The Hind foot of Primitive Reptiles

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The Hind foot of Primitive Reptiles

On the hind foot of a typical modern lizard the outside toe is quite short, but the next one is extremely long, the next only a little shorter, and the other two shorter still. We can see the sense in this if we look at the hind leg of the lizard in its usual position, sprawled out at the side. The foot is essentially making contact with the ground along its leading edge, and this arrangement of toes means that it can grip the ground with four claws while in this position. This arrangement of toes in a primitive fossil reptile gives a clue that this animal must have moved like a modern lizard with its limbs sprawling out at the side.walking dinosaur costume

 

Sometimes, however, the feet have a symmetrical shape The middle toe is long and those to the side become progressively smaller. This is the foot of an animal that walks with its lower leg held vertically, rather than out to the side, like a crocodile when it is walking with its belly off the ground. In an animal such as this the foot is turned to point forwards in the direction of travel.

 

We can tell how ancient animals walked by looking at their foot bones.

 

PAREIASAURS

The heyday of the parareptiles came in the Permian and early Triassic periods, with the evolution of the pareiasaurs. These were the major plant-eaters, and were big9 slow-moving hippopotamus-like animals. They evolved quickly to become huge though they tended to become smaller and increasingly armoured as they evolved. They are represented in the modern fauna by turtles and tortoises.