Pharyngolepis oblongus

Pharyngolepis oblongus

Name: Pharyngolepis oblongus [Oblong scaled pharynx]

When: Late Silurian Period, 430 - 423 million years ago

Where: Norway

Claim to fame: Pharyngolepis is a handsome representative of Anaspida - the "shieldless ones" - so called because of their light strap-shaped scales. As vertebrates go, anaspids like Pharyngolepis are primitive: Jawless, with only a single nostril and lacking paired fins.

Its closest living relatives are eel-like hagfish and lampreys. Unlike them, it has a tall tail-fin, making it a more effective swimmer, but in addition to being jawless, it lacks the specialized mouthparts of either of its living relatives. How did it eat? In all likelihood, it was a deposit-feeder, slurping up mud from the sea floor and digesting whatever was digestible in it.