By Stephanie Pappas | LiveScience / MSNBC

Peer far enough back in the human family lineage, and you’ll find a fishy ancestor that looked surprisingly like a shark.

In fact, this now-extinct fish was among the first to split from sharks, whose bones are made of cartilage, to evolve into a line of tough-boned species that includes everything from bony fish to human beings. A new analysis finds that this controversial class of animals was more shark-like than expected.

"The common ancestors of all jawed vertebrates today organized their heads in a way that resembled sharks," study researcher John Finarelli, a vertebrate biologist at University College, Dublin, said in a statement. "Given what we now know about the interrelatedness of early fishes, these results tell us that while sharks retained these features, bony fishes moved away from such conditions."

Molds of the cranium of Acanthodes Bronni. Megan Doherty / University of Chicago