Question

it can be seen on a cladogram that modern birds and reptiles share a common ancestor. select the piece of evidence that best supports this idea.
feathers are a derived characteristic that first evolved in reptiles.
birds have the derived characteristic of being warm blooded, like mammals.
birds have evolved into many groups.
reptiles are also related to mammals.

Explanation:

To determine the best evidence that modern birds and reptiles share a common ancestor, we analyze each option:

• Option 1: Feathers being a derived characteristic that first evolved in reptiles shows a shared evolutionary trait (a derived character) between birds (which have feathers) and reptiles, supporting a common ancestor.
• Option 2: Birds being warm - blooded like mammals relates birds to mammals, not reptiles, so it doesn't support a common ancestor with reptiles.
• Option 3: Birds evolving into many groups is about bird diversification, not their relationship with reptiles.
• Option 4: Reptiles being related to mammals doesn't directly support a common ancestor between birds and reptiles.

Answer:

A. Feathers are a derived characteristic that first evolved in reptiles.