Three mammal-like reptiles, known as placerias, standing in water


Placerias was, at 3.5m in length, the largest herbivore of the Late Triassic Period, whose chunky, barrel-like body may have weighed a little under a tonne. Despite its appearance, Placerias was not a dinosaur, but a type of mammal-like reptile. It was the last of the Dicynodonts, so with its extinction that whole lineage disappeared. Like other dicynodonts, Placerias had tusks which it used to dig up roots and a beak to chop up its food.

Scientific name: Placerias

Rank: Genus

Common names:

broad body

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Discover what these behaviours are and how different plants and animals use them.

Additional data source: Animal Diversity Web

When they lived

Discover the other animals and plants that lived during the following geological time periods.

Triassic period Triassic period
The Triassic began after the worst mass extinction ever, at the end of the Permian. Life on Earth took a while to recover and diversify.

What their world was like

Desert Earth Desert Earth
A vast desert formed in Earth's prehistoric past when the supercontinent of Pangaea straddled the equator and stretched to the poles. Pangaea's position influenced ocean circulation patterns, and its huge size meant that there were vast areas where moist air from the oceans never penetrated.

What killed them

Triassic-Jurassic mass extinction Triassic-Jurassic mass extinction
During the final 18 million years of the Triassic period, there were two or three phases of extinction whose combined effects created the Triassic-Jurassic mass extinction event. Climate change, flood basalt eruptions and an asteroid impact have all been blamed for this loss of life.


  1. Life
  2. Animals
  3. Vertebrates
  4. Synapsids
  5. Therapsids
  6. Kannemeyeriidae
  7. Placerias