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Size and stuff
Regarding size discussions and various input: The size differential
from Veloc. to JP's rators is about a factor of 2, which is relatively
small and probably easy to achieve within a genus. Between Dein. and
JP raptors its a factor of 1.5, maybe, easy to see even within a species
in things like reptiles and also not unreasonable within genera in birds and
mammals. Going from a small lizard (6") to a Komodo Dragon (15') is about
a factor of 30, which is way way bigger and, I'll happily admit, probably
not going to happen within a genus even.
Growth studies suggest that size increases follow a geometric progression
and, consequently, using linear measurements, seems to jump during stepped
increases. I'm talking about size increases within lineages/taxa. This is
supposedly a consequence of cell multiplication geometry. In arthropods,
for example, during molting size jumps volumetrically by a factor of 2
on the average for each instar giving a linear jump of the cube root of 2
or about 1.26. When size varies within genera for different species,
you can get the same stepped differences between the maximum adult sizes
of congeneric species. Similar size relations are described for many taxa
including mammal, bird and reptile groups also.
Consequently, size factors of 2 or 1.5 are relatively minor and easily
expected within genera so I'm confortable fully with JP's raptors being
a species of Velociraptor or Dein., maybe even the known species of Dein.
RE: Dilophosaurus - dwarfing certainly would also be reasonable as well and
the small size of their Dilo. was not troubling, although it certainly
made them less fearsome to me. The frill was more troubling and, I thought,
unnecessary although I seem to remember something about using genes from
the frilled lizard in Dil. generation, which explains the frill in
non-dinosaurian terms - which can explain lots of the oddness in any dinos
in JP (sort of their dramatic loophole for everything).
RE: Greg Paul. Greg is a friend of mine. I almost never agree with him and
think he goes overboard at times but I respect his artwork and think he
does contribute to our collective dinosaurian thought process and would
happily call him a paleontologist. I would have liked Predatory Dinosaurs
better if it had an active editor working on it and if the taxonomic part
was structured differently to avoid its being relevant to the taxonomic
nomenclature. I don't think it is a proper place to suggest some of the
revisions he suggests. I guess that's getting sorted out. But I like
Greg even if he always seems to say things I disagree with.
RE: Chatterjee. SC works hard and finds some neat stuff. I agree with him
even less than I do with Greg Paul and thinks he is almost inevitably off
base. However, if he pulls together scholarly papers presenting his ideas
and makes his specimens available for study by others then he's doing a
service to paleontology. Guys like him keep the rest of us honest.
Well, enough diatribe for now.
Ralph E. Chapman, Applied Morphometrics Laboratory
National Museum of Natural History, Smithsonian Institute