We now have a series of transitional fossils documenting the evolution of the mammalian ear
How could people be so sure, before these fossils were known, that the "new" ear ossicles in mammals (malleus and incus) were derived from the bones that formed the original gnathostome jaw joint?
Studies of mammalian embryology clearly show the homologies. These bones originate from the mandibular arch in development (and are originally attached to the forming jaws), while the other ear ossicle (the stapes) originates from the hyoid arch.
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