For questions about mammals as they evolved on Earth. This may include, but is not limited to, warm-bloodedness, the possession of fur, the ability to secrete milk, and the bearing of live young.

Mammals generally, though not always, possess four traits:

  • Warm-bloodedness
  • Fur or hair
  • Secretion of milk
  • Bearing of live young

When designing a fictional creature with these or similar qualities, is always appropriate. Consider also and .

history | excerpt history