Terrific Tetanurae! #8 The “Ashdown Maniraptoran”

Hello all! Welcome to Terrific Tetanurae! #8. Enjoy!

Today we take a look at one of the smallest non-avian dinosaurs. Enter the “Ashdown maniraptoran.” In 2011, Darren Naish and Steve Sweetman published a paper describing a single, tiny vertebra from an adult theropod. This specimen was collected from the Lower Cretaceous Wealden Supergroup in England. Because the dinosaur is only known from a single bone, it’s hard to definitively place this animal in any family of theropod dinosaurs, but we can be pretty certain it is some sort of maniraptoran based on the morphology of the vertebra.

The vertebra itself is a tiny cervical. I mean a really tiny one. And because there is no neurocentral suture perceivable, we can surmise that the animal was full grown. Besides the initial description and Darren Naish’s blog post on the animal, there really hasn’t been much discussion of this guy.

Contrary to popular thought, I don’t believe the vertebra came from a protoarchaeopterygid (although I should note that even those who have supposed this animal to be a protoarchaeopterygid have considered their hypotheses highly speculative). Rather, I think it may be a more derived oviraptorosaur. Indeed, the X-shape of the vertebra in dorsal view, as noted by Darren Naish, is also found in a variety of oviraptorosaurs, namely Microvenator. The “Ashdown maniraptoran” vertebra also seems more mediolaterally compressed then that of oviraptorosaurs like Microvenator. However, mediolateral compression is found in the vertebra of some derived oviraptorosaurs, namely Nomingia. 

I hope you enjoyed Terrific Tetanurae! #8, and thanks for reading! 

References

1. Naish, D. & Sweetman, S. C. 2011. “A tiny maniraptoran dinosaur in the Lower Cretaceous Hastings Group: evidence from a new vertebrate-bearing locality in south-east England.” Cretaceous Research 32(4):464-471.

2. Makovicky, P. J. & Sues, H. D. 1998. “Anatomy and phylogenetic relationships of the theropod dinosaur Microvenator celer from the Lower Cretaceous of Montana.”  American Museum Novitates 3240:1-27.

3. Barsbold R., Osmólska, H., Watabe M., Currie, P. J. & Tsogtbaatar K.  .2000. “New oviraptorosaur (Dinosauria, Theropoda) from Mongolia: The first dinosaur with a pygostyle.” Acta Palaeontologica Polonica 45(2):97–106.

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