The so-called "Thecodont" reptiles (such
as _Belodon, Thecodontosaurus_, and _Paloeosaurus_, fig. 152,
c, d, e) are also nearly related to the Crocodiles, though
it is doubtful if they should be absolutely referred to this
group. In these reptiles, the teeth are implanted in distinct
sockets in the jaws, their crowns being more or less compressed
and pointed, "with trenchant and finely serrate margins" (Owen).
The bodies of the vertebrae are hollowed out at both ends, but
the limbs appear to be adapted for progression on the land. The
genus _Belodon_ (fig. 152, c) is known to occur in the Keuper
of Germany and in America; and _Paloeosaurus_ (fig. 153. e)
has also been found in the Trias of the same region. Teeth of the
latter, however, are found, along with remains of _Thecodontosaurus_
(fig. 153, d), in a singular magnesian conglomerate near Bristol,
which was originally believed to be of Permian age, but which
appears to be undoubtedly Triassic.
[Illustration: Fig. 152.--Triassic Reptiles. a, Skull of
_Nothosaurus mirabilis_, reduced in size--Muschelkalk, Germany; b,
Tooth of _Simosaurus Gaillardoti_, of the natural size--Muschelkalk,
Germany; c, Tooth of _Beladon Carolinensis_--Trias, America; d,
Tooth of _Thecodontosaurus antiquus_, slightly enlarged--Britain;
e, Tooth of _Paloeosaurus platyodon_, of the natural
size--Britain.
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