Current ExhibitsTerrestrial Palaeozoic

Dimetrodon

Often mistaken for a dinosaur, Dimetrodon (dye-mee-TROH-don) was the most impressive mammal-like reptile of the Permian Period. With its large skull and two types of teeth—sharp canines and shearing teeth—it was at the top of the food chain. The sail on this animal’s back may have been an early experiment in thermo-regulation, allowing the sun to rapidly heat its body so that it was active earlier in the day than other animals. Dimetrodon was a member of a group of reptiles that gave rise to mammals.

Age of Insects

Insects first appeared about midway through the Palaeozoic and extremely large forms soon evolved. The fossil record of insects is not very good as their thin, brittle external skeletons break down quickly after death and do not fossilize easily. The best insect fossils have been found smothered in layers of ancient lakes deposits or embedded in amber.

Dragonflies are primitive flying insects. Their ancestors first appeared about 300 million years ago and had wingspans of up to 70 cm.

Amphibians Rule

The Permian Period is also called the “Age of Amphibians” as it was during this time that amphibians were most abundant. What prompted this population growth is considered the greatest evolutionary development in the Carboniferous, the development of the amniotic egg, which had a shell to prevent the embryo inside from drying out.

This shell allowed eggs to be laid on land and provided an expanded niche for early tetrapods—vertebrates with four limbs. Amphibians increased in numbers, but remained fairly small. One of the first amphibians to appear was Ichthyostega, (ICK-thee-oh-STEG-ah). It had four legs with feet suitable for traveling on land, but also had long fins on its tail to help it swim in the water.