Date:

Ichthyosaur found on remote Artic island upends previous evolutionary theory

Palaeontologists have found the remains of an Ichthyosaur on the island of Spitsbergen, located in the Svalbard archipelago in northern Norway.

Ichthyosaurs are large extinct marine reptiles that thrived during much of the Mesozoic era. They first appeared around 250 million years ago (Ma), with one species of the order known as Ichthyosauria, surviving until around 90 million years ago into the Late Cretaceous.

- Advertisement -

During the Early Triassic epoch, it was believed that ichthyosaurs and other ichthyosauromorphs evolved from a group of unidentified land reptiles that returned to the sea. Over time, these early amphibious reptiles became more efficient at swimming and eventually modified their limbs into flippers. They developed a ‘fish-like’ body shape and started giving birth to live young; thus, severing their final tie with the land.

On the southern shores in the Ice Fjord in western Spitsbergen, an expedition in 2014 collected a large number of concretions which were transported to the Natural History Museum at the University of Oslo for further study. The concretions were formed by limey sediments that settled around decomposing animal remains on the ancient seabed.

A study of the concretions found bony fish and bizarre ‘crocodile-like’ amphibian bones, together with 11 articulated tail vertebrae from an ichthyosaur in concretion deposits supposedly too old for ichthyosaurs to have existed.

Also, rather than representing the textbook example of an amphibious ichthyosaur ancestor, the vertebrae are identical to those of geologically much younger larger-bodied ichthyosaurs, and even preserve internal bone microstructure showing adaptive hallmarks of fast growth, elevated metabolism and a fully oceanic lifestyle.

- Advertisement -

Geochemical testing of the surrounding rock confirmed the age of the fossils at approximately two million years after the end-Permian mass extinction. Given the estimated timescale of oceanic reptile evolution, this pushes back the origin and early diversification of ichthyosaurs to before the beginning of the Age of Dinosaurs; thereby forcing a revision of the textbook interpretation and revealing that ichthyosaurs probably first radiated into marine environments prior to the extinction event.

Excitingly, the discovery of the oldest ichthyosaur rewrites the popular vision of Age of Dinosaurs as the emergence timeframe of major reptile lineages. It now seems that at least some groups predated this landmark interval, with fossils of their most ancient ancestors still awaiting discovery in even older rocks on Spitsbergen and elsewhere in the world.

Uppsala University

Header Image Credit : Esther van Hulsen

- Advertisement -

Stay Updated: Follow us on iOS, Android, Google News, Facebook, Instagram, Twitter, Threads, TikTok, LinkedIn, and our newsletter

spot_img
Mark Milligan
Mark Milligan
Mark Milligan is a multi-award-winning journalist and the Managing Editor at HeritageDaily. His background is in archaeology and computer science, having written over 8,000 articles across several online publications. Mark is a member of the Association of British Science Writers (ABSW), the World Federation of Science Journalists, and in 2023 was the recipient of the British Citizen Award for Education, the BCA Medal of Honour, and the UK Prime Minister's Points of Light Award.
spot_img
spot_img

Mobile Application

spot_img

Related Articles

Trove of medieval treasures unearthed in Oslo

Archaeologists have unearthed a trove of nearly 3,000 medieval objects in Oslo’s port district of Bjørvika, Norway.

Archaeologists find tomb of Caracol’s first ruler

After more than four decades of excavations at the Maya city of Caracol, University of Houston archaeologists Arlen and Diane Chase have uncovered the long-lost tomb of Te K’ab Chaak, the city's founding ruler.

Carved human face found in Polish lake

Archaeologists from the Nicolaus Copernicus University (NCU) have made the remarkable discovery of a carved wooden beam in the waters of Lake Lednica, located between Poznań and Gniezno in west-central Poland.

Crystalline arrowhead among new discoveries at Hedkammen

Archaeologists from Arkeologerna have uncovered a crystalline arrowhead crafted from quartzite during excavations south of Skellefteå in northern Sweden.

Lost medieval town rediscovered

Archaeologists from the Norwegian Institute for Cultural Heritage Research (NIKU) have uncovered physical remains of the lost medieval town of Hamarkaupangen in Hamar, Norway.

Blocks from the Lighthouse of Alexandria recovered from seabed

Archaeologists have recovered twenty-two stone blocks from the Lighthouse of Alexandria, one of the Seven Wonders of the Ancient World.

Gravestone depicting 13th century knight unearthed in central Gdańsk

Archaeologists from ArcheoScan have unearthed a rare gravestone depicting a medieval knight during excavations in the centre of Gdańsk, Poland.

Angler unexpectedly fishes out a mysterious medieval sword

An angler fishing in the Vistula River in Warsaw has made an unexpected discovery, a medieval sword dating back hundreds of years.