Pelvic fins available on fish that is fossilperhaps not unlike those from the living coelacanth above) are perhaps proof of the very first “true intromittent organ” in vertebrates—that is, the one that inserts into another system during sexual activity.

The organ that Long’s group found on Incisoscutum is really a “protopenis”—in component because, unlike the penises we’re familiar with, the proto one faces backward, far from the mind for the fish that is male.

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