They are the first ever, true, vertebrate land-lubbers; the very first reptile...Petrolacosaurus.
— Allen, describing Petrolacosaurus

Petrolacosaurus (name meaning "Rock Lake lizard") is a genus of diapsid reptile that originated during the Early Carboniferous Era in what is now North America. A primitive lizard measuring a little over a foot long, it was also the very first and earliest reptile ever to evolve.

In the episode "Arthropods Swamp", several Petrolacosaurus were brought back to the park from the Late Carboniferous 300 million years ago.


Era & DiscoveryEdit

Petrolacosaurus lived during the Carboniferous period, 350-280 million years ago. It shared its environment with the giant insects and amphibians is lived alongside with. However, it was fairly low on the food chain. Petrolacosaurus was among the very first reptile that ever lived on Earth.

The first Petrolacosaurus fossil was found in 1932 in Garnett, Kansas by a field expedition from the University of Kansas Natural History Museum.

Physical AttributesEdit

Petrolacosaurus was small, about 40 centimeters long, and it had the body shape similar to a modern-day lizard, like the slender body and splayed out limbs. It also had a row of bumps and knobs running down its back. It was green with white patterns and had a shade of red around its eyes.

Although it was very small, Petrolacosaurus often hunted smaller insects on the forest floors of the Carboniferous. However, the creature itself was fairly low on the food chain.

Unlike amphibians, Petrolacosaurus, like all reptiles, had tough, scaly skin which trapped moisture inside their bodies, vital for all land dwellers. Because they didn't dry out in the sun, they could venture away from water. They also had evolved a complex heart, which was much more efficient than their enemies. In fact, their hearts were the templates for our own. In the case of Petrolacosaurus, it was a powerful pump that pushed blood and oxygen around their bodies to their muscles so they could run at high speeds without stopping for a rest.

Behavior & TraitsEdit

Petrolacosaurus may have often spent time in wholes. However, with stamina and speed on their side, they did not use nor need burrows and holes in order to avoid danger. This reptile was a carnivore which mainly fed on small insects, arthropods and maybe even the corpses of larger animals, like Megarachne.

Once hatched from eggs, baby Petrolacosaurus would be completely independent. Living on their own, they were vulnerable to attack from the supersized arthropods around during the Carboniferous. However, it was a relatively fast animal, therefore it could outrun its pursuers.

But in the next episode, Allen gets the group of Petrolacosaurus into the Aviary with frogs and lizards.


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