Question

julia is trying to place a duckbilled platypus, lizard, bear, and monkey on a phylogenetic tree. she learns that the duckbilled platypus, bear, and monkey are classified as mammals. she also learns that mammals share a common ancestor with reptiles. which additional piece of information will be most helpful to julia to properly build her phylogenetic tree?
the platypus has fur like other mammals
the platypus does not have feathers like a bird.
the platypus lays eggs like a reptile.
the platypus does not have fins like a fish

Explanation:

A phylogenetic tree shows evolutionary relationships. Since mammals share a common ancestor with reptiles, knowing that the platypus (a mammal) lays eggs (a reptile - like trait) helps in placing it on the tree. This trait provides a connection to the reptile - mammal common ancestor. The other options (fur - already known as a mammalian trait, no feathers - not relevant to reptile - mammal connection, no fins - not relevant to reptile - mammal connection) do not add as much value for building the tree as the egg - laying trait.

Answer:

The platypus lays eggs like a reptile.