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What is a dinosaur?
Dinogeorge wrote (01/10/96; 9:27p):
>The simplest definition of a dinosaur is cladistic (amazingly enough): a
>dinosaur is any archosaur descended from the common ancestor of the
>_Megalosaurus_ and _Iguanodon_, which coincidentally are the first two
>dinosaur genera to be scientifically described. This set of animals
>a wide variety of creatures, even modern birds.
Yes, but show an average person a stegosaur, and she will have no idea
whether it was descended from the common ancestor of _Megalosaurus_ and
I like Colin McHenry's (posting of 01/11/96; 12:10a) suggestion that all
of these large, extinct reptiles could be called saurians. But is
saurian (as in "Sauria") used already to refer to a formal taxonomic
category? Assuming we can use that term, then you could specify that
"true" dinosaurs are saurians that have an erect posture (their legs
extend vertically beneath the body, as in horses, elephants, and birds).
Yes, I know there has been some debate about the posture of pterosaurs
(and let's wait until there is a consensus about it before including
pterosaurs with the dinosaurs), and if you want to leave no doubt about
also excluding the swimmers, you could say that dinosaurs are non-flying
terrestrial saurians with erect posture. Actually, it may be adequate
just to say "saurians with erect posture."
Norman R. King tel: (812) 464-1794
Department of Geosciences fax: (812) 464-1960
University of Southern Indiana
8600 University Blvd.
Evansville, IN 47712 e-mail: email@example.com