The common ancestor of all jawed vertebrates on Earth resembled
a shark, according to a new analysis of the braincase of a
290-million-year-old fossil fish that has long puzzled
paleontologists. New research on Acanthodes bronni, a fish from
the Paleozoic era, sheds light on the evolution of the earliest
jawed vertebrates and offers a new glimpse of the last common
ancestor before the split between the earliest sharks and the
first bony fishes — the lineage that would eventually include
human beings. "Unexpectedly, Acanthodes turns out to be the best
view we have of conditions in the last common ancestor of bony
fishes and sharks," said Michael Coates, PhD, professor of
organismal biology and anatomy at the University of Chicago and
senior author of the study published in Nature. "Our work is
telling us that the earliest bony fishes looked pretty much like
sharks, and not vice versa. What we might think of as shark
space is, in fact, general modern jawed vertebrate space." The
group gnathostomes, meaning "jaw