Hey Folks,
Earlier in the week, MSU news service published an article featuring my research on fossil marine mammals.
You can view the article here: http://www.montana.edu/cpa/news/nwview.php?article=9818&origin=homepage-l
perspectives on marine vertebrate paleontology
Thursday, May 5, 2011
Tuesday, May 3, 2011
Thesis defense: Passed
Hey Folks,
Sorry for the unannounced month-long delay; I have had zero time to contribute to the blog because I've been busy trying to finish my master's thesis, which I successfully defended a week ago today. I've been consumed with edits and other last minute work over the last week, and still have a bit of thesis writing left for this iteration.
I'm nearing the end of the master's degree journey and all that crap; my folks are flying up here for my graduation on Friday.
Once I have my next draft in, I'll be writing up an actualistic taphonomy article on "What's currently happening to Osama Bin Laden's corpse?" In addition to its humorous objectives, it really will be an exercise in deep-sea taphonomy.
Sorry for the unannounced month-long delay; I have had zero time to contribute to the blog because I've been busy trying to finish my master's thesis, which I successfully defended a week ago today. I've been consumed with edits and other last minute work over the last week, and still have a bit of thesis writing left for this iteration.
I'm nearing the end of the master's degree journey and all that crap; my folks are flying up here for my graduation on Friday.Once I have my next draft in, I'll be writing up an actualistic taphonomy article on "What's currently happening to Osama Bin Laden's corpse?" In addition to its humorous objectives, it really will be an exercise in deep-sea taphonomy.
Wednesday, April 6, 2011
Deadline for Aquatic Tetrapods meeting has been extended
For all you other marine (and aquatic) tetrapod paleontologists (and biologists and anatomists) out there, the deadline for abstract submission for the 6th Triennial Conference on Secondary Adaptation of Tetrapods to Life in Water has been extended to May 1st.
That means that any of you who were hesitant about submitting something because you didn't have time because your master's level comprehensive exams were scheduled for the same day as the abstract deadline (and you totally kicked comps in the ass like a boss, and got your abstract on marine vertebrate taphonomy submitted anyway) can go ahead and take a couple more weeks to think about what you're going to submit.
Seriously, it should be a totally awesome meeting; aside from having events at a totally awesome institution like the San Diego Natural History museum and being organized by a couple of really great paleontologists (Annalisa Berta, Tom Demere, and their postdoc Eric Ekdale), it's in San Diego.
San Diego. In June. San Diego in June.
It's like going to Mexico for spring break, except there's marine mammal fossils, other paleontologists, the San Diego Zoo, and you don't have to worry about getting beheaded by drug cartel members and someone finding your head in a cooler on the side of the road (although if you decide to take a side-trip to Tijuana that could be a possibility).
I strongly urge all marine tetrapod folks to seriously think about submitting something; there are still plenty of slots open for oral and poster presentations, and the email that Eric sent out indicates that you can submit abstracts for an oral and poster presentation.
If you have projects concerning any of the following, SUBMIT SOMETHING!
-Cetaceans & other aquatic cetartiodactyls
-Pinnipeds
-Sirenians
-Desmostylians
-Other semiaquatic basal tethytheres
-Otters
-Polar bears
-semiaquatic rodents
-aquatic sloths
-Functional morphology of any of these critters
-Plesiosaurs & 'Pliosaurs'
-Placodonts
-Other whacky sauropterygians
-Thalattosaurs
-Mosasauroids and other 'pythonomorphs'
-Ichthyosaurs
-marine crocodylians
-TURTLES
-Marine iguanas
-Hesperornithiformes
-Penguins!
-Plotopterids
-Auks and Puffins! (Alcidae)
-Flightless cormorants (and other diving birds)
-all sorts of nonmarine aquatic birds I've forgotten
-Tanystropheus!
Again, here's the conference website:
http://www.sdnhm.org/satlw/
That means that any of you who were hesitant about submitting something because you didn't have time because your master's level comprehensive exams were scheduled for the same day as the abstract deadline (and you totally kicked comps in the ass like a boss, and got your abstract on marine vertebrate taphonomy submitted anyway) can go ahead and take a couple more weeks to think about what you're going to submit.
Seriously, it should be a totally awesome meeting; aside from having events at a totally awesome institution like the San Diego Natural History museum and being organized by a couple of really great paleontologists (Annalisa Berta, Tom Demere, and their postdoc Eric Ekdale), it's in San Diego.
San Diego. In June. San Diego in June.
It's like going to Mexico for spring break, except there's marine mammal fossils, other paleontologists, the San Diego Zoo, and you don't have to worry about getting beheaded by drug cartel members and someone finding your head in a cooler on the side of the road (although if you decide to take a side-trip to Tijuana that could be a possibility).
I strongly urge all marine tetrapod folks to seriously think about submitting something; there are still plenty of slots open for oral and poster presentations, and the email that Eric sent out indicates that you can submit abstracts for an oral and poster presentation.
If you have projects concerning any of the following, SUBMIT SOMETHING!
-Cetaceans & other aquatic cetartiodactyls
-Pinnipeds
-Sirenians
-Desmostylians
-Other semiaquatic basal tethytheres
-Otters
-Polar bears
-semiaquatic rodents
-aquatic sloths
-Functional morphology of any of these critters
-Plesiosaurs & 'Pliosaurs'
-Placodonts
-Other whacky sauropterygians
-Thalattosaurs
-Mosasauroids and other 'pythonomorphs'
-Ichthyosaurs
-marine crocodylians
-TURTLES
-Marine iguanas
-Hesperornithiformes
-Penguins!
-Plotopterids
-Auks and Puffins! (Alcidae)
-Flightless cormorants (and other diving birds)
-all sorts of nonmarine aquatic birds I've forgotten
-Tanystropheus!
Again, here's the conference website:
http://www.sdnhm.org/satlw/
Tuesday, March 29, 2011
Fossil Fur seals from Northern California, part 2: The Gilmore Fur Seal
In 1948, Gretchen Burleson published a short article on some fossil pinniped jaws discovered in the Pliocene San Diego Formation, a sandstone mollusk-bearing unit that forms the hills of the San Diego area. These were some of the earliest pinniped fossils to be described from California - previously only a handful had been described, including the strange phocoid Allodesmus from the Sharktooth Hill Bonebed near Bakersfield, California, the woefully incomplete walrus (then assumed to be an otariid) Pliopedia pacifica from the Kettleman Hills, the hopelessly squashed fur seal Pithanotaria from Santa Barbara, and the even stranger Dusignathus santacruzensis from Santa Cruz.
All of these creatures were assumed then to belong to sea lions: most of them were large, and relatively robust, and differed markedly in many respects from true seals. Most of the early descriptions of pinnipeds we now know to be walruses are seemingly obsessed with comparing them to sea lions, and no doubt early workers such as Kellogg were frustrated with the alien nature of many of the fossils: they were about the same size as sea lions, but there were just so many little differences. The answer would not come until much later when decidedly modern researchers like Charles Repenning realized the true walrus affinities of many of these critters (like Pliopedia and Dusignathus).
Unlike the rather large and aberrant jaws of Allodesmus kernensis and Dusignathus santacruzensis, the fossil jaws from San Diego looked like a perfect match for a modern sea lion or fur seal: it had a shallow jaw with small triangular cuspate teeth, and the jaw was rectangular (i.e. the dorsal and ventral margins are parallel). The larger jaws of other better known pinnipeds had too many specialized features to be ancestral to sea lions: Dusignathus had widely flaring jaws without incisors and a canine that projected anteriorly, while Allodesmus lacked cusps on its postcanine teeth, which looked instead like little onions or bulbs. Burleson (1948) assigned these specimens to Pithanotaria, despite the much older age of Pithanotaria starri material described by Kellogg (1922) and the lack of actual morphological characters that identified the jaw of Pithanotaria. Burleson (1948) thought this specimen had a morphology intermediate between Pithanotaria and the modern Northern Fur Seal, Callorhinus.
Skull and dentition of a modern female Callorhinus ursinus, showing
In a much later paper by the preeminent paleo-pinnipedologist Charles Repenning and carnivoran researcher Richard Tedford (1977), this specimen was briefly discussed and they concluded that it did not represent Pithanotaria and was likely much closer to Callorhinus ursinus. After observing trends within the dental evolution of walruses like Imagotaria, Repenning and Tedford (1977) had identified the utility of the stage of root fusion as a taxonomic guide. For example, all modern otariids (fur seals and sea lions), the walrus, and some seals have single rooted teeth, while primitive pinnipeds and terrestrial carnivorans retain a number of double and triple-rooted teeth. For whatever reason, these root lobes coalesced through time and resulted in single rooted teeth in a number of taxa.
Repenning and Tedford (1977) were surprised that Burleson (1948) had not noticed the interesting configuration of the tooth roots of this specimen: the third and fourth premolars and the molar were still double rooted, while only the first and second premolars were single rooted; in the modern Northern Fur Seal, Callorhinus ursinus, all the lower premolars and molar are single rooted. It was indeed a fur seal, but retained some interesting primitive features.
In 1986, after an extensive excavation of a bonebed in the San Diego Formation that would be christened the Mission Hills Bonebed, additional remains of this fossil pinniped were discovered including several jaws, teeth, skull fragments, and postcranial bones. The discovery of a partial skeleton of an immature female skeleton allowed Annalisa Berta (San Diego State University) and Tom Demere (San Diego Natural History Museum) to describe the San Diego fur seal as a new species - and sure enough, they found that its features placed it as a close relative of the modern Northern Fur Seal, Callorhinus. They named it Callorhinus gilmorei, named after Dr. Raymond Gilmore. In other regards, Callorhinus gilmorei was a relatively small fur seal - substantially smaller than modern skeletal remains, with less strongly developed cusps on postcanine teeth, and a more 'primitive' state of root fusion.
The new specimen of Callorhinus gilmorei from the Rio Dell Formation of Northern California described by Boessenecker (2011)
All of these creatures were assumed then to belong to sea lions: most of them were large, and relatively robust, and differed markedly in many respects from true seals. Most of the early descriptions of pinnipeds we now know to be walruses are seemingly obsessed with comparing them to sea lions, and no doubt early workers such as Kellogg were frustrated with the alien nature of many of the fossils: they were about the same size as sea lions, but there were just so many little differences. The answer would not come until much later when decidedly modern researchers like Charles Repenning realized the true walrus affinities of many of these critters (like Pliopedia and Dusignathus).
Unlike the rather large and aberrant jaws of Allodesmus kernensis and Dusignathus santacruzensis, the fossil jaws from San Diego looked like a perfect match for a modern sea lion or fur seal: it had a shallow jaw with small triangular cuspate teeth, and the jaw was rectangular (i.e. the dorsal and ventral margins are parallel). The larger jaws of other better known pinnipeds had too many specialized features to be ancestral to sea lions: Dusignathus had widely flaring jaws without incisors and a canine that projected anteriorly, while Allodesmus lacked cusps on its postcanine teeth, which looked instead like little onions or bulbs. Burleson (1948) assigned these specimens to Pithanotaria, despite the much older age of Pithanotaria starri material described by Kellogg (1922) and the lack of actual morphological characters that identified the jaw of Pithanotaria. Burleson (1948) thought this specimen had a morphology intermediate between Pithanotaria and the modern Northern Fur Seal, Callorhinus.
Skull and dentition of a modern female Callorhinus ursinus, showingsingle rooted, cuspate teeth.
In a much later paper by the preeminent paleo-pinnipedologist Charles Repenning and carnivoran researcher Richard Tedford (1977), this specimen was briefly discussed and they concluded that it did not represent Pithanotaria and was likely much closer to Callorhinus ursinus. After observing trends within the dental evolution of walruses like Imagotaria, Repenning and Tedford (1977) had identified the utility of the stage of root fusion as a taxonomic guide. For example, all modern otariids (fur seals and sea lions), the walrus, and some seals have single rooted teeth, while primitive pinnipeds and terrestrial carnivorans retain a number of double and triple-rooted teeth. For whatever reason, these root lobes coalesced through time and resulted in single rooted teeth in a number of taxa.
The dentary of the holotype of Callorhinus gilmorei, from Berta and Demere 1986.
Repenning and Tedford (1977) were surprised that Burleson (1948) had not noticed the interesting configuration of the tooth roots of this specimen: the third and fourth premolars and the molar were still double rooted, while only the first and second premolars were single rooted; in the modern Northern Fur Seal, Callorhinus ursinus, all the lower premolars and molar are single rooted. It was indeed a fur seal, but retained some interesting primitive features.
In 1986, after an extensive excavation of a bonebed in the San Diego Formation that would be christened the Mission Hills Bonebed, additional remains of this fossil pinniped were discovered including several jaws, teeth, skull fragments, and postcranial bones. The discovery of a partial skeleton of an immature female skeleton allowed Annalisa Berta (San Diego State University) and Tom Demere (San Diego Natural History Museum) to describe the San Diego fur seal as a new species - and sure enough, they found that its features placed it as a close relative of the modern Northern Fur Seal, Callorhinus. They named it Callorhinus gilmorei, named after Dr. Raymond Gilmore. In other regards, Callorhinus gilmorei was a relatively small fur seal - substantially smaller than modern skeletal remains, with less strongly developed cusps on postcanine teeth, and a more 'primitive' state of root fusion.
The new specimen of Callorhinus gilmorei from the Rio Dell Formation of Northern California described by Boessenecker (2011)Subsequently, Kohno and Yanagisawa (1997) reported a tiny partial jaw from the late Pliocene of Japan. This jaw exhibited double rooted cheek teeth (although the anterior premolars were not preserved), and had accessory cusps on the cheek teeth, so they identified it as Callorhinus gilmorei. This extended the range of the Gilmore fur seal to the western Pacific - similar to the range of the modern Callorhinus ursinus.
Needless to say, I had a few ideas to follow once I started looking into Bushell's fur seal specimen. Fossils of C. gilmorei had so far only been found in Middle to Late Pliocene deposits, whereas in the late Miocene and earliest Pliocene of Japan, California, and Mexico the earlier fur seal Thalassoleon occurred (which has all double rooted teeth, and lacks cuspate cheek teeth, among other differences). The new specimen only has one cheek tooth - but it has a well developed accessory cusp, like C. gilmorei, and the first two premolars are both single rooted - also like C. gilmorei. In addition, it is relatively small - many other modern otariids are substantially larger. Furthermore, C. gilmorei appears to be the only middle-late Pliocene otariid in the entire Northeastern Pacific fossil record, which made the identification process somewhat easier.
Next up: Other fossil otariids from California and Oregon, and the Pleistocene Callorhinus
specimen.
References:
Berta, A., and T. A. Demere. 1986. Callorhinus gilmorei n. sp., (Carnivora: Otariidae) from the San Diego Formation (Blancan) and its implications for otariid phylogeny. Transactions of the San Diego Society of Natural History 21:111–126.
Boessenecker, R.W. 2011. New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution. Journal of Vertebrate Paleontology 31:2:454-467.
Burleson, G. L. 1948. A Pliocene pinniped from the San Diego Formation of southern California. University of California Publications in Zoology 47:247-254.
Kellogg, R. 1922. Pinnipeds from Miocene and Pleistocene deposits of California. University of California Publications, Bulletin of the Department of Geological Sciences 13:23–123.
Kohno, N., and Y. Yanagisawa. 1997. The first record of the Pliocene Gilmore fur seal in the Western North Pacific Ocean. Bulletin of the National Science Museum, Tokyo 23:119–130.
Repenning, C. A., and R. H. Tedford. 1977. Otarioid seals of the Neogene. US Geological Survey Professional Paper 992:1–87.
Needless to say, I had a few ideas to follow once I started looking into Bushell's fur seal specimen. Fossils of C. gilmorei had so far only been found in Middle to Late Pliocene deposits, whereas in the late Miocene and earliest Pliocene of Japan, California, and Mexico the earlier fur seal Thalassoleon occurred (which has all double rooted teeth, and lacks cuspate cheek teeth, among other differences). The new specimen only has one cheek tooth - but it has a well developed accessory cusp, like C. gilmorei, and the first two premolars are both single rooted - also like C. gilmorei. In addition, it is relatively small - many other modern otariids are substantially larger. Furthermore, C. gilmorei appears to be the only middle-late Pliocene otariid in the entire Northeastern Pacific fossil record, which made the identification process somewhat easier.
Next up: Other fossil otariids from California and Oregon, and the Pleistocene Callorhinus
specimen.
References:
Berta, A., and T. A. Demere. 1986. Callorhinus gilmorei n. sp., (Carnivora: Otariidae) from the San Diego Formation (Blancan) and its implications for otariid phylogeny. Transactions of the San Diego Society of Natural History 21:111–126.
Boessenecker, R.W. 2011. New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution. Journal of Vertebrate Paleontology 31:2:454-467.
Burleson, G. L. 1948. A Pliocene pinniped from the San Diego Formation of southern California. University of California Publications in Zoology 47:247-254.
Kellogg, R. 1922. Pinnipeds from Miocene and Pleistocene deposits of California. University of California Publications, Bulletin of the Department of Geological Sciences 13:23–123.
Kohno, N., and Y. Yanagisawa. 1997. The first record of the Pliocene Gilmore fur seal in the Western North Pacific Ocean. Bulletin of the National Science Museum, Tokyo 23:119–130.
Repenning, C. A., and R. H. Tedford. 1977. Otarioid seals of the Neogene. US Geological Survey Professional Paper 992:1–87.
Monday, March 28, 2011
Only four more days to submit an abstract for the Aquatic Tetrapods Conference!
All you marine vertebrate folks out there reading my blog (admittedly a very small minority of a minority of the vert paleo community) and not working on the abstract you should be for the Aquatic Tetrapods meeting, listen up! Abstract submission closes on friday, April 1st: I've been informed that not too many people have registered so far, so get on it!
FYI: you have to register for the meeting before you can submit an abstract.
For more information, check out the conference website:
https://www.sdnhm.org/satlw/index.php
FYI: you have to register for the meeting before you can submit an abstract.
For more information, check out the conference website:
https://www.sdnhm.org/satlw/index.php
Saturday, March 26, 2011
Fossil Fur seals from Northern California, part 1: discovery
Earlier this week saw the publication of my third article, concerning fossil fur seals of the genus Callorhinus from the Pliocene and Pleistocene of Humboldt County in Northern California. This paper has been in the works since 2006; I presented a poster on this topic at SVP in 2007. I did some of the initial research in 2006 and 2007, and after my SVP poster, I tried a couple more drafts of the manuscript - but it, along with a couple of other projects, fell by the wayside until I started graduate school. It wasn't until I had the herpetocetine jaw paper off my plate that I returned to this project, and in may of last year I submitted my completed MS to the Journal of Vertebrate Paleontology after three years of intermittent research.
The first page of Boessenecker (2011)
The story really starts in 2004. My buddy Ron Bushell, who helped me identify many of my fossils when I was still in High School, was collecting at a fossil site in Humboldt County, California. At this particular locality, he was looking for large concretions from the Rio Dell Formation which occasionally bear beautiful scallops (Patinopecten) the size of dinner plates, and incredible 6-10" long gastropods.
Ron and his collecting partners walked down the riverbank looking for nodules bearing mollusks, and thought he had hit the jackpot when he found a large nodule, about 2 feet in diameter, just sitting there in the gravel bar. Now, Ron is an experienced nodule collector - he's spent a lot of time collecting nodules with mollusks from the Pliocene and Pleistocene of Humboldt County, and Eocene crabs from Oregon and Washington.
So, if you're a nodule collector, naturally you take out a sledge hammer and attempt to destroy the concretion. Many concretions have nothing in them, and it is better to crack them in the field rather than lug them home and find out later (at some crab localities, Ron knows well enough which concretions will have crabs, and which ones won't, and packs them all out, and cracks them in his garage). Well, he broke this concretion open, and instead of white shells being exposed, familiar (but much rarer) brown fragments flew out onto the river bank - he immediately knew that he had found bone.
Initial preparation of the Bushell specimen.
Continued preparation of the Bushell specimen.
As it turned out, Ron had found two associated lower jaws (left and right) of a small fur seal, preserved beautifully in relief in a large concretion. He posted these photos on the old "Collecting fossils in California" forum, and I was very interested once I saw it. After a few emails, he offered to let me study the specimen - an opportunity I was most excited for.
Finished preparation of the Bushell specimen.
The Bushell specimen as it was when I first saw it.
Boessenecker, R.W. 2011. New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution. Journal of Vertebrate Paleontology 31:2:454-467
The first page of Boessenecker (2011)The story really starts in 2004. My buddy Ron Bushell, who helped me identify many of my fossils when I was still in High School, was collecting at a fossil site in Humboldt County, California. At this particular locality, he was looking for large concretions from the Rio Dell Formation which occasionally bear beautiful scallops (Patinopecten) the size of dinner plates, and incredible 6-10" long gastropods.
Ron and his collecting partners walked down the riverbank looking for nodules bearing mollusks, and thought he had hit the jackpot when he found a large nodule, about 2 feet in diameter, just sitting there in the gravel bar. Now, Ron is an experienced nodule collector - he's spent a lot of time collecting nodules with mollusks from the Pliocene and Pleistocene of Humboldt County, and Eocene crabs from Oregon and Washington.
So, if you're a nodule collector, naturally you take out a sledge hammer and attempt to destroy the concretion. Many concretions have nothing in them, and it is better to crack them in the field rather than lug them home and find out later (at some crab localities, Ron knows well enough which concretions will have crabs, and which ones won't, and packs them all out, and cracks them in his garage). Well, he broke this concretion open, and instead of white shells being exposed, familiar (but much rarer) brown fragments flew out onto the river bank - he immediately knew that he had found bone.
Initial preparation of the Bushell specimen.Normally, Ron would keep any vertebrate fossils from this locality, due to their rarity. However, he also noticed a tooth fragment - and he knew he had found something pretty important. So, just like any crab or mollusk fossil, he collected all the pieces, took them home, and glued them all together in his garage, and begun airscribing the fossil.
Continued preparation of the Bushell specimen.As it turned out, Ron had found two associated lower jaws (left and right) of a small fur seal, preserved beautifully in relief in a large concretion. He posted these photos on the old "Collecting fossils in California" forum, and I was very interested once I saw it. After a few emails, he offered to let me study the specimen - an opportunity I was most excited for.
Finished preparation of the Bushell specimen.
The Bushell specimen as it was when I first saw it.The following summer, my fiancee (then girlfriend) and I drove out to California for the summer, but took a detour through Oregon and Humboldt County in order to visit Ron and pick up this beautiful specimen. Thanks to Ron's generosity, this fossil was made available to study - and now (finally, five years later) Ron's wish that it be studied finally culminated in my paper in the Journal of Vertebrate Paleontology.
Next up - introduction to the "Gilmore Fur Seal", Callorhinus gilmorei.
Next up - introduction to the "Gilmore Fur Seal", Callorhinus gilmorei.
Boessenecker, R.W. 2011. New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution. Journal of Vertebrate Paleontology 31:2:454-467
Monday, March 21, 2011
NYCOM "Evolution of Whales and Dolphins" website is finally up!
A new website detailing the evolution of cetaceans is up on the New York College of Osteopathic Medicine website, and can be explored here.
Jonathan Geisler asked me to write for this website last year, and in February I flew to Long Island to visit NYCOM and sign all the necessary paperwork for the website. It is still very much a work in progress, but we hope to eventually have a large body of public-friendly articles on the website detailing many aspects of whale evolution and the cetacean fossil record.
Specific pages include:
Summaries of recently published articles on whale evolution
Summaries of fossil and modern cetaceans (modern cetaceans will come soon)
Research papers by undergraduate students (Georgia Southern University)
Georgiacetus!
Project Personnel
Enjoy, and stay tuned for updates!
Jonathan Geisler asked me to write for this website last year, and in February I flew to Long Island to visit NYCOM and sign all the necessary paperwork for the website. It is still very much a work in progress, but we hope to eventually have a large body of public-friendly articles on the website detailing many aspects of whale evolution and the cetacean fossil record.
Specific pages include:
Summaries of recently published articles on whale evolution
Summaries of fossil and modern cetaceans (modern cetaceans will come soon)
Research papers by undergraduate students (Georgia Southern University)
Georgiacetus!
Project Personnel
Enjoy, and stay tuned for updates!
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