Tuesday, May 1, 2018

Paleofest 2018 Report

Two months ago, I had the privilege of attending Paleofest, the yearly Paleontology symposium at the Burpee Museum in Rockford, Illinois. The Master of Ceremonies remains Scott Williams, now at the staff of the Museum of the Rockies, and once again there was an excellent variety of speakers. There was no particular theme this time, predominantly dinosaurs but with a fair amount of other paleolontology.  While there was mostly American paleontology, other continents were represented in some talks. Unfortunately, my camera malfunctioned, so if you want pictures, please contact my and Scott’s friend Todd Johnson for his excellent photojournalism.

The talks started with David Evans of the Royal Ontario Museum talking about Zuul, a new, perfectly preserved ankylosaur described by him and his ROM compatriot and ankylosaur expert Victoria Arbour. It is by far the most perfectly preserved ankylosaur, found in the Upper Bearpaw shale. This would mean it would be part of the Judith River fauna 75 million years ago. It was found by fossil collectors in a quarry-as they excavated a Gorgosaurus skeleton, they found this fully articulated fossil.  Over 20 feet long, this relative of Euoplocephalus and other ankylosaurs was named after the demon Zuul from the film Ghostbusters.

The next talk by Amy Atwater of the Museum of the Rockies. Unlike most of the MOR experts, she studied early American primates. Specifically, it’s a study of Onomyids, tiny relatives of today’s tarsiers. Known from mostly teeth, these animals like todays tarsiers are closer to true monkeys than the lemurlike Adapids. She made a survey of these Omomyid microfossils from the Friars Formation, a Uintan age formation near La Jolla. In her survey, she identified three related but distinct species, possibly even different genera based on jaw and tooth material.  She proposes that as the Adapids declined in the Uintan (starting 45 million years ago), the populations of Omomyids diversified and speciated.

As usual, there is a talk on Tyrannosaurus. This one by Ada Bailleul covered jaw hinges-specifically the otic joint. In extant archosaurs, this joint is a ball-and-socket construction but differs in histology.  For the stiff jaws of crocodilians, there is only one side of the joint covered in cartilage, and fiber connects it to the other joint. For the emu, both sides have cartilage surrounding the bone, but fiber still connects them. Finally, for ducks, not only do both sides have a cartilage coat, but instead of fiber there is a fluid allowing for even more flexibility. The histological study of the B.rex specimen reveals that Tyrannosaurus had cartilage covering both sides of the join, but whether fiber or liquid connected them has yet to be revealed. 

Jumping back to the Permian and Triassic, Brandon Peecook of the Field Museum investigated the early diapsids.  True reptiles in the Permian are represented by herbivores, the giant armored pareiosaurs and the lizardlike hook-snouted capitorhinids. FMNH expeditions to Tanzania reveal a massive fossil gap, however, in terms of archosaurs and lepidosaurs between Permian and Triassic times.  This isn’t just in Tanzania, but also in South Africa and Russia despite their own fossil richness. Conventional wisdom simply would imply them being too rare, but what if there is a geographic bias? Turns out our Permian knowledge comes from subtropical and temperate regions-perhaps the synapsids evolved endothermy first which would restrict the early reptiles to the tropics. As it turns out, the only large archosauromorph in the Permian is Protorosaurus, a lizardlike animal from Germany. In Italy, a trackway of a similar animal is called Prochirotherium. Since Central Europe was in a tropical region during the Permian, this would mean that the diapsids were indeed restricted to the tropics until the end of the Permian. 

Another nondinosaur talk focused on Trilobites. Thomas Hegna of Western Illinois University wanted to find Trilobite eggs. While the oldest eggs have been found from the Precambrian, and even arthropod eggs were discovered from the Cambrian, no trilobite eggs were reported.  One researcher even proposed they were asexuals who budded like cnidarians.  However, finds from the Whetstone Gulf Formation (Ordovician age) in New York show special preservation: this rock indicates it was the bottom of the ocean, a low oxygen environment that preserved the animals perfectly. Not only is the preservation excellent, but the way the minerals formed ensured that the fossils turned into pyrite crystal. So we have fossils of Triarthus not only made of Pyrite, but with eggs fossilized in pyrite. As in their closest living relative, horseshoe crabs, trilobites spawned their eggs in their “headpiece”. It seems that Triarthus may have brooded its eggs and hatchlings, so that it would have a better chance of being fossilized with its eggs.

Eva Koppelhus of the University of Alberta did her talk on late Cretaceous ferns of Antarctica. Since paleobotany is a weak point of mine, I’m afraid I don’t have much in the way of notes, only that by the end of the Mesozoic, ferns had evolved into the same physiology as today’s ferns. While angiosperms did exist in Antarctica at the time, the flora was predominantly ferns, indicating a very wet environment despite the seasonal chills.

Fortunately, the next talk was much more interesting. Evalon Hekkala from the American Museum presented a study on the crocodiles of Madagascar. The crocodiles of Africa have for a century only been classified as a single species: Crocodylus niloticus. In Madagascar, two species were recognized by naturalists: the extinct Crocodylus robustus (Called Mamba by the Malagasy) and the extant Crocodylus madagascarensis (called Voay). Brochu had classified robustus as a new genus, Voay. However, genetic testing was finally done in 2004 to reveal that the African Crocodile is actually two species: C. niloticus in East Africa and the Nile, and C. suchus West Africa. In ancient times, the Egyptians recognized them as two different animals, worshiping the tamable C. suchus and fearing the aggressive C. niloticus. Only the suchus species is mummified. Hekkala took these findings into account while looking up the Madagascar species: she discovered via genetic testing that while robustus did exist as a distinct species, it was still within Crocodylus, while C. madagascarensis is an invasive group of Nile crocodiles. It seems at C. niloticus has evolved more recently and has been genetically swamping the other African crocodiles.

The day ended with a treat: Phillip Currie, founder of the Royal Tyrell Museum, discussed the widespread but mysterious dromaeosaur Saurornitholestes. The first specimen was simply a frontal bone of the skull, a handful vertebrae and ribs, and scattered teeth found by Irene Vanderloh and described by Hans Sues. A new specimen, identified as UALVP 55700 shows more of the animal than before-the maxilla is diagnostic, proving it indeed that genus. The teeth are unique, distinguishing it from Atrociraptor and Dromeosaurus. The old tooth taxa Paronychodon proves to be Saurornitholestes, and while Saurornthiolestes is more widespread, in terms of teeth Dromeosaurus is far more common. Like many other subfamilies with more than one genus present in Dinosaur Park, it seems that there was dromaeosaur niche partitioning.

The next day started off with Cary Woodruff from the University of Toronto talking Pachycephalosaurs. As he pointed out, they have a plain body but an extraordinary head. Relatives of the ceratopsians, they ranged North America and East Asia from the Santonian to the end of the Cretaceous. The tail is unique, showing parallel evolution with the ornithopods-while the ornithopods have ossified tails with stiffening bone rods, pachycephalosaurs had strong fibers surrounding the caudal vertebrae. The Dome is made of the frontal and parietal bones. Unfortunately, Woodruff agrees with Horner and Longrich’s truly bad ideas about pachycephalosaurs: that the thick domed skulls were equivalent of the wide, long, thin frills of ceratopsians and used only for display, and that many species of Pachycephalosaurs were the same species. Both these points have long been pet theories of Horner, theories without much in the way of evidence or logic but are widely accepted anyway. 

Unfortunately the next talk was canceled, as Lauren Sallan was unable to make it. Thomas Carr picked up for her-of course this became about Tyrannosaurs. Carr once had an interesting hypothesis: Tyrannosaurus had a face covered in keratin. A microanalysis of the Tyrannosaur skull however has led him to a different, still debatable and controversial conclusion: the animal had gums around its teeth like that of a crocodile, with keratinized patches around nerves. This is a counterpoint to Larson and Reisz’s argument for lips covering the teeth. Either possibility has strong evidence and logic behind it, and it will be interesting to see what their further studies will reveal.

The next talk was far more interesting-Michael Habib of the University of Southern California reviewed material from the Four Corners region of the Southwest USA. He went on to describe two southern giants from the end of the Cretaceous: Quetzalcoatlus and Alamosaurus. The former, a giant pterosaur he memorably described as “Giant flying murder heads”, had a stronger neck, more flexible wing fingers, and a more far-forward center of mass than previously thought, and probably launched itself quadrupedally.  The latter, a giant titanosaur, had strong ossified neck tendons allowing for the cervical and neck muscles to lift the head high in the air. He concluded that the longer the dinosaur’s neck, the higher it could be lifted. This, combined with a more generous range of movement proposed by Mike Taylor and Matt Weddell, has solved an old question of sauropod biomechanics. Excitingly, some of this titanosaur material from New Mexico may yet prove to be a new species or even genus.

Lydia Tackett of North Dakota State University presented on invertebrates-namely predation’s effect on patterns of benthic (animals living on the bottom of the sea) evolution in the Triassic. After the Permian extinction finished off the trilobites and Eurypterids, brachiopods and crinoids bounced back. However, during the Norian period, there was a shift in biomechanics: static species gave way to those who either burrowed into the sand, could swim for short distances, or excreted organic “cement” to adhere themselves to the ocean floor. A study of shell damage in both extinct and extant shellfish reveals patterns of predation: ammonites often have holes corresponding to predation by other ammonites, while a study of living shellfish showed crabs to be more significant than other predators in driving shell thickness. Turns out, this sudden change coincided with new forms of predators: fish (semionotids and pycnodonts), reptiles (placodonts) and sharks (hybodonts) with durophagous adaptations in their teeth and jaws.  This Norian exploitation of shellfish almost 
certainly caused the prey animals to evolve new strategies.

The next talk was a step down-while ostensibly about the Carboniferous and Permian temperate marine fauna of Argentina, Kathryn Pauls of the University of Wisconsin-Milwaukee, it was more on the deposition and sedimentology. The fauna in question is mostly brachiopods, particularly small specimens. However, as the Permian went on, ice age pulses showed their effect-there was major silt deposition, the most common brachiopods went extinct, and  instead bivalves made up most of the fauna. The Permian extinction would finish off inarticulate brachiopods and deal the bivalve in turn a major blow, but the main insight from this talk was that even before the end of the Permian, there were several minor faunal extinctions. 

One of the most hotly debated questions in American paleoanthropology is which route the first humans took to get here. Anders Carlson of Oregon University challenged the popular argument that the Ice-Free Corridor never existed. In 1931, , W.A. Johnston proposed that there must have been a gap between the Cordilleran and Keewater ice sheets that allowed humans to pass from Alaska into the rest of the continent. Recently,   Knute Fladmark , Charles Schwege and Lionel Jackson have argued in their papers that this passage simply did not exist, and that the humans took a coastal route. 

Throwing more confusion is the fact that artifacts are inconclusive on when humans first appeared in the Western Hemisphere-they could have arrived anytime between 30,000 and 10,000 BC.  Duane Froese and Beth Shapiro have used bison fossils to propose that an ice-free corridor did indeed exist around 12,000 BC. What Carlson and his colleges have done is turn to geology-looking at the weathering and movement of the rocks in Western Canada by glacial movement and dating with Beryllium 10. They came to the conclusion that the corridor existed 17,000 BP. He further argued against the coastal route as a better route-the ice sheets that would have made passage in the interior would have extended into the coast and into the sea and made sea passage even more difficult.

Nadia Rasolofomanana of the University of Antananarivo was supposed to give the next talk, but unfortunately couldn’t get her visa cleared in time. Instead, her colleague Karen Samonds presented on their team’s findings in Madagascar. The Sambaina basin in the central Analamanga region has been previously unexplored for fossils, and the team probed it. A  last minute discovery thanks to the help of local farmers revealed that the muddy rice fields contained over a thousand fossils. While many contemporary marsh birds were found, such as Malagasy Pond Heron and Bernier’s teal, many extinct species were found with them, such as the Malagasy shelduck and the two genera of Elephant bird. However, 80% of the fossils belong to a single species: a hippo. Unfortunately which species is uncertain-according to some, there are three species of extinct hippopotamus in Madagascar, while others say they are all the same species. Even more confusing is the relationship between this animal and the mainland hippos, which have their own taxonomic controversies to even the generic level: hopefully someone will make a detailed study on the family to clarify the relationships. Crocodiles have also been found at the site, but likewise their species has yet to be determined.

The last talk for the year was by the legendary Thomas Holtz of the Smithsonian Institution and University of Maryland. This talk was on an extraordinary specimen found by the Burpee Museum and the Museum of the Rockies in a joint expedition. The specimen is named Pearl, an Anzu. Anzu was a genus first discovered in the 1990s, when Trielbold Paleontology assigned it to the known American animals Chirostenotes and Caegnagnathus. In 1998, two good specimens were found by Triebold and the Carnegie Museum. This animal joined the new fossil hall when the museum renovated in  2007, unnamed, but impressive. The  creature was finally named in 2014 by a team including Emma Schachner, Matthew Lamanna, Tyler Lyson, and Hans Dieter-Sues as Anzu wylei. 

This new specimen fills in the gap. The Caegnathids are rare and mysterious, known in both Asia and North Africa, first appearing in Aptian China and surviving to the late Maastrichtian, when Anzu lived. Oviraptorans are divided into two families: the shorter-legged, slender-jawed, more gracile Caegnathids and the classic Oviraptorans. The Caegnathids also tend to be larger-the largest Oviraptorid is Citipati at probably 300 lbs, but Anzu could have been up to 600 lbs, and the largest Caegnathid was the enormous Gigantoraptor at least 1500 lbs.  These animals seem to have been fond of wetlands like Hell Creek, where Anzu would have probably been prey for Tyrannosaurus and Dakotaraptor.  Oviraptorans are more derived than Therizinosaurs, Ornithomimids and Tyrannosaurs, but less so than dromaeosaurs, troodonts, and birds. They seem to have occupied a different niche than the Ornithomimids, coexisting with them despite being related omnivores. Hopefully Pearl and other oviraptors will fill in some of the missing parts of this mysterious group.

So, I thought for the most part, Paleofest was a great deal of fun-plenty of new discoveries, plenty of controversy and debate, and plenty of different topics. Hope the next one will be even better!

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