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The Coastal Paleontologist, atlantic edition





Updated: 2016-01-24T12:59:42.168-07:00

 



The last decade of Marine vertebrate paleontology in the Pacific Northwest

2016-01-18T14:13:31.691-07:00

A scene from one of my favorite movies, The Goonies - with Haystack Rock (a Neogene igneous intrusion) and Cannon Beach in the background, and typical Oregon coast weather.Another famous sea stack at Olympic National Park in Washington. The Pacific Northwest - the "top left" corner of the United States (and British Columbia!), if you will - is a land that most people will associate with The Goonies, grunge rock, good coffee, D.B. Cooper, Tillamook ice cream (and cheese), lumberjacks, tall trees, totem poles, sasquatch, and Cascade volcanoes. To vertebrate paleontologists like myself, however, the Pacific Northwest is a playground of discovery including some of the most spectacular and desolate coastlines on the continent, with magnificent redwood and pine forests marching right down to concretion-riddled rocky shores. Some of the earliest marine mammal fossils found on the west coast were discovered along the coast of Oregon - Pontolis magnus, a giant walrus from the Empire Formation of Oregon (Coos Bay) described in 1903, and the pseudo-sea lion Desmatophoca oregonensis, named in 1906 from the Astoria Formation near Newport, Oregon. Since then many prominent paleontologists and amateur collectors have scampered along the deserted windblown shoreline of the Pacific Northwest in search for Cenozoic marine vertebrates, such as Earl Packard, Douglas Emlong, Guy Pierson, Jim and Gail Goedert. I've done a small amount of fieldwork, largely constrained to Lincoln County, Oregon, Cape Blanco, Oregon, and the Eel River Basin near Eureka, California. Paleontological fieldwork in the Pacific Northwest is challenging - the maximum and minimum tides are more extreme than central California, the localities are often more isolated, it's usually far windier and colder - and I've been rained out of fieldwork along the Oregon coastline nearly 3/4 of the time.  Doug Emlong with one of his skulls of Proneotherium repenningi from the Astoria Formation, Oregon.              With few exceptions (e.g. the Goederts and Bruce Welton), the story marine vertebrate paleontology in the Pacific Northwest is dominated by amateur collectors. This is in stark contrast to the bulk of marine mammal material from central and southern California collected in the 1970s and 1980s, mostly collected by professional paleontologists and students on field trips from UCMP, LACM, and SDNHM. Unlike the California coast, which has many fossil sites conveniently located within an hour's drive of various large universities and other paleontological institutions, most of the fossil sites in the Pacific Northwest are a bit further of a drive. Coastal fossil sites need semi-constant monitoring, as erosion is rapid and new fossils can be exposed after every storm at some localities. At some fossil sites in central California, I preferred to visit them three times a year - winter, spring, and summer (erosion was slowest in the fall). As a result, the most successful collectors in northern California, Oregon, and Washington have mostly been amateur collectors or professionals able to go on long trips; being based nearby and with the ability to visit a locality often is key to collecting well in the Pacific Northwest. Doug Emlong - one of my heroes - is probably the most famous, a brilliant, gifted and admittedly tortured individual who amassed a spectacular collection of fossils from the Oligocene and Miocene of Oregon and beyond. Many new species, genera, and families have been named from his collection at the Smithsonian, and several have been named after him including Enaliarctos emlongi (a pinniped), Seuku emlongi (a desmostylian), Squaloziphius emlongi (an enigmatic dolphin), and Mancalla emlongi (a large flightless auk).One of Ray Troll's famous maps - this one showing Washington and the Pacific coast; a much larger map is coming as part of Kirk Johnson & Ray Troll's sequal to "Cruisin the Fossil Highway", "Cruisin the Eternal Coastline".          [...]



Paleontological research tips I: field notes for amateurs and professionals alike

2015-10-19T09:48:36.433-06:00

I'm starting off a new series of posts that will cover various aspects of paleontological research. When I started doing paleo research I was a bit lost when it came to organizing my thoughts. After all, there's a lot of work involved in taking fossils and squeezing information out of them and arriving at a published article. Following the underpants gnomes meme from South Park:Step 1: fossilsStep 2: ??Step 3: paper (profit)This new series will cover everything in step 2. It's "easy" to go out and find a fossil, but much more difficult to distil that into a publication. I'll be giving plenty of examples of dos and don'ts, personal anecdotes, ideas, and personal preferences. There are some very basic rules, but most of these are going to be recommendations - it's all about finding the perfect balance. With a few exceptions, there are no absolutes or strict rules; it really does boil down to preferences. Also, if any colleagues or readers have bright ideas, comment away!Field notes! Everybody hates them but you need to do them. For starters, this post is directed just as much at my amateur colleagues as it is for professionals and students alike. Good - or at least satisfactory - field notes are an absolute must. This is one of the few examples of things that absolutely must be done if you want to do field paleontology well; almost everything else will be up to personal taste, but there must absolutely be a chain of evidence for fossils and paleontological data. Here's a series of real world examples:Scenario 1: Joe Blow is a shark tooth collector in Florida, and typically finds over a hundred shark teeth a day when he goes out digging. Occasionally rarer finds are made; on one particular day he comes across a Pleistocene horse skull sticking out of the gravel at the top of the quarry. He knows its important, digs it out, sets it in a box in the back of his pickup, and drives home. Joe doesn't have a particularly sharp long term memory, and five years later can't remember what quarry or what unit the fossil was collected. When Joe offers to donate the fossil to a museum, an interested paleontologist questions him on its provenance but is disappointed at the lack of detail.Scenario 2: John Doe is an avid master's student prospecting for trilobites for his thesis on trilobite paleoecology. It's been a long, hard day in the horrendously hot Marble Mountains of Southern California; he's got a bad headache, sunburned, and is thinking longingly of sweet, cold beer back at camp - there's only one day left on his Marble Mountain trip. He's spent all week collecting hundreds of samples, bagging them, labelling them, and cross-referencing these field numbers in his notebook. At the end of the day he finds fragments of a very large invertebrate - perhaps it's something like Anomalocaris! He quickly chisels out a slab, but is quickly getting tired and the prospect of beer is more and more attractive. It's not a locality he's collected from before that he could quickly write "refer to locality X on page X"; he doesn't have time to turn on his GPS, so he marks a cairn and will write everything down the next day. The following day, a flash flood washes out a bridge on the way there, and John returns to school to begin his horrendous advanced stratigraphy class. Months later he takes everything out, but finds that no information is associated with the anomalocarid and he's not even certain what formation it came from.Scenario 3: Jane Doe (no relation) is a diligent student collecting stratigraphic data along the coast, and has been collecting fossils as she goes, though it's not necessarily for her thesis research. She takes the fossils and shoves them into a plastic bag with the date written on it in permanent ink. She takes fossils from several different layers and puts them in the same bag; her notes are perhaps just as well curated as the rest of John's notes.Scenario 4: Dave Mould is collecting (with permission) from the Hell Creek Formation for a well known museum within a few hundred meters of a property[...]



Summer adventures, part 4: Montana trip II

2015-10-07T20:33:44.917-06:00

 More from the Montana segment of the trip!On our way back from Cooke City MT we got this fabulous red exposure which I'm guessing can only be the Triassic Chugwater Formation. On our way to Yellowstone, we passed by this famous outcrop on the way to the Mammoth/Gardiner entrance to the Park. The red stripe is called Devil's Slide, and is an exposure of vertically oriented Chugwater Formation. This exposure shows nearly the entire Mesozoic-upper Paleozoic section of southwestern MT, starting with the Madison Group to the right (Mississippian), potentially the Permian Phosphoria (can't remember if that's exposed around Bozeman/Yellowstone), overlain by the Triassic Chugwater, Triassic Dinwoody Limestone, Morrison Formation, all four members of the Kootenai/Cloverly Formation (KK1 - very prominent sandstone ledge; KK2, less prominent limestone; KK3, non-prominent mudstone; KK 4, limestone) and then a bunch of other Cretaceous rocks I'm not sure of but probably belonging to the very thick Bridger Group to the left. I hadn't been to the lip of Yellowstone Falls since I was a young child - so Sarah and I made the walk down. Hearing people bitching and moaning about how far the walk was was our first experience remembering how lazy other Americans can be since getting back into the US. Also, I politely asked some guy to not cut corners on the trail... then he tried to fight me. He wouldn't stop yelling. He really wanted to beat me up over his right to mess up nature. So yeah, true story.No trip to the park is complete without watching Old Faithful with 5,000 of your closest friends. Most of the time we went in the off season as students and usually had this view to ourselves, so sharing it like people at a baseball game was a bit weird. Grand prismatic spring, one of my favorite parts of the park.A panoramic of Grand Prismatic with bonus wife sighting. Some tourist who didn't speak any english lost his hat, and then tried to go after it - which simultaneously risked 1) ruining the fragile sinter deposits around the spring by leaving footprints and 2) his life. The trail here is raised on a boardwalk because sinter deposits are like swiss cheese - and the voids are filled with boiling water, or worse - steam which can cause severe, life-threatening burns. There's no way to know if a steam conduit is just inches below the surface, and all over the place you can see where bison hoof prints have collapsed the surface into steam vents. Several park visitors have died by stepping off trail and causing the roofs of these steam filled cavities to collapse, resulting in extensive third degree steam burns followed shortly by death. This was one of like three or four people we almost watched die in a 30 hour period in the park. It's not a complete Yellowstone trip unless you almost see somebody die.Nearby is Excelsior Geyser, which exploded in the 1980's and is now a huge crater with a beautiful gigantic blue hot spring. We saw somebody else's hat lost down here. After leaving the park, we drove west across Idaho to another volcano - here's Craters of the Moon National Monument in eastern Idaho.Coming soon: Photos from Oregon, thoughts on my new digs in South Carolina, and some actual content-rich posts reviewing tips on research - everything from field notes, maintaining a research notebook, to photography and figure construction. [...]



Summer adventures, part 4: Montana trip I

2015-09-27T12:27:20.892-06:00

Okay, some time to blog again. This is a picture heavy, text-light post with some pretty fossils, wildlife, and aurorae. After being in New Zealand for almost four years, we made a trip to Billings, Montana, to hang out with Sarah's half of the family. We spent about two weeks there, and got to visit Beartooth Pass, Cooke City, and our eternal buddies Liz Freedman and Denver Fowler while they spent the summer at the Great Plains Dinosaur Museum in Malta on the high line. First I'll post pics I took with my actual camera; I've got all of my phone pics online still, so the next post will have some of the goofier stuff (and some panoramics).We hadn't visited Museum of the Rockies in years - in the intervening time, friends of ours had completed their theses and moved on to new institutions. Our friend Jade Simon had finished her master's thesis on giant oviraptorid eggs - Macroelongatoolithus - from the Wayan Formation of eastern Idaho/western Wyoming, and now her key specimen was on display at MOR, shown here. Those are some enormous eggs; Jade was just beginning preparation of them before I graduated from MSU in spring 2011. Jade is now an adjunct (like me!) at Boise State U. in Idaho. There's now a mounted skeleton of the burrowing ornithopod dinosaur Oryctodromeus cubicularis - described by our undergrad adviser Dave Varricchio in 2007, and studied as part of Jamie Fearon's master's thesis on forelimb digging adaptations. Jamie did some teaching at Luther College and is now looking to start a Ph.D. program. An oldie but a goodie: the skull and neck of Edgarosaurus, described by former MSU master's student and current curator of the Museum of the North at U Alaska-Fairbanks Patrick Druckenmiller; this is a short necked plesiosaur from the Thermopolis shale of south central Montana. Another new specimen on display: this is a marine crocodile, Terminonaris, also from the Thermopolis shale near the Pryor Mountains of Montana. I helped dig this specimen up, along with Lee Hall, Mike Knell, Dave Varricchio, Bob Harmon, and of course, the discoverer - Cathy Lash. It's an articulated anterior skeleton, and a total beaut; we nicknamed this "Cathysuchus". Seen on the beartooth highway - adorable, but this is how you get bubonic plague. And encourage bad behavior. A trip to Montana always means the possibility of seeing the aurora borealis. Sarah and I were sicker than shit, but we decided to brave a drive up to the rimrocks northwest of Billings to see if we could see anything... and man, was it gorgeous.We were particularly happy, because we had a solar maximum while living in NZ, but were too poor to have a car, and we lived in an area with 1) a big hill to the south and 2) too much light pollution. So, pretty much everybody else got to see the aurora australis aside from us.Which is fine, because the aurora borealis is way better. Also, there's just something uniquely montanan about watching the northern lights in a cow pasture.A toad! This adorable little guy was discovered by Liz Freedman while digging a hole to bury a few bone fragments for a kids dig; she was horrified and thought she had killed it. A pretty thistle flower. Once in Malta, the four of us decided to try and do some birding at the Bowdoin National Wildlife Refuge. In the 1980's Jack Horner wrote about trying to study pelican nesting grounds as a modern analog of fossil Maiasaura nesting grounds. We couldn't get anywhere close to the pelican island nesting ground, but it was a nice place to visit. Here's an avocet.And another. And the closely related black necked stilt. Both of 'em! And again. I couldn't believe I spent 8 years in Montana without seeing laughing gulls, or even knowing they were even around! They're all over the place here in South Carolina, and they do sound hilarious. I love their penguin-like faces. Can't remember if this is a willet or a godwit, but it's something like that. We also saw a mother pheasant... ...who thought we were going to murder all of her bab[...]



Summer adventures, part 3: a visit to Santa Cruz

2015-08-29T10:29:42.080-06:00

In June Sarah and I visited Santa Cruz two days in a row, and found quite a bit down there - here's  brief "slideshow" of some of what we saw, paleontological and otherwise.Carcharodon hastalis tooth collected by Sarah from the lower Purisima Formation; teeth from this spot are often missing the root.Pigeon guillemots roosting in exposures of the Santa Cruz Mudstone near Natural Bridges State Beach - one of the best sightings I've had of these guys! Pigeon guillemot coming in for a landing over Monterey Bay. Pigeon guillemots are members of the family Alcidae, the group including murres, auks, and puffins.A medium-sized sperm whale tooth from the Purisima Formation! I was particularly happy about this find.A skull of "Balaenoptera" portisi, from the Purisima Formation and on display below the mounted blue whale at the Long Marine Lab in Santa Cruz. The remains of the middle of a balaenopterid (rorqual) skull destroyed when somebody inadvertently chopped through it cutting surfer's stairs into the cliffs. Beautiful view of the Santa Cruz coastline. Bonebed 5 from my master's thesis/PLoS One article, showing fissure fill in a large burrow likely formed by a large boring pholad clam.In Capitola there is an entire retaining wall constructed from blocks of concretions from the beach (mostly bonebed 6 of my PLoS One paper), but in one spot a caudal vertebra of a baleen whale was carefully chosen to be placed as a building stone...  At Capitola, beautiful invertebrates are exposed - hundreds of thousands of shells - including these large cockles, Clinocardium meekianum. Here's a smaller nodule containing a collection of partially associated/articulated Clinocardium meekianum. Elsewhere shellbeds are not quite so concreted - here sandy bottom bivalves (Anadara, Macoma) form beautiful lenses, pavements, and stringers within beautifully colored "blue sandstones". But vertebrates are what I really care about! Here's a nice lumbar vertebra of a dolphin, in a large chunk of concretion that makes it not worth the effort to haul it off the beach.I first spotted this skull in 2009, and after three years of erosion while living in New Zealand I can finally identify it as the tip of a baleen whale palate - possibly Herpetocetus.And here's a small balaenopterid whale skull which I first spotted back in 2002. We're looking at the bottom of the skull......and here's a closeup of the auditory bones, in particular the curly looking orange element, which is the tympanic bulla. It's possible that this is an early gray whale, but unless the impossibly hard matrix was cleaned off (after removal of the impossibly heavy block, of course) we'll probably never know.This is for certain a new Herpetocetus skull - mostly embedded in impossibly hard concretionary matrix.And this is also a Herpetocetus braincase, one which I first came across back in 2008 or so while on a visit with Sarah (girlfriend at the time). Ten years later, and she's still sleeping on the job.[...]



Summer adventures, part 2: return to Point Reyes

2015-08-09T02:18:41.029-06:00

Before leaving New Zealand, I made sure to submit another permit application to the US National Park Service to continue fieldwork within Point Reyes National Seashore. Guilty admission: I remembered to start work on a permit application when I saw in the news that one hiker died and a second hiker was seriously injured in a cliff collapse at Arch Rock in southern Point Reyes. Sarah and I made it up to Point Reyes a few times - here's some photos from our fieldwork in May and early June, including the excavation of our most exciting find - a partial skeleton of a small dolphin or porpoise, including a complete skull. Sarah and the NPS paleo intern Lillian Pearson walking along the shore of Drake's Estero. One of exactly two sea cow fossils I've seen at Point Reyes - this is a huge concretion with some enormous ribs, clearly identifiable as a sea cow rather than a baleen whale by their oval, inflated cross section (cetacean ribs are typically flattened distally and quadrate or rhomboidal proximally) and their complete lack of a marrow cavity. The second specimen is a petrosal I collected nearby (fortunately, not in a concretion). A stitched view of the broken concretion with the ribs sticking out.Lillian (red) and Sarah (blue) walking along a hill at Point Reyes. We had some adorable company. Lillian was at Point Reyes all summer doing a pilot project as part of a GeoCorps internship with NPS, surveying fossil sites along the coast in order to assess which cliffs would be best to monitor for a paleontological monitoring project. As part of this, she found these three associated baleen whale vertebrae. These apparently all belong to the same individual, but weathered out in a low-energy setting and the bones weren't scattered by currents after being eroded out. Lillian with her vertebrae. All three vertebrae were also dorsoventrally flattened - rare for Purisima Formation marine mammals, given how sandy the unit typically is. At Point Reyes, it is typically more muddy than in Santa Cruz and Halfmoon Bay, but compaction of bones like this is still unusual. All three showed this, further supporting identification as the same specimen. However, no skull or mandible parts were found, so we decided to leave it. We were also really, really exhausted, and hungry. It was also like 7:30 at night.  Sarah looking for fossils, Lillian and others in the background. A couple of weeks before flying home from New Zealand, Lillian found and photographed an interesting specimen I thought could be a nearly complete (or nearly completely eroded) odontocete (dolphin) skull. After giving a talk at the visitor center, we headed out along with UCMP's own Erica Clites (yellow) and her volunteer Kathy Zoehfeld (black). Sarah, Lillian, and I starting the excavation of the dolphin. As it turned out, not only did it have a complete skull - oriented parallel with the cliff for once - it had a mandible, teeth, ribs, an atlas, a humerus, several other vertebrae, and to make matters even better it was exposed with perhaps less than 10" of overburden. We started to dig a trench around the back - and fortunately, aside from a couple of damaged ribs, the skeleton didn't continue into the cliff. It's not evident in the photo, but the way this valley behind us is set up, it channels the wind so that at this spot, there were more or less continues 30 mph winds during the entire excavation - hence the glacier goggles (a lifesaver for windy coastlines). All of our eyes were sore and red the next day from getting sandblasted.  Within an hour, we got our hands dirty and put a plaster jacket. Here's Sarah and Lillian with the prize - undercut, and flipped over. Since the wind was so damn miserable, we didn't waste any time in moving the jacket into the dunes where the wind was less extreme. It was about 6pm now, so we decided to leave the open jacket back in the dunes, cover it with driftwood, and[...]



Summer adventures, part 1: Halfmoon Bay field recon

2015-07-26T15:14:49.698-06:00

 I've got quite a bit to catch up on from this summer - I've been busy (too busy, in fact). So, here's a selection of photos from the first part of our vacation back in the USA. We didn't waste much time heading back out to some choice localities in Halfmoon Bay. However, the drought and lack of erosion/storms has really taken its toll on local fossil sites, and as a result the beaches are high and the fossils hidden under a year's worth of dust and grime.Sarah had a bit of a spill on the way down to the beach - in one gulley there was a thin layer of sand overlying (and hiding) a thicker layer of mud, which she jumped down onto from a log.A Clinocardium cockle peeking out from the sand. A pretty fragment of bull kelp sitting on the beach. Several years ago I spotted this huge thing weathering out of the cliff about 25 feet above the beach. I got a better photograph of it in the field, and finally figured out what it is. I always knew it was some sort of a huge cetacean skull, probably baleen whale, but couldn't make heads or tails out of its shape. Here's a marked up version of the photo. This clearly shows that it's the posterior end of an upside-down baleen whale braincase- likely a balaenopterid whale - poking out, with some of the left braincase broken away and missing. The condyles, foramen magnum, right exoccipital, and even a tympanic bulla are evident. Judging from how far up this is, the skull is well over a meter wide, putting it somewhere in the size range of a Sei whale (Balaenoptera borealis). This specimen is a bit of a heartbreaker, because it would be impractical - if not impossible - to safely collect. People have seen this photo and suggested ropes, scaffolding, jackhammers, and all sorts of wild ideas but the simple truth is 1) digging that far in would likely trigger a cliff collapse and 2) far more easily collectable specimens are waiting to be collected on other beaches, without the need of all sorts of equipment I don't have the training or funding to operate.This hole was dug five years ago by my field assistant/fossil buddy Chris Pirrone (attorney at law), and yielded a beautiful little "river" dolphin skull with a partial rostrum, mandible, and left and right tympanoperiotics which I referred to Parapontoporia sternbergi in my 2013 Geodiversitas paper.Gooseneck barnacles and a single mussel poking out. A piddock clam whose rocky home is being eroded more quickly than it can bore, beautifully showing how it forms boreholes. A large green anemone lightly dusted with sand from the last high tide, within a shallow sandy tidepool.   View of the dramatic cliffs of Purisima Formation at the northern side of Tunitas Beach - one of the most scenic beaches in Halfmoon Bay, if not also one of the dirtiest; it's difficult to get to, and most people who go there to have barbecues and drink leave all of their trash in kind of a big heap at the bottom of the trail.Stay classy, Halfmoon Bay.Vertebrate fossils here are rare - this was my first discovery - a couple of associated dolphin vertebrae. The rock was far too hard to even think about removing them. Invertebrates are not rare, however, and clusters of the slipper shell Crepidula princeps are quite common, such as this rather nice example. The Purisima Formation here reflects deeper shelf sedimentation, and the traces can be quite large; here's a medium-sized Teichichnus trace. Elsewhere in the Purisima Formation Teichichnus traces can exceed 1 meter diameter (!) and approach 2 meters (!!!). Here's a thalassinidean shrimp claw, complete with the dactyl and chela. My wife hard on the search for fossils.[...]



The Coastal Paleontologist returns!

2015-07-25T14:11:23.512-06:00

Hey all!It's been a while, and a lot has happened since I took a bit of a break. All good, mind you. I took a break from blogging in March so that I could focus on something that was a tad more important - finishing my Ph.D. I submitted my doctoral thesis for external review in February. At Otago and elsewhere in NZ, the Ph.D. finalization process is a bit more hair-raising than in the USA. In the USA, you give your committee (mostly all in your deptartment, with perhaps one external reviewer) weeks before your defense date; they read it, and at your defense, give you a list of final corrections to make - and upon completion, you submit the final thesis and you're basically done. The point is, you pick the schedule. At Otago, all reviewers are external (at least for our lab's research, since there aren't really any other cetacean morphologists in New Zealand). When you submit, your scholarship stops, and you have the option of starting a publishing bursary - which has a maximum of three months. So, you hope that your reviewers are kind enough to get their reviews back to you before your funding runs out, as you either have the choice of 1) leaving the country before your reviews come in or 2) living in a cardboard box in an alleyway and waiting (NZ is prohibitively expensive).Initially I had opted for option 1, and in fact had already bought my plane tickets when I heard that my reviews were miraculously coming in two weeks before I was set to fly home and we scrambled to get a Skype Ph.D. defense set up. Other students had to opt for option 1, and some reviewers who couldn't be bothered took longer than three or four months. Fortunately I didn't have to worry about that, as all of my reviewers kindly returned their commentary within two months. A week and a half after passing my Ph.D. oral exam, Sarah and I hopped on a plane and headed back to the USA - where we were immediately amazed not only at the nice weather (winter in California is often better than summer weather in Dunedin) but also at how cheap groceries are (we spent on average 200-300$ on groceries a week).We didn't wait long until we went out to do summer fieldwork along the California coast - we've gone out and visited fossil sites in Halfmoon Bay, Santa Cruz, Marin County, and Mendocino County, as well as going to Lake Tahoe, Monterey Bay, San Francisco, Berkeley, and other great spots. I'll be doing a series of posts on summer paleo adventures soon.Special delivery from down under: big beautiful hardbound copy of my thesis, in red! Last week I found out that my thesis was formally accepted by the school and that I will in fact be graduating on August 15, after which I will be Dr. Robert Boessenecker (thank you very much), and that my thesis will be added to the "List of Exceptional Doctoral Theses" for the University of Otago Division of Sciences - a prestigious designation given only to the top 10% of theses in the school (so, basically I got an "A" or "A+" on my last piece of schoolwork ever). Let me explain why that's amazing: I was a D average student in high school, and perhaps a C average student my first few years of my Bachelor's program. I was never a good student until the end of my undergraduate career; I think the first time I ever got a 4.0 GPA was during my master's program (and, at that, only got a "B" in a single class during my master's - the only blight on an otherwise perfect record). So, it's really just been the last 6-7 years or so. They say graduate school is harder - and in some ways, it is - but because I actually care about the subject, I pour my heart and soul into it (maybe too much, in some cases), and so regardless of how hard grad school is, in most ways it just became easier and easier.Museum curator Mace Brown with one of the Charleston specimens I'll be working on - an adult eomysticetid skull, possibly Micromysticetus rothauseni.Wh[...]



Advances in marine vertebrate taphonomy - last 5 years (2010 to early 2015)

2015-03-08T05:53:04.315-06:00

The major focus of this blog is fossil marine vertebrates, but my secondary research interest is taphonomy - the study of fossil preservation. For a number of reasons, the preservation of terrestrial organisms is much better understood and more frequently studied than that of marine organisms. Many who dabble in marine taphonomy come at it from a background in marine vertebrate paleontology, or perhaps from nonmarine taphonomy; the body of knowledge available to us in this field is sort of cobbled together and no good summary articles really exist for the novice. People die in the ocean and wash up on beaches all the time - but surprisingly, the focus on studying forensic taphonomy in marine settings is even proportionally smaller than the marine taphonomic focus within paleontology. When one comes from an auxiliary discipline, it's easy to miss some of the more recently published, relevant articles in marine vertebrate taphonomy. So, to help out anyone with an interest in the preservation of marine vertebrates - here's a (hopefully) comprehensive list of publications from the past 5 years that you may not have noticed. If there is something that I've missed, I want to know! I'd love to include it. Abstracts are copied/pasted below as well.Acosta-Hospitaleche, C., Marquez, G., Perez, L.M., Rosato, V., and Cione, A.L. 2011. Lichen bioerosion on fossil vertebrates from the Cenozoic of Patagonia and Antarctica. Ichnos 18:1-8.Different traces occur on fossil bones and teeth coming from the Early Miocene Gaiman Formation (Patagonia, Argentina). Most traces were attributed to the action of terrestrial and marine predators and scavengers. However, other traces on bones and teeth from this unit and one tooth from the Eocene La Meseta Formation (Antarctica) are attributed to chemical corrosion by lichens in recent times, that is, in a very late diagenetic time. The living lichens and calcium oxalate deposits occurring on the traces and their particular pattern indicates that they were not produced by vegetal roots. The lichens include reproductive structures which allowed a proper determination. A kind of corrosion pattern (Type 1) on bones and teeth from Patagonia is associated to Sarcogyne orbicularis Korber, Verrucaria sp. Schrad, and Buellia aff. punctiformis (Hoff.) Massal. The lichen Aspicilia aff. aquatica produced rounded holes on an Antarctic tooth (Type 2). On the same tooth, the epilithic lichen Caloplaca sp. Th. Fries did not leave any kind of mark on the enameloid.Anderson, G.S., and Bell, L.S. 2014. Deep coastal marine taphonomy: investigation into carcass decomposition in the Saanich Inlet, British Columbia using a baited camera. PLoS One 9:e110710.Decomposition and faunal colonization of a carcass in the terrestrial environment has been well studied, but knowledge of decomposition in the marine environment is based almost entirely on anecdotal reports. Three pig carcasses were deployed in Saanich Inlet, BC, over 3 years utilizing Ocean Network Canada’s VENUS observatory. Each carcass was deployed in late summer/early fall at 99 m under a remotely controlled camera and observed several times a day. Dissolved oxygen, temperature, salinity, density and pressure were continuously measured. Carcass 1 was immediately colonized by Munida quadrispina, Pandalus platycerosand Metacarcinus magister, rapidly scavenged then dragged from view by Day 22. Artifacts specific to each of the crustaceans’ feeding patterns were observed. Carcass 2 was scavenged in a similar fashion. Exposed tissue became covered by Orchomenella obtusa (Family Lysianassidae) which removed all the internal tissues rapidly. Carcass 3 attracted only a few M. quadrispina, remaining intact, developing a thick filamentous sulphur bacterial mat, until Day 92, when it was skeletonized by crustacea. The major difference between the deploym[...]



Introducing Eotaria crypta from the Miocene of Southern California - the oldest known otariid pinniped

2015-02-19T14:42:23.369-07:00

Photos of the holotype specimen and life restoration of Eotaria crypta, with Allodesmus for scale (Allodesmus is roughly the size of an adult male Steller's sea lion). Artwork by yours truly. Fur seals and sea lions are grouped into the family Otariidae, and are otherwise known as eared seals; each informal group used to be considered as clades, and were grouped into the subfamilies Arctocephalinae and Otariinae (respectively). Modern fur seals are the most diverse, and include the northern fur seal (Callorhinus ursinus) and many species of southern fur seal within the genus Arctocephalus (some of which have been grouped into the genus Arctophoca; more on that later). Sea lions include the Steller’s sea lion (Eumetopias), California, Japanese (recently extinct), and Galapagos sea lions (Zalophus spp.), South American sea lion (Otaria), and the New Zealand (Phocarctos) and Australian (Neophoca) sea lions. Sea lions are generally larger than fur seals, lack underfur, and have thicker blubber. The problem is, most of the features that have been used to consider fur seals as a monophyletic group are primitive or associated with small body size, and morphological analyses have had trouble recognizing these two subfamilies, and molecular analyses have completely failed to support monophyly of each group. In simple terms, according to more robust molecular studies, the fur seal “morphotype” evolved at least twice, and the sea lion “morphotype” may have evolved up to three times – there’s not really much distinction between, and most modern otariids appeared to have diverged rapidly and recently, within the last 3 million years – the sole exception is the northern fur seal, fossil evidence of which indicates it’s been around, perhaps as an unbranching (anagenetic) lineage since the Pliocene (~3-4.5 Ma).The great thing about the fossil record is that it often helps sort out these biological dilemmas; fossils are the only evidence we have for biological events that took place before people started writing anything down (e.g., most of earth’s history). Molecular phylogeny is a powerful tool, but it’s a bit like trying to figure out how big a cave is or what it looks like inside from looking at the entrance. Unfortunately, in this case, there are a few problems with the otariid fossil record. So as not to appear too negative, I’ll start with what we do know. We know that “sea lions” have a sporadic fossil record restricted to the Pleistocene, almost all of which are identifiable to modern genera or were very similar to modern genera (Proterozetes ulyssesfrom the middle Pleistocene of Oregon, for example, may be a species of Eumetopias). Some fossil sea lions were slightly outside their current range (Neophocapalatina, for example, is known from the Pleistocene of New Zealand instead of Australia). All published pre-Pleistocene otariids are what we would call fur seals: relatively small bodied, similar to Callorhinus and Arctocephalus. No known examples of co-occurring otariid species exist prior to the Pleistocene; all Miocene and Pliocene marine mammal assemblages appear to have only a single species of otariid, whereas Pleistocene assemblages will have one sea lion and one fur seal (and in at least one case – two sea lions and a fur seal). Pre-Pliocene otariids are known only from the North Pacific; Thalassoleon(9-4 Ma) is known from Japan, California, and Baja California, the earlier otariid Pithanotaria is known from California only, and a Pithanotaria-like otariid has been reported from the early late Miocene of Japan (~12.5-11 Ma). No older fossils existed, but the fossil record of true seals possibly extends back to 19 Ma, and the fossil record of walruses extends back to 17 Ma, indicating a ~5 My ghost lineage for otariids. A ghost lineage is where we [...]



Thesis submission - return to blogging

2015-02-17T17:11:38.461-07:00



It’s time for a triumphant return from a self-imposed hiatus! Last week I finished my Ph.D. thesis (not called a dissertation here in NZ for some reason) on Oligocene eomysticetids from New Zealand, got all four copies printed, and formally submitted it to the university. Unlike schools back in the USA, most theses are reviewed externally, after formal submission; master’s theses in the US are typically reviewed in-house, with all the corrections being completed prior to formal submission – so at the time of submission, you’re finished. US Ph.D. dissertations are reviewed on a similar time frame but with one external committee member. Here, the thesis is reviewed externally and often takes up to three months after formal submission, so now we play the waiting game. I’ll start the publishing bursary soon, where the school pays you to stick around for three months to publish individual chapters from your thesis (while you wait). Anyway, just a quick update – and coming soon will be a post about the newly described fur seal Eotaria crypta

 
Four printed copies of the thesis for review, with Yoshi Tanaka in the background. 
      Photo (c) R. Ewan Fordyce.


(image)



2014 in review: Advances in marine mammal paleontology

2014-12-29T15:56:22.284-07:00

Merry Christmas/Happy Hannukah/Chrimbus/Festivus! Welcome to the third annual review of advances in marine mammal paleontology! There were over 50 new publications in marine mammal paleontology this year, and this took quite a while to work up; about 1/3 of the papers I didn’t even really get a chance to read until this winter (er, summer). As usual, this list is supposed to be comprehensive, so if I have missed something, please let me know – hopefully I’ll have time to update it. I may not, because ultimately my thesis is more important. As in the past two years, I include papers that have been published since January 2014 – however, for papers that came out online in 2013 and were only included in published journal issues in 2014 – these will remain in last year’s post (and the same goes for some of the following studies, some of which will almost certainly have permanent 2015 citation dates despite online publication in late 2014). There are three or four I still have yet to add, so stay posted and check again in a few days. It does bug me when I see new papers that have left out citations to important new research; I try to devote some time to reading new publications as they come out, and hopefully with these posts statements like “well I didn’t really know about such and such article, I don’t know how to use google” or “I’ve literally been living under a rock” will no longer be decent excuses. Anyway, I hope this huge review will be of service for other marine paleomammalogists!Aguirre-Fernandez, G. and R.E. Fordyce.2014. Papahu taitapu, gen. et sp. nov., an early Miocene stem odontocete (Cetacea) from New Zealand. Journal of Vertebrate Paleontology 34:195-210.This paper formed one of the core chapters of former labmate Gabriel Aguirre-Fernandez’ doctoral thesis, and reports a well-preserved and beautifully prepared odontocete skull from the lower Miocene Kaipuke Siltstone in northwest Nelson, South Island, NZ. This specimen was for years thought to be the earliest record of kentriodontids (but keep reading). The skull is rather small, perhaps similar in size to a Hector’s dolphin or harbor porpoise. It appears to have had a polydont single rooted dentition and a subtriangular, acutely pointed rostrum and convex palate – overall not terribly different from a dwarfed Waipatia aside from the tooth rooting. Cladistic analysis indicated rather strongly that this is no kentriodontid, and is in fact a stem odontocete of uncertain position; it’s more derived than xenorophids (see Geisler et al., below, for more on xenorophids), but more primitive than beaked whales and sperm whales. They named the new dolphin Papahu taitapu, meaning dolphin from Te Tai Tapu (the area of Nelson where it was collected from) in Māori.Amson, E., Muizon, C. de, Laurin, M.,Argot, C., and Buffrenil, V. de. 2014. Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru. Proceedings of the Royal Society B 281:20140192.One of the most profound and strangest discoveries in marine mammal paleontology is the discovery of aquatic adapted sloths from the Miocene and Pliocene of Peru (and now Chile as well). These were first named Thalassocnus in 1995, and in the following decade a number of additional species and a ton of skeletons were reported and described. Common questions I get about these from colleagues in non-mammalogical fields of paleontology are “How do we know they’re actually aquatic and not just terrestrial sloths that floated out to sea?”. It’s an excellent question that can be addressed taphonomically and adaptationally. Taphonomically speaking, these skeletons have only been found in marine sediments and none yet from terrestrial deposits – which have other types o[...]



New publications: new eomysticetid Tohoraata, and trace evidence of predation on bone-eating worms in eomysticetid bones

2014-12-07T20:37:09.468-07:00

Over the past couple of weeks I've had two papers from my Ph.D. thesis published with my adviser, R. Ewan Fordyce. The first of these, published in mid November in the new journal Papers in Palaeontology, deals with resolving the identity of the fragmentary fossil cetacean "Mauicetus" waitakiensis from the late Oligocene of New Zealand, and another new species.Tohoraata - dawn whales from the Oligocene of New ZealandMauicetus waitakiensis was described in 1956 by former Zoology professor (and Zoology Chair) Brian J. Marples, although collected somewhat earlier by him. Marples was an arachnologist originally, and according to Ewan Fordyce, probably stumbled upon fossils while looking for trap door spiders in North Otago. During the 1940's and 1950's Marples and his sons dug up several cetacean skulls and partial skeletons, also including the dolphin Otekaikea marplesi, recently redescribed and renamed by my labmate/office partner Yoshi Tanaka. Two of these new cetaceans appeared to be baleen whales, and included one specimen with a complete braincase, fragmentary mandible, well-preserved tympanic bullae, scapulae, and some vertebrae; the other included only a fragmentary braincase, tympanic bullae, and neck vertebrae. Both were collected from the Kokoamu Greensand. At the time of writing, only one baleen whale had been named from NZ: Mauicetus parki, an archaic mysticete from the somewhat younger (earliest Miocene) Milburn Limestone, much closer to Otago campus (perhaps only a 45 minute drive out of town). At the time it was reasonable to allocate these new species to Mauicetus: the Mauicetus holotype was fragmentary, seemed to correspond well to what Marples had collected, and the periotic (inner ear bone) had not yet been removed. So, Marples named these two species Mauicetus lophocephalus (for the more complete specimen) and Mauicetus waitakiensis (for the less complete specimen).Note: this can get somewhat confusing, as Dr. Benham originally named the type species as Lophocephalus parki (which he thought was an archaeocete, until Remington Kellogg corrected him), and upon realizing that Lophocephalus was preoccupied, he named the new genus Mauicetus for it. So Marples, perhaps confusingly, recycled the name for one of his new species of Mauicetus.The holotype skull and tympanic bulla of "Mauicetus" waitakiensis, figured and described for the first time. From Boessenecker and Fordyce (2014A).The relationships of Marples' Mauicetus species have remained contentious for nearly 60 years. Unfortunately, Marples never figured more than the first and second vertebrae of Mauicetus waitakiensis, even though it had a partial skull and earbones. To make matters worse, the skull of Mauicetus lophocephalus was chucked in the trash when the Zoology Dept. switched buildings sometime before 1962 - less than six years after being published! The next paleocetologist who came along and had the opportunity to look at this specimen was R.E. Fordyce when he began his Ph.D. in the late 1970's, and the skull of one of the most significant cetacean fossil discoveries in NZ had disappeared without a trace. Fordyce noted in several earlier studies that the remaining material of these two species differed strongly from all previously known baleen whales, and that the material likely represented a baleen-bearing mysticete but more primitive than any described. In 2002, Eomysticetus whitmorei was described by Al Sanders and Larry Barnes from the Oligocene Chandler Bridge Formation of South Carolina - an early toothless baleen whale that had features intermediate between toothed baleen whales and most groups of baleen whales from Neogene rocks, filling a critical gap in cetacean evolution. Eomysticetus had a long, narrow rostr[...]



Sorry for the hiatus - GSNZ conference and field trip to Waihi/Ohawe beaches, Taranaki

2014-12-07T15:51:57.385-07:00

Hey all, as promised, I've only had a minimal amount of time to contribute to blogging this fall, owing to more pressing concerns (such as my thesis, which I have about two months left to complete). It's been one week since I've been back from the Geoscience Society of NZ annual conference, where I presented on my dissertation research on Oligocene eomysticetids from the south island of NZ, specifically on feeding strategy of the earliest toothless mysticetes. I actually won 1st runner up for best student oral presentation, and labmate Yoshi Tanaka received the award for best poster presentation for his poster on Oligocene platanistoid dolphins from the same localities. Otago students did exceedingly well, sweeping 5 out of 6 best presentation awards, all with the exception of top oral presentation. To be fair, Otago students made up almost half of all students attending the conference, but then again we received more than half the awards. All this highlights Otago as one of the best places to study geology in NZ.Not all of the days were paleontology themed (in fact, only one was) so some plans were made to go out into the field. I have long wanted to visit some fossil sites in South Taranaki, which have recently been getting some attention on places like The Fossil Forum thanks to a series of remarkable discoveries by some private collectors on the North Island. I flew up to Wellington the day before the conference started, rented a car with labmate Josh Corrie, and swung by Waihi Beach.Fossil invertebrates are abundant in the cliffs, and require little more than a knife or a few casual taps from a rock hammer to be pried loose from the rather soft siltstone. Large scallops, beautifully preserved oysters, and spectacular gastropods are in abundance. Occasional barnacles are present, and bryozoans are rare; I found a single, beautifully preserved bryozoan colony that I handed to Alan Tennyson for Te Papa (National Museum of New Zealand) fossil collections. In concretions, much larger oysters and scallops can be found, but are substantially more difficult to prepare.Fossil vertebrates include seals (known from isolated braincases, mandibles, humeri, innominates, femora, other postcrania, and partial associated skeletons), dolphins (known from several skulls, mandibles, a single periotic, and vertebrae), rare baleen whales (mostly ribs, although a partial skull and skeleton of a new species of Balaenoptera are in collections at Te Papa), and marine birds including shearwaters, giant petrels, albatrosses, a spheniscid penguin, and a pelagornithid bird (skulls, jaws, partial skeletons). Bony fish and sharks are also known - I saw vertebrae from lamniform sharks including a candidate for Carcharodon carcharias, and toothplates of the elephant fish Callorhynchus (a chimaera) and a single associated set of mandibular/palatoquadrate cartilages with teeth of the angel shark Squatina also exist in private collections. Vertebrates are almost always in small concretions, and are cracked open with large sledgehammers. The view to the west from Waihi stream. A large scallop exposed in the Ohawe Siltstone. Further up the beach, here's the view towards Ohawe Beach off in the distance. Large gastropods make for a nice prize. Fordyce student Josh Corrie looks for concretions at Waihi Beach. Right around this spot, a pelagornithid jaw (seen below) was collected less than two months ago.Some examples of bones in concretions in a private collection from Ohawe/Waihi beach. A pelagornithid humerus in a concretion, with the Pelagornis sp. I described from the Purisima Formation back in 2011 with N. Adam Smith for comparison.Spectacular pelagornithid jaw with pseudoteeth from Waihi Beach. Nearby i[...]



The evolutionary history of walruses, part 5: what did tusks evolve for?

2014-11-03T19:20:21.166-07:00

 This is the last text-heavy post in the walrus evolution series; one last post remains, which will be up in a few days. I've been busy with job applications and thesis writing, and finalizing and submitting three short manuscripts on various subjects.Sexual dimorphism in the walrus - male in the background, female in the foreground. Photo from www.marinebio.net.Tusks in Odobenus rosmarusTusks in the modern walrus Odobenus rosmarus occur in both sexes, but are generally larger and longer in males – and like most other pinnipeds, they are polygynous (a single male mates with multiple females) and sexually dimorphic (males are larger than females). The walrus is restricted to the Arctic – and owing to this, tusks were usually assumed to have something to do with ice. For example, walruses tend to use their tusks to assist in hauling out onto ice, leading many to originally propose that tusks evolved for this purpose. Other workers erroneously identified tusks as being used for excavation of mollusks on the seafloor. However, observations by Francis Fay (1982) and Edward Miller (1975) indicate that a use in feeding or haul out behavior is unlikely. Miller (1975) studied aggressive behavior in male walruses, and observed that tusks perform a central role in male interactions. Most interactions consist of tusk threat displays – the aggressor leans his head back so that the tusks are horizontal and pointing toward the target. If the target is somewhat submissive the aggressor will perform a “stabbing” motion. In more aggressive interactions the aggressor strikes the target with the tusks using the same downward stabbing motion, typically striking the hindquarters, back, or neck. These strikes commonly draw blood but Miller (1975) doubted that many cause serious injury (similar to elephant seal combat). Tusks were also frequently used to parry strikes close to the face. Predictably, walruses preferentially threatened smaller males; perhaps more adorably, juvenile males that even lacked tusks performed play fighting that was similarly ritualized. Strikes tended to follow visual threats, and Miller (1975) indicated that ritualized aggressive behavior like this is fundamentally similar to that seen in sea lions, who perform visual displays (prior to striking) by similarly leaning back and opening the mouth to show the canines. Interestingly, the pattern of scarring is completely opposite to the pattern of observed tusk strikes: scarring is mostly present on the anterior neck region, and Miller (1975) attributed this to several reasons: 1) his observations were on land and 2) during the summer. He hypothesized that during the breeding season, more intense “face to face” combat on ice (or more likely, in the water, as some rare anecdotes suggest) is the origin of anterior scarring. So, the relatively violent behavior that Miller (1975) described is not even that which is known to cause the most scarring on walruses – which seems to suggest that walrus breeding behavior might be a bit terrifying and may give the elephant seal a run for its money.Walrus tusk display and combat. Threat displays frequently prelude tusk strikes. Photo from www.flickr.com             Many earlier workers (see Fay, 1982: 134-135 and references therein) concluded that walruses dug prey items out of seafloor with their tusks, and this was based primarily on observations of tusk abrasion in dead animals. At least one early study suggested that walruses scraped the seafloor with their tusks in a posterior direction, but later revised to a side-to-side motion as no abrasion exists on the posterior side of the [...]



Paleontology "kickstarter": relationships of Allodesmus

2014-10-23T18:05:43.917-06:00



A mount of the partial holotype skeleton of Allodesmus kelloggi, a junior synonym of Allodesmus kernensis (at the Natural History Museum of Los Angeles).

My colleague Reagan Furbish - a master's student under Dr. Annalisa Berta at San Diego State University, has started a kickstarter campaign to fund some of her master's thesis research. Reagan is studying the phylogenetic relationships of the fossil pinniped Allodesmus: controversy exists whether or not it was more closely related to true seals (Phocidae) or to sea lions (Otariidae) and walruses (Otarioidea). She needs to visit several museums including the American Museum of Natural History in New York, the Smithsonian Institution in Washington D.C., and the Natural History Museum of Los Angeles. Reagan asked me to post this here - if any readers happen to have a few spare bucks they can part with, think about sending some in Reagan's direction! I will note that recently, my colleague Rachel Racicot successfully funded some future CT work on the bizarre porpoise Semirostrum using an Experiment.com kickstarter. Go donate!

Here's the link: https://experiment.com/projects/written-in-bone-was-the-fossil-allodesmus-a-seal-or-sea-lion(image)



Beautiful new Oligocene dolphin in the prep lab

2014-10-19T02:33:45.581-06:00

 A couple of months ago the Haugh's quarry triage project started - we had dozens of unopened plaster jackets from Haugh's Quarry in South Canterbury. About a dozen medium to large size jackets were prepped out, including this one, which was found to have a beautifully preserved odontocete skull, mandible, and partial postcranial skeleton from the upper Oligocene Otekaike Limestone.Here's a view of the skull and mandible; the gray pieces at the upper right are parts of a large echinoid.And a mandible with numerous in situ teeth - with the exception of a handful of specimens, most fossil odontocetes in the Otekaike Limestone have teeth that are mostly disarticulated. And the skull has quite a nice dentition as well! Unfortunately, the tip of the rostrum is missing. Here it is with a little more preparation. The teeth are quite a bit narrower and more needle-like than other Otekaike Limestone odontocetes. Here's some nice postcrania... And more teeth; a single tooth resembles Microcetus hectori (a taxon currently being redescribed by Yoshi Tanaka). There are some tusk-like teeth that were found loose - almost all of the Oligocene odontocetes from NZ appear to have had procumbent tusk-like anterior teeth. Provisionally the skull is similar to odontocetes that have been identified previously as "dalpiazinids". It should be a beauty when preparation is done![...]



How should we report the age of fossils? Pitfalls and implications for paleontologists.

2014-10-14T20:52:36.521-06:00

A few years ago during a talk I was watching at a conference (the details are better left unstated), I realized that there is quite a variety - both in terms of methodology (or lack thereof) and quality of format - of ways to report the geologic age of fossils. Ever since I have wanted to write up a post since the topic has been nagging at the back of my mind. Paleontologists often frustrate geologists for poor understanding of certain major geological principles - something I never really understood when I was an undergraduate student; at Montana State U., we had a pretty strong background in geology. Further to the point, my undergraduate Dave Varricchio is a specialist in taphonomy, and hammered into our poor little heads the importance of geology in our field - which was subsequently galvanized by a master's thesis in the subject, my adviser for which was (gasp!) a sedimentologist (Jim Schmitt). After attending various conferences, however, statements about geology and taphonomy in various talks have left me slack-jawed, and I unfortunately understand why paleontologists get ribbed about it. I'll start by saying this:  we study fossils because they give us unique insight into the history of life on earth, and we risk missing the true impact of paleontological data if we are careless about it. Now that that's out of the way, here's some of the topics I'm going to touch on: 1) basics of geologic age, 2) sources of age data, 3) recently proposed best practices for reporting ages for molecular clock data, 4) dates from the paleontologic and stratigraphic literature, 5) pitfalls of the paleobiology database, and 6) some suggestions for how to present age data for paleontologists. I'll try to keep this informative and useful instead of a rant, but there will be specific points where I just won't be able to help myself. As a quick note: while I am perhaps conversant in stratigraphy and geology, I am by no means an expert (I spend far more time looking at bones!), so anybody who knows better than I do - if you have anything to add to this, whether it be corrections, hate mail, tweaks to suggestions or even additional suggestions - your input can help improve this. Basics of Geologic AgeI think that since this blog attracts readers with a wide variety of experience, some very basic geology is worth retreading what some have probably/hopefully read elsewhere. The geologic time scale was first assembled during the early 19th century in western Europe primarily based upon biostratigraphy. Pioneering geologists like William Smith used index fossils to identify zones that he identified as being the same age, and in 1815, Smith published the first large geologic map - looking at the beautifully exposed bands of strata in England, it's no wonder it formed the basis for the early understanding of geologic time and stratigraphy.Charles Lyell introduced the terms Paleozoic, Mesozoic, and Cenozoic, to replace the Primary, Secondary, and Tertiary "periods" (as they were known then; Tertiary is the only one that lingers on). Lyell also introduced epoch divisions for the Cenozoic, and coined the epochs Pliocene, Miocene, and Eocene - at first, these formed the only divisions of the Cenozoic. Eocene roughly translates to "new dawn", referring to the dawn of the "new" Cenozoic invertebrate fauna; Miocene translates to "less new" and Pliocene as "more new", and the latter roughly means "continuation of the recent", referring to the relatively "young" aspect of the invertebrate fauna. These epochs were originally defined by Lyell based upon what percentage of invertebrates wer[...]



The evolutionary history of walruses, part 4: the odobenines and the evolution of the modern walrus

2014-10-07T14:41:29.476-06:00

“The Walrus (Trichechus rosmarus) is a very fat, clumsy brute, much uglier than his picture, with a coarse, oily skin all wrinkled and scarred; long, protruding tusks; bristly whiskers and scuffling flippers that barely serve to move his bulky body over the land. In the water he is more at home, and though it does not require a high degree of strength and skill to dig clams, that being his daily occupation, yet he is able to keep very fat on the fruits of his industry and has much leisure to swim about or doze on ice floes and sea beaches.” – Dane Coolidge, Birds and Nature 10:2, September 1901First introductory note: I have varied so far in writing in a chronological order in terms of the history of research or phylogenetic order (e.g. up the cladogram one node at a time). However, because the majority of non-odobenine odobenids (e.g. “Imagotariinae” and Dusignathinae) were not recognized as walruses until the 1970’s, only the odobenines were recognized as walruses during the early history of fossil walrus research. Because of this, the story of odobenines can largely be told in chronological order.Second introductory note: This is by far and away my longest post ever on coastal paleo, so bear with me – save a half hour, or bookmark the page and come back. More has been published on odobenines than the rest of the odobenids combined, so there is quite a lot to summarize – and I think it’s quite a fascinating story.The unfortunate taxonomic history of AlachtheriumThe first fossil walrus was described in the mid 19th century by Du Bus (1867) and named Alachtherium cretsii based upon a well-preserved mandible from the lower Pliocene Scaldisian sands of Belgium. This mandible shares several features with modern Odobenus including an elongate mandibular symphysis and small coronoid process, a lower canine that is reduced to the same size as the cheek teeth, and incisors that are positioned anterior to the canine and in line with the toothrow (rather than medial to the canine). However, the mandible differs in its much larger size, having an upturned and unfused symphysis, and primitively retaining a fourth lower premolar (lost in Odobenus, which only has p1-3). Van Beneden (1877) later referred a partial braincase and humerus to the species, but Rutten (1907) thought the braincase and mandible were incompatible and erected a new taxon for the braincase, Trichechus antverpiensis*. This braincase is also larger than modern Odobenus rosmarus, and differs principally in having a rectangular dorsal margin in posterior view. Further unnecessary complications arose when Hasse (1910) described some partial skulls and postcrania of several individuals from the slightly younger, upper Pliocene Merxemian sands, which he named Alachtherium antwerpiensis (note: antverpiensisversus antwerpiensis) as he also considered the new material incompatible with the type.*Note that early workers often included walrus in the genus Trichechus, which is the genus that the manatees belong in; most recent works do not discuss the errors of earlier workers, and a bit of searching on google has failed to enlighten me any further. I assume that superficial similarities such as blubber and a short muzzle as well as bottom feeding contributed to the confusion of earlier workers. However, Linneaus originally got it right by naming the species Phoca rosmarus – obviously not a phocid in the modern sense, but Linneaus placed practically all pinnipeds within the genus Phoca, so at least he recognized the pinniped affinities of the walrus.Beautiful illustration[...]



The evolutionary history of walruses, part 3: double tusked walruses - the dusignathines

2014-09-10T18:17:13.145-06:00

The fossil that started it all - the weird holotype mandible of Dusignathus santacruzensis. In the 1920’s, a rather strange pinniped fossil was collected from a cliff near the Santa Cruz wharf. In 1927, the fossil – including a fragmentary skull and a well preserved pair of mandibles – was described by preeminent marine mammal paleontologist Remington Kellogg (the same guy who described Allodesmus, Neotherium, and a ton of fossil cetaceans) as Dusignathus santacruzensis. The name Dusignathus means “jaw of the setting sun”, referring to the occurrence of this fossil on the west coast. Dusignathus santacruzensis was originally thought to represent a strange sea lion; the fragmentary skull shows that Dusignathushad a low sagittal crest, procumbent but gracile upper canines (later suggesting to other workers that the type specimen is a female), single rooted teeth with simple bulbous crowns, and a robust mandible with a procumbent canine, short lower toothrow, and an enlarged flange for the insertion of the digastric muscle. Furthermore, the mandible of Dusignathus santacruzensis is unique amongst pinnipeds in having the left and right canines nearly contacting medially, and having the left and right mandibles diverge from the chin at a relatively wide (60˚) angle. Because of its incompleteness, Dusignathus continued to be enigmatic for another 50 years until Repenning and Tedford (1977) published the pinniped bible. Thanks to the realization that other fossil pinnipeds like Neotherium and Imagotaria were early sea lion-like walruses, Repenning and Tedford (1977) identified Dusignathus as another walrus, albeit a stranger one. However, in 1962, Ed Mitchell described a partial forelimb (from the type horizon of Dusignathus) with very robust ulna and radius which he identified as an unknown walrus; this specimen was later identified by Repenning and Tedford (1977) as possibly representing Dusignathus santacruzensis. They also referred some isolated Imagotaria-like bones from the Purisima Formation to Dusignathus, and subsequent discoveries of associated postcrania from the Purisima Formation and the St. George Formation near Crescent City have confirmed the referral of these postcranial elements (more on that in the future). Repenning and Tedford (1977) erected the subfamily Dusignathinae, in which they included Dusignathus, Imagotaria, and Valenictus.The first cranial restoration of Dusignathus santacruzensis, from Mitchell (1975). Compare this with the updated reconstruction provided below, in which I based missing skull parts and proportions on more complete material of Dusignathus seftoni.Mitchell's (1962) walrus forelimb from the Purisima Formation at Santa Cruz, which now appears to actually represent Dusignathus santacruzensis (based on unpublished studies by yours truly).In 1980, a gigantic walrus skeleton was discovered in exposures of the Capistrano Formation in the city of San Clemente in Orange County, California. This large walrus was named Gomphotaria pugnax in 1991 by Larry Barnes and Rodney Raschke – it roughly means “pugnacious bolt-toothed sea lion”. The type specimen of Gomphotaria includes a nearly complete, 40 cm long skull (2/3 the size of Pontolis magnus) with a large, California sea lion-like sagittal crest that would’ve given the animal a domed forehead in life, a pair of enormous but short and procumbent (e.g. nearly horizontal) tusks, single rooted and highly abraded cheek teeth, and a robust lower jaw with enlarged, procumbent lower tusks. That’s right – Gomphotaria h[...]



The evolutionary history of walruses, part 2: the larger imagotariines: Pseudotaria, Pelagiarctos, Imagotaria, and Pontolis

2014-11-03T18:43:27.588-07:00

The previous post dealt primarily with the earliest diverging walruses – generally speaking, these were the smaller-bodied “imagotariines”. The “Imagotariinae” is a paraphyletic grade consisting of stem-walruses, and existed during the middle and late Miocene. The earliest diverging imagotariines detailed in the previous post include Prototaria, Proneotherium, Neotherium, and Kamtschatarctos. More derived imagotariines include Pelagiarctos from the middle Miocene of California, Pseudotaria muramotoi from the late Miocene of Japan, and Imagotaria downsi from the late Miocene of California and Oregon. Another problematic walrus is the giant Pontolis magnus from the late Miocene of Oregon, which may be an imagotariine, or possibly a dusignathine walrus – but will be discussed here rather than the next post on dusignathines.Although small-bodied enaliarctine-like imagotariine walruses like Prototaria and Proneotherium are the earliest diverging walruses, the larger-bodied and later diverging walrus Pelagiarctos actually constitutes the earliest record of the family. Specifically, the mandibles of Pelagiarctosthat Morgan and I published on in PLOS One (Boessenecker and Churchill, 2013) are from the “Topanga” Formation of Orange County, which is 17.5 Ma at the oldest, and thus either the same age as Prototaria from Japan and Proneotheriumfrom Oregon, or slightly older. This suggests that when they first appear in the early Middle Miocene, there were already three genera of walruses and already a bit of size disparity. The holotype skull of the imagotariine Pseudotaria muramotoi from the late Miocene of Hokkaido, Japan. From Kohno (2006). Despite its smaller size and earlier diverging position on the cladogram, Pseudotaria muramotoi appears about 5-7 million years after Pelagiarctos, and was reported from the late Miocene of Hokkaido by Dr. Naoki Kohno (2006). Pseudotaria is intermediate in morphology and geochronologic age between the middle Miocene Neotherium and the late Miocene Imagotaria downsi. The holotype skull of Pseudotaria lacks the front of the rostrum and has no teeth, but is otherwise characterized by a wide and slightly arched palate, double-rooted cheek teeth, a braincase with a rounded lateral margin (e.g. lacking a box-shaped braincase of earlier odobenids and enaliarctines). Pseudotaria is more derived than Neotherium in the loss of a third root on the upper first molar, the loss of a furrow on the lateral side of the braincase corresponding to the pseudosylvian sulcus of the brain, and a slightly arched palate. However, more derived odobenids differ in having a wider and pentagonal basioccipital, and by lacking an upper second molar. Another imagotariine from the same formation representing a new genus is currently being described by my labmate Yoshi Tanaka and Dr. Naoki Kohno.Specimens of Pelagiarctos sp. from the "Topanga Formation" (A) and Pelagiarctos from the Sharktooth Hill Bonebed (everything else).Pelagiarctos is known only from a handful of specimens – the holotype of Pelagiarctos thomasi is a fragmentary “chin” consisting of left and right mandibles with poorly preserved teeth from the middle Miocene Sharktooth Hill Bonebed, collected by LACM head preparator Howell Thomas. Barnes (1988) also referred a handful of isolated cheek teeth to Pelagiarctos. Pelagiarctos thomasi is large – at least the same size as Imagotaria if not somewhat larger – and with noticeably larger cheek teeth than Imagotaria. Pelagiarctos thomasi is unique am[...]



The evolutionary history of walruses, part 1: Introduction, and the earliest walruses

2014-08-20T06:07:41.853-06:00

Note: A bit of a disclaimer is necessary. This will probably be one of my most indulgent post series, as this is probably my most favorite topic in paleontology. Walruses are a totally weird and fascinating group to study, and I hope some of my enthusiasm for these fantastic blubbery beasts shines through.IntroductionThe walrus (Odobenus rosmarus) is one of the most peculiar and charismatic of all modern mammals, and easily the most distinctive of all pinnipeds. The modern walrus is characterized by its great bulk and most obviously by its large tusks; currently the walrus is restricted to the Arctic region, inhabiting the coasts of Greenland, Baffin Island, and Northern Quebec in the Northwestern Atlantic region, Svalbard, Novaya Zemlya, the Barents Sea, and the Laptev Sea in the Arctic region, and the Chukchi Sea and Bering Sea around Alaska and the Anadyr Peninsula (Russia). The modern walrus feeds predominantly on mollusks, and uniquely feeds by placing the shell inside its lips and sucking the muscle tissue directly out of the poor little clam: the shell never enters the mouth, and the teeth are not used at all during feeding. Instead, the highly vaulted palate of the walrus permits the muscular tongue to act like a powerful piston as it is retracted. It also allows the walrus to jet out water onto the seafloor to uncover individual mollusks during foraging. The walrus is otherwise unique amongst pinnipeds by routinely mating in the water; unlike many other pinnipeds, the walrus also is flexible when it comes to where it hauls out – it can haul out on icepack or rocky beaches. Many other pinnipeds only haul out on a certain substrate, whether its sand (e.g. NZ sea lion, elephant seals), rocky shore (NZ fur seal), or ice (most arctic and Antarctic true seals). Most famous of all, however, are the spectacular tusks of walruses – greatly enlarged upper canines that are so long they protrude eternally from the animal’s mouth. What did tusks evolve for? A few studies have advanced various hypotheses, and the evolution of tusks will be considered in a later post in this series.A somewhat outdated hypothesis of walrus relationships (from Barnes et al., 1985) - however, this figure is still informative, and is one of the only cladograms labeled with anatomical illustrations. I'm currently working on enough skull illustrations to make a modern version with an updated phylogeny. Notably absent from this phenogram are true seals, which were left out in the spirit of pinniped diphyly. The most up-to-date hypothesis of walrus phylogeny, showing many of the interrelationships amongst the Odobenidae. For the purpose of this blog post, note the basal position of Prototaria, Proneotherium, Neotherium, and Kamtschatarctos. From Boessenecker and Churchill (2013).Lastly, the phylogenetic relationships of walruses have proved contentious. Although the relationships within the family Odobenidae are fairly well resolved (compare the cladistic results of Deméré, 1994, Deméré and Berta, 2001, Kohno, 2006, and Boessenecker and Churchill, 2013), the relationships of the family to other pinniped clades has been a major point of debate, if not a source of ideological schism within pinniped paleontology (an admittedly small subdiscipline). Traditionally, walruses have been placed into a clade called Otarioidea including all pinniped groups except for the Phocidae; Otarioidea (or a much more taxonomically inclusive Otariidae of some authors, e.g. Mitchell and Barnes) would [...]



Farewell to Mike Gottfried - annual NZ research visit

2014-08-19T05:17:56.643-06:00

Today is visiting paleoichthyologist Dr. Mike Gottfried's last day on his research visit to our department. Mike comes down to New Zealand once a year during the southern winter to collaborate on various research projects with Ewan. Prior projects have resulted in the description of an associated dentition and vertebral column of the giant shark Carcharocles angustidens, the giant moonfish Megalampris keyesi, and the billfish Aglyptorhynchus hakataramea.


Mike's current visit has been to identify Paleogene sharks and fish collected during the Lost Mammals of Zealandia project, in addition to describing a new genus and species of Cretaceous-Paleogene tarpon from the Chatham Islands (in tray in photograph). It's always a pleasure to have Mike down here, least of which because it's always nice to commiserate with another Yankee, but also nice to have someone to talk about fossil sharks. I'll be graduated before Mike's next visit to New Zealand, so farewell Mike! Have fun stateside.(image)



New publication: phylogenetic relationships of fur seals and sea lions (Otariidae)

2014-08-19T05:54:55.015-06:00

Last week saw publication of a new study by Morgan Churchill, Mark Clementz, and myself, which presents a new cladistic analysis of the pinniped family Otariidae (Morphobank account/matrix available HERE) - known informally as fur seals and sea lions. I've been fascinated with fossil otariids since I started research on a specimen of the Pliocene dwarf fur seal Callorhinus gilmorei from the Rio Dell Formation in Northern California. This collaboration has been about two years in the making, and began shortly after we started work on the Pelagiarctos study published last year in PLOS One.There are about 13-16 species of modern otariids in 7 (or 8) genera - 9 of which are fur seals in the genera Arctocephalus (some may be Arctophoca) and Callorhinus. Fur seals are generally smaller-bodied than sea lions, and are primitively characterized by retaining dense underfur - whereas sea lions have a thicker blubber layer, only possess hair (as opposed to underfur) and are generally much larger. Modern otariids are externally very similar, and it can be very difficult to tell them apart. Fur seals (with the exception of the Northern Fur Seal Callorhinus ursinus which has a distinctive snout shape) in particular are nearly impossible to tell apart externally, and identifications of osteological remains are often made based upon the geographic location as few geographically overlap with one another. Different species of Arctocephalus are nearly identical in skull morphology - however, sea lions are more morphologically distinct from one another. For example, California sea lions (Zalophus californianus) have a huge sagittal crest but an otherwise Arctocephalus-like skull, and the Steller's sea lion (Eumetopias jubatus) and New Zealand sea lion (Phocarctos hookeri) have a "domed" forehead. The Australian sea lion (Neophoca cinerea) has an unusually robust intertemporal region, while the South American sea lion (Otaria byronia) has a very elongate palate, procumbent upper third incisors and canines, and rugose tubercles on the side of the braincase (an elongate palate is also present in Phocarctos).Relative to other pinnipeds (walruses, Odobenidae, and true seals, Phocidae), otariids primitively possess external ear pinnae (the type genus Otaria comes from the greek Otarion, meaning little ear, the most adorable name possible for such an intimidating monster as the south american sea lion), and can rotate their hindflippers forward and walk when on land - walruses are capable of this type of terrestrial locomotion as well, but true seals have an ankle that is more extremely adapted for swimming and can no longer rotate forward. The result is that their feet are permanently extended posteriorly - the same motion your ankle makes when standing on on your tiptoes. The long wing-like forelimbs of otariids permits underwater flying, in a manner reminiscent of bird flight.Pinniped phylogeny of Barnes et al. (1985). Note that true seals are notably lacking from this hypothesis: most studies of pinniped evolution prior to the late 1980's were done under the now-outdated paradigm of pinniped diphyly.Modern hypotheses for fur seal and sea lion relationships began under the assumption of pinniped diphyly, and this idea is pervasive in practically all papers on pinniped evolution published between 1960 and 1987 - while the idea has mostly faded away, a few paleontologists adhere to the idea. Effectively, pinniped diphyly maintains[...]



Holotype worship and the Hypodigm

2014-08-15T20:29:52.556-06:00

I thought a short essay on the treatment of holotypes would be worthwhile. In zoological sciences, many of us are involved in describing and naming new species - in order to maintain taxonomic stability, a type specimen must be designated in a new publication naming a new species. In plain english, the type specimen - also known as a holotype - is the specimen demonstrating the physical evidence for which a new species is named upon. Often when a new species is discovered, researchers will leap to name it - so often, we're stuck with a species named upon a single specimen. It happens frequently in paleontology; finding good fossils is (often) more difficult and more dependent upon sheer luck than going out and finding a second specimen of a newly discovered modern species. As a result, much of the vertebrate fossil record is composed of "singletons" - fossil species represented by single specimens. This problematic nature of the vertebrate fossil record is a favored talking point of young earth creationists, and has also unfortunately contributed to the bizarre opinion amongst some radical cladists that ancestor-descendant relationships are impossible to determine in the fossil record. Radical ideas by folks such as Nature editor Henry Gee come to mind, who rejects all non-cladistic methods in paleontology as being unscientific - an easy position to take if used to the fragmentary vertebrate record of singletons, but difficult to maintain in the face of the enormous and densely sampled record of fossil invertebrates (mollusks and foraminifera come to mind, in which non-cladistic methods can identify speciation events and bouts of anagenesis in vertical successions of fossil assemblages).The typically fragmentary nature of the vertebrate fossil record, and dealing primarily with singletons, can lead one astray. Subdisciplines divorced from extant relatives and flooded with researchers who do not really look at modern species to get an idea of morphological variation  - dinosaur paleontology comes to mind - may be dominated by an overabundance of taxonomic "splitters" (disclaimer: I have many friends who are dinosaur paleontologists and have a rather sober idea of morphological variation). For the uninitiated, splitters are researchers who tend to name more species than is probably likely; the opposite are "lumpers", who tend to lump species together into a more reasonable framework of fewer names. Many in biology prefer to use a third but unnamed category for the middle ground - I do not, as I consider the "lumper" category the middle ground, and "extreme lumpers" to be on the other end. One marine mammal related example of an extreme lumper is work by Caretto (1970) who lumped all known fossil balaenopterids into a single subspecies, including fossils now known to likely represent several genera. Most "lumpers" I know tend to use morphological variation in related extant species as a tool for interpreting species-level identifications/naming in the fossil record, which sounds reasonable ("eminently sensible" as my adviser would say) - and so I consider anyone reasonably taking a middle ground approach to fossil identification/naming a lumper (versus an extreme lumper).Many smaller subdisciplines dominated by just a handful of researchers working more or less "unopposed" (i.e. without professional rivals to rigorously dispute work) may be plagued by splitting until some you[...]