Page 85 - Prehistoric Animals

Mix-O-Sorus

Mixosaurus

Mixosaurus (Mixed lizard) is an extinct genus of
ichthyosaur*. It lived in the Middle Trias-
sic (Anisian and Ladinian ages) around 247 million
years ago until 242 million years ago. It varied in length
from the shortest measuring 73 to 100 cm to the long-
est around 2 meters. Its weight was around 2.2 to
5.7 kg .

The genus was named, Mixosaurus, meaning
‘Mixed lizard’, in 1887, by George H. Baur. His naming
of the genus ‘Mixed lizard’ is an appropriate choice as
Mixosaurus is believed to be an ancient relative of the
ichthyosaurs group of marine reptiles. Although, Mixo-
saurus has been found across the globe, on its own, it is
somewhat unassuming; it is however, a crucial species,
as it’s considered a - transitory. A transitory species is
one who’s present and successive line of distant de-
pendents will eventually culminate in a modern day
species.

Mixosaurus was relatively small and primitive,
with a long slender tail, and short stubby fore and aft
fins. It was not designed for speed, and it probably
spent most of its time in the shallow nutrient-rich
coastal waters. Millions of years ago, the worlds land
mass formed one super continent. This continent split
apart and subdivided into the familiar continents we
know today. As the continents drifted apart the seas
around them, fed by nutrients from the land, became
more abundant with life.

It’s around this time that Mixosaurus descend-
ants appear. Fossils found dating from this time show
these descendants were larger and faster with large
curved tails and streamlined fins more suited for the
fast aquatic life. With more and more fossils found and
the increase in the number of species discovered, aca-
demic debates will fester on into the future, or, until
that elusive successive line that starts with the humble
Mixosaurus eventually ends with a modern day species.

*Any of several marine reptiles of the Mesozoic having a body
like a porpoise with dorsal and tail fins and paddle-shaped limbs