Digging up eomysticetid whales in two hemispheres: a titanic plaster jacket from New Zealand

 Excavation of the holotype skull and skeleton of Tokarahia kauaeroa - nicknamed for a while as the "big scapula mysticete" - OU 22235. Photos by Ewan Fordyce, 1990s.

Nobody wants to be forever defined by their Ph.D. research - for a number of reasons: you might get sick of the topic through saturation, and want to see something different - or maybe you don't want to be boxed in to that topic and let it define you for the rest of your life. It's a bit like an actor who's been typecast. I studied eomysticetid whales for my Ph.D. in New Zealand from 2012-2015. When I finished up, eomysticetids were thought to be a relatively diverse, well-defined radiation of long-snouted baleen bearing mysticetes, possibly with vestigial teeth. Their radiation was short lived, as all their fossils are known from Oligocene age marine rocks (~30-23 million years in age). Despite this short time frame, they managed to travel across the world's oceans quite rapidly, being found in Japan, New Zealand, the Pacific Northwest, South Carolina, and Europe (Paratethys sea deposits); isotopic evidence confirms they ate prey relatively low in the the food chain (sorry, trophic ladder is the preferred term these days) and perhaps even migrated. I published most of my thesis chapters in 2014-2015, with a couple later in 2017 - and shortly thereafter started working chiefly on fossil odontocetes from Oligocene rocks in Charleston, South Carolina, where I still am. I'm immensely proud of my work on eomysticetids, and still think these are the highest quality, most informative, and carefully interpreted papers that serve as the defining work on the clade.

 A slide from a talk I presented at the 2014 Geological Society of New Zealand meeting - the specimen on the right is the holotype of Tokarahia kauaeroa, not yet named.

In 2015, when I began this job, I was happy to leave behind eomysticetids as I *thought* that I had done a good job 'writing the book' on them, so to speak: I had a half dozen published articles naming and stabilizing the taxonomy of the family, firmly establishing a solid list of synapomorphies, interpreting the bauplan and functional anatomy of the earliest 'true' baleen-bearing mysticetes (Chaeomysticeti), and even aspects of their taphonomy, biogeography, and possible survival into the Miocene. I thought the book was closed on them - and on the seventh day, I rested (and promptly got to work climbing up the other side of the cetacean tree of life to work on early dolphins).

 A skull of Micromysticetus rothauseni which I referred to the species in my 2017 paper on Matapanui - this is CCNHM 169, I first saw it shortly after it had been prepared in October 2012. I've got this specimen about halfway described in my notes.

But it seems I cannot escape these lovely beasts. I knew that there were some nice eomysticetid skulls needing study here at the Mace Brown Museum of Natural History, but given the glut of papers I had just published, there was more to be gotten by studying the far more important early odontocetes in our collection, as well as the toothed baleen whale we would name a couple years later as Coronodon havensteini. Further, in 2016 and 2018, two new mysticetes were named from the Pacific Northwest - Sitsqwayk and Maiabalaena - which were supposedly *not* eomysticetids, despite possessing all of the obvious synapomorphies. Further, the 2018 study of Maiabalaena pitched the daring proposal that Maiabalaena lacked teeth *and* baleen, and that baleen whales went through a toothless, baleen-less intermediate stage prior to the evolution of Eomysticetidae. Suddenly I was getting emails from my colleagues on the west coast - including one of my unofficial mentors, Tom Deméré, asking me over numerous phone calls about the exact pattern, distribution, size, and shape of palatal foramina in the eomysticetid whales I had studied in New Zealand, and in one of our specimens here at the Mace Brown Museum of Natural History. And here I thought that I had published such straightforward science from my Ph.D. that eomysticetids would never be controversial - now, they were being brought in to bear in the great debate over the origin of baleen! I never imagined.

Spoiler: Sitsqwayk and Maiabalaena are both eomysticetids, and are not very relevant towards the origin of baleen, and you can read the proof of that on April 14.

The holotype skull and skeleton of Sitsqwayk cornishorum on display at the Burke Museum. Photo taken by Ron Eng.

 The holotype skull of Maiabalaena nesbittae.

 

The holotype skull of Tokarahia lophocephalus, as prepared (left) and as encountered in the field during excavation (right), from Marples (1956). The skull was lost sometime between Marples' retirement and the arrival of Ewan Fordyce at Otago, likely thrown in the rubbish skip when the Biology Department moved buildings in the late 1960s.

 

 

 Skeletal comparison of the three key specimens of Tokarahia: the holotype of Tokarahia kauaeroa (seen in the excavation photos at the beginning), a referred specimen of Tokarahia lophocephalus from Hakataramea Quarry (this is the specimen with a preserved tooth), and the holotype of Tokarahia lophocephalus - the mandible, earbones, and vertebrae of which survive, though the skull does not.

A bit of background. The very first eomysticetid whales were named back in the 1950s by kiwi arachnologist Brian Marples - including "Mauicetus" lophocephalus and "Mauicetus" waitakiensis from the Kokoamu Greensand (late Oligocene) of New Zealand (South Island). Three things happened in parallel. 1) In 1975, a nearly complete long-snouted mysticete skull was discovered in what would later be named the Chandler Bridge Formation of Summerville, South Carolina (only a few miles from where I am typing this with a warm cuppa), and eventually published as Eomysticetus whitmorei by Al Sanders and Larry Barnes in 2002. 2) Ewan Fordyce, shortly after getting the University of Otago paleontology program funded by National Geographic, goes off and starts digging up a ton of Oligocene cetaceans and penguins from the Kokoamu Greensand and Otekaike Limestone of New Zealand - setting the stage for my Ph.D. research. 3) An unusual skull is discovered in 1981 in Oligocene rocks of the island of Kyushu in Japan - preserved in a concretion and slowly prepared over the following two decades; it is briefly described by Yoshihiko Okazaki in 1995 and formally named Yamatocetus canaliculatus in 2012. The naming of Yamatocetus was quite timely, right after I arrived to begin studying eomysticetids - I ended up providing new genera for both "M." lophocephalus and "M." waitakiensis - Tokarahia and Tohoraata, respectively - though these genera were based on more complete material, Tokarahia kauaeroa and Tohoraata raekohao, with the species named by Marples transferred to these new genera. I also named Waharoa ruwhenua and Matapa waihao, the latter of which had a genus name preoccupied by a goddamn butterfly from Sri Lanka, so I re-named it Matapanui waihao.

 

Loading up the trailer outside the geology building with all of our tools and supplies.

 Ewan Fordyce organizing tools from the museum basement. I am not a morning person, and slept in, and still had a half hour walk to campus - and I recall Ewan was a bit cross with me that morning.

In January 2013, about a year into my program and when I was just about getting my legs under me, we got a call from the quarry operator at Haugh's* Quarry - also called Hakataramea Quarry or just "Haka" (or HQ in most of our notes). The operator indicated that they had done some grading, and were about to shut down quarry operation for the fall/winter, and had found quite a lot of bone in the exposed parts of the quarry. Remember, southern hemisphere: February in NZ is basically August, March is September - and because NZ is quite far south (45S, comparable to Seattle and Portland in terms of climate) - it is rainy and overcast nearly half the year; winter is long, cold, and wet, and summer is brief and cool. Those are the basic two seasons: summer is from December to February/mid March, and winter basically lasts from late March through to September/October - owing to the Antarctic climate - it's quite binary. This means most of our fieldwork had to balance the weather, as well as the quarry activity.

*Pronounced like "Whores". The first time I heard this at an SVP talk by Fordyce in 2005 - my first ever SVP at the age of 20 - my jaw hit the floor. My labmate Felix Marx assured me it was some strange Irish name. 'Haka', by the way, with the kiwi accent, was usually pronounced like "hecka", which I always found a bit charming.

Hakataramea quarry, August 2013. The bench up at the top (but to the right of this image) is where the 2013 excavations were, near the top of the Otekaike Limestone.

 We headed up to the quarry on a beautiful January morning and sure enough, found two mysticete skeletons and lots of other bones in the area. Accompanying us were Travis Park, then a Ph.D. student at Monash University in Australia, and Alan Tennyson, a paleornithologist I quickly befriended at Te Papa Tongarewa National Museum of New Zealand in Wellington. Travis had flown into Wellington for a research trip and had driven down to Dunedin - they also both participated in a necropsy of some beaked whales near Invercargill with us. Upon searching more, we also located at least two odontocete skeletons and a penguin skeleton. I recall pulling a 4 cm long mako-like tooth out from one of the skeletons and remarking "you know, the exact species this belongs to has never really been figured out" - Fordyce shrugged and told me to get on with the penguins and cetaceans and didn't seem to interested in isolated teeth.

 

Ewan Fordyce beginning a trench with his famous chainsaw - he would take a break, and we would go through and dislodge each block with a pick and cart them off into a pile.

 Marcus Richards (left), Sophie White (middle) and Felix Marx (right) uncovering an eomysticetid whale at Hakaramea Quarry.

 

Ewan Fordyce powering up the Pionjar rock drill while Sophie White (in back) and Yoshi Tanaka (right) watch. Every time a power tool was started up was a brief little lecture on use and safety. You can see the pile of discarded limestone blocks, as well as the wooden planks on the plaster jacket that would permit the use of metal rollers to move the jacket around; this is the smaller jacket with a scapula inside.

We uncovered some material, and came back a month later in February - it was still quite nice out. One of the two mysticetes included a nearly complete scapula and some ribs, and sadly, not much else - this specimen was quickly trenched and undercut with Fordyce's chainsaw, and then jacketed. The other mysticete had a bit more overburden and was proving to be quite large. I only have photos from the earlier stages of the excavation - we brought out a generator and powered 'zip guns' and even an airscribe as Felix Marx attempted to remove the tympanic bulla so we could get an identification. We returned in March for an overnight visit, staying in bunkbeds at a youth hostel in the sprawling metropolis of Kurow, Fordyce's favorite spot for stopping for ice cream at the local dairy* after digging. The mattresses were literally foam - which was surprisingly comfortable. By the time we returned for this weekend in March (remember, September here) it was already quite a bit cooler. On the second day, we had most of the big skull outlined - and it seemed to be about 2 meters long, with at least one mandible - and the jacket ended up being about 2.5 meters, as there were some associated elements near the back of the skull.

*Dairies are what convenience stores are called in NZ - chiefly because they sell milk cartons, but more importantly perhaps, is that they also sell one of the staples of a NZ diet - killer ice cream. NZ has the best ice cream in the world, I'm convinced, and definitely makes up somewhat for some of the unfortunate culinary choices elsewhere in NZ. Ice cream is also "cheap as chips" as they say down there - 2/3 the cost of ice cream in the US, and when served on a cone, a single NZ scoop is about the size of a baseball with an extra half scoop added. This is typically the volume of a 'double scoop' at most ice cream parlors in the US.

 

 

Labmate Yoshi Tanaka toiling away on the eomysticetid skull - one of the mandibles is in articulation and the other is diving down towards us.

 

 Ewan Fordyce holding the jacketed section of mandible that was sticking off to the side after returning to campus - photo from the Otago Daily Times.

The tympanic bulla of the eomysticetid whale exposed during fieldwork.

 

Ewan busy photo-documenting the new eomysticetid skull, while Sophie White (crouching) watches; Yoshi Tanaka is in the background.

Sadly, I did not participate in the completion of the excavation - within two days of returning I started developing this strange rash in my armpits, belly, chest, and thighs - had I caught some strange fungal infection from the hostel? After a few days of supreme discomfort, I went to the campus doctor, who diagnosed me with pityriasis rosea - a weird skin condition where you get rashes all over your trunk, and occasionally upper arms and thighs. Fortunately it is not permanent - but it does last for SIX TO TWELVE WEEKS! Fortunately my case did calm down and disappear after about eight weeks, but it was uncomfortable to walk, let alone do fieldwork, so I opted out of all field outings for the remainder of that fall. [I've since developed psoriasis, which is worse, and sadly permanent, though unlike pityriasis, it responds to treatment. Pityriasis, if you get it, is basically 2-4 months of misery - though like chicken pox, you only develop it once. It's also idiopathic - the origin and cause are unknown. In my case, it might simply be related to my overactive immune system].

Yoshi Tanaka (left) and Ewan Fordyce (right) looking simultaneously excited and defeated by the discovery of an even larger, more gigantic mysticete - this one was collected in a couple jackets that weren't quite as big, but I remember the bone scatter being about 6x12 feet across (2x4 meters). I couldn't participate.

I returned to the quarry, rash-free, the following spring, when we had to drag out the completed jacket which some of us nicknamed the 'star destroyer' owing to its distinctive triangular shape and massive size. Luckily, Fordyce had been able to store one jacket under a tarp in a safe area - the 'star destroyer' had been jacketed and flipped, but left in its hole. We had brought Fordyce's 'ute'* and a trailer to bring the jacket back to Dunedin. My memory is a bit fuzzy (this was 8-9 years ago now), but Fordyce used the chainsaw to cut out a nice ramp out of the excavation hole, and we used a series of wooden 'timbers' (2x4s) and metal pipes to coax the behemoth out of its sandy grave. We tied a rope around the jacket and then to the trailer hitch on his truck, and like a modern day version of Egyptian pyramid builders - began to tow the jacket slowly down this earthen ramp in the quarry, the crew of graduate students - all hands on deck if memory serves, about eight of us - running the 2x4's from behind the slowly moving jacket to build a temporary track in front of it. You see, with big jackets like this, we would install a wooden frame on one side so that when it flips over, it's 1) supported by the frame and 2) there's a nice flat hard surface that can work with metal rollers and slide over the concrete outside the Geology building and the floor of the museum.The jacket would roll along these metal pipe rollers, which were situated between the wooden pieces of 'track' we were constantly adding to in front of the jacket (and removing behind it), and constantly replacing the metal pipes out in front - it was beautifully coordinated. On a couple of occasions, the jacket started approaching the edge of the ramp, and we were worried it might roll sideways down the hill; much jostling of the jacket with crowbars was needed to gently nudge it back into the right direction down the ramp - you see, the ramp was curved - and once the truck started going around the curve, the jacket wanted to follow in a straight line rather than the curved safe path down the ramp. If memory serves, we either tried (or successfully) hammered one of our tools into the ramp and used it as a pulley to bend the rope in the right direction. At one or two points we weren't quite fast enough with placing the wooden planks in front of the jacket, and it did a brief nose dive into the sandy ramp, and refused to budge: the jacket was too heavy, and the substrate too soft, for the truck to just pull it without our Egyptian roller system. But, after an hour or so of this, we managed to get the enormous jacket rolled up a small ramp into the back of the museum trailer, safely stowed. After returning to Dunedin, Ewan indicated that this was the largest single plaster jacket he had ever collected, and in his typical understated fashion, stated that it was probably the single largest individual jacketed fossil collected from the country.**

*ute is short for utility vehicle in Kiwi slang - known in the US as a pickup truck.

**The heavyweight champion belt for largest single fossil from NZ, however, goes to Kaiwhekea katiki, an unusual aristonectine plesiosaur Ewan collected in the 1980s from a massive concretion collected in blocks; the whole concretion was like 20-30' wide. Also known as "Shagosaurus" given its locality, Shag Point. Shag as a British word usually reminds folks of Austin Powers (certainly the joke in the nickname) but Shag Point itself is named for cormorants, which are called shags in British English.

 

Adding "nose art" to plaster jackets was a time-honored tradition at Museum of the Rockies in Montana, and I brought it to NZ.

 

Some penguin bones found scattered around the quarry - Platydyptes, if I remember right.

 A beautiful shell of the spiny, low-spired gastropod Guildfordia from Hakataramea Quarry.

The jacket did not get opened up until at least a year after I graduated - which was fine, since both Fordyce and I would have been sorely tempted to include it in my thesis had it been even partially prepared in time - and I was not interested in holding off on publishing since it would be difficult to return to NZ (and indeed, it will have been eight years next month, and I've not been able to). Ewan and my old labmate Marcus Richards indicated that the specimen was now likely an eomysticetid - while I did not know it at the time, I did actually participate in the collection of an eomysticetid whale in NZ.

References:

Boessenecker RW, Fordyce RE. 2015a. A new eomysticetid (Mammalia: Cetacea) from the late Oligocene of New Zealand and a re-evaluation of ‘Mauicetus’ waitakiensis. Papers in Palaeontology. 1:107–140.

Boessenecker RW, Fordyce RE. 2015b. A new genus and species of eomysticetid (Cetacea: Mysticeti) and a reinterpretation of “Mauicetus” lophocephalus Marples, 1956: transitional baleen whales from the upper Oligocene of New Zealand. Zoological Journal of the Linnean Society. 175:607–660.

Boessenecker RW, Fordyce RE. 2015c. Anatomy, feeding ecology, and ontogeny of a transitional baleen whale: a new genus and species of Eomysticetidae (Mammalia: Cetacea) from the Oligocene of New Zealand. PeerJ. 3:1–69.

Boessenecker RW and Fordyce RE. 2017. A new eomysticetid from the Oligocene Kokoamu Greensand of New Zealand and a review of the Eomysticetidae (Mammalia, Cetacea). Journal of Systematic Palaeontology.

Marples BJ. 1956. Cetotheres (Cetacea) from the Oligocene of New Zealand. Proceedings of the Zoological Society of London 126: 565–580. 

Okazaki Y. 2012. A new mysticete from the upper Oligocene Ashiya Group, Kyushu, Japan, and its significance to mysticete evolution. Bulletin of the Kitakyushu Museum of Natural History and Human History Series A (Natural History). 10:129–152.

Sanders AE, Barnes LG. 2002. Paleontology of the Late Oligocene Ashley and Chandler Bridge Formations of South Carolina, 3: Eomysticetidae, a new family of primitive mysticetes (Mammalia: Cetacea). Smithsonian Contributions to Paleobiology. 93:313–356.

Geology by paddleboard and other geological (and paleontological) snapshots from the tropics

This Friday Sarah and I are heading to Playa del Carmen with my family for spring break - since 2018 we've been going to the Caribbean/tropical Atlantic for spring break, since the tropics are so damn close to Charleston and it's pretty affordable* to get to. We've done the Bahamas, Turks and Caicos, and Grand Cayman (twice) and seen some neat stuff. This time, we get to combine the tropical Caribbean with the terrestrial biodiversity of the Yucatan peninsula and the cultural/archaeological heritage of the Mayan civilization - I'm 1/4 Mexican, and while my Spanish is admittedly rudimentary, I love the food, history, and culture and this will be my third time to Mexico since I first went to Baja for Shark Week in 2019 and Mexico City a few months later. The best part about going to Playa del Carmen is the fact that we won't be anywhere near Cancun during spring break and away from all of those college students I have to be around during the school year!

 Regardless, I've been meaning to share these photos for quite some time, and since I'm getting excited for our upcoming trip to Mexico, here are a number of snapshots with no particular theme other than showcasing some neat outcrops I paddleboarded by and some various tropical fossils from Turks and Caicos in 2020 and Grand Cayman in 2022. The 2020 photos are taken with a GoPro and aren't great, but the 2022 shots I believe are all with an Olympus TG6 and the photo quality is quite good.

*For our very, very delayed honeymoon (delayed because of my Ph.D.; we wanted to go to Rarotonga in the Cook Islands, just a few hours flight from NZ, but couldn't afford it; after moving to South Carolina it took a few years to scrape anything together owing to how expensive rent is) - we thought about going to the Bahamas, but was uneasy about plane tickets. One day while walking past my colleague's office door I saw a map of Florida and saw that Grand Bahama island is actually on the same map and only like 90 miles offshore - we could probably take a boat! There's a three hour ferry ride to Grand Bahama from Fort Lauderdale and it only costs like 100-150$  per person, round trip. Once there hotels cost ~90-200$ per night. We were able to do five nights and all travel for about 1200$.

A nice afternoon paddle and workout on the canals on the south side of Providenciales in Turks and Caicos - this is taken March 18, 2020 - we were supposed to be enjoying vacation in the tropics but lockdowns started happening across the USA after we left. We flew on a plane weeks before masks were even recommended or the virus thought to be spread through respiratory droplets, unlike SARS-CoV-1. Needless to say our 2020 trip was not the most relaxing. The day we arrived was the first day of panic-buying in grocery stores on the island.

 

 Shortly after venturing out down the canals I noticed these beautiful exposures of cross-bedded oolites - oolites are a type of carbonate sand (oolite) made out of ooids, which are tiny limestone grains that grow through time. Many beautiful white sand beaches in the Bahamas and Turks and Caicos are made of ooids.

It may be difficult to make out here, but this photo shows that the lower part of the section has smaller scale cross-bedding than that above - trough cross-bedding, with individual beds terminating over a distance of 1-2 meters instead of being dominated by laterally extensive, seaward-dipping planar laminations above. Trough cross-bedding suggests subtidal migration of ooidal sand dunes to me, and the planar laminated oolite above is likely instead a beach deposit - the swash zone on the beach itself where the waves go up and down in the intertidal zone. If this is correct then the 3-4 meter sequence here represents shoaling from subtidal to relatively shallower intertidal deposits. I'm not certain whether or not these are early Holocene or Pleistocene sediments. There isn't much published on the sedimentology of this island, which I find surprising.

What a geologist on vacation sees! This is a large cross-bed in the upper unit, showing a bit more complex bedding than normal - there was likely some sort of channel here perhaps. Click on the lower photo to see my annotations and the pattern of bedding. According to some very, very coarse geological maps there are Pleistocene beach deposits along the south side of the island in this area, so perhaps the swash zone of the beach is a reasonable interpretation.

 A couple of queen conch shells (Lobatus/Strombus gigas) in ?Pleistocene beach deposits on the north side of Providenciales.

 And modern queen conch shells in modern ooidal sand on the south side of Providenciales. Here's a tip for those who want a nice conch shell to bring home (provided the country allows it - which Turks and Caicos does not) - find a seafood restaurant that serves conch fritters (an amazing appetizer in the Caribbean) and go exploring nearby. Frequently, you'll find some piles of shells (and trust me - you'll smell them first, so walk upwind - if you dare!) and will be able to pick out a couple of nice trophies.

A queen conch (Strombus/Lobatus gigas) shell from the Ironshore Formation near Smith's Barcadere in Grand Cayman. I have no idea if collecting such a specimen is legal or not so I left it.

Several queen conch shells in situ within the Ironshore Formation at Smith's Barcadere on Grand Cayman.

 

A large brain coral - perhaps Pseudodiploria (symmetrical brain coral), one of the more commonly seen large brain corals in the area today. However, there are certain corals that are completely extinct today in the Caribbean that occur in the Ironshore Formation.

 Many transported brain coral fragments mixed together with queen conch shells - under the Dunham classification scheme for limestones, since the large bioclasts are touching, I think this would be classified as a rudstone. None of these corals looked to be in situ.

 

A relatively large top snail - Lithopoma most likely, species uncertain owing to the age. It seems to be ornamented with larger, smoother ribs than extant Lithopoma americana. The modern snails below are beaded periwinkles, Cenchritis muricatus, which were perhaps 1 cm in length, and this fossil shell was about 2-3 cm in diameter.

 

 At the other end of the island we chanced upon another exposure of the Ironshore Formation at Barefoot Beach after our last round of snorkeling on our 2022 trip. I found one of the most interesting fossils of the trip - this fossil Pocillopora, a cauliflower coral! Pocillopora is perhaps one of the most characteristic corals found today in Indo-Pacific reefs - but preserved in the Caribbean during the Pleistocene. Fossils like this one indicate that it became regionally extinct sometime after 125,000 years, which is the age of the Ironshore Formation. Similar specimens dating to the Sangamonian interglacial ~125 Ka have also been reported from rocks of the Dry Tortugas at the southwest end of the Florida Keys.

 

 

An excellent but small brain coral in the Ironshore Formation, Barefoot Beach, Grand Cayman.

 

 

These last two are admittedly more geomorphological than geological, but I never get tired of these extreme wave cut overhangs (coastal notches) in tropical limestone. Note the solution pitting on the roof of the notch -this indicates that on some level dissolution of limestone is occurring. As it happens, this is actually a bit of a controversy in tropical geology: seawater in the tropics is saturated with respect to calcium carbonate and quite basic, so how is there any dissolution occurring, which requires a low pH? pH changes, perhaps dissolution occurs during the winter when the water is undersaturated - perhaps this dissolution is mediated by algae. Most of the notch formation is probably from sandblasting, but there is *some* degree of dissolution happening, and in other tropical settings estimated to account for 10% of notch formation (presumably by volume). I wondered how the hell these notches formed because the waves are not large, and the notch is very shallow and very deeply incised (laterally anyway). Along temperate coastlines notches tend to be much shallower, and without much solution pitting.

 

Updates from the CCNHM prep lab: mystery bone (Pliocene Purisima Formation, California)

Frequently I am able to identify vertebrate fossils in the field based on their cross-section or if a little bit of the bone is exposed: when dealing with fieldwork in the Miocene-Pliocene Purisima Formation in Northern California, perhaps 80-90% of vertebrate fossils are ribs and vertebrae from cetaceans (whales and dolphins). If I can tell something is a whale rib or vertebra, I move on - these bones are not particularly useful or informative. And, to be clear, I'm talking about whether or not such a specimen could be published - does it represent a new record for the fossil assemblage? Is it diagnostic enough to name a new species from? If I can tell it's something else - a flipper bone, particularly a humerus, radius, or ulna from a whale, dolphin, or pinniped - that's something I can work with. Some vertebrae are even useful - particularly the atlas or axis from a cetacean. Skull bones, earbones, partial skulls, and complete skulls are desirable (and in that order). Skeletons are most exciting - but very, very rare in the Purisima Formation owing to the rapid skeletonization and disarticulation that occurs in shallow well-oxygenated marine shelf settings. Usually, I can narrow down a marine mammal bone to one of these categories - 'not interesting', 'possibly/probably worth collecting', or 'holy shit!' A vertebra, possible skull bone, and a nice skull would fall into these categories (respectively). 

All of this is a long-winded way of saying when I find something in the middle category - probably interesting - I usually leave the field with the fossil, but maybe not a clear idea of what it is.That usually changes after a little bit of preparation. Rarely, do I ever continue to prepare something and have no clue what the hell it is after much of the bone is exposed - this has happened to me with Purisima Formation fossils only once before - a weird bone fragment I collected in 2007, which is still not identified. Well, it happened again! I am once again stumped. And I LOVE getting stumped. When I get stumped, it generally means that whatever I'm trying to identify is either 1) a tiny uninformative piece of something really big or 2) something really unusual and exciting. 

 

The mystery bone in situ in the Purisima Formation.

How I initially interpreted the specimen in the field - as a tuskless, isolated left maxilla of a small specimen of the walrus Valenictus (specimen at San Diego Natural History Museum shown upside down for comparison). I thought the part labeled in blue was the edge of a tusk socket and the foramen in red as the infraorbital foramen. However, there was quite a bit more, and the other side was somewhat cylindrical.
 

In December I collected a relatively large bone fragment from near the top of the Purisima Formation under a state parks permit - it's a locality I've collected and studied extensively, but is still providing new surprises and challenges. When I first spotted the bone, I thought that maybe - just maybe - it was the tusk socket from a partial walrus skull. When I pulled the whole thing out, it was certainly not that - the back side was smooth, finished bone, almost resembling a rib - though it was clearly not a rib. I shrugged and then wrapped it up in paper towel, and when I got back to my folks' house, wrapped it in a bit more newspaper and in an oversized ziplock bag for the flights back to the east coast. On Friday of last week I opened it up, and thought if I started prepping it I would have an ID before I went home for the weekend - but I was wrong.

 The mystery bone in three different views, as I left it Friday night.

  The mystery bone after a little bit more preparation earlier this week.

 

So far, there are a few possibilities - but let's discuss what it is NOT first: it's pretty clearly not a vertebra fragment or a rib, unless it's a very messed up (e.g. pathologic) rib. I also do not think it's part of a baleen whale mandible, though there are some vague similarities. I've also compared it with limb bones from the sea cow Hydrodamalis and walruses, for which it is no match, and can confirm immediately that it's not a part of a cetacean forelimb bone. So, some possibilities in no particular order:

1) Partial walrus pelvis. Several candidate walruses are present in the California Pliocene, and they have big, chunky pelves. This would be neat, but it's not quite a good match - there isn't anything that looks like an acetabulum (hip socket).

2) Unusual baleen whale mandible, posterior end. The expanded feature at one end looks like it could be a broken mandibular condyle, and there is a bony flange below that somewhat resembles an angular process - however, there is no mandibular canal.

 

3) Sea cow premaxilla. There are some similarities between this and the left premaxilla of Hydrodamalis, which is already known from the Pliocene of California - Hydrodamalis cuestae, a larger extinct relative of the recently extinct Hydrodamalis gigas. The match isn't perfect, and some parts bother me. One problem is that the texture seems to be somewhat too porous.

The squamosal of baleen whales is quite diagnostic, and there are some similarities with the squamosal of a dwarf right whale, but it is not a great match.

Comparison of mystery bone with the left squamosal of Balaenula astensis, a dwarf right whale from the Pliocene of Italy (photos by Felix Marx). The mystery bone is quite flattened from front to back. However, the small size of the mystery bone would necessitate this specimen being very small, likely a juvenile, and perhaps some of the differences in morphology could be explained by growth.

4) Squamosal from a very tiny dwarf right whale. In this scenario the expanded process I initially mistook for a tusk alveolus would be the glenoid fossa (jaw joint) of the squamosal, and the small flange opposite would be the zygomatic process. If this is accurate, it would be a very, very small right whale, smaller than the Pliocene taxon Balaenula, and perhaps as tiny as Balaenella brachyrhynus from the Pliocene of Belgium. However, there is one major problem here: the bone is just not wide or deep enough, and there's no hint of the occipital articulation - the occipital shield is the triangular part at the back of the skull, and there should be radially oriented ridges for the occipital bone along with a platform raised up from the rest of the squamosal.

5) And here we're starting to get desperate: baleen whale pelvis. There's a slim resemblance, but admittedly it is less than fantastic.

6) Some unusual sort of land mammal bone. This part of the Purisima Formation is late Pliocene, so there are already some large ground sloths and a slew of elephants present in North America. However, nothing immediately comes to mind that looks similar.

7) One last possibility, and I need to humble myself here: perhaps this bone falls into the first category from further above in the post - a smallish piece of something really big, now too small to recognize immediately.

There is more preparation to tackle, so hopefully after some more cleaning the identity will be clarified!

Fieldwork snapshots: prospecting dredging spoils along Charleston Harbor

Amidst the panic of end-of-semester grading, exam writing and proctoring, and preparations for heading to California and Montana for the holidays, Sarah and I managed to have a day free to head out to a dredge spoil site out on Charleston harbor with our friend Ashby Gale. Ashby runs a fossil collecting tour guide business (Charleston Fossil Adventures), and has recently bought a boat that can help get out to some places a bit too far - or too rough/risky - for kayaking. Ashby and his clients have put together a pretty spectacular collection of dolphin periotics from our waterways, and these trips are a great way to add a few more - and a good opportunity to find the occasional trophy tooth. This particular day in December was one of the coldest - there was frost on our grass when I woke up and it was 43F (about 6C for our foreign readers) at the boat landing at 8am, meaning I was fairly apprehensive about getting wet or falling in the drink; the high would only be in the mid 50s (~12-13C) so drying off would be unlikely.

Captain Ashby bringing us in! This is actually Ashby's second boat, a somewhat larger Carolina skiff than the one he had before, and he had not yet installed his depth finder, so we were using the old fashioned 'stick a paddle in the water to estimate how deep it is' method. And we, as in me. Recall the frigid temperatures. Ashby was nervous about getting the propeller blades in the sand (which he had done with his first boat on the very first outing he invited me along on) or running the hull aground, as the larger, heavier boat would be more unlikely to be freed if stuck in the mud. We coasted in, and when the paddle indicated about 2' depth, Ashby told me to stop, and we coasted in for a few more seconds before he instructed me to hop off the front. I couldn't see the bottom - our water here is notoriously murky, with 18" visibility (meaning that if you see the bottom, it's shallow enough for your boots to keep you dry). Being another eagle scout I had my full faith in Ashby and jumped - into water two inches deeper than my boots! Frigid saltwater filled both up. Some choice words I won't repeat then filled the vicinity. Since I was already soaked and cold, I dropped off my bag and carried Sarah to shore so she would at least stay dry. On shore, I took off both boots and dumped out a half gallon of water each. My feet never quite went numb and my socks never quite dried out, but the fluid that was in there eventually, after about two hours, finally warmed up.

Within five minutes of getting ashore, I found this nice medium-sized tympanic bulla from a dolphin - probably an Oligocene waipatiid dolphin - with some brown siltstone matrix embedded within the tympanic cavity. If matrix inside this cavity becomes phosphatized, this is basically the only way you'll find a dolphin bulla with the outer lip attached.

Ashby quickly found this very nice dolphin periotic after paddling himself in - these periotics have a mixture of features found in eurhinodelphinid and waipatiid dolphins and are challenging to place. There's at least one soon-to-be published dolphin from the lower Miocene of Europe with similar periotics that may represent a new family. Regardless, the immediate discovery of a bulla and complete periotic helped me relax somewhat and realize that at least my freezing feet were not in vain and we would end up with at least a couple of nice earbones.

Sarah found this unusually complete and unscavenged longnose gar (Lepistoseus osseus) - who knows how it ended up here! The harbor is completely saltwater - apparently they can tolerate some salinity, but I generally don't hear about them much in the harbor; I imagine this individual died inland in a swamp or at least brackish water drainage and drifted out with the tide.

Our dredge spoils here in the lowcountry are generated from harbor excavations meant to deepen and/or maintain required depths for shipping lanes. This does two things: 1) dumps fossil-bearing sand and gravel above water onto dredge spoils and 2) occasionally incises into fossiliferous bedrock. Fossils from modern sediments were eroded out and reworked sometime, likely in the Holocene (but are all pre-Holocene). Owing to the abundant fossils in our subsurface, there's just a ton of shark teeth wherever dredging occurs. Here are a couple of sand tiger teeth (Odontaspididae).

About an hour in I found my first periotic of the day, this little beauty - which at first I thought rather looked like Papahu, a dolphin my Otago doctoral colleague Gabriel Aguirre-Fernandez described in 2014, but after brushing it off and looking it over, it rather looks like the more gracile periotic Ashby found earlier in the morning.

Here's the other side:

There really is a variety of neat stuff out there, including teeth of the considerably more rare megatoothed shark, Parotodus. Most of the teeth of Parotodus are P. benedeni, though elsewhere in Charleston an older unnamed species bearing lateral cusplets and resembling the Paleocene-Eocene species Otodus obliquus can be found. This is a small P. benedeni. Many folks go diving for meg teeth, but these ones are a bit more prized because they are considerably more rare.

A horseshoe crab cephalothorax plate, with a nice little erosional scour around it.

We find tons and tons of phosphatized steinkerns throughout the lowcountry, some of which are identifiable. In this case, we've got a cone snail steinkern. Cone snails, or cone shells (Conidae), are more common and diverse at tropical latitudes - and are famous for being absurdly venomous.

Here's a partial Carcharocles tooth one of us found - we've generally not had much luck with enormous teeth out here. This one's about 3 inches long (~7 cm).

A very nice little periotic I found in our third or fourth hour out there - one of about a dozen or so lowcountry specimens I believe are close to Eoplatanista italica from the lower Miocene of Italy.

A nice little Carcharocles megalodon tooth found by Sarah.

Nearly at the end of the day I found this ~3.5" (8 cm) busted up Carcharocles tooth that had escaped detection - possibly the last rain had just exposed it, though there were no shortage of bootprints in the vicinity.

I realize you've probably already seen this image a few times on other posts, but we really did have a pretty good day out there when it comes to earbones. The big partial one in the middle was found by Ashby in the last 30 minutes, and is a partial periotic of Ankylorhiza - and a great match for "Genus Y" proper, an unnamed species represented by the big skeleton over at Charleston Museum.