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| Plesiosaurus |
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| Plesiosaurus (Greek:
plesios, near to + sauros, lizard) was a large (about 3 to 5
meters long), marine Sauropterygian reptile that lived during the early
part of the Jurassic period, and is known by nearly complete skeletons
from the Lias
of England and Germany. It was distinguished by its small head, long and
slender neck, broad turtle like body, a short tail, and two pairs of
large, elongated paddles. It lends its name to a larger group of
reptiles as a whole Plesiosauria, of which it is an early but fairly
typical |
| At one time, Plesiosaurus was a wastebasket taxon used to
describe any Mesozoic plesiosaur of generally similar appearance. More
recently there has been a number of revisions in sauropterygian
taxonomy, and many species previously included here have been moved to
other genera
and families. Only two species are unambiguously recognized.
Plesiosaurus dolichodeirus is the type species, known from the Lower
Lias (Sinemurian) of Lyme Regis, which was about three metres long.
Other plesiosauria from the same formation seem to have measured five to
six metres in length.
Plesiosaurus guilelmiimperatoris is known from a large almost
complete skeleton from the Upper Lias (Toarcian) of Württemberg. There
seems to be the impression of a rhomboidal flap of skin in a vertical
plane; if so, many plesiosaurs may have been equipped in this way.
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