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I had thought that there was consensus about the dates used for
Triassic/Jurassic/Cretaceous, but apparently the reference I've been using
for my latest project is contradicted by some later material.
Sattler's DINOSAURS OF NORTH AMERICA (1981) gives:
Triassic 190-225 mya
Jurassic 140-190 mya
Early Cretaceous 100-140 mya
Late Cretaceous 65-100 mya
But, in trying to track down why one reference thinks Dilophosaurus might
have been Late Triassic and another calls it Early Jurassic, I ran into
this schedule; it's in Lessem's KINGS OF CREATION, and matches the one in
the Dino Society Encyclopedia -
Triassic 208-245 mya
Jurassic 145-208 mya
Cretaceous 65-145 mya
So we agree on the end of the Cretaceous, but we're 5 million years
different on its beginning; we differ by 18 million years on the beginning
of the Jurassic; we differ by 20 million years on the beginning of the
Is there that much dispute, or has there been a systematic reorganization
of the periods, or what?
Steve Jackson, firstname.lastname@example.org - this will do till I fix my .sig file . . .