The evolutionary lineage and diversity of ichthyosaurs may be extended far beyond what paleontologists had previously thought.
Valentin Fischer from the Royal Belgian Institute of Natural Sciences worked with other scientists from Belgium and the UK on a study published in the journal Biology Letters that describes a new ichthyosaur species, Malawania anachronus, who lived much later than most other ichthyosaurs.
Ichthyosaurs were marine reptiles that resembled large dolphins and could grow up to 15 feet long. They were predators in prehistoric seas beginning around 245 million years ago.
Fischer and his colleagues reanalyzed a fossil skeleton found in a slab of rock from the Kurdistan region of Iraq that was initially unearthed in the 1950’s. They studied spores and pollen that were preserved in the rock and determined that the organism had fallen to its death during the Cretaceous—the geological time period that lasted from 145 to 66 million years ago. This makes it the only ichthyosaur to be discovered in the Middle East that lived after the Triassic (250 to 200 million years ago).
The rock from Iraq that holds the fossil of M. anachronous, the youngest ichthyosaur ever discovered in the Middle East.
The Malawania skeleton was intricately preserved—except it was missing its head. This prehistoric sea monster measured 10 feet long. Its body shape and size, especially its chest and fin, were similar to that of the earliest ichthyosaurs—indicating that this certain line of ichthyosaurs weren’t evolving that much, or evolving very slowly.
M. anachronous belonged to an earlier ichthyosaur lineage that paleontologists had thought went extinct during the early Jurassic—200 to 175 million years ago. The oldest ichthyosaurs had many descendants. Most of these ancestral lineages reached their peak in the early Jurassic and died out around 95 million years ago. Now they aren’t so sure—perhaps many species lasted until the early cretaceous.
It’s quite possible that a variety of ichthyosaur species did exist beyond what scientists had assumed to be the end of ichthyosaur diversity. Perhaps fossils from later times, such as that of M. anachronous, just haven’t been unearthed.
Read the original study in the journal Biology Letters.
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