The world’s best Tenontosaurus skull
August 19, 2015
As stinkin’ ornithischians go, Tenontosaurus is near and dear to my heart. For some reason beyond the ken of mortals, the Antlers Formation of southeast Oklahoma has yielded only a small handful of Acrocanthosaurus (Stovall and Langston 1950; Currie and Carpenter 2000), one partial Deinonychus skeleton and a few dozen shed teeth (Brinkman et al. 1998), the single, lonely, woefully incomplete holotype specimen of Sauroposeidon (Wedel et al. 2000a, b) – and roughly five flarkjillion skeletons of Tenontosaurus. I know a lot of those skeletons intimately: between 1994 and 2001, I went on about two dozen OMNH digs to pull them out of the ground, and I worked on a couple as a volunteer preparator.
I was off to Berkeley in 2001, so I missed the fun when another crew got the best-ever Tonto specimen, OMNH 58340. Except for the back half of the tail, which had eroded away, almost every bit of the skeleton was preserved in perfect articulation, even the hyoid apparatus, terminal phalanges, proatlas, and atlas cervical ribs. The skull was a bit disarticulated – half of the rostrum had floated out of position, and the stapes and palpebrals were missing – but it’s still the nicest Tonto skull ever found, and one of the best-preserved fossils to ever come out of the Antlers Formation.
Now that skull has been very thoroughly described by Andrew Thomas. Andrew wrote it up for his MS thesis under my first mentor, Rich Cifelli, and it was published last month in Palaeontologica Electronica (Thomas 2015). I had dinner with Andrew and his family when I visited the OMNH in the spring of 2014, and he showed me a down-scaled translucent 3D print of the left half of OMNH 58340. I learned more about ornithischian skulls playing with that thing over dinner than I had in the previous two decades of (admittedly quarter-assed) study.
So there’s me, playing with a down-scaled 3D print of a Tonto skull. Why am I telling you about this? Because if you want to print your own, you can – digital models of the complete cranium, and all of the individual elements, are available as STL files published along with the paper. Getting to the models takes some doing – they’re in a ZIP file linked from the paper’s Appendix 4, which you can access directly here.
Thomas (2015) has a lot more than just cool 3D models – there’s a lot of descriptive goodness, including the cranial endocast, cranial nerves, inner ear labyrinth, and hyoids; a whopping 62 figures, most in full color; and a phylogenetic analysis that incorporates the new morphological data on Tenontosaurus. No revelations there – despite all the nice specimens, Tonto remains an enigma from the murky realm between basal ornithopods and Iguanodontia. But if Oklahoma’s most abundant dinosaur is a bit of a phylogenetic mystery, it’s also becoming a paleobiologic gold mine, thanks in large part to the bone histology studies of Sarah Werning and colleagues (Lee and Werning 2008; Werning 2012 – also see Horner et al. 2009 on histology of Tenontosaurus from the Cloverly Formation of Montana). With the publication of this paper, Andrew Thomas is now part of the “Tenontaissance”. Congratulations, Andrew, and well done!
Now if we could just get some more Sauroposeidon…
- Brinkman, D. L.; Cifelli, R. L.; & Czaplewski , N. J. (1998). First occurrence of Deinonychus antirrhopus (Dinosauria: Theropoda) from the Antlers Formation (Lower Cretaceous: Aptian–Albian) of Oklahoma. Oklahoma Geological Survey Bulletin 146: 1–27.
- Currie, P. J., & Carpenter, K. (2000). A new specimen of Acrocanthosaurus atokensis (Theropoda, Dinosauria) from the Lower Cretaceous Antlers Formation (Lower Cretaceous, Aptian) of Oklahoma, USA. Geodiversitas, 22(2), 207-246.
- Horner JR, de Ricqlès A, Padian K, Scheetz RD (2009) Comparative long bone histology and growth of the “hypsilophodontid” dinosaurs Orodromeus makelai, Dryosaurus altus, and Tenontosaurus tilletti (Ornithischia: Euornithopoda). Journal of Vertebrate Paleontology 29: 734–747.
- Lee, A. H., & Werning, S. (2008). Sexual maturity in growing dinosaurs does not fit reptilian growth models. Proceedings of the National Academy of Sciences, 105(2), 582-587.
- Stovall, J. W., & Langston, W. (1950). Acrocanthosaurus atokensis, a new genus and species of Lower Cretaceous Theropoda from Oklahoma. American Midland Naturalist, 43(3), 696-728.
- Thomas, D. Andrew. 2015. The cranial anatomy of Tenontosaurus tilletti Ostrom, 1970 (Dinosauria, Ornithopoda). Palaeontologia Electronica 18.2.37A: 1-99.
- Wedel, M.J., Cifelli, R.L., and Sanders, R.K. 2000a. Sauroposeidon proteles, a new sauropod from the Early Cretaceous of Oklahoma. Journal of Vertebrate Paleontology 20: 109-114.
- Wedel, M.J., Cifelli, R.L., and Sanders, R.K. 2000b. Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. Acta Palaeontologica Polonica 45:343-388.
- Werning, S. (2012). The ontogenetic osteohistology of Tenontosaurus tilletti. PLoS ONE 7(3): e33539. doi:10.1371/journal.pone.0033539