Ichthyosaur Jawbone Unearthed: 85-Foot-Long Giant Marine Reptile Lived During The Age Of Dinosaurs

Thomas HartwellAP Images

Blue whales continue to be the largest animals to have ever lived, but the bones of a giant ichthyosaur unearthed under an England beach could be a close runner-up.

The jawbone of the prehistoric reptile dates back to 205 million years ago. Hence, it belongs to the late Triassic period. Researchers from the State University of New York College at Brockport, New York, and the University of Manchester calculated the size of the ichthyosaur based on the jawbone relic found and estimated it to be 26 meters or 85 feet long. According to the study published in the PLOS One journal, the bone fragments could be mistaken to be that of a dinosaur given its size. This also proves that giant ichthyosaurs lived into the Rhaetian Stage

Prehistoric Giants

Ichthyosaurs were part of the marine ecosystem from the Early Triassic until they went extinct in the early Late Cretaceous period. The ichthyosaur closely resembled the modern day whale, and they gave birth to live offspring instead of laying eggs. Researchers found ichthyosaurs interesting because of their terrestrial ancestors, which remain unidentified.

Paul de la Salle, who found the species, thought it was a piece of rock at first. He brought in Dean Lomax and Judy Massare. Meanwhile, Ramues Gallois dated the fossil remains.

The jawbone specimen found in Lilstock, Somerset, was a large but incomplete jawbone, which comes in five fractured pieces and preserved in three dimensions. As reported by Newsweek, the ichthyosaur specimen was compared to relics at Canada’s Royal Tyrell Museum of Palaeontology.

Ichthyosaur Size Estimation

Massare of SUNY at Brockport explained the process through which they determined the size of the animal from the bone fragments they found.

“We compared our jawbone to that of Shonisaurus sikanniensis, the largest ichthyosaur previously known, with an estimated length of up to 21 meters. Our bone was about 25 percent deeper. The estimate assumes that the two animals had a similar shape for this bone, as neither specimen preserves the entire bone.”

Lomax of the University of Manchester explained how challenging it was to come up with an estimate of the size of the creature due to the incomplete specimen. However, they were able to use a scaling factor to determine the size of the ichthyosaur.

Based on their comparison, the Lilstock ichthyosaur is most likely between 20 to 25 meters or 67 to 82 feet. However, he reiterated that these measures are a mere approximation.

“Of course, such estimates are not entirely realistic because of differences between species,” Lomax said in a statement. “Nonetheless, simple scaling is commonly used to estimate size, especially when comparative material is scarce.”

Aside from estimating the size of the giant ichthyosaur from the Lilstock specimen, researchers also suggested that the bone fragments unearthed in Aust, a village in Gloucestershire, could also belong to an ichthyosaur. The remains unearthed back in 1850 were identified to be that of a large terrestrial archosaur or a dinosaur, yet could actually be that of an ichthyosaur much larger than the one found in Lilstock.