[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Tiny dinosaur on verge of swearing off meat



> <Do heterodontosaur fangs have serrations? It'd seem odd for a dinosaur to 
> possess canine-like (ie non-serrated) fangs specifically for eating meat, 
> rather than the typical serrated blade-like teeth characteristic of 
> theropods. Did the carnivorous ancestors of heteros also have 'fangs'? If 
> not, then they would appear to be an adaptation unique to heteros -- 
> therefore something that evolved through positive selection rather than 
> something passively retained from their ancestors.>
>
>  Yes. Quite nice, actually. Not oblique to the crown but perpendicular as in 
> many theropods. However, these canines exist in *Goyocephale*, as well, and 
> as such appears to be basal to pachycephalosaurs. Basal ceratopsians also 
> have large premaxillary teeth with coarse serrations, and likely derived from 
> the finely serrated form as in *Heterodontosaurus*.
>

Except for the enlargement of the canines, the basal position within
Ornithischia now hypothesized for Heterodontosaurus by Butler et al.
(2007) suggests that these theropod-like tooth may be just
plesiomorphic retentions, unless Silesaurus and Azendohsaurus (with
basally constricted teeth) turn out to be successive outgroups of
Ornithischia and Dinosauria. That the serrations of the crown are
perpendicular instead of oblique would represent a further
plesiomorphy.