Paleofest Report 2019

Welcome back! It’s this time of year again where I go down the annual Paleofest Symposium, held every March at the Burpee Museum in Rockford Illinois. There’s always new discoveries, new experiences, and a lot of great talks about paleontology research. For further details, I once again recommend our MC Scott Williams, for tweets check out Dr. Thomas Holtz’s twitter, and for images ask Todd Johnson. Once again there’s no particular theme, but once again younger researchers and women researchers take the foreground on a wide variety of topics.

The first talk was by Aaron Van der Reest of the University of Alberta, on preserved dinosaur tissue. It was interesting to learn that not only do have that Tyrannosaurus’ bone marrow but earlier formations. An Ornithomimus was found not only with feathers (symmetrical but without barbules), but the keratin in the feathers survived in the fossil.  The Foremost, Dinosaur Park, Brazeau and Wapiti Formation were all examined. Dinosaur Park has Gorgosaurus and Laterivenatrix fossils with blood cells but without osteocytes (bone cells). The Brazeau formation does have a lot of osteocytes, while the Wapiti has a small amount but they are still present.  Frustratingly, we have yet to find out why these tissues preserve and why not in other geological layers. Hopefully further research will reveal why.

This was followed by a great talk by Denise Su from the Cleveland Museum of Natural History.  Her studies focused on hominin paleoecology, a subject very close to me and my academic background.  Laetoli, Tanzania is known for its footprints of Australopithecus, but the paleoecology was not yet studied. There is a mixed fauna of browsers and grazers, but grass species and bovid species indicate a dry grassy habitat-rabbits outnumber rodents, and the only aquatic animals are gastropods. This suggests a mosaic habitat of open parkland with ponds and streams. The sites of Hadar (home of Lucy) and Woranso-Mile not only have more Australopithecus remains and more species of Australopithecus, but the fossils suggest a much wetter environment. These sites, combined with microwear and carbon isotopes, suggest Australopithecus was a flexible generalist that preferred soft fruits in wet environments.

Carrie Levitt-Bussian’s talk was on the Kaparowitz Formation in Utah, and specifically the growth rates of the Chamosaurines found there. Ectotherms today like reptiles grow slowly and continuously through their lives, with adulthood slowing down the rate but never really stopping, while endotherms like birds have cyclical, fast growth, and both are shown in bone histology. I can’t reveal the details, but suffice to say we have a variety of different warm blooded but very different bone growth patterns from different species.

 Roy Plotnick’s talk was very different. Instead of existing fossils, he predicted current patterns of fauna and what the paleontologists millions of years from now would find.  He argued that humans would leave more fossils than artifacts, let alone very fragile history.  He noted that taphonomy bias such as the difficulty of upland and forest environments in preserving fossils, and estimated only 8% of all current species would be preserved. Using the mammal populations in Michigan, he used statistics to show biomass: the majority is humans, followed by livestock, then finally wildlife dominated by deer. Livestock would be preserved as middens and trenches, humans in cemeteries, although both environments would be vulnerable to later climate change that might interfere with fossilization. It was chilling but thoughtful.

My favorite talk of the day was from Ashley Poust from the University of California Berkley.  His talk was on Creodonts, a strange group of carnivorous mammals from 60-15 million years ago.  Hypercarnivores already existed in the Cretaceous, but as mammal prey got bigger, mammal predators also increased in size (the phrase “Sea going murder factories”  is used to apply to whales hilariously) . The focus was primarily on the Hyenodonts, as Oxyaenids are more obscure, rare, primitive and ill-defined.  Hyeanodonts, defined by 3 pairs of carnassials, ranging from weasel to rhinoceros size, reaching their apex in the middle and late Eocene, are in turn divided into the northern Hyeanodontidae and the African Hyainailuridae. In bone histology, we see two forms of growth: fast and disordered, or ordered and slow. Looking at 18 femurs, Poust found that the growth beings fast, then slows, slower than modern carnivores (but at the same rate as contemporary carnivorans), but in the same pattern. However, the Hyainailurids have even slower growth.  A new possibility raises its head: African hyenodonts are not related to the Hyeanodonts, but actually Afrotheres like Hyrax, Tenrecs, and Elephants! 

The next talk was also about mammals-in this case metatherians. Metatherians contain marsupials and their relatives, and existed in the Cretaceous period. North American metatheres, represented by mostly tooth taxa, went extinct in the K-Pg extinction, but their relationship with existing metatheres is still a mystery. Alexandria Brannick of the University of Seattle has recently found significant fossils however-excavating in Egg Mountain, a late Cretaceous site that gives paleontologists a great look into dinosaur behavior and environments in an upland environment, she has found significant material of Alphadon, . This includes a complete skull, as well as unpublished material that is suffice to say exciting. Brannick has concluded on these new finds that North American metatheres like Alphadon from the middle to late Cretaceous are actually closer to South American marsupials than contemporary South American metatheres as well as the Sparassdonts, a group of metatheres that evolved into large hypercarnivores during the Cenozoic. 

The obligatory invertebrate talk was by James Lamsdell of West Virginia University, looking spiffy in a Ravenclaw scarf. He argued that Eurypterids were model organisms, as they were well preserved and show very interesting patterns of evolution. Eurypterids, also called sea scorpions, are diverse (150 different species ranged in shape, ecology, and the size of a toothpick to the size of an alligator), variable, and well-preserved, with a robust and well-established phylogeny. They were the first arthropods with large pincers and claws, which were generalized in immature stages and specialized in maturity. They peaked in the Devonian, but the Devonian extinction caused the marine species to die out, succeeded by unrelated bottom-feeding freshwater groups in the Carboniferous: the tiny progenic (possessing adult traits immediately) Adelophthalmids and the giant neotenous  (keeping juvenile traits in adulthood) Mycteropoids.  Eurypterids are also an evolutionary transition-they have pseudotrachae like marine isopods, transitioning from true gills to book lungs used by terrestrial arthropods.  There’s new material that shows more revelations, but it’s unpublished. 

The last talk was by Jade Simon of the University of Toronto, about new Anzu material. This is such new material I am not permitted to reveal exactly what she found in terms of new oviraptorid material from Hell Creek. However, I did also learn about the differentiation between the clades of Oviraptors. Oviraptors are divided into Oviraptorids from Asia, and Caegnathids from both Asia and North America.   The difference is in their morphology and habitats: Oviraptorids are in dry habitats, with deeper mandibles and short metatarsals, and are overall more common, while Caegnathids have long flat mandibles, long metatarsals, are much rarer, and are more associated with wetlands.  The diet remains unknown-both carnivore, herbivory, and omnivory have been suggested. She revealed more, very exciting discoveries to boot, but they are not yet published. Just get excited.

The next day started out with a look at the neglected Chugwater fauna of Triassic Wyoming by David Lovelace of the University of Wisconsin.  The Late Triassic is abundant, with sites in Mexico to Canada, from California to Virginia. And yet the Chugwater basin remains the “Red bedded stepchild” of well studied locations Arizona-New Mexico Chinle formation and Texas’ Dockum formation.   The first fossils in Chugwater were invertebrate ichnofossils, joined by other footprints from Rauisuchians naad Rhynchosaurs. After 100 years of neglect, new finds reveal new phytosaur, metoposaur, and Dicynodont material. Phytosaurs in particular include well-preserved Palaeorhinus, which resembles basal animals. There are also mass mortality beds of Koskinonodon, giant predatory amphibians-interestingly enough, those at Chugwater are much smaller than the individuals elsewhere.  Finally, there are burrows-for decades these burrows found in Triassic rock were assumed to be tiny lungfish; however, these new finds reveal they were created by Triassic caecilians, limbless amphibians inhabiting tropical, wet forests.   Once again, there’s some revolutionary finds, but I cannot disclose their identity at the moment.

The next talk is also about the late Triassic, in this case the Dockum’s freshwater fish. Sarah Gibson of St Cloud University studies Redfieldiform fish, a group of mysterious rayfinned fish of the Triassic ranging from the Karoo of Africa to the Newark of the USA. These fish are characterized by their short and spiky snouts, and in the Dockum the remains are excellent. Found here are Cionicthys and Lasalicthys, also found in the Chinle. Especially interesting however is Hemicalypterus, a spiky-snouted fish that has armored ganoid scales in front and tiny regular scales in back. Most intriguing, Hemicalpyterus has spork-shaped teeth: rounded with small points. No other fish in the formation has those. However, a greater scope comparison reveals that this tooth morphology is found in herbivorous fish: particularly those specialized in scraping algae off rocks. The conclusion: Hemicalypterus is the first herbivorous fish. The teeth, the morphology, and the armor arrangement is parallel to catfish in convergent evolution.  This is a real revelation for me, and a fascinating discovery.

The next talk was the weakest of the weekend, but still had some interesting ideas and potential for further research. Armita Manafzadeh of Brown University studied locomotion using an X-ROMM, using X-rays to see the skeletal elements of a moving animal.  Her particular issue was with Pterosaurs, commonly shown with splayed hindlimbs. After examining bird and reptile leg mechanics and range of motion on 3 axes, she scanned pterosaur hindlimbs and animated them in a computer program. Her conclusion was ligaments present in living taxa would prevent the hindlimbs. Her main mistake was using birds rather than bats, phylogeny rather than actual morphology, a mistake she admitted, pointing out that phylogeny is not guaranteed to explain biomechanics. She made three mistakes: first is not talking with pterosaur experts, the second is not taking account of the flight membrane that stretched across the animal’s limbs, and finally she did not take into account actual pterosaur footprints that showed exactly how they locomoted. Her criticism comes off as attacking a strawman of how scientists actually think pterosaurs moved, and not providing any alternative model. However, she did succeed in showing the potential for this technology to imply the range of motion for animals, and she did make valid points that we need new rules of biomechanics, more joint studies, and studying the mechanics of an entire limb anatomy rather than just joints.

The next talk was excellent-Eva Hoffman of Harvard University brought new discoveries to light on Kanyentatherium’s reproduction. Hatchling synapsids are rare in the fossil record, so we don’t know their litter size.  Short-tailed Tenrecs, small mammals from Madagascar, have litter sizes of 16, with one individual giving birth to 32.  So it was an amazing find to discover hatchlings of the one of the last non-mammal synapsids. This genus is Kayentatherium, a tritylodont cynodont that lived in the shadow of Dilophosaurus and other dinosaurs. One individual was found with its clutch: while the soft, uncalcified eggshells did not fossilize, at least 38 babies were found. We don’t know if they had just hatched or died unhatched, but these tiny fossils show that large litter sizes existed. Cynodont ontogeny is shown as they have small postdentaries and brains compared to adults, but unlike modern cynodonts (mammals), their heads are the same proportions and shapes as adults, whereas their living relatives had rounder, proportionally larger skulls.  Hoffman has discovered an inverse correlation-the larger the brain, the smaller the clutch, and vice-versa. 

Thomas Cullen, the new dinosaur expert at the Field Museum, gave a talk about Sue. While the discoveries made during Sue’s renovation remain unpublished, what I can repeat is his pitch for the new exhibit. I am a docent for the Evolving Planet exhibit that Sue’s exhibit is attached to, and it’s an excellent update; Sue is placed in context in both history and ecology. The Gastralia and furcula have been finally added to the skeleton, and the right leg repositioned to be anatomically correct. A light-and-sound presentation shows the highlights of Sue and their pathologies as well as Tyrannosaurus anatomy in general. Bone histology has been studied, but since the revelations are unpublished, I cannot reveal them. I can only say they are fascinating if you have any interest in bone histology.

The next two talks were about the palaeobotany of the Late Cretaceous/Early Paleogene transition. The first was by Antoine Bercovici of the Smithsonian Institution, who took floral inventory at the Marmoth site near Bowman, North Dakota. Both pollen, wood, and leaf imprint fossils were all studied and counted. At the Cretaceous layer, angiosperms, flowering plants, dominate. Right above the iridium player is a spike in fern fossils, which is typical for plant growth after a defoliating disaster like a volcanic eruption. The most significant change is that out of over 100 species, only 3 survived. Insect numbers correlate-all the specialized insect species go extinct.   Likewise with birds-of all the dinosaurs, only the toothless birds survived.  The biggest revelations are that no families of plants went extinct-only genera, and that the Deccan eruptions’ impact seems to have been overstated: their release of CO2 actually enriched the plant taxa in both number and diversity.

Regan Dunn, his counterpart at the Field Museum, did a focused study on the canopy cover. What exactly killed all these plants would be the earthquakes and shockwave of the impact itself, followed by a brief superheat, then choking clouds of soot and dust as nuclear winter set in and the temperature dropped 25 degrees Celsius, then acid rain as the toxic sulfur combined with the water vaporized by the earlier heat.  How to measure canopy cover? Dunn looked at leaf area index which indicates how much of light reached the ground. The higher up the leaf, the smaller it is in area, and vice-versa, creating two subtypes of leaves on the same tree: sun leaves and shade leaves. Phytoliths and cuticles were added to the material, using cell morphology and modern analogies.  However, the final data is unpublished and cannot be divulged. 

The last talk was again from Thomas Holtz of the University of Maryland, on Dinosaur Integument. The first dinosaur scales were discovered in 1851, and mummies of many lineages were found with fossil scale impressions. However, there was always this suspicion that some dinosaurs were birdlike, and might have had feathered. Ornitholestes was once pondered to have been feathered in 1910, but this was ignored. In the 1970s when the Dinosaur Renaissance began, paleoartists like Landry and Paul suspected that dinosaurs had feathers.  In 1996, the feathered dinosaurs began to show up-Sinosauropteryx, a juvenile Scirimimus, Yutyrannus of the theropods, then Tianyulong and Kulindadromeus in ornithischians. What Holtz calls “the Great Enfluffening began”. And then came the question-which dinosaurs had feathers and which didn’t? There are three phylogenies ordering sauropods, theropods, and beaked dinosaurs, and they all are valid (the saurichian-ornithiscian split seems to be the best-supported, but only marginally).  Another unfortunate problem is that most environments don’t preserve feathers-we find Archaeopteryx with feathers, but also Archaeopteryx without fossils. 

Holtz then pointed out that most animals in real life have multiple integruments-birds have naked skin, monofilaments, feathers, and scales on the same skin.  Scales even vary on the same animal-crocodiles have fine scales, cracked skin on the mouth, and osteoderms.  Pterosaurs have been found with “Fuzz”-filaments that can be classified as feathers, and some even with multiple fibers growing from the same root.   Body size SOUNDS like a sound idea, but we have 2 ton Tyrannosaurs covered in fibers, and giant Deinocherius has a tail vetebra that looks like it might have had supported plumes, wooly mammoths in mammals, and even elephants today can be quite furry on occasion. Indeed, it’s commonly assumed that giant sloths had fur, even though we haven’t found direct evidence of it-could they have been scaly? His conclusion was a fascinating one: it’s just as likely that Tyrannosaurus had feathers as it had filament fuzz as it had scales, and they could have been in any combination.  It’s a genuine mystery-and one that allows for a lot of variation in paleoart. 

So it was a great set of talks this year, and I’m looking forward to the releases of more finds, more papers, and more paleofests!