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RE: dinosaur nail-hooves??
Thanks for that information. So if some small sauropods or
ornithischians had survived K-T, the expanding grasslands of the Cenozoic
could have seen the evolution of ruminant-like or perissodactyl-like
dinosaurs with convergently similar "dino-hooves" for faster running
I can just hear Stephen Gould crying out--- "historical contingency"
and "let's rerun that Cenozoic tape again starting with a few minor
From: "Thomas R. Holtz, Jr." <email@example.com>
To: <firstname.lastname@example.org>, <email@example.com>
Subject: RE: dinosaur nail-hooves??
Date: Mon, 21 May 2001 10:44:49 -0400
> From: firstname.lastname@example.org [mailto:email@example.com]On Behalf Of
> Ken Kinman
> Dear All,
> I am wondering if any of the big non-theropod dinosaurs
> might have had
> evolved something like the nail-hooves of elephants. Or are
> nail-hooves and
> true hooves unique to mammals which evolved faster runners in the
> of the Cenozoic?
The flattened unguals in big sauropodomorphs and ornithopods and
thyreophorans look like they would have supported "nail-hooves" rather than
the hooves of, inter alia, ruminants, horses, and lipoterns. Furthermore,
the big plant eating dinos never reached an unguligrade stance as seen in
some of those mammals: the non-ungual phalanges touched the ground, as well
as (in many cases) a metatarsal pad.
> And also a question about the number of toes. At least some of
> mammalian pseudoungulates have a different number of toes on the
> front and
> back legs. Does this occur in any of the big non-theropods? Maybe
> are dumb questions, but I'm not normally very interested in the
In big ornithopods there were three digits in the feet and five (primitive)
or four (hadrosaurids) in the hand, but it should be said that of the
only II-IV were weight-bearers. In neoceratopsians, five manual digits
(with IV & V rather small) and four pedal. In ankylosaurs, 5-4 manual
digits and 3-4 pedal. In stegosaurs, 5 manual digits (or at least 5
metacarpals) and 3 weight-bearing pedal digits.
In sauropods, five metacarpals and five metatarsals, but as for which
exactly had weight-bearing digits (and which may have been weight-bearing
metapodials lacking digits!) varies from group to group.
Thomas R. Holtz, Jr.
Department of Geology Director, Earth, Life & Time Program
University of Maryland College Park Scholars
College Park, MD 20742
Phone: 301-405-4084 Email: firstname.lastname@example.org
Fax (Geol): 301-314-9661 Fax (CPS-ELT): 301-405-0796
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