#ostracoderms

Ostracoderms, armored fishes without jaws

It’s hard to imagine a life without a jaw—we need one to eat and interact with one another through speech. Yet like every other part in our body, it didn’t always exist back in life’s evolutionary history.

Strange as it may seem, these fishes thrived in the waters of this planet over 450 million years ago. They were common animals, with fossils of these peculiar creatures having been unearthed since the 1830s. Even with their limited knowledge of the deep time, the era’s scientists noticed that these fishes clearly looked like no other living animal they knew.

—

Hundreds of millions of years before the sharky blockbuster from 1975, lived a unique menagerie of fishes that lived just fine without jaws.

Ostracoderms, jawless fishes of Silurian and Devonian times. Shown in one sketch as they might have appeared while searching for food on the floor of a Devonian sea. All were probably suspension-feeders, but employed a strong pharyngeal pump to circulate water rather than the much more limited mode of ciliary feeding used by their protovertebrate ancestors and by amphioxus today. Modern lampreys are believed to be derived from the anaspid group.

EDIT: Did I mention they have armor? 'Cause they were totally armored fish. HOW COOL.