It is possible that the middle ear fully separated from the lower jaw at least twice within the mammalian lineage. Evidence of this convergent evolution comes from
A) a new fossil of a monotreme-like mammal with the bones of its middle ear still connected to its lower jaw.
B) a new fossil of a therian-like mammal with the bones of its middle ear still connected to its lower jaw.
C) a new fossil of a monotreme-like mammal with the bones of its middle ear fully separated from its lower jaw.
D) There is no evidence; the mammalian middle ear could only have evolved once.

Question

Quizplus · Accepted Answer

The presence of a therian-like mammal fossil with middle ear bones still connected to the lower jaw suggests a separate evolutionary event from monotremes, indicating convergent evolution in the separation of middle ear bones from the jaw in mammals.

It Is Possible That the Middle Ear Fully Separated from the Lower