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 does not have feathers like a bird.
the platypus does not have fins like a fish.
the platypus has fur like other mammals.
the platypus lays eggs like a reptile.

Explanation:

A phylogenetic tree shows evolutionary relationships. Since mammals share a common ancestor with reptiles, information about the platypus (a mammal) having a reptile - like trait (laying eggs) helps in showing its position relative to other mammals (bear, monkey) and the reptile (lizard) on the tree. The other options (not having feathers or fins, having fur) are either about excluding other non - relevant groups (birds, fish) or a general mammalian trait (fur) which is already known (as platypus is a mammal). The egg - laying trait (a reptile - like trait in a mammal) is key for phylogenetic tree construction.

Answer:

The platypus lays eggs like a reptile.