Page 91 - Prehistoric Animals

Mos-A-Sorus

Mosasaurus

Mosasaurus is an extinct group of aquat-
ic lizards that populated the world’s oceans during
the Cretaceous Period, about 145 million to 66 mil-
lion years ago. There are many species and sizes of
the genus, most species being around 2 metres in
length, and the largest estimated to be around 13
metres.

In the 18th century no one knew these marine
reptiles existed, so when the first fossils were found
they were thought to be of crocodiles or whales. In
1808, Georges Cuvier concluded they belonged to a
giant marine lizard. However, no name was allocated
to this new species until 1822, when Daniel Cony-
beare named it; Mosasaurus.

Although the species varied in length they all
had one thing in common, their bodies were robust
and powerful. They had a large scull, with huge jaws
lined with sharp pointed teeth. Its lower jaw could
open in a sideward motion allowing it to grab and
hold the largest of prey. It had four large flat fins
that could easily help propel it through the water at
speed if the need arose. Studies on fossils, however,
has shown Mosasaurus had a very poor sense of
smell, normally an absolute necessity, as smell, for
marine life, is usually the first contact when hunting
for prey. To compensate for this, many believe Mo-
sasaurus must have had above normal vision, this
they say, would account for the success of the spe-
cies.

Mosasaurus has been found worldwide, in
every ocean and climate. It was clearly a top preda-
tor. Its diet is thought, was possibly all aquatic life,
including birds, sea turtles and even other Mosasau-
rus. However, its success began to end in the late
Maastrichtian when sea levels began to drop chang-
ing the nutrient patterns of the oceans and reducing
its habitats. Its final extinction was the result of the
devastating Cretaceous-Paleogene extinction
event which also wiped out all non-avian dinosaurs.