According to the fossilized remnants of an ichthyosaur that lived not long
after the Permian mass extinction, the prehistoric marine creatures first
appeared before the devastating event.
A new research reveals that "fish-lizards" existed in the seas of the Earth
250 million years ago, much earlier than previously believed.
2014 saw the discovery of ichthyosaur fossils on Spitsbergen, a sparsely
populated Arctic territory in Norway's Svalbard region. The ancient
ichthyosaur was a lizard that resembled fish and had a body form similar to
that of dolphins and toothed whales today. The fossils are the oldest
ichthyosaur remains ever discovered and the earliest proof of aquatic
lizards. The remains, which comprise of 11 tail vertebrae, were imprisoned
inside a limestone boulder that dates to the early Triassic era.
It was once believed by scientists that ichthyosaurs and all other aquatic
reptiles appeared after the Permian mass extinction event, also known as the
"Great Dying," which took place about 251.9 million years ago and caused
about 90% of all species on Earth to disappear. As of now, the earliest
fossilized marine lizards date to 249 million years ago and come from
smaller, less aquatically developed groups. This suggests that marine
reptiles first appeared soon after the catastrophic incident.
But in a recent study, researchers contend that the size and makeup of the
ichthyosaur bones are proof that the enormous ocean predators may have
appeared before the Permian extinction took place. The study was released on
March 13 in the journal
Current Biology.
It is thought that icthyosaurs and other marine reptiles came from
land-dwelling reptiles that gradually adapted to aquatic life to cover an
ecological void left after the extinction of oceanic carnivores. The first
marine lizard species, which probably had dense bones, less streamlined
bodies, and did not reach great sizes, were consequently not ideally adapted
to an underwater existence.
The biggest ichthyosaur to ever swim in Earth's seas, according to a tooth
found in April 2022, was probably bigger than the current record bearer
Shastasaurus sikanniensis, which was 69 feet (21 meters) long.
The bones of the recently discovered ichthyosaur are the same size as those
of later ichthyosaurs, which reached lengths of about 9.8 feet (3 meters).
Additionally, the bones have a spongy design that seems well suited to
underwater living. Because it is improbable that they could have developed
these sophisticated characteristics in the less than 2 million years
following the calamitous event, the team believes that the ichthyosaur
lineage likely originated before the end-Permian mass extinction.
The findings might make palaeontologists reevaluate their assumptions about
the Permian global extinction catastrophe.
The experts said in a
statement
that "it now seems that at least some groups predated this landmark
interval." They added that additional old ichthyosaur fossils as well as
reptiles from the time of the dinosaurs may be hiding somewhere else in the
globe.
