ALL TEETH: UP CLOSE AND PERSONAL WITH DINOCROCUTA

More than a decade ago I made a reconstruction of the head of Dinocrocuta for the book “Mammoths, sabertooths and Hominids”. Back then I had not seen a single postcranial bone of the animal, but its head was impressive enough to set it apart from any other carnivore.

Here is the reconstruction of the skull and head of Dinocrocuta which I created for “Mammoths, Sabertooths and Hominids”
dinocrocuta revised skull and head

The skull is enormous, and yet it seems to provide barely enough room for the outsized cheek teeth. And that visual impression is well founded: if we compare the tooth row of Dinocrocuta with that of a more “typical” carnivore, such as the wolf, we notice that the premolars have become huge and they have pushed the carnassial back, farther back than the orbit. In comparison, the carnassial of the wolf is actually ahead of the orbit. As the emphasis became so strong on the function of the premolars, the molars behind the carnassials (still well developed in the wolf) became reduced or eliminated, there was simply no room for them!

In this working sketch which I did during the preparation of the illustration shown above, we can see the position of the upper and lower carnassials (marked in red) in the tooth row
Dinocrocuta with carnassials

In comparison, the carnassials of the wolf, seen below, are in a much more anterior or rostral position, well ahead of the orbits, and unlike the case of Dinocrocuta, there are still several sizeable molars behind them.
wolf skull with carnassials

The functional reason for these transformations in the dentition of Dinocrocuta is clear: just as in the true hyenas, the premolars are the bone-crushing teeth in these animals, and in order for them to exert the greatest force on the bitten object, they need to be as close as possible to the articulation between the skull and the mandible, so the whole premolar row is pushed back.

The result is a skull desing that parallels the features of bone-cracking hyenas, as has been confirmed by a Finite Element Analysis of CT Scans of the fossils (see the paper here: http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8312.2008.01095.x/abstract). But just like modern spotted hyenas the animal was also well prepared to take its own prey, thanks to its powerful canines and incisors. This is confirmed by evidence provided by one of the victims of this fearsome predator. Effectively, a skull of a Miocene rhino of the genus Chilotherium from China bears canine marks that fit nicely with the size and shape of the canines of Dinocrocuta, which also happens to be present in the same fossil site (see the paper here: http://link.springer.com/article/10.1007/s11434-010-3031-9#/page-1). The rhino, however, managed to escape that particular attack, and the bone shows evidence of healing; a rare example of an animal that got up close and personal with Dinocrocuta and managed to escape with its life!

Posted on 13/01/2016, in Uncategorized. Bookmark the permalink. Leave a comment.

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