In immediately’s oceans, sea turtles, marine iguanas, saltwater crocodiles, and sea snakes are the first reptilian residents amongst tons of mammals and fish. This was not all the time the case, as fossil proof reveals that about 252 million years in the past reptiles dominated the seas. Now, an worldwide group of scientists have put collectively one other piece of this puzzle and recognized the oldest fossil of a sea-dwelling reptile from the Southern Hemisphere. The vertebra fossil belonged to the ocean dragon-like nothosaurus and was present in a stream mattress on New Zealand’s South Island. The findings are described in a research printed June 17 within the journal Current Biology.
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When reptiles dominated the seas
Millions of years earlier than dinosaurs roamed the Earth, reptiles have been the kings of Earth’s seas.
The most numerous and geologically longest surviving group of those extinct marine reptiles are the sauropterygians. They have an evolutionary historical past spanning over 180 million years. Sauropterygians included the long-necked plesiosaurs–which appeared like the favored picture of the Loch Ness Monster.
The nothosaur was a distant predecessor of the plesiosaurs. They have been roughly 23 toes lengthy and used 4 paddle-like limbs to swim and flattened skulls with slender conical enamel inside their mouths that have been used to catch fish and squid.
The nothosaurus vertebra discovered on this research dates again to when current day New Zealand was situated on the southern polar coast of an enormous super-ocean referred to as Panthalassa. When a mass extinction referred to as the Great Dying devastated marine ecosystems about 250 million years in the past, the surviving reptiles discovered alternative in Earth’s oceans.
Scientists have discovered proof of this evolutionary benchmark on the Arctic island of Spitsbergen, northwestern North America, and southwestern China. This single nothosaur vertebra fossil within the research is likely one of the newest finds from this time interval and will shed new gentle on the historical past of ancient sea reptiles from the Southern Hemisphere.
A brand new have a look at an previous fossil
The New Zealand nothosaur was initially found throughout a geological survey in 1978, embedded in a boulder in a stream on the foot of Mount Harper on the South Island of New Zealand. The significance of this was not totally acknowledged till a group of paleontologists from Australia, East Timor, Norway, New Zealand, and Sweden collaborated to look at and analyze the vertebra and different fossils.
“The nothosaur found in New Zealand is over 40 million years older than the previously oldest known sauropterygian fossils from the Southern Hemisphere,” Benjamin Kear, a research co-author and paleontologist at The Museum of Evolution at Uppsala University in Sweden, stated in an announcement. “We show that these ancient sea reptiles lived in a shallow coastal environment teeming with marine creatures within what was then the southern polar circle.”
The oldest recognized nothosaur fossils are roughly 248 million years previous. They have primarily been discovered alongside an ancient northern low-latitude belt that stretched from the distant northeastern to northwestern borders of the Panthalassa super-ocean.
Surfing the Panthalassa super-ocean
Paleontologists are nonetheless debating the origin, distribution, and timing of when nothosaurs reached these distant areas. Some prevailing theories counsel that they both migrated alongside northern polar coastlines, swam via inland seaways, or utilized currents to cross the Panthalassa super-ocean. Now, this new nothosaur fossil is throwing some chilly water on these hypotheses.
“Using a time-calibrated evolutionary model of sauropterygian global distributions, we show that nothosaurs originated near the equator, then rapidly spread both northwards and southwards at the same time as complex marine ecosystems became re-established after the cataclysmic mass extinction that marked the beginning of the Age of Dinosaurs,” stated Kear.
[Related: This Jurassic-era ‘sea murderer’ was among the first of its kind.]
When the Age of the Dinosaurs started, the Earth was going via an excessive interval of world warming. The heat temperatures allowed these marine reptiles to thrive at Earth’s South Pole. Kear and the group imagine that this implies the ancient polar areas have been seemingly the first route for the nothosaurus’ earliest international migration. This is just like the extremely lengthy migrations undertaken by immediately’s whales.
More research is required to substantiate this and can solely come from digging up extra stays of this ancient real-life sea dragon.
“Undoubtedly, there are more fossil remains of long-extinct sea monsters waiting to be discovered in New Zealand and elsewhere in the Southern Hemisphere,” says Kear.