Hope you're all having a wonderful holiday break!
Image ©2013 alexine-pankhurst
Imagine the scene. It is 96-91 million years ago, during the Late Cretaceous, in Gondwanan Patagonia. A coelurosaurian theropod dinosaur, Aniksosaurus darwini, lays dead next to a river. A small crocodile strips flesh from the carcass, concentrating on the right thigh, revealing the femur (thigh bone) beneath. The femur detaches from the carcass and is washed into the river, where it is scratched and dented as it bashes into rocks and scrapes its way along the river bottom. It finally comes to rest, and is buried along with the rest of the right lower leg and foot.
How did this fleshless femur roll along in a river, being damaged as it went, but part of the lower leg and foot (tibia, tarsals, metatarsals, and phalanges) remained protected and attached to it?
One word: podotheca.
The taphonomy of the Aniksosaurus darwini holotype, including an articulated right leg complete with femur, tibia, metatarsals and phalanges, has been examined in a new paper by Casal et al. (2013). Unfortunately I can't read Spanish, so I can't read the rest of the paper beyond the translated English abstract. And the paper doesn't appear to be available online.
But from what I can glean from the abstract, the authors found the fossil in an overbank deposit of a fluvial system - essentially, buried in an ancient river bank. Weathering patterns and crocodile tooth marks were found on the femur, that were not present on the rest of the lower leg bones. The authors suggest that the lower leg of the theropod was protected from weathering by a soft tissue resembling the podotheca: the scaly covering of the foot of a bird or reptile.
The podotheca of a peacock. Image by Brett Fernau
Interestingly, in my search for images for this post, I came across a newspaper article about what appeared to be a rhea carcass found near Tealing, Scotland. The reporter didn't know how a rhea ended up wandering around and dying in the Scottish countryside, but what interested me was the attached image:
Possible rhea leg from Tealing, Scotland, collected by a passer-by. Image from the Daily Mail.
Look familiar to a scenario-which-I-just-described-were-you-paying-attention?
The femur (top most bone in image) has been stripped of flesh, as has the knee and part of the tibia/fibula (second bone from top of image). The podotheca remains below the ankle along the length of the foot. There would be little to no damage on the bones beneath the podotheca. And everything has remained articulated! It's an almost perfect analogue for the situation described for the theropod remains by Casal et al. (2013), sans river.
So would the presence of podotheca mean this rhea leg could remain articulated while transported downriver? As I can't read the rest of the paper beyond the abstract, I'm not sure what Casal et al. might have to say about that. But as for myself? ...Possibly, if the leg was only floating for a day or two before burial.
More importantly, the inference by Casal et al. (2013) that A. darwini had a podotheca-like covering on the lower leg could suggest that this feature first appeared in basal coelurosaurians.
Casal, G. A., Martinez, R. D., Ibiricu, L. M., Riga, B. G., Foix, N. 2013. Taphonomy of the theropod dinosaur Aniksosaurus darwini, Bajo Barreal Formation, Late Cretaceous of Patagonia (Argentina) [In Spanish, English abstract]. Ameghiniana, 50: 6.
Podcasts are a wonderful beast. Apple have yet to monopolise the platform, allowing many wonderful shows to be distributed through iTunes as well as private websites for free.
And have I only just discovered this?
... maybe. But I'll make up for living under a rock, for I hereby present to you: two awesome palaeontology themed podcasts, Past Time and Palaeocast.
Past Time is hosted by Adam Pritchard and Matt Borths, two graduate students from Stony Brook University, New York. Topics cover vertebrate palaeontology theory and recent fossil discoveries, from mammals to dinosaurs, crocodiles to birds. If you've wanted to brush up on evolutionary theory, this is the place to come.
I especially appreciate the effort made with editing: sound bites from interviewees are spliced with clarifications from the hosts (similar in style to Radiolab, an amazing science and philosophy podcast - check it out!) and ambient sound effects. Sometimes quite distracting sound effects, but still useful in creating the right atmosphere.
The banter between the hosts is also enjoyable to listen to. It's like you're part of a conversation, where sometimes one host will play the "devil's advocate", and the other will spend time explaining the evidence behind their position.
Hosted by Dave Marshall (Marshall Biostratigraphic) and Joe Keating (The University of Bristol), Palaeocast covers a broad range of topics including palaeobotany, and invertebrate and vertebrate palaeontology.
Palaeocast follows a one-on-one interview style format, where you feel like you're in the room listening to the interviewer and interviewee converse live (think Inside the Actor's Studio or The 7.30 Report). It's the closest you can come to speaking directly to the experts themselves, and it's quite nice to hear the interviewees wax lyrical about their subject matter. They clearly love what they do!
They have also recorded podcasts from palaeontology conferences (including the 2013 Society of Vertebrate Palaeontology and the 2013 Geological Society of America Annual Meeting) including interviews from attendees presenting new palaeontological research. For those of us who have either not enough time or money to attend these conference, and would otherwise miss out on all the cool palaeo-goss, we salute you.
Both Past Time and Palaeocast supplement their podcasts with online material, including images, videos, and summary blog posts. I think both palaeontology enthusiasts and professionals can gain a lot from both these shows. Saying, "I'm a palaeontologist" often leaves you open to any question about any fossil spanning THE ENTIRE HISTORY OF THE EARTH. These are two excellent podcasts for increasing your general knowledge, and more importantly, keeping up the all-seeing, all-knowing palaeo persona.
So let me know: do you listen to these podcasts? What do you think of them? And are there any other palaeontology podcasts out there I've missed?
About the author
Dr Caitlin Syme is a palaeontologist who recently finished her PhD at The University of Queensland, studying the taphonomy (preservation state) of fossil non-avian dinosaurs, crocodiles and fish from the Winton Formation, Queensland, Australia. Think forensic science or CSI for fossils, and you're on the right track!
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