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A 380 million-year-old fish heart found embedded in a chunk of Australian sediment has scientists’ pulses racing. Not only is this organ in remarkable condition, but it could also yield clues about the evolution of jawed vertebrates, which include you and me.
The heart 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 — and it’s a good 250 million years older than the jawed-fish heart that currently holds the « oldest » title. But despite the fish being so archaic, the positioning of its S-shaped ticker 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, but these ancient fossils suggest there was a larger leap between jawless and jawed vertebrates, » said professor Kate Trinajstic, a vertebrate paleontologist at Australia’s Curtin University and co-author of a new study on the findings. « These fish literally have their hearts in their mouths and under their gills — just like sharks today, » Trinajstic said.
