A 380 million-year-old fish heart was found embedded in a chunk of sediment in Western Australia. It belonged to an extinct class of armored, jawed fish called arthrodires that thrived in the Devonian period between 419.2 million and 358.9 million years ago. Despite the fish being so archaic, the positioning of its S-shaped heart with two chambers led researchers to observe surprising anatomical similarities between the ancient swimmer and modern sharks. “Evolution is often thought of as a series of small steps,” study co-author says.Read Long Article
