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Re: A Clutter of Duckbills
<<Hypacrosaurus, Corythosaurus, and Lambeosaurus, for example.
Without the crests, it is rather hard distinguishing one animal from
the other. Indeed, one juvenile AMNH specimen of a lambeosaurine
duckbill could easily have either been a Corythosaurus or a
Lambeosaurus (I think the final arguments placed it in
Lambeosaurus). Thats how undistinguishable those species are.
What details keep this lump of animals in different genera?
Actually, what kind of details keep one species in one genera or the
other? The details on these three lambeosaurine genera certainly
indicate how closely related they are. Hypacrosaurus and
Corythosaurus have the same type of crest, the "helmet" crest, and
Lambeosaurus has a similar crest except that the lambeosaurus
crest has a thin spine sticking backwards on it. Without these
crests, the rest of the skeleton indicate that these animals had
probably evolved from a recent common ancestor a few million years
before they came about.
What keeps Lambeosaurus, Corythosaurus, and Hypacrosaurus in
different genera? Stanley Friesen suggested to me that all of the
species of these three genera may actually belong to only one genus
-- the first one coined, Hypacrosaurus.
Sounds like a decent lumping to me. (Much more probable that
lumping Deinonychus into Velociraptor.)>>
I like that idea. It was argued by Horner and someone else (sorry) I
think, that Lambeosaurus was almost certainly ancesteral to
Corythosaurus, and that Corythosaurus was almost certainly
ancesteral to Hypacrosaurus; so it's not too much of a stretch to put
them all in the same genus. I like the sound of Hypacrosaurus
lambei better than Lambeosaurus lambei; a little to cheezy to have
the same word in the generic and specific name (sort-of like
Prenocephalus prenus). In any case I like this idea. Does anyone
know however, if Procheneosaurus (the juvinile) was named before or
after Hypacrosaurus; since it almost certainly belongs in that genus
(in the big lumped sense, that is), it should have priority over
Hypacrosaurus IF it was named first.
<<Another group of hadrosaurs that confuse me are Gryposaurus,
Hadrosaurus, Kritosaurus, and Brachylophosaurus. I know little
about these genera in particular, except for the fact that they are so
closely related and similar. Any thoughts about which genus and
species should go where? Which one was coined first?
Hadrosaurus was the first good hadrosaur skeleton to be
discovered in N. America. Just how good was it? Was it good
enough to show that Gryposaurus, Kritosaurus, and
Brachylophosaurus were actually different species of
George Olshevsky has shown that Hadrosaurus is (no joke) a
nomum dubium! Since there was no skull associated with the
original, no one can really decide which later, and better, described
genus really belongs in Hadrosaurus, if any at all. Horner has some
strange ideas about Brachylophosaurus being a sister taxa to
Maiasaura (an idea I don't buy for a second). He also puts
Kritosaurus in with Anasazisaurus and Naashoibitosaurus in the
Saurolophines (I think). He has seperated Gryposaurus from
Kritosaurus (something he claimed was not possible a few years
ago) and put it into its own subfamily. I'm not sure why; in my
opinion Kritosaurus, Gryposaurus, Anasazisaurus,
Brachylophosaurus, and Naashoibitosaurus should be put in a
subfamily together; seperate from Saurolophs + Edmontosaurs.
Anyways.... Those are just my opinions.
In case any of you are wondering (like you haven't figured it out
already) I tend to lump genera, and split species and families.