Third SeAVP meeting, Day 1

The third annual meeting of the Southeastern Association of Vertebrate Paleontology got underway this morning, hosted by the South Carolina State Museum in Columbia, SC. Jonathan Mitchell and Andrew Heckert presented the first talk of the day, on a fascinating archosauriform called UatchitodonUatchitodon, which is known only from teeth, was first described from Triassic sediments at the Tomahawk Creek site near Richmond, Virginia in the early 1990s. It has since been found in Chinle deposits in the western United States, and Mitchell and Heckert reported them from the Deep River Basin in North Carolina. The really cool thing about Uatchitodon is that the teeth have grooves for injecting venom; it was poisonous! Mitchell and Heckert showed that the North Carolina and Virginia Uatchitodon are likely different species, and that probably all the teeth in the mouth had venom channels (not just the front teeth).

Steven Wallace spoke about the affinities of a machairodont cat jaw from the Bone Valley site in Florida. The jaw was originally referred to the genus Megantereon, but Wallace thinks it represents some other taxon, perhaps Machairodus itself (Machairodus skull at the top, on exhibit at AMNH). This talk is a good example of how small esoteric details can have much broader importance. The identification of this specimen as Megantereon or not affects hypotheses about what continent sabre-toothed cats evolved on and how they dispersed to other areas.

The next two talks concerned paleontological techniques used for studying fossils. Richard Hulbert and Sari Sanborn examined the usefulness of rare earth element (elements 57-71 on the periodic table) dating on Pliocene and Miocene deposits in Florida; this is a relatively new dating technique that has mostly been used on younger sediments. Brian Beatty and Matthew Mihlbachler looked at techniques for studying microwear on tooth enamel, and specifically how that applied to sirenians (manatees and dugongs). Unlike land herbivores, in which scratches are largely controlled by the type of plant material eaten, in sirenians different microwear patterns seem to be largely controlled by how much and what type of sediment is taken into the mouth during feeding. Dugongs (like the one below from AMNH) primarily feed on seagrass rhizomes and have lots of scratches while manatees (below the dugong) tend not to root around in the sediment as much and show fewer scratches. Moreover, changes in the types of microwear in Florida sirenians since the Miocene might be due to environmental changes over the same time.

I gave the next talk, which was an overview of all the cetacean (whale and dolphin) species found at Carmel Church so far. I’m not going to go into great detail about my talk right now, since I’ll be discussing all these things in their own blog posts, but in summary we now have a total of 17 cetacean species from the Calvert Formation at Carmel Church (there are more in the St. Marys Formation). These include at least 5 mysticetes (baleen whales) and 12 odontocetes (toothed whales/dolphins).

In the next talk, Alan Coulson tackled the daunting task of using oxygen isotope ratios to determine water temperatures in the Western Interior Seaway (WIS), the inland sea that divided North America in half during the Cretaceous Period. Part of the difficulty with this technique is that you have to calibrate your measurements by knowing the “normal” oxygen ratios for the time in question; by seeing how the ratios deviate from this baseline, you can calculate paleotemperature. But how to determine the baseline? Coulson used oxygen ratios in sea turtle bones (such as Archelon below, from NMNH) to determine the base ratio (after showing that modern turtles could be used for this). His results suggested that the water in the southern WIS were around 18-19 degrees C (64-66 F), but the temperature rapidly decreased to the north.

Laura Gilmore and Steven Wallace presented a talk on injuries suffered by a specimen of the rhinoceros Teleoceras hicksi from Gray Fossil Site (another GFS Teleoceras is shown below).

They suggested that the nature of a rather severe rib injury in their specimen indicates that Teleoceras didn’t possess a sharp horn like the white rhino Ceratotherium (below):

Instead, it may have head-butted without a horn, or perhaps with a blunt horn like that in the Indian rhino Rhinoceros:

But perhaps the most interesting injury on the GFS Teleoceras was a crushed toe on the back foot. Gilmore and Wallace proposed that their specimen was a male, and that the toe injury may have occurred during mating when the female stepped on the male’s foot.

Andrew Heckert, Jonathan Mitchell, and Vincent Schneider presentedon the microvertebrate fauna from the Moncure Site in the Deep River Basin, the same North Carolina site that produced the Uatchitodon teeth. They recovered 50,000 vertebrate fossils from just 25 pounds of sediment, of which about 90% were fish scales. The remaining 10 % included a variety of archosauriforms and synapsids, as well as the Newark Supergroup’s first lungfish.

Alex Hastings, Jonathan Block, and Carlos Jaramillo presented on a new dyrosaurid from the Paleocene of Colombia (the same site that produced the giant snake Titanoboa). Dyrosaurids were gharial-like (at least in this case) crocodilomorphs that apparently originated in Africa and then spread into the Americas during the Cretaceous.

In the last talk of the day Patrick Hawkins and Steven Wallace presented a talk extolling the virtues of collecting roadkills and deceased zoo animals for both soft tissue studies and comparative bone collections. I’ve collected some roadkills in my time, but never black bears like the ones in this talk!

We have a few more talks in the morning, and then the poster session. With a fairly light schedule tomorrow, I’m hoping to get a chance to see some the museum exhibits.

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3 Responses to Third SeAVP meeting, Day 1

  1. Doug says:

    Sounds like some great stuff. I’ve been waiting for this since you first put up the logo on the main page.

    Interesting about the rhino. You’d think they’d be fighting with those lower incisors (looking like a prehistoric forklift).

  2. Alton Dooley says:

    Apparently those lower teeth are sexually dimorphic, so they may have been doing some fighting with them.

  3. Nick Gardner says:

    It would be fascinating if we could only find more remains of the animal that Uatchitodon teeth belong to. 😉

    Dyrosaurids, and their maybe close relatives the pholidosaurids, are very interesting crocodyliforms indeed Alton.=D

    Depending on whose phylogeny you refer to however would probably have an affect on their divergence date. For instance, Jouve (2009) reconstructs this part of Neosuchia with Stolokrosuchus as the basal most member of the clade, then dyrosaurids, then pholidosaurids, and then thalattosuchians. Pholidosaurids and thalattosuchians date back to the middle jurassic, so there’s a heck of a ghost lineage going on here back for these taxa. Sereno and Larsson (2009) recovered goniopholids as basal members of the longirostrine clade, but excluded thalattosuchians from Metasuchia and Stolokrosuchus was recovered as a peirosaurid, either way you’re looking at a MJ-LJ divergence from other crocodyliforms…. so there’s a whole lot of aquatic croc fossils out there waiting to be found in this part of the tree (and we’re not even going to talk about the other parts of the tree that have similarly long ghost lineages) Lol =o

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