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Re: 225 Million-Year-Old Dinosuar Found in New Mexico



>Scientists Call 225 Million-Year-Old Dinosaur Remains Earliest in N. America
>By JANE E. ALLEN
>October 25, 1994

[most deleted]

>Scientists disagree about the age of dinosaur remains. Some theorize that
>dinosaurs evolved 228 to 230 million years ago. But because the Fort Wingate
>footprint evidence corroborates European footprints that French scientists
>claimed were 240 million years old, Hasiotis believes "it's more likely that
>dinosaurs evolved earlier, at least as early as 240 million years ago."

Although the ca. 240 Ma date is reasonable, it has not been shown that the
French (and equivalent age U.S.) footprints are actually from dinosaurs.
Thne problem comes from the fact that the immediate ancestors of dinosaurs,
primitive forms such as Marasuchus and Pseudolagosuchus, do not differ from
true dinosaurs in foot morphology.  These little guys (which are just the
right size for some of these prints) are already known from the Middle
Triassic, so their footprints are expected.

Thus, we still have no hard evidence of pre-Carnian dinosaurs.  Certainly
some existed, but how early has yet to be documented from the skeletal
record.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.