However, some of the earliest known mammals include:
* Morganucodon: This small, shrew-like creature lived around 205 million years ago during the Late Triassic. It is considered by some to be the earliest true mammal, though others argue it was still a transitional form.
* Megazostrodon: This mammal, also from the Late Triassic, was slightly larger than Morganucodon and had some features that are more characteristic of mammals, such as a more developed jaw joint.
It's important to note that these are just two examples, and there are many other early mammals that are still being discovered and studied.
The evolution of mammals from their reptilian ancestors is a complex process that took millions of years. Key adaptations that helped define mammals include:
* Hair: Mammals have a coat of fur or hair for insulation.
* Mammary glands: Females produce milk to nourish their young.
* Three middle ear bones: These bones help to transmit sound vibrations, giving mammals better hearing.
* Endothermy: Mammals are warm-blooded, allowing them to be active in a wider range of temperatures.
It's an exciting area of study, and new discoveries are constantly rewriting our understanding of mammalian evolution!