Rare Fossil Discovery Sheds Light on Extinct Dolphin-Like Reptiles

A new study sheds unprecedented light on a fossil discovered in 2010 by paleontologist James Crampton, providing new insights into a partial ichthyosaur skeleton. The fossil is an extinct dolphin-like reptile that may have lived during the Late Cretaceous era, just under 100 million years ago. Crampton discovered it while working in North Canterbury, New Zealand.

The fossil was concealed within a hard concretion after discovery, taken from Coverham Station in Clarence Valley to storage at GNS Science, remaining there until 2021. Due to its signature hourglass-shaped vertebrae, the fossil was effectively identified as an ichthyosaur while it was in storage.

The new study provides a deeper understanding of the fossil, which is now more complete than any other ichthyosaur skeleton in the country. This is because, before Crampton’s discovery, the only ichthyosaur pieces in the country were jaw fragments and vertebrae from different specimens.

The extinct dolphin-like reptiles were misunderstood in New Zealand due to poor fossil preservation

The lack of well-preserved ichthyosaur specimens makes it very difficult for scientists in New Zealand to understand these dolphin-like reptiles. This fossil promises to change this, as experts will use medical CT scanners to image the bones that were too difficult to prepare.

The specimen’s bones were 3D-rendered using virtual preparation to enhance understanding of the prehistoric animal’s morphology.

The fossils that the new study uses include the skull’s base, parts of the animal’s shoulder, front flippers, and the left pelvis. This reconstructed skeleton is particularly special, as it is around 98 million years old, meaning it’s from around 4 million years before its species’s final extinction. This makes this fossil one of the youngest semi-complete ichthyosaur skeletons known.

The ichthyosaur’s evolutionary links

The scientists could determine some of the ichthyosaur’s evolutionary links from the physical characteristics studied through these scans.

For instance, they determined that the specimen is closely related to an Australian species known as the Platyperygius Australis and other similar variations found in Europe.

Remarkably, the fossil of this extinct, pre-historic dolphin-like reptile shows that it is unrelated to the Western Gondwana ichthyosaurs. The creature’s habitat was in modern-day South America. This shocked scientists, as 98 million years ago, South America and New Zealand were very close to each other.

This would also suggest that the species in New Zealand are separate from the South American ones, suggesting regionalism among this species. It contradicts ancestry patterns from younger marine reptile fossils in South America, New Zealand, and Antarctica. This suggests a relationship between these regions’ animals.