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Day 4 at SVP

http___vertpaleoDay 4 and the last day at SVP. After this, we will return to our regularly scheduled sorts of posts.Another day of talks and poster sessions, the last chance to meet friends and colleagues and discuss what you’ve heard and what people are doing. Although frankly, I think most people are tired and ready to go home by this point. Some people thrive on the highs of shared creativity and knowledge and find  the end of the meeting and going back to regular work depressing, I think the most common reaction is the feeling of being rejuvenated by the meeting, so that you can’t wait to go back and start developing the new ideas created at the meeting, the chance to put those creative juices to work before the distractions of everyday life dry them up.

A lot of people don’t like having their talks on the last day. People are going home, they are tired, their attention flags, but this meeting showed a strong turnout for the last set of talks. The symposium scheduled for today was “Patterns from the poles: biodiversity and paleoecology of high latitude fossil vertebrates,” which I, at least, found interesting and worth attending. I didn’t attend too many of the talks though, because there was also a session on the evolution of early birds, which I found even more interesting, as well as a session on mammals, which had several talks discussing how different mammal groups adapted to climate change in the past. Several talks introduced new fossils and what they contributed to our knowledge of evolution within those groups, such as a new Devonian fish from Siberia, the first pterosaur from Antarctica, a new sauropodomorph (early versions of animals that would  become sauropods, the oldest mammal from Antarctic and a new Arctic camel, new birds, seals, sirens, dolphins, and whales. All in all, good reasons to stick around.

Anchiornis_martyniuk, wikimedia

Anchiornis_martyniuk, wikimedia

Rui Pei reported on a new specimen of Anchiornis, the first animal in which fossil evidence in the feathers was used to determine coloration. Anchiornis lived 10 million years before Archaeopteryx and there has been some debate about whether it was a true bird or still a non-avian dinosaur. Pei’s analysis of the new specimen indicated that Anchiornis was a troodontid, so not quite yet a  bird. This is another great example that the transition between birds and other dinosaurs is so well documented that the line is an arbitrary classification with no biological relevance. Speaking of feather colors, William Gearty found new ways to study the melanosomes in the feathers providing colors, finding that, in addition to color, he could tell color gradients as well. he also concluded that melanosomes stiffened the feathers, making them more resistant to wear, but also carried more bacteria, thus representing an additional resource cost for the animals (some of this work can be found online at PLOS One).. Justin Hall found that feather asymmetry, long thought to be important for flight, turned out not to have the aerodynamic significance we thought, as it didn’t really affect the ability to fly.  Ashley Heers found trade-offs in locomotor ability: the more investment in wings, the less was put into the legs, and this trade-off could change as the bird grew so that chicks may emphasize the wings or legs while the adults emphasized the other.

Cryolophosaurus, Royal Ontario Museum. Wikimedia.

Cryolophosaurus, Royal Ontario Museum. Wikimedia.

Several studies showed the difficulties inherent in paleoecology interpretation. Peter Makovicky found that the horned ceratopsids showed different growth rates between northern and southern populations, the duck-billed ornithopods did not, and the carnivorous theropod Cryolophosaurus showed different growth rates in different areas of the same body in the northern individuals, but not in the southern individuals. According to Bergman’s rule, we should expect to see animals get bigger and stockier the farther north they are found. Anthony Fiorillo found that the small troodontids followed the rule, but northern individuals of the large tyrannosaurs were only 40% the size of the southern ones. In this case, it is likely that resource supply kept the tyrannosaurs smaller. Patrick Druckenmiller reported on a diverse Arctic dinosaur fauna including toodontids, dromaeosaurs, thescelosaurs, hadrosaurs, pachycephalosaurs, and tyrannosaurs, despite mean annual temperatures near freezing. While similar to southern forms, all the species were different, indicating a discrete, provincial ecosystem. John Tarduno argued that the presence of champsosaurs (a type of early crocodylian) and turtles indicated the weather was too warm for ice to be present even during winter, but as proven by an earlier talk, we know this is incorrect (a great example of science correcting itself). He proposed volcanism forming a series of shallow, freshwater connections between North America and Asia during the latest Cretaceous allowing interchange between the continents, which will need more study to determine if that proposal is true. Judd Case found that even though modern fish fauna show a drop in diversity with lower temperatures, thisi was not the case in the Cretaceous. As the temperature in the Cretaceous dropped 8-10 C in the Antarctic oceans, the fish didn’t really change, although marine reptiles increased in diversity while the ammonite diversity dropped.

Figure from Fletcher et al. 2010, showing FEA analysis, indicating stress points near the joint.

Figure from Fletcher et al. 2010, showing FEA analysis, indicating stress points near the joint.

Rodrigo Figueiredo  presenting evidence that predators who pursue their prey (as opposed to ambush predators  attacking large prey and those that pounce on smaller prey) may not have evolved to go after herbivores, but to prey on the pounce predators themselves, much like wolves will sometimes hunt foxes and weasels. Michael Greshko presented a study finding that herbivores known as generalists (able to eat a wide variety of plants) mostly consist of different individual specialists who eat only a narrow range of foods. This is rather like why a pizza buffet needs to stock a lot of different types of pizza even though any particular customer may only eat one or two different types. Speaking of eating, Emily Rayfield gave a possible answer to why mammals reduced the number of bones in the mandible to just one, as opposed to having several bones in the lower jaw like other groups of animals. Using Finite Element Analysis, an engineering method designed to test mechanical strength of materials, found that the one bone provided a stronger bite while reducing stress. Alistair Evans used a program called GEOMAGIC to study tooth shape in early mammals and predict what tooth shape should be like to help sort out all the isolated teeth for which we have no idea what they belong to. in this way, he is making predictions of fossils that have not yet been discovered.

Gephi.org BON graph

Gephi.org BON graph

In addition to the software programs mentioned previously, several others were mentioned in talks this day. Most biogeography methods these days are done using phylogenetic methods to help inform how animals spread out across the globe, but Chris Sidor presented Bipartite Occurrence Networks (BON), using Gephi to visualize the patterns, which just uses locality connectedness and found that therapsids (proto-mammals, aka mammal-like repties) were pretty widespread and cosmopolitan before the Permian extinction event, but became much more provincial and limited in range afterwards. Paul Upchurch used TREEFITTER to map pterosaur biogeography, finding support for sympatry (speciation within the same region) with an origin in eastern Asia. Diego Pol used Ancestral Area Reconstruction methods to conclude that dinosaurs probably originated in South America, along with most, but not all, mammals, but crocodylamorphs originated in China. Graeme Lloyd used GEIGER to study evolutionary rates and Akinobu Watanabe used PERDA (Polymorphic Entry replacement Data Analysis, a script running in TNT, a phylogenetics analysis program) to simulate poor sampling of phylogenetic data, finding that if a trait, or character, has multiple possibilities within a single species, it seriously messes up results unless multiple individuals covering all the possibilities are included in the analysis. John Alroy found that no current method is very good for finding the first appearance of taxa, but Bayes Theorem methods, such as used in MrBayes, produce better estimates of extinction times.

Figure from Sansom and Willis 2013 showing fossilization study results.

Figure from Sansom and Willis 2013 showing fossilization study results.

The last two talks I would like to mention are from Robert Sansom and David Grossnickle. Sansom found that loss of soft tissue characteristics resulted in changes in cladograms drawn from the data for vertebrates, but not for invertebrates. In other words, if one only looked at hard parts, the evolutionary relationships changed, and more often than not, made the animal appear to be more ancestral than it really was. This occurred even if the characters were recorded as unknowns and not simply listed as absent. Grossnickle looked at morphological disparity in Mesozoic mammals, i.e. the diversity of body form. What he found was that most Mesozoic mammals were carnivorous/omnivorous, with a low level of diversity which gradually increased until the middle Cretaceous. At some point in there, they hit a botttleneck. Their diversity crashed and, while it did start going up again,never reached the previous diversity levels until after the K-T extinction event. What is interesting about this is that pretty much everything else was diversifying, while mammmals were not. Another interesting thing about this is that according to molecular data, mammals were diversifying, so the apparent diversification did not show up as morphological diversity.

This is the end of my discussion about the science presented at SVP. There were so many more talks and posters that I did not mention and i make no claim that the ones I mentioned are even the best or most important, nor are they even all the ones I attended and learned something from, but it would take me until the next meeting to discuss all of them. The point is that meetings like this are incredibly fascinating places to see what  is going on in science right now. Anyone who thinks science is a bunch of stale facts in textbooks or that scientists even pretend to have all the answers is seriously mistaken. The search for truth is asymptotic, you can get ever closer to a totally clear understanding of reality, but you will never reach it. Science is all about going over the data, tossing out ideas that don’t succeed and developing ones that do, with each step opening up new avenues of exploration.

Steven Spielberg on set of Jurassic park. Spielbergfancluc.com

Steven Spielberg on set of Jurassic park. Spielbergfancluc.com

I will end this discussion with the awards banquet held on the evening of the last day. During this banquet, we are told how much the auction collected to support the society, important news, memorials for those we lost recently, and people are recognized for their hard work and contributions to the field of vertebrate paleontology. Students are awarded their prizes and scholarships they have won, artists are awarded for best art in different categories, and people are recognized for outstanding careers that have progressed the field. This year, one of the biggest awards went not to a scientist, but to a science advocate. Perhaps because the meeting took place in Los Angeles, special recognition went to Steven Spielberg, for the money he has donated to the Jurassic Foundation and other places to support paleontology research and education and for the Jurassic Park movies, which brought paleontology to the center of the public eye and has inspired many to enter the field and make their own contributions. Officially, the meeting ended here. There was an after-hours celebration, which is always fun from what I hear, but I was beat and had a plane to catch early in the morning, so I called it a day. Until next year!


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