The early appearance of sharks can be attributed to the aquatic environment of the Devonian seas. Water, despite its penchant for chaos and turbulence, provided a stable medium for life due to ...

The Devonian ancestors of fishes living today belonged to two main nonarmored groups. The cartilaginous fish, so-called because cartilage formed their skeletons, later gave rise to sharks and rays.

It was also around this time that the first plants invaded the land. The earliest shark-like teeth we have come from an Early Devonian (410-million-year-old) fossil belonging to an ancient fish called ...

researchers believe it retained many larval traits and was likely a distant relative of modern sharks. “Discovery of the mysterious animal Palaeospondylus in the Early Devonian of Australia ...

They had internal cartilaginous skeletons like sharks and rays but with an armour ... most abundant and diverse group of fish during the Devonian period, which was 419 to 359 million years ago.