Are the days of parsimony numbered? Probably.

8 Oct

April Wright recently published a cool paper looking at how to bring morphological analyses of evolutionary relationships into the Bayesian realm. This is her take on it – enjoy! 

Author Bio: My name is April Wright, and I’m a graduate student in David Hillis’ lab at the University of Texas at Austin. I’m largely interested in the estimation and use of phylogenetic trees to answer questions about evolution. Particularly, I’m investigating how we can make the best possible use of our fossils in an era increasingly dominated by genome-scale data. You might say I’m a little bit of a ‘small data’ scientist, though my questions often involve a multitude of small data sets.

Today I’d like to talk a little bit about a recent paper I published as part of my PhD thesis work.

[...]

IPC Day 2 – The evolution of giants

3 Oct

This is a slightly delayed summary of the sauropod symposium on day 2 of IPC4, following sessions the previous day on vertebrate taphonomy and diversity and extinction in the fossil record. This is also the final of these little summaries, and for that I apologise – my laptop is a bit kaput atm, and needs power sockets to run and which were not available in some of the rooms. I might be a little cheeky and ask a couple of the attendees to write personal summaries for here, but we’ll have to wait and see! Make sure you’re keeping a check on Palaeocast too, as Dave has been reporting non-stop from the conference.

On to sauropods, those giants of the Mesozoic!

Martin Sander launched right into the meat of things discussing the latest advances in trying to understand the physiology of gigantism in sauropods. A large team of researchers have been working on a cascade model of evolution featuring traits, selective advantages and feedback loops that lead to increasing body size in sauropods.

John Frominos switched modes completely to his investigation of the comparative function of vertebrae between sauropods and crocodylians. It seems that generally, concavo-convex vertebrae in crocs don’t offer much advantage in terms of flexibility, so the same may be true for sauropods. This talk was of particular interest for me, as atoposaurid crocs are some of the first crocodyliforms (early non-crown group crocs) to have procoelous vertebrae (with a convex front edge and concave back edge).

Jorge Calvo filled in with a replacement talk to describe some new remains of Futalognkosaurus from the Late Cretaceous of Argentina. Turns out it’s just a really cool, massive dinosaur, and among one of the largest and most well-known of sauropods.

Bernardo J. González Riga described new sauropod remains from Mendoza Province, and new information on the evolution of the sauropod pes (foot). Two new titanosaur species with unusual characteristics of their feet were mentioned, which is great as it sheds light on the evolution of locomotion in these big boys. Bernardo was also cool enough to take us to his lab to see the amazing new specimens, and provide wine and empanadas, so on the off chance that he reads this – thanks Bernardo and everyone else!

One of the leg bones of one of the new dinosaurs! A very humerus photo.

One of the leg bones of one of the new dinosaurs! A very humerus photo.

Matthew Lamanna, one of the chaps involved in the recent discovery of Dreadnoughtous, described some new Moroccan sauropods, and their implications for sauropod ecology and diversity in Africa. He provided the first evidence for theropods preying on sauropods, which is great as the large theropod fauna of North Africa, including Spinosaurus, were usually thought to have fed on a range of fish. Through detailed anatomical investigations, he also provided evidence for allopatric speciation in North African sauropods, at a time when the region was cut by a large epicontinental sea.

Kristi Curry-Rogers revealed to us new sauropods from Madagascar, as well as details on their evolution, ecology, and palaeobiology. One of the coolest findings was a giant hollow osteoderm, possibly used as a mineral reserve similar to modern camels! She announced the discovery of lots of new fossil sites, so the future of Madagascaran dinosaur discoveries should be exciting in the future.

Philip Mannion, my PhD supervisor, launched into a comprehensive new phylogeny of Jurassic-Cretaceous Gondwanan sauropods. Phil has been conducting first hand taxonomic revision of many old and new species around the world, and has built a new tree that paves the way for new biogeographic  and macroevolutionary analyses.

Jeffrey Wilson described a wonderful new skull of the titanosaur Tapuiasaurus that provides insights into their feeding behaviour. This is one of the few known titanosaur skulls, and shows some unusual features including a tooth wear pattern similar to heterodontosaurs (early ornithischian dinosaurs), and the animal may have even had a keratinous beak.

Diego Pol finished the session off by discussing faunal replacement in Jurassic sauropods. I didn’t catch the details on this though, as the session was running late and I had to dash to go and present my poster on the evolution and diversity of atoposaurid crocodyliforms! More on that once I’m back and have had time to recover though, although check out my recent PeerJ paper that describes a lot of what we presented.

So there we have it, still lots going on and plenty to discover about the biggest animals to ever walk the Earth! If you’d like to know more, leave a comment, or get in touch with one of the authors.

IPC4 Day 1 – Death is the road to awe

30 Sep

Following on from the previous post, the afternoon symposium was all about the applications and implications of vertebrate taphonomy.

Matt Carrano kicked things off with a great talk on how microfossil bonebeds help to guide our understanding of terrestrial palaeoecosystems. Using sites from the well-known but poorly understood Cloverly Formation, he provided a key insight from abundances from terrestrial microsites into the composition of faunas. This was a particularly appealing talk for me as it contained atoposaurids!

Carina Colombi asked what the effect was of atmospheric CO2 on the evolution and preservation of the terrestrial fauna of the famous Ischigualasto Formation. It seems that decreases in atmospheric CO2 may explain decreases in the number of preserved vertebrate fossils in different horizons.

Tao Deng explored the taphonomy of the vertebrate fauna in the Linxia Basin in Gansu, China. Older individuals from particularly abundant rhino fossils seem preferentially preserved, based on ages inferred from tooth eruption

Adriana Mancuso described her research into taphonomic modes in a Triassic-Jurassic loessite (wind-blown deposit) from Patagonia. Different taphonomic regimes suggest aspects of social aggregation in some animals, for example from the accumulation of groups of juvenile specimens.

Alexander Parkinson gave an interesting talk on insect-bone interactions from the “Cradle of Humankind” in South Africa. There were plenty of types of boring trace, with a possible new ichnotaxon. The spatial distribution and mode of preservation of the fossils suggests extremely rapid burial and fossilisation.

Raymond Rogers brought us back to microfossil bonebeds, from the Upper Cretaceous Judith River Formation in the US. He was looking at huge numbers of fragmentary fossils and what their size and shape can tell us about their diagenensis, in particular how the deposits formed and where the fossils were sourced from.

Vijay Sathe discussed the taphonomy of a new large mammalian fauna from the Quaternary of India, and the possibility of their mode of death. It seems some may have fallen into pits, and subsequently scavenged by predators, with the preferential preservation of younger and older animals.

Leif Tapanila finished things off by looking at the effect of impermeable ash layers within geological basins, and whether their distribution affected the preservation potential of fossil layers by changing hydraulic regimes.

End of day 1! The best part for me of this second symposium was the potential that fossil microsites have in greatly increasing our understanding of diversity through time. Hopefully much more on this in the future.

IPC4 Day 1 – Using the past to inform the present

30 Sep

Welcome to the fourth International Palaeontology Congress! 900 palaeontologists have piled into the land of steak, sun, and malbec in Mendoza, Argentina, for the biggest palaeontology conference that draws from all parts of the field.

What I want to do with these posts is just provide snapshot summaries of the talks I’ve been at to provide a window into the conference and the amazing diversity of research being conducted by a global team of awesome researchers. It’s not all just dinosaurs you know! Results will not be discussed in any detail for obvious reasons.

The first symposium I attended was on the “Coevolution of the Earth and life: the role of the physical environment in species’ evolution.”

[...]

Follow

Get every new post on this blog delivered to your Inbox.

Join other followers: