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also used for digging up roots. The mouth
ended in a beak used for slicing through
the tough vegetation. They were 3 m
(10 ft) in length, but weighed well over
1 tonne.
Very different to the dicynodonts were
the cynodonts, the ancestors of the true
mammals. These had long, slender bodies
and there is some evidence that they were
covered in fur; in some ways they were
closer to mammals than to reptiles. They
are known only from two large molar teeth
from the Petrified Forest, but from
complete skeletons from South Africa.
Most were carnivorous, but the molars
may have been used for crushing seeds
and roots. There is also evidence that they
lived in pairs in burrows and were mostly
cat-sized. The Chinle forms, however, were
probably larger, up to 1.5 m (5 ft) in
length.
Other reptiles and amphibians
More typical of the Chinle reptile fauna
are the various semiaquatic crurotarsal
archosaurs, the crocodile lineage. These
include the phytosaurs (a primitive
group), the crocodylomorphs (which
include the extant crocodiles), and the
rauisuchids. All of these were carnivores,
and
Postosuchus
(a rauisuchid;
137
) was the
top carnivore of its time, typical of this
group of fast-running predators that
evolved before the dinosaurs, up to 6 m
(20 ft) in length, and with an armored
back and powerful jaws. Also present are
136
136 Reconstruction of
Placerias.
137
137 Reconstruction of
Postosuchus.
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