a mandible or postcrania, especially from the North Atlantic, where the record is numerically richest - with a couple of exceptions. The situation in Peru is very different since skeletons are often found out in the desert and can be excavated carefully. For some reason, the skulls of North Atlantic specimens both on the east coast and the low countries in Europe are always fractured prior to discovery and tend to be very fragmentary. Anyway, this paper reports some fantastically preserved specimens of the extinct monk seal Eomonachus from New Zealand - and demonstrates that even the monachines must have undergone a period of southern hemisphere evolution.

Rule et al. 2020. A new large-bodied Pliocene seal with unusual cutting teeth. Royal Society Open Science.
Link: https://royalsocietypublishing.org/doi/10.1098/rsos.201591
Today, monachine seals display the largest body sizes in pinnipeds.
However, the evolution of larger body sizes has been difficult to assess
due to the murky taxonomic status of fossil seals, including fossils
referred to Callophoca obscura, a species thought to be present
on both sides of the North Atlantic during the Neogene. Several studies
have recently called into question the taxonomic validity of these
fossils, especially those from the USA, as the fragmentary lectotype
specimen from Belgium is of dubious diagnostic value. We find that the
lectotype isolated humerus of C. obscura is too uninformative; thus, we designate C. obscura
as a nomen dubium. More complete cranial and postcranial specimens from
the Pliocene Yorktown Formation are described as a new taxon, Sarcodectes magnus.
The cranial specimens display adaptations towards an enhanced ability
to cut or chew prey that are unique within Phocidae, and estimates
indicate S. magnus to be around 2.83 m in length. A parsimony phylogenetic analysis found S. magnus
is a crown monachine. An ancestral state estimation of body length
indicates that monachines did not have a remarkable size increase until
the evolution of the lobodontins and miroungins.

Rule et al. 2020. Colonization of the ancient southern oceans by small-sized Phocidae: new evidence from Australia. Zoological Journal of the Linnean Society.
Link: https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlaa075/5877026?redirectedFrom=fulltext
Most of the diversity of extant southern true seals (Phocidae:
Monachinae) is present in the Southern Ocean, but a poor fossil record
means that the origin of this fauna remains unknown. Australia
represents a large gap in the record bordering the Southern Ocean that
could possibly inform on the origins of the extant Antarctic monachines,
with most known fossils remaining undescribed. Here we describe the
oldest Australian fossil pinniped assemblage, from the Late Miocene to
the Early Pliocene of Beaumaris. Two fossils are referrable to
Pinnipedia, five (possibly six) to Phocidae and a humerus is referrable
to Monachinae. The humerus is not referrable to any extant tribe,
potentially representing an archaic monachine. The description of this
assemblage is consistent with the Neogene pinniped fauna of Australia
being exclusively monachine before the arrival of otariids (fur seals
and sea lions). The Beaumaris humerus, along with other Neogene phocids
from the Southern Ocean margins, were smaller than their extant
Antarctic relatives, possibly driven by longer food chains with less
energy efficiency between trophic levels. This suggests that small
archaic phocids potentially used the Southern Ocean as a means of
dispersal before the arrival of extant Antarctic monachines.

Rule et al. 2020. Pliocene monachine seal (Pinnipedia: Phocidae) from Australia constrains timing of pinniped turnover in the southern hemisphere. Journal of Vertebrate Paleontology.
Link: https://www.tandfonline.com/doi/full/10.1080/02724634.2019.1734015
A turnover of the pinniped fauna took place in the Southern Hemisphere
during the Pliocene, based on evidence from South America and South
Africa. This resulted in the extinction of early phocids, which were
replaced by otariids dispersing from the North Pacific. There is
currently a lack of evidence of a similar event from Australia, with the
only confirmed phocids from the Miocene–Pliocene boundary and the
earliest confirmed otariids from the late Pleistocene. Here, we report a
fossil monachine tooth from the Pliocene Whalers Bluff Formation of
Portland (Victoria). The tooth represents an extinct monachine seal; it
does not resemble either crown lobodontins or miroungins. This is the
geologically youngest pre-Holocene occurrence of Phocidae in Australia,
and one of the youngest pre-Pleistocene records of phocids in the
Southern Hemisphere. It extends the maximum known geochronological range
of monachines in the fossil record of Australia to between 6.2 and 2.67
Ma. It is possible that pinniped faunal turnovers in the Southern
Hemisphere all occurred during the late Pliocene, with the turnover in
Australia occurring sometime after 4.31 Ma. The description of
additional Australasian fossil pinnipeds will further constrain this
faunal turnover event.

Shinmura and Kimura. 2020. Digital 3D model of natural history museum specimens and its application: creating an illustration of the Kentriodon nakajimai (Odontoceti, Kentriodontidae). Bulletin of the Gunma Museum of Natural History.
Link: http://www.gmnh.pref.gunma.jp/research_no24
[no english abstract]
Tanaka et al. 2020. A new member of fossil balaenid (Mysticeti, Cetacea) from the early Pliocene of Hokkaido, Japan. Royal Society Open Science.
Link: https://royalsocietypublishing.org/doi/10.1098/rsos.192182
The family Balaenidae includes two genus and four extant species.
Extinct balaenids are known for at least four genus and 10 species. The
oldest known record of members of the Balaenidae is known from the early
Miocene, but still need more early members of the family to provide
better phylogenetic hypotheses. FCCP 1049 from the lower part of the
Chippubetsu Formation, Fukagawa Group (3.5–5.2 Ma, Zanclean, early
Pliocene) was preliminary described and identified as Balaenula
sp. by Furusawa and Kimura in 1982. Later works discussed that FCCP 1049
is different from the genus, and is placed in different clade from Balaenula astensis. The result of our phylogenetic analysis places FCCP 1049 basal to Balaenella brachyrhynus, and is again separated from B. astensis. In this study, FCCP 1049 is re-described and named as Archaeobalaena dosanko gen. et sp. nov. Archaeobalaena dosanko is distinguishable from other balaenids by having a deep promontorial groove of the pars cochlearis of the periotic. Archaeobalaena dosanko can be differentiated from other balaenids, except Morenocetus parvus by having a slender zygomatic process, and posteriorly oriented postorbital process in dorsal view. Archaeobalaena dosanko adds detailed skull, periotic and bulla morphologies for the earlier balaenids.
Comments: The paper that broke the camel's back - and by camel, I mean Balaenula, the extinct dwarf right whale. Archaeobalaena was named off of a partial skull that had been under study for a couple of decades, and I am relieved to finally see it published. This was long known as the "Japanese Balaenula" but now appears to sit in a different phylogenetic position as a stem Balaenid, complicating identification of small balaenids in the fossil record. This paper was published within 24 hours of the paper on Antwerpibalaena, which was quite strange!
Tanaka et al. 2020. A new skull of an early diverging rorqual (Balaenopteridae, Mysticeti, Cetacea) from the late Miocene to early Pliocene of Yamagata, northeastern Japan. Palaeontologia Electronica.
Link: https://palaeo-electronica.org/content/2020/2943-fossil-rorqual-from-japan
The family of rorquals and humpback whales, Balaenopteridae includes the largest living animal on Earth, the blue whale Balaenoptera musculus. Many new taxa have been named, but not many from the western Pacific, except Miobalaenoptera numataensis from Japan. Here we describe an early balaenopterid, cf. M. numataensis from
a late Miocene to early Pliocene sediment in Yamagata Prefecture,
northeastern Japan. The species has a straight and sharp lateral ridge
of the fovea epitubaria at the ventral surface of the periotic, and a
dorsoventrally thin pars cochlearis. The new specimen provides knowledge
of supposed ontogenetic variation and periotic morphology in poorly
known fossil balaenopterids.
Tate-Jones and Peredo. 2020. The dawn of Desmatophocidae: a new species of basal desmatophocid seal (Mammalia, Carnivora) from the Miocene of Oregon, USA. Journal of Vertebrate Paleontology.
Link: https://www.tandfonline.com/doi/full/10.1080/02724634.2020.1789867
Desmatophocidae (Mammalia, Carnivora) represents the first of the four
major pinniped clades to appear in the fossil record. However, the
majority of its known diversity consists of derived species and little
is known about the nascence of this early pinniped lineage. Here we
report the discovery of Eodesmus condoni, gen. et sp. nov.,
represented by a nearly complete cranium from the Burdigalian Iron
Mountain Bed of the Astoria Formation from the central coast of Oregon,
U.S.A. Notably, this specimen possesses nasolabialis fossae, a
plesiomorphic trait shared with stem pinnipedimorphs and the basal
phocid Devinophoca sp., but not with any other desmatophocid. Phylogenetic analysis (98 characters, 27 taxa) resolved Eodesmus condoni
as the most basal desmatophocid yet described. Poor support for the
monophyly of Otarioidea, Odobenidae, and Phocoidea demonstrate that
high-level relationships within Pinnipedia have yet to be conclusively
resolved. The identification of another desmatophocid species at the
already pinniped-rich Iron Mountain Bed suggests that the approximately
synchronous mid-Miocene Climatic Optimum played a role in this increase
in pinnipedimorph species diversity.

Tonomori et al. 2020. Large-sized cetacean fossils from Tonohama Group in the Iwado area, Muroto City, Kochi Prefecture, Japan. Bulletin of the National Museum of Natural Sciences Series C.
Link: https://www.kahaku.go.jp/english/research/publication/geology/v46.html
Two cetacean specimens (humerus and lumber vertebrae) derived from the latest Miocene to early Pliocene shallow marine deposit (ca. 5.6–3.8 Ma) in the Iwado area, Muroto City, Kochi Prefecture, Shikoku, Japan, are reported. Owing to the partially preserved state of the specimens, it is difficult to identify them even at the suborder level. However, on the basis of their morphological features and a comparison of extant cetaceans, the humerus specimen was derived from a large-sized (11 to 15 m) cetacean and the lumbers also as large as, or larger medium-sized (4 to 10 m) cetacean, indicating both specimens of whale-sized cetacean provenance. This is the first report of large-sized cetacean fossil from Shikoku. At present, some species of large-sized cetaceans inhabit offshore waters around Kochi (e.g., Eden's whale (Balaenoptera edeni) in Tosa Bay). Therefore, this study indicates that large-sized cetaceans have lived in the area since at least the early Pliocene (Zanclean: ca. 3.8 Ma). Although the divergence of cetaceans in Japanese waters during the middle Miocene to Pliocene is considered to be associated with the development of the Kuroshio Current, which flows along the southern coast of Japan with its northern limit being located off the coast of the Boso Peninsula in Chiba Prefecture, this is only supported by fossil fauna from limited areas: the Kakegawa fauna of Okinawa Pref., southernmost Japan. This study indicates that the distribution of cetaceans around the southern coast of Japan was more extensive along the Kuroshio Current during the late Miocene to Pliocene.

Tsai et al. 2020. A Pliocene gray whale (Eschrichtius sp.) from the eastern North Atlantic. Rivista Italiana di Paleontologia e Stratigrafia.
Link: https://riviste.unimi.it/index.php/RIPS/article/view/13040
The gray whale Eschrichtius robustus, the only living member of
the eschrichtiid lineage, currently inhabits only the North Pacific.
Interestingly, however, the holotypes of both E. robustus and the late Miocene Archaeschrichtius ruggieroi
(the oldest known eschrichtiid species) come from the North Atlantic
and the Mediterranean, respectively. Here we describe a partial
mysticete mandible from the Pliocene (3.71–2.76 Ma) of Belgium (Eastern
North Atlantic). This new fossil displays a combination of morphological
features that makes it nearly identical to modern E. robustus. Nevertheless, given its incomplete nature, the studied specimen is here identified in open nomenclature as belonging to Eschrichtius sp. The recognition of such an early record of Eschrichtius in
the North Atlantic suggests that this genus developed a circum-Northern
Hemisphere distribution not later than in Pliocene times, thus
complicating our understanding of its origin, evolutionary history, and
palaeobiogeographic patterns.

Tzuzuku and Kohno. 2020. The oldest record of the Steller sea lion Eumetopias jubatus (Scheber, 1776) from the early Pleistocene of the North Pacific. PeerJ.
Link: https://peerj.com/articles/9709/
The extant genera of fur seals and sea lions of the family Otariidae
(Carnivora: Pinnipedia) are thought to have emerged in the Pliocene or
the early Pleistocene in the North Pacific. Among them, the Steller sea
lion (Eumetopias jubatus) is the largest and distributed both in
the western and eastern North Pacific. In contrast to the limited
distribution of the current population around the Japanese Islands that
is now only along the coast of Hokkaido, their fossil records have been
known from the middle and late Pleistocene of Honshu Island. One such
important fossil specimen has been recorded from the upper lower
Pleistocene Omma Formation (ca. 1.36–0.83 Ma) in Kanazawa, Ishikawa
Prefecture, Japan, which now bears the institutional number GKZ-N 00001.
Because GKZ-N 00001 is the earliest fossil having been identified as a
species of the sea lion genus Eumetopias, it is of importance to
elucidate the evolutionary history of that genus. The morphometric
comparisons were made among 51 mandibles of fur seals and sea lions with
GKZ-N 00001. As results of bivariate analyses and PCA based on 39
measurements for external morphologies with internal structures by CT
scan data, there is almost no difference between GKZ-N 00001 and extant
male individuals of E. jubatus. In this regard, GKZ-N 00001 is identified specifically as the Steller sea lion E. jubatus.
Consequently, it is recognized as the oldest Steller sea lion in the
North Pacific. About 0.8 Ma, the distribution of the Steller sea lion
had been already established at least in the Japan Sea side of the
western North Pacific.

Uhen and Taylor 2020. A basilosaurid archaeocete (Cetacea, Pelagiceti) from the late Eocene of Oregon, USA. PeerJ.
Link: https://peerj.com/articles/9809/
Basilosaurid archaeocetes are known from the
Late Eocene of virtually all coastlines bearing coeval marine rocks
except the North Pacific Basin, until now. Here we report on three
consecutive posterior thoracic vertebrae of a large, basilosaurid
archaeocete from a Late Eocene horizon in the Keasey Formation in
Oregon.
These vertebrae were morphologically and morphometrically compared to other vertebrae of similar age from around the world.
The specimens were determined to be different from all currently
named species of fossil cetacean, but most similar to those found in the
Gulf Coast region of North America. These vertebrae represent the first
confirmed specimen of a Late Eocene basilosaurid from the North
Pacific. These and other basilosaurids known only from vertebrae are
reviewed here in the context of Late Eocene paleoceanography and
cetacean evolution.
Comments: Finally! Kellogg reported a basilosaurid like vertebra from Vancouver Island back in the 30s, but it was subsequently reidentified as a mysticete based on its Oligocene age. There aren't a whole lot of vertebrate-bearing Eocene rock units on the west coast - and those in the Pacific Northwest are generally deep water, so fossils are very few and far between, and poorly exposed (e.g. cliffs along rivers and creeks, and occasional coastal cliffs). It's about damn time.
Valenzuela-Toro and Pyenson. 2020. Extreme dispersal of human transport? The enigmatic case of an extralimital freshwater occurrence of a southern elephant seal from Indiana. PeerJ.
Link: https://peerj.com/articles/9665/
Elephant seals (Mirounga spp.) are the largest
living pinnipeds, and the spatial scales of their ecology, with dives
over 1 km in depth and foraging trips over 10,000 km long, are
unrivalled by their near relatives. Here we report the discovery of an
incomplete Holocene age Southern elephant seal (M. leonina)
rostrum from Indiana, USA. The surviving material are two casts of the
original specimen, which was collected in a construction excavation
close to the Wabash River near Lafayette, Indiana. The original specimen
was mostly destroyed for radiometric dating analyses in the 1970s,
which resulted in an age of 1,260 ± 90 years before the present. The
existence of sediments in the original specimen suggests some type of
post depositional fluvial transportation. The prevalent evidence
suggests that this male Southern elephant seal crossed the equator and
the Gulf of Mexico, and then entered the Mississippi River system,
stranding far upriver in Indiana or adjacent areas, similar to other
reported examples of lost marine mammals in freshwater systems. Based on
potential cut marks, we cannot exclude human-mediated transportation or
scavenging by Indigenous peoples as a contributing factor of this
occurrence. The material reported here represents by far the
northernmost occurrence of a Southern elephant seal in the Northern
Hemisphere ever recorded. The unusual occurrence of a top marine
predator >1,000 km from the closest marine effluent as a potential
extreme case of dispersal emphasizes how marine invasions of freshwater
systems have happened frequently through historical (and likely
geological) time.
Comments: Definitely the weirdest paper out this year!
Van Vliet et al. 2019. A Palaeogene cetacean from Maastricht, southern Limburg (the Netherlands). Cainozoic Research.
Link: https://natuurtijdschriften.nl/pub/713993
We report on the find of a partial cetacean skeleton from Palaeogene
strata exposed in the former ENCI-HeidelbergCement Group quarry at
Sint-Pietersberg, south of Maastricht (southern Limburg, The
Netherlands). The material available, collected in 1979,
comprises a series of fragmentary vertebrae and ribs from the basal
portion of the so-called ‘Laagpakket van Klimmen’ (Klimmen Member,
Tongeren Formation; Middle North Sea Group), a shallow-marine unit of
Late Priabonian (Late Eocene) to Early Rupelian
(Early Oligocene) age that rests unconformably on biocalcarenites of
latest Cretaceous (Late Maastrichtian) age. These associated skeletal
remains, assumed to be from a single individual, constitute the first
in-situ record of a Palaeogene (presumably Late
Priabonian) cetacean from the Netherlands. The material is tentatively
interpreted as a large-sized basilosaurid archaeocete, although the
possibility that it represents an archaic mysticete cannot be ruled out
entirely.
Note: this paper was published in 2019, but I believe I accidentally left it out.
Van Vliet et al. 2020. Eocene cetaceans from the Helmstedt region, Germany, with some remarks on Platyosphys, Basilotritus, and Pachycetus. Cainozoic Research.
Link: Not online yet.
New archaeocete remains from the Helmstedt region, Germany, are reported. The first series of bones is from the open cast mine at Alversdorf, 2 km to the northwest of Offleben, consisting of isolated vertebral centra, rib fragments and two teeth. The second series of bones, a skull fragment, an unidentifiable, triangular bone, vertebrae and rib fragments, as well as a distal tibia fragment, has been found in the open cast mine Treue, about 5 km to the northeast of Schöningen. Historically, from the same Helmstedt region, cetacean vertebrae and rib fragments have been described by Van Beneden in 1883 (and also published by Geinitz, 1883b). He regarded the remains as belonging to mysticetes from the Oligocene, for which he erected the genus Pachycetus. Here, Pachycetus robustus Van Beneden, 1883 is assigned as type species. Vertebra NsT90 is herein assigned as lectotype for that species. Kuhn (1935) ascribed these fossils to archaeocetes and added some newly found vertebrae in his description. Lienau (1984) figured additional cetacean remains from the same region. Presumably all these finds (the older as well as the new material here reported for the first time) have been derived from marine beds of the Gehlberg Formation, which is Bartonian to Priabonian in age. At least two taxa are recognised: a large one (consistent with Pachycetus Van Beneden, 1883), and a smaller one (consistent with a small ‘dorudontine’). A comparison is made between the new material and the earlier described finds, as well as with archaeocete fossils from eastern Europe (Ukraine and southwestern Russia). Some notes are added on the validity of the genus names Platyosphys Kellogg, 1936 and Basilotritus Gol’din & Zvonok, 2013, which are here referred to as Pachycetus.
Comments: The fossils are reasonably unspectacular, though some serious taxonomic changes have been made based off of them. I still haven't had a chance to read this, but when I do, I'll have to update my 'obscure controversies I' post on basilosaurid taxonomic conflicts.
Viglino et al. 2020. First toothless platanistoid from the early Miocene of Patagonia: the golden age of diversification of the Odontoceti. Journal of Mammalian Evolution.
Link: https://link.springer.com/article/10.1007/s10914-020-09505-w
Lower Miocene outcrops from Patagonia (Gaiman Formation, Burdigalian)
may reveal more clues for the yet unknown aspects for this period in the
evolution of odontocetes. Here, we present the first toothless
platanistoid dolphin from the lower Miocene of Patagonia, Dolgopolis kinchikafiforo,
gen. et sp. nov. The specimen includes an incomplete skull, with no
mandibles or earbones, but sufficiently different from other named
odontocetes to propose a new genus and species. Phylogenetic analyses
indicate it is a platanistoid of uncertain position within the group,
and that it shares some homoplastic characters with physeteroids and
ziphioids. Given the absence of defined alveoli and teeth and an
inferred moderately short and wide rostrum, we interpreted this new
species as most likely a capture suction feeder. Based on our
phylogenetic hypothesis, the optimization of feeding strategies
recovered raptorial feeding as the plesiomorphic method, and convergent
evolution of capture suction feeders in at least four lineages.
Platanistoids recorded all feeding strategies during the late
Oligocene-early Miocene, although raptorial is the predominant method.
This suggests a partitioning of the ecological niches in the early
phases of platanistoid evolution, as well as a high diversification of
feeding methods previously underestimated for this period. Thus,
ecological adaptations have a strong evolutionary pressure in odontocete
communities and should be further explored.

Voss 2020. Re‑evaluation of the taxonomic and systematic status of “
Halitherium”
antillense Matthew, 1916 (Mammalia, Sirenia). Pal Z.
Link: https://link.springer.com/article/10.1007/s12542-020-00532-9
Halitherium antillense Matthew, 1916 was established on a left
mandibular fragment and two vertebrae from late Oligocene deposits of
Puerto Rico. This species was only provisionally referred to the genus Halitherium and its taxonomic status and systematic affinities remained doubtful. In the course of the revision of the Halitherium-species complex and the meanwhile invalid generic name “Halitherium”,
the holotype, and only known specimen, is re-investigated. A number of
morphological characters usually diagnostic in sirenians are determined.
However, the holotype material of “H.” antillense is not
informative enough and, as such, neither can be assigned to any known
species nor is it possible to define a taxon that can be clearly
distinguished from other species. Unlike other, now revised species
originally grouped under “Halitherium”, the establishment of a new taxonomic combination for “H.” antillense is not possible. As a nomenclatural consequence, the name “H.” antillense is only applicable to a single specimen, the holotype, and declared as a nomen dubium.

Zalmout et al. 2020. Marine mammals (Cetacea and Sirenia) from the middle and late Eocene of Jordan. Neues Jarbuch fur Geologie und Palaontologie.
Link: https://www.ingentaconnect.com/content/schweiz/njbgeol/2020/00000298/00000002/art00001
Marine mammals including archaeocete Cetacea and dugongid Sirenia are
reported from two Eocene localities in Jordan. The first locality, Jebal
eth Thuleithuwat, is Lutetian or Bartonian middle Eocene in age. Jebal
eth Thuleithuwat has yielded the astragalus and other skeletal elements
of a protocetid archaeocete, possible fragments of basilosaurid teeth,
and the virtually complete rib of a dugongid (all gen. et sp. indet.).
The second locality, Qa' Faydat ad Dahikiya is Priabonian late Eocene in
age. Qa' Faydat ad Dahikiya has yielded teeth or postcranial remains of
four
basilosaurid archaeocetes (Stromerius nidensis, Dorudon atrox, Masracetus markgrafi, and Basilosaurus isis) and postcranial remains of a dugongid (Eotheroides sp).