THE  THERAPSIDS 

— Long Before the Rise of the Dinosaurs —
The Story of the Permian Therapsids

Therapsids
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The Therapsids of the Permian  —  the Ancestors of the Mammals
This is a story about ancestors – your ancestors. Two hundred and seventy million years ago – 50 million years before the first dinosaur appeared – an entirely new group of animals, the therapsids, burst onto the scene.  Welcome to the Permian.

These therapsids were unlike any animals that have appeared on the earth  —  before or since. Elephantine therapsid plant-eaters with horns, or thick skulls, for head-butting and sharp tusks for self-defense. Saber-toothed therapsid carnivores who killed their prey with a single stab. Strange tusked and turtle-beaked plant-eaters as small as
a rat or as big as a hippo. Even a lion-sized meat- eater complete with snake-like venomous fangs.

   And one small, seemingly insignificant, otter-like therapsid — Procynosuchus — who just
   happens to be the distant ancestor of you, and me, and every other hot-blooded mammal.

Eoarctorps vanderbyli and Tapinocaninus pamelae  —  above left
The attackers are the small gorgonopsids, Eoarctops ('dawn bear face' - skull 12.25cm) — great muscle power was needed to take advantage of that imposing 90° gape [see: Gorgonopsid Jaw Muscles and Bite ].  Their unfortunate victim is the early dinocephalian, Tapinocaninus ('low canine'* - total length 3.0m).

Tapinocephalus atherstonei mother with her young  —  above right
Tapinocephalus ('low head' - skull 60cm) uncovers her clutch of eggs in time for hatching. Were therapsids really egg-laying animals who practised active parenting?  We have no fossilized evidence of therapsid eggs so, artistic license has been used.**  The mammals most resembling therapsids, the monotremes –  platypuses and echidnas –  do lay eggs. Unlike hard-shelled birds' eggs, monotremes lay a leathery and sticky egg which is nearly spherical.  Perhaps the therapsid egg was similar.

* In the translation of Tapinocaninus, 'low' refers to the position in the rock strata where the fossil was found, rather than the canine-like tooth itself.  A wonderful life-sized Tapinocaninus robotic model has been created at the Bernard Price Institute in South Africa.  (Video)

** The same applies to therapsid mothering. Most modern reptiles abandon their clutch. Crocodiles protect their eggs until the hatchlings can disperse — meat-eating therapsids likely did the same.  However, the plant-eaters have more reason to mother.  Their young are born without the bacteria needed to digest tough plant material — they must acquire these digestive symbionts from an adult of their species.

Therapsids of
the Permian


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Therapsid Ancestors
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