A Mystery of Caenagnathidae


Some time ago, Michael Mortimer posted on his site the idea that the Dzharakuduk avian Kuszholia mengi might actually be an oviraptorosaur! The similarities in the vertebrae (based mostly on sacrals) were starling. But also convergent. Was it? The Dzharakuduk locality has also produced definite jaws of oviraptorosaurs, so the question of whether these jaws and those vertebrae belonged together was raised. Continue reading

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A Look Back at the Bite Stuff, 2014 Edition


Another year over, and a new one’s about to begin.

It’s the [western] new year, and it’s been a little more bumpy than normal. Big things happened! I blogged less, but the blogging was more radical. Continue reading

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‘Tis the Season


Not one to celebrate most holidays, it rarely occurs to me to accommodate others. This holiday season, many of my non-religious friends join in the merriment of their more religious friends, and at the same time family (mostly a-religious or at least not associated with one of the Soltice-based traditions) find themselves enjoying this season because from Thanksgiving onward we found ourselves gathering together. It was a way for some families to find meaning in the season, and we could also take joy in the season’s “traditional” secular festivities. I am talking, of course, of The Nightmare Before Christmas.

Still from The Nightmare Before Christmas @1993 Touchstone Pictures, Inc. Image stolen brazenly from “Why ‘The Nightmare Before Christmas’ is a Christmas Movie” by Rachel Ganzewinkel (2011). Click image for link.

I love this movie and its Addams Family-esque approach to normalcy, so for this holiday season I felt what better gift for you all than a joyful skull? In The Nightmare Before Christmas, our hero Jack assembles a parody on Claus’ sled, pulled by reindeer skeletons. So it stood to reason I should gift you all with a reindeer (Rangifer tarandus) skull. In festive cheer.

'Tis the season ... for skulls!

Happy Holidays to you and yours. Enjoy the marvel of this cold-adapted cervid, its never-shedding antlers in both sexes, and its huge honking (but seldom glowing red) nose (Jack had to get a dog to glow for him, which makes much more sense).

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Shell Crushing Pterosaurs and Bad Posture


Small post here. This one is going to seem incomplete, the title a tease. It’s a premise for more things. But you’ll see where I’m going with this. This concerns the issues of how we look at pterosaurs when they’re walking around on all fours. Continue reading

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Orpheus Rex


He doesn't look like he just lost his wife...Last time I talked about Erlikosaurus andrewsi, it was Stephan Lautenschlager’s paper with Larry Witmer, Perle Altangerel, and Emily Rayfield discussing the biomechanical aspects of toothloss and beak formation in Erlikosaurus andrewsi. That work indicated a far likelier restoration of this almost-most-famous therizinosaur as having a beak at the tip of its jaws (a proposition that isn’t exactly perfectly obvious, nor has it been subject to much testing). This week, a new paper by the authors of that paper discusses the second of Erlikosaurus‘s cranial osteology papers, a follow-up to the older Perle et al. paper which examined the skull at hand. Lautenschlager et al. have CT scanned the holotype skull and thus have been able to look far deeper into regions of the skull than any previous worker (Lautenschlager et al., 2012; Lautenschlager, 2013) , examined the neural endocranial vault and cranial nerve pathways, and looked in detail at the distribution of cranial airsacs that invade the bones of the skull, previously only examined through breaks in the specimen. The influence of cranial pneumaticity and toothloss on the evolution of the therizinosaur cranium is, sadly, only approachable in limited scope: A complete skull is known only for one two taxa (Beipiaosaurus inexpectatus, Erlikosaurus andrewsi, while in the former the skull is preserved in 2.4D and hasn’t been examined in high detail), and partial skulls known for two additional taxa (Falcarius utahensis, Nothronychus mckinleyi), both of which were subjected to CT examination but are otherwise far less complete and prevent tracking the more extensive cranial evolution of therizinosauroids.

But knowing the detailed pneumatic expansions into the skull, and the deeper underlying anatomy that so fascinates with the peculiar skulls of therizinosaurs, tells us a lot about the mechanical stresses that may have permitted pneumatic invasion, limited it, and the conflicting or covariant mechanisms that affected bite performance. These things require more work like this, and deeper understanding of cranial anatomy without preconceptions about evolutionary relationships. This work precedes arguments of evolution, but at the same time influences and is influenced by it. Groundwork anatomical understanding helps provide the basis for phylogenetic information, but context of that anatomy requires a phylogenetic framework; and the use of the phylogenetic bracket, a tool of logical inference for muscle reconstruction and anatomical interpretation, informs both.

Lautenschlager, S. 2013. Cranial myology and bite force performance of Erlikosaurus andrewsi: a novel approach for digital muscle reconstructions. Journal of Anatomy 222: 260-272.
Lautenschlager, S., Rayfield, E. J., Perle A., Zanno, L. E. & Witmer, L. M. 2012. The endocranial anatomy of Therizinosauria and its implications for sensory and cognitive function. PLoS ONE 7: e52289.
Lautenschlager, S., Witmer, L. M., Perle A. & Rayfield, E. J. 2013. Edentulism, beaks, and biomechanical innovations in the evolution of theropod dinosaurs. Proceedings of the National Academy of Sciences, Philadelphia 110 (51): 20657-20662.
Lautenschlager, S., Witmer, L. M., Perle A., Zanno, L. E. & Rayfield, E. J. 2014. Cranial anatomy of Erlikosaurus andrewsi (Dinosauria, Therizinosauria): New insights based on digital reconstruction. Journal of Vertebrate Paleontology 34 (6): 1263-1291.

 

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Toothed Birds


It soars over the tossing waves on enormous, outspread wings. With nary a flap, the bird is soaring dynamically high above the ocean, its eyes scanning the sky around it and sea below. It may seem unremarkable to us today: the feet are webbed and extend behind it, the tail is short and blunt, the body rounded and muscular, but encased in a bullet-like shell of feathers, dark above and light below. The wings are mostly arm, the hand bones short. The feathers are short, and the arms make up most of the wing length. It looks like an albatross, but is several times larger than any living albatross; but it is otherwise unremarkable in its appearance from any other great seabird. That is, until you examine its head.

There are many types of ocean-going flyers, pelagic birds of one type or another. Those that hug the shores or feed in the shallows such as cormorants and auks, and those that make vast searches of the ocean such as boobies, and albatrosses. Examining their wings will tell you much about how they get around; and examining their jaws will tell you how they might catch their prey — together, these tell you what they might feed on, what they prefer. Continue reading

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What Else Happened? II – More Tails of Pterosaurs


Continuing a story of the low-key, not-Spinosaurus paleontological papers recently published, discussing our bizarre Mesozoic macrofauna, this installment covers a few pterosaur tidbits.

The first of these is an amazing assemblage of scattered bones of numerous different-sized individuals that are all almost certainly a single species of pterosaur. What is remarkable about this assemblage is that there are several extremely well-preserved remains of individuals, including skulls, with further support for sexual-dimorphism of the cranial crest in some pterosaurs. The second of these is a paper on the tail of an heretofore otherwise un-tailed group of pterosaurs, Anurognathidae, and the implications of this tail relating to their phylogenetics.

Continue reading

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