Obscure Dinosaur of the Week: Eoabelisaurus mefi
Lateness due to confirmation preparation. Awesomeness due to the origin of abelisaurid short arms!
Name: Eoabelisaurus mefi
Etymology: From the greek "eos" (dawn), and Abelisaurus, type genus of the Abelisauridae; and the popular abbreviation of the Museo Paleontologico Egidio Feruglio (MEF)
Distribution: Middle Jurassic (Aalenian-Bajocian) of Patagonia
Type Specimen: Near complete skeleton, missing only some neck and tail vertebrae (cervical and caudal), and the lower jaw (mandible)
Estimated size: 6 - 6.5 m in length
Interesting fact: Evidence of tiny arms pushed back 40 million years
Ever wondered where those preposterously short arms of Tyrannosaurs and other large theropods came from?
Meet Eoabelisaurus mefi, a recently discovered abelisaurid (theropod dinosaur) from Patagonia. The skull is in the top left corner of the frame, with the tail stretching to the right. Just look at those shoulder blades in the top left, compared with the upper arm, and even smaller lower arm! Interestingly, this species pushes back the appearance of short arms by 40 million years, from the early Cretaceous back to the mid Jurassic. And as the authors so cleverly state, "The apparent rarity of ceratosaurs in the Jurassic does most probably not reflect true low taxonomic diversity, but is owed to the poor fossil record of Jurassic theropods in the Southern Hemisphere" (Pol et al., 2012); i.e. either fossils haven't been found yet, good rock outcrop doesn't exist, or the carcasses weren't fossilised in the first place. Taphonomic bias strikes again!
Simplified cladogram of all dinosaurs. E. mafi was an abelisaurid, within theropoda.
Pol, D., Rauhut, O. (2012). A Middle Jurassic abelisaurid from Patagonia and the early diversification of theropod dinosaurs. Proceedings of the Royal Society B, 1-6: 10.1098/rspb.2012.0660
Stressmares
I'm handing in my confirmation document tomorrow. I feel like I'm on top of everything, having made about 1 billion edits to the document, and a few last minute changes, and I'm feeling pretty good about it. Except I must be stressed, because I can't sleep at night, and keep having nightmares! Well, at least my waking hours are calm...
Obscure Dinosaur of the Week: Dacentrurus armatus
Name: Dacentrurus armatus
Etymology: From the Greek "da" (very), "kentron" (sharp point) and "oura" (tail); and from the Latin for "equipped with armour"
Distribution: Late Jurassic (Kimmeridgian) of England
Type Specimen: Partial skeleton including the pelvis, femur and some vertebrae
Estimated size: 10 m long and 4.5 m wide
Interesting fact: Dacentrurus armatus was the first Stegosaur ever found!
It must have been amazing to be a palaeontologist in England in the 19th century. The term 'Dinosauria' was coined by Richard Owen in 1842 to classify all the seemingly 'weird' reptile fossils being discovered across England and mainland Europe. And then for Owen to find and describe something like Dacentrurus armatus in 1875, unrecognisable even within the newly formed 'Dinosauria', would have caused a stir!
As more species of Dacentrurus were described, it became clear that it possessed sharp spines that ran along the whole length of the spine to the tip of its tail, forming a 'thagomizer' - it is still not certain whether the thagomizer was used for display or defensive purposes. It was also one of the larger stegosaurs, with average stegosaur length measuring around 5.5-6 m. Of course, when working with small sample sizes, it's hard to clarify whether fossils found are truly representative of their species, or whether they were abnormally small or large!
The original illustration of the type specimen of D. armatus, described by Richard Owen in 1875, showing the pelvic region, various vertebrae and femur. I think as well as a excellent descriptive diagram, it's a wonderful piece of art!
Simplified cladogram of all dinosaurs. D. armatus was an stegosaur, within thyreophora.
Owen, R. 1875. Monographs of the fossil Reptilia of the Mesozoic formations (Pt. II) (genera Bothriospondylus, Cetiosaurus, Omosaurus). Palaeontographical Socoiety Monographs 29; 15 - 93.
Recieved feedback lately?
I'm sitting in my office, working on my confirmation document late into the evening... and although that might a good opener for a whinging session, I'm actually having fun!
Fun you say? Well, I've just received some constructive critiques from my supervisors regarding my soon-to-be-completed PhD confirmation document. The confirmation process is the first 'milestone' in your PhD at UQ: it's a chance to prove that your project is significant as well as feasible. And although most people wouldn't want to stay back late and read critical comments of their work, I am lucky that I:
a.) have super supportive and friendly supervisors, and
b.) have an attitude of "Oh well, if I'd got it perfect the first time, I technically wouldn't need to do a PhD!"
It's only natural that I'm going to get sidetracked/forget to link key concepts in the document, which is exactly why us PhD's have supervisory teams to train us how to do successful and efficient research!
Anyway, working on the document straight away has given me the chance to write down everything while it's fresh in my mind. Don't get me wrong: I've stopped to have dinner, Skype my parents, and generally mess around on Facebook, but sometimes working at a slower pace late into the night is better than rushing the day before it's due! I also won't wake up with the "I really should have started those edits" guilt tomorrow, but instead wake to "HAH edits! In yo FACE!" It's also nice to have the office to myself and sing along to The Smiths... not that I do that, but I could, if I wanted to. Ahem.
Obscure Dinosaur of the Week - Cedarpelta bilbeyhallorum
I've been caught up in finishing off my first draft of my PhD confirmation document, so apologies for the late Obscure DotW!
Name: Cedarpelta bilbeyhallorum
Etymology: After the Cedar Mountain Formation in which is was found, and Latin for shield; and the discoverers Sue Ann Bilbey and Evan Hall.
Distribution: Early Cretaceous of Utah, U.S.A.
Type Specimen: Disarticulated and complete skulls, ischium
Interesting fact: Disarticulation allowed for first 3D examination of skull elements
One of the skulls of C. bilbeyhallorum was discovered in a disarticulated state: that is, the elements that made up the skull were found in separate pieces instead of being fused together. This allowed for the first three dimensional examination of ankylosaur skull elements. The hypothesis behind why the skull was disarticulated was that the individual was a juvenile, whereas in adulthood the skull elements would have been completely fused.
The disarticulated skull of C. bilbeyhallorum. From Carpenter et al., 2001.
It also represents one of the larger ankylosaurids found so far; with a 60 cm long skull it is calculated to be approximately 7.5-8.5 m long. Previously described ankylosaurs have been estimated at between 3 and 7 m long.
Simplified cladogram of all dinosaurs. C. bilbeyhallorum was an Ankylosaurid, within Thyreophora.
Carpenter, K,. Kirkland, J. I., Burge, D., and Bird, J., 2001. Disarticulated skull of a new primitive ankylosaurid from the Lower Cretaceous of Utah. In: "The Armored Dinosaurs", edited by Carpenter, K., Indiana University Press, p. 211 - 238.