Re: Dino sterna (was Re: Rahonavis....a Bird?....a Dino?)

[tsg94001@uconnvm.uconn.edu]

>They are recovered from one _Archaeopteryx_
>(where it isn't proportionally much different in size than in other typical
>coelurosaurs), but not the others.  It seems pretty clear that we aren't
>seeing multiple evolutionary origins of sterna, but instead a spotty pattern
>of ossification of this (otherwise non-ossified) structure and/or failure to
>recognize and recover the element in the field.

I'm guessing the same holds true for the furcula ("wishbone").  Norell and
Clark (1997) described a furcula in a _Velociraptor_ skeleton from
Tugrugeen Shireh, the first for any dromaeosaurid.  Norell and Clark
mention that this specimen is a particularly large individual, and so
probably fully-grown.  I had assumed that ossification of the furcula was
perhaps an age-related thing, with younger theropods having a purely
cartilaginous furcula (or clavicles).

I wonder, is the one _Archaeopteryx_ specimen which shows an ossified
breastplate any larger than the other specimens in body size?


References

Norell, M.A. and Clark, J.M. (1997).  A Velociraptor wishbone.  Nature 389: 447.


TJW