What are large thick skinned animals such as elephants and hippos called?

There isn't a single specific term for large, thick-skinned animals like elephants and hippos. However, you can describe them using a few terms:

* Pachyderms: This term, derived from Greek words meaning "thick-skinned," is often used to describe elephants, rhinoceroses, and hippos. However, it's not a scientifically accurate classification, as it doesn't reflect their evolutionary relationships.

* Megafauna: This term refers to large animals, typically weighing over 45 kg (100 lbs), and includes many thick-skinned animals.

* Large mammals: This is a general term for mammals that are significantly larger than humans.

* Thick-skinned animals: This is a more descriptive term that accurately reflects their key characteristic.

Ultimately, the best term depends on the context and what you want to emphasize.