Page 97 - Prehistoric Animals

Pelon-Es-Tes

Peloneustes

philarchus

Peloneustes (mud swimmer) is a genus of plio-
saurid plesiosaur. It roamed the waters around Europe in
the Middle Jurassic about 174 to 163 million years ago. It
had a total length of 3 to 4 metres.

Most of what is known about Peloneustes comes
from the numerous fossils found across Europe. Of
Course, the Europe Peloneustes knew was vastly different
from the Europe we know today. It was an archipelago of
a dozen or so large islands surrounded by water. The
amount of different aquatic fossilized remains found
across Europe is a good indication these waters were
teaming with life, making them an ideal hunting ground
for a marine reptile like Peloneustes.

Peloneustes was not a large pliosaurid, but it was
well adapted for an aquatic life. Its body tapered down to
the back and its large head supported long streamline
jaws which would have sliced through the water with
ease. It had four paddle shaped fins with the front pair
being larger than the rear. These would have helped pro-
pel it through the water at speed. Peloneustes may not
have been big, but on its side it had speed and surprise.
Its jaws were lined with two sets of teeth. At the rear it
had short, not too sharp, teeth and at the front longer
teeth. This suggests it could hunt both soft flesh prey, like
fish, and shelled prey, possibly, Belemnites and Ammo-
nites.

Harry Govier Seeley first described Peloneustes as
a species in 1869, but it wasn’t until 1889 that Richard
Lydekker named it as a genus. Since then several fossil-
ized remains were found and added to the genus Pe-
loneustes. However, after further study all were ejected
after being found to be of a different genus, leaving Pe-
loneustes philarchus the only valid specie of the genus
Peloneustes.

Although it’s unclear what caused Peloneustes de-
mise it’s thought a drastic reduction in bacteria in the
oceans due to worldwide water levels dropping. This is
known to have occurred around the late Jurassic period,
and would have greatly reduced the aquatic wildlife Pe-
loneustes depended on for its survival.