STL Science Center

STL Science Center

19 June 2013

Everything is Bland

Heterodontosaurus, aside from the tusks and other two types of teeth, is a very typical little dinosaur. Heterodontosaurus was small enough to be compared to a modern retriever and would have been susceptible to attacks from larger dinosaurs but also animals as small as Coelophysis (not that Coelophysis was the smallest predatory dinosaur ever). The little tusks, or fangs as they have been alternately described, would have come into play in predator-prey situations. Undoubtedly the tusks could be used as defensive weaponry against attackers; however, the idea that the tusks represent a characteristic of a sexually dimorphic tradition in Heterodontosaurus means that the females of the species (or males if we reverse the assumption of dimorphism) were much less able to defend themselves in terms of anatomical weaponry.

In terms of where those little tusks/fangs were seated in the skull we are talking about the caudal body of the premaxilla. The bone itself is adjusted so that the teeth sit comfortably into the notch, or diastema, that is formed by this adaptation of the bone. The maxilla itself joins the premaxilla in a way that forms the caudal wall of the diastema where the tusks are situated. The skull is actually, despite the images shared showing the skull earlier in the week, not as exaggerated as we have assumed. Reconstructed in three dimensions, this formation in the skull that houses the tusks is really little more than a narrowing of the solid oral cavity in the area where the teeth are pronounced upward into the mouth. See below:
From The Dinosauria
Reference to check out today:
Weishampel, D. B. and Witmer, L. M. (1990). Heterodontosauridae. in Weishampel, D. B., Dodson, P., & Osmólska, H. (Eds.). Pgs. 486-497. The Dinosauria. Univ of California Press.

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