Time for a really long description, yay...
So for the last month or so, I’ve been working on this much anticipated Mosasaurus hoffmanni skeletal. After being known to science for over 200 years, I found it kinda shocking how literally no digital skeletals of this species exists on the internet and as a result, I've probably made one of the most rigorous restorations of this animal to date. I feel like I say that every time, but once you stick to the science it can be pretty jarring how different these creatures look from popular renderings.
Tylosaurus-clone Mosasaurus restorations can piss off, basically.
If this skeletal has taught me anything, it's that the most important thing any paleontologist worth anything needs to document as many bones as they can in clear photographs, or at least rigorous drawings. It was shocking how much we apparently know of the genus, even this particular species, yet how little of it's actually pictured. How is anyone supposed to reconstruct this animal properly without appropriate images to work from?
Also, Mosasaurus is also not 17m, despite some erroneous claims. That is a fact. There is no way the 1:10 head to body length ratio estimated in Russell 1967 stands for this genus. This thing has a HUGE skull relative to body size among mosasaurs, and a short tail to boot. Even the giant Russian specimen caps out at about 13m. It's entirely possible that Tylosaurus turns out to be the longer animal. However, while it's not exactly 17m massive, Mosasaurus is still pretty massive. Easily heavier than a Tylosaurus of a comparable length. Easily. It's just... big...
Finally, if his skeletal has also taught me nothing else, it's that drawing vertebrae is tedious and I hate it.
I'm not terribly fond of the silhouette I've currently given it. I may come back to it and make a few tweaks but as far as I'm aware, the bones are at least fine. As always, I'm more than willing to make adjustments according to new data that comes my way or if someone spots a glaring error or something.***
As usual, give me a shout if you restore something based off my skeletal work. I like to see what people come up with. And you'll likely get a free fave too.
And now details. Fairly sure I'm going to forget a few specimens or papers used, but I'll edit if I remember anything else:SPECIMENS USED:
Mosasaurus hoffmannii - CCMGE 10/2469, MNHN AC 9648, IRSNB 1624, IRSNB R24, IRSNB R26, IRSNB R299, IRSNB R300, NHMM 006696, NHMM 1193024, NHMM 2013001, RMDRC 14-015
Mosasaurus conodon - AMNH 1380, MOR 006
Mosasaurus sp. - UCMP 61221
Moanasaurus mangahouangae - S34-S77BONES USED:
Skull - Heavily modified from the composite as seen in Street and Caldwell, 2017. Substituted the parietal provided with that from CCMGE 10/2469, and a modified brain case from Lingham-soliar 1995. Fixed the pterygoid to better fit the holotype's provided in the paper. Further details are listed in Street and Caldwell 2017. Sclerotic ring restored from NHMM 2013001.
Vertebrae - Bones restored from pictured elements from various specimens. Atlas from IRSNB R 300. Axis from IRSNB R26. Cervicals restored from NHMM 006696. Dorsals restored from IRSNB 1624, NHMM 006696 and S34-S77. Tail mostly restored from S34-S77 to fit UCMP 61221. Vertebrae count based on details listed for M. hoffmannii and M. conodon, Russell 1967 and Ikejiri and Lucas, 2015.
Ribs - Primarily speculative based on written descriptions provided by Russell 1967 and Lingham-Soliar 1995. Otherwise poorly documented in photo format save for a couple of fragments.Pectoral girdle - Scapulocoracoid restored from IRSNB R26 and NHMM 006696. Damage restored with reference to MOR 006.
Sternal elements speculative.
Forelimb - Restored from IRSNB R26, IRSNB R 299, NHMM 1193024, and RMDRC 14-015.
Pelvic Girdle - NHMM 006696.
Hindlimb - Restored from AMNH 1380, MNHN AC 9648, and NHMM 006696.
A = MNHN AC 9648 (Holotype)
B = CCMGE 10/2469 (Largest recorded specimen)All scale bars represent 1m (with 10cm intervals) in relation to their respective specimen.
Grigoriev, D.V., 2014. "Giant Mosasaurus hoffmanni (Squamata, Mosasauridae) from the Late Cretaceous (Maastrichtian) of Penza, Russia." Труды Зоологического института РАН, 318(2), pp.148-167.
Ikejiri, T. and Lucas, S.G., 2015. Osteology and taxonomy of Mosasaurus conodon Cope 1881 from the Late Cretaceous of North America. Netherlands Journal of Geosciences, 94(1), pp.39-54.
Lindgren, J., Caldwell, M.W., Konishi, T. and Chiappe, L.M., 2010. Convergent evolution in aquatic tetrapods: insights from an exceptional fossil mosasaur. PloS one, 5(8), p.e11998.
Lindgren, J., Polcyn, M.J. and Young, B.A., 2011. Landlubbers to leviathans: evolution of swimming in mosasaurine mosasaurs. Paleobiology, 37(3), pp.445-469.
Lingham-Soliar, T., 1995. "Anatomy and functional morphology of the largest marine reptile known, Mosasaurus hoffmanni (Mosasauridae, Reptilia) from the Upper Cretaceous, Upper Maastrichtian of the Netherlands." Philosophical Transactions of the Royal Society of London B: Biological Sciences, 347(1320), pp.155-172. Vancouver
Russell, D.A., 1967. Systematics and morphology of American mosasaurs (Reptilia, Sauria) (Vol. 23). Peabody Museum of Natural History, Yale University. Vancouver
Street, H.P., and Caldwell, M.W., 2017. “Rediagnosis and redescription of Mosasaurus hoffmannii (Squamata: Mosasauridae) and an assessment of species assigned to the genus Mosasaurus,” Geological Magazine. Cambridge University Press, 154(3), pp. 521–557. doi: 10.1017/S0016756816000236.
Wiffen, J., 1980. Moanasaurus, a new genus of marine reptile (Family Mosasauridae) from the Upper Cretaceous of North Island, New Zealand. New Zealand journal of geology and geophysics
(4), pp.507-528. Vancouver
, and for keeping me on track during the creation of the skeletal.
for his Tylosaurus, alongside the Platecarpus from Lindgren et al. 2010, was vital for restoring the posture of this Mosasaurus skeletal.
***I feel the need to make a disclaimer for this given how surprisingly often it's come up in response to what is primarily an osteological study. Yes I am aware that mosasaurs, like any squamate, would have had lips. I omitted them from this restoration partly because Scott Hartman excluded them from his Tylosaurus skeletal to showcase the teeth, and mostly because I couldn't get them to look right. Please refrain from having to remind me about it. I know already. I will likely address this issue in the future should I make changes to the silhouette of the skeletal. Thanks.