[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Protoceratops Gender
do we actually KNOW which one is which? (i.e. Could the
small-bump-and-large-wide-frill specimens actually be the females?) Has
anyone looked into chevrons at the base of the tail, or anything like that,
to try to determine the gender, like people were doing for
Part of the problem is that determining the presence of sexual dimorphism is
devilishly tricky in the fossil record, and only a few dinosaurs meet the
criteria in the first place (_Coelophysis_, _Allosaurus_, among theropods).
But, even with a less than perfect sample size, you can still begin to make
conclusions, provided you have at least a partial growth series. The
question then becomes, to me, how many catalogued and described specimens of
_Protoceratops_ are there?
And if sexual dimorphism is present, you would need a way to determine which
morph corresponded to which sex (as you noted in the original e-mail). I'm
not too familiar with ceratopsid paleobiology, but it would stand to reason
that the larger frill would correspond to the male, for simple reasons of
display. However, this may not be the case, and the bad part is that there
really is no good way at all to tell which sex is which in the fossil
record, except in very unusual circumstances (i.e. an icthyosaur giving
birth). Some have suggested using chevrons, but there has turned out to be
no real correlation there. Some have suggested using relative robustness,
but this is equivocal, because robustness varries among genders, depending
on the taxon. For dinosaurs, some have suggested that the pelvic opening
that is wider was the female, because it would accomodate an egg. But, there
is nothing saying that the large opening couldn't have been used to support
the male sex organs. Unless you have an egg (which we don't have for most
dinosaurs), this claim cannot be substantiated.
Conclusion (IMNSHO): You can determine if sexual dimorphism is present in
the fossil record, but not which morph corresponds to which sex.
Student of Geology
Northern Arizona University
Biological Science Tech
Manti-La Sal National Forest
"A _Coelophysis_ with feathers?"
Get your FREE download of MSN Explorer at http://explorer.msn.com