Page 71 - Prehistoric Animals

List-Ro-So-Rus

Lystrosaurus

Lystrosaurus (shovel lizard) is an extinct genus of herbivorous dicynodont therapsids. It
lived from the late Permian and Early Triassic, around 250 million years ago. There are several dif-
ferent species and sizes ranging from the small to a large animal measuring around 3 metres in
length.

Lystrosaurus was an herbivore with a short snout but no chewing teeth. It ‘chewed’ its food
by grinding it down with a horny secondary palate in its mouth aided by jaws that moved backward
and forwards rather than up and down or to the side. It collected its food with two tusk-like up-
per canines and a horn beak on the end of its snout. Its body was stout and covered in dimpled,
leathery, hairless skin. It had short but robust
legs. Its front legs were more powerful, suggest-
ing they were used for burrowing. It had a short
thick tail that tapered to a point.

Lystrosaurus is found across the globe in Antarc-
tica, India, China, Mongolia, Russia and South
Africa. This wide distribution is thought to have
occurred when the supercontinent of Pangaea di-
vided and split into the subcontinents we are fa-
miliar with today. At that time Lystrosaurus
numbers would have been kept in check by the
numbers of its preying predators. However, all
that was about to change. In the Permian Era, in-
to the Triassic, 251 million years ago the world
experienced its biggest extinction event ever, kill-
ing off around 70 to 80% of all land vertebrates.

Lystrosaurus survived this event. Some say it did this by burrowing
underground to stay safe, others say; in an atmosphere greatly deplet-
ed of oxygen, its large lungs could survive with less oxygen. Other
claim it simply went into short periods of hibernation and slept
through most of the event. Whatever the reason, with little or no nat-
ural predators Lystrosaurus numbers exploded and it soon became a
dominant species in areas it resided.

The vast numbers of bone deposits found on the con-
tinents it inhabited are a testimony to its success.
Yet, it vanished from the face of the earth. Theorists
have put forward many reasons why it disappeared so
suddenly and mysteriously. Maybe, it had just
reached the end of its evolutionary cycle and couldn’t
change, or it did not have enough time, because the
world it lived in had changed much faster.