THEROPODS ("beast feet") are a group of bipedal
saurischian dinosaurs. Although they were primarily carnivorous,
a number of theropod families evolved herbivory during the Cretaceous
Period. Theropods first appeared during the Carnian age of the
Late Triassic about 230 million years ago (MYA) and were the sole
large terrestrial carnivores from the Early Jurassic until the
close of the Cretaceous, about 65 MYA. Today, they are represented
by the 9,300 living species of birds, which evolved in the Late
Jurassic from small specialized coelurosaurian dinosaurs.
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The
pictures of theropods and herrerasaurs are grouped alphabetically
on these tabbed pages. |
HERRERASAURIANS are among
the oldest known dinosaurs, appearing in the fossil record about
228 million years ago (mid-Triassic). They became extinct by the
end of the Triassic Period. Herrerasaurs were small to medium-sized
carnivores generally resembling theropods, which may be their
closest relatives. The best known representatives of this group
are from South America (Brazil, Argentina), where they were first
discovered in the 1960s. A nearly complete skeleton of Herrerasaurus
ischigulastensis was discovered in the Ischigualasto Formation
in San Juan, Argentina, in 1988. Less complete herrerasaurians
have been found in North America, and they may have inhabited
other continents as well.
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