THE  THERAPSIDS 

Therapsids
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The Therapsids
Introduction

Bone Heads
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Gorgonopsids, Dicynodonts, and Others – the Rivals and Relatives in a Dinocephalian-Dominated World
Gorgonopsids were the sabre-toothed killer therapsids of the Permian world. Galesuchus ('cat crocodile' – skull 12.5cm – seen in hot pursuit of tiny Robertia, a dicynodont therapsid, at right) was a very early gorgonopsid of moderate size.  Normally, prey for Galesuchus would likely have been the smaller dinocephalians or the largest of dicynodonts.  However, few predators will turn their noses up at an easy meal.  Robertia measured only 19.5cm long  –  not much of a meal but, once flushed from cover, easy for the longer-limbed 'gorgon' to catch.  Like many dicynodonts, Robertia may have lived in a burrow  —  safe from  the  elements  as well  as from toothy opportunists like  the  Galesuchus!

Fossil footprints of early dicynodonts (probably Diictodon) have been found in the Karoo of South Africa. These trace fossils suggest a toed-in, slightly waddling gait.  Dicynodonts were not fast-moving animals.  Gorgonopsids like Galesuchus, on the other hand, always seemed to move with their feet facing straight forward. The gorgonopsids were likely the first animals able to trot  —  a very frightening prospect for prey of any size!

Gorgonopsid Leontocephalus intactus warily circles a wounded pareiasur, Pareiasuchus nasicornis  —  top left
The gorgonopsian
Leontocephalus ('lion head' - skull 32cm, total length 1.75m) has been very well studied.  A very readable undergraduate research paper, The Morphology and Behaviour of Gorgonopsids... by Alexandra Freeman examines the fossil remains of Leontocephalus intactus in great detail and results in a fascinating 'life restoration'.

The pareiasaur, Pareiasuchus ('cheek crocodile' – skull 50cm, total length 3m+), is the intended victim. Pareiasaurs were 'para-reptiles' which may have separate origins from other reptiles  ( connections with turtles have also been suggested ). This big plant-eater was heavily armored with scutes  –  tough bumps and plates imbedded in its skin or attached to its bones.  The pareiasaurs' upright, therapsid-like hindlegs are a good example of parallel evolution.

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Gorgon's Bite
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