In today’s oceans, sea turtles, marine iguanas, saltwater crocodiles, and sea snakes are the primary reptilian residents amongst tons of mammals and fish. This was not always the case, as fossil evidence shows that about 252 million years ago reptiles dominated the seas. Now, an international team of scientists have put together another piece of this puzzle and identified the oldest fossil of a sea-dwelling reptile from the Southern Hemisphere. The vertebra fossil belonged to the sea dragon-like nothosaurus and was found in a stream bed on New Zealand’s South Island. The findings are described in a study published June 17 in the journal Current Biology.
[Related: New species of extinct marine reptile found with help from 11-year-old child.]
When reptiles ruled the seas
Millions of years before dinosaurs roamed the Earth, reptiles were the kings of Earth’s seas.
The most diverse and geologically longest surviving group of these extinct marine reptiles are the sauropterygians. They have an evolutionary history spanning over 180 million years. Sauropterygians included the long-necked plesiosaurs–which looked like the popular image of the Loch Ness Monster.
The nothosaur was a distant predecessor of the plesiosaurs. They were roughly 23 feet long and used four paddle-like limbs to swim and flattened skulls with slender conical teeth inside their mouths that were used to catch fish and squid.
The nothosaurus vertebra found in this study dates back to when present day New Zealand was located on the southern polar coast of a vast super-ocean called Panthalassa. When a mass extinction called the Great Dying devastated marine ecosystems about 250 million years ago, the surviving reptiles found opportunity in Earth’s oceans.
Scientists have found evidence of this evolutionary…
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