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 -
spot_img
Mark Milligan
Mark Milligan
Mark Milligan is 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

Mobile Application

spot_img

Related Articles

Pyramid of the Moon marked astronomical orientation axis of Teōtīhuacān

Teōtīhuacān, loosely translated as "birthplace of the gods," is an ancient Mesoamerican city situated in the Teotihuacan Valley, Mexico.

Anglo-Saxon cemetery discovered in Malmesbury

Archaeologists have discovered an Anglo-Saxon cemetery in the grounds of the Old Bell Hotel in Malmesbury, England.

Musket balls from “Concord Fight” found in Massachusetts

Archaeologists have unearthed five musket balls fired during the opening battle of the Revolutionary War at Minute Man National Historical Park in Concord, United States.

3500-year-old ritual table found in Azerbaijan

Archaeologists from the University of Catania have discovered a 3500-year-old ritual table with the ceramic tableware still in...

Archaeologists unearth 4,000-year-old temple complex

Archaeologists from the University of Siena have unearthed a 4,000-year-old temple complex on Cyprus.

Rare cherubs made by master mason discovered at Visegrád Castle

A pair of cherubs made by the Renaissance master, Benedetto da Maiano, have been discovered in the grounds of Visegrád Castle.

Archaeologists discover ornately decorated Tang Dynasty tomb

Archaeologists have discovered an ornately decorated tomb from the Tang Dynasty (AD 618-907) during excavations in China’s Shanxi Province.

Archaeologists map the lost town of Rungholt

Rungholt was a medieval town in North Frisia, that according to local legend, was engulfed by the sea during the Saint Marcellus's flood in 1362.