According to paleontologists from the University of Chicago and the University of Michigan, long-extinct Bandringa sharks migrated downstream from freshwater swamps to the ocean to spawn in shallow coastal waters and left behind fossil evidence of one of the earliest known shark nurseries.
The long-snouted Bandringa shark (Elasmobranchii, Chondrichthyes) – a bottom-feeding predator that lived in an ancient river delta system in what is today the Upper Midwest – is likely one of the earliest close relatives of modern sharks.
It resembled present-day sawfish and paddlefish, with a spoon-billed snout up to half its body length. Juveniles were 4 to 6 inches long and grew into adults of up to 10 feet.
Bandringa sharks were discovered in 1969 and soon became one of the most prized fossils from the well-known Mazon Creek deposits in northern Illinois.
Until now, paleontologists believed that the genus Bandringa contained two species – B. rayi and B. herdinae, one that lived in freshwater swamps and rivers and another that lived in the shallow ocean.