Wednesday, 23 January, 2019

Jawbone Fossil found in 2016 belongs to Giant ichthyosaur

The jaw bone has been identified as that of a giant ichthyosaur up to 26m long The jaw bone has been identified as that of a giant ichthyosaur up to 26m long
Theresa Hayes | 11 April, 2018, 01:44

The fossil remains of ichthyosaurs suggest that they lived throughout the Mesozoic era, 251 million years ago and up to 65 million years ago.

They discovered many similarities and concluded that the fossilized maxillary bones found on Lilstock Beach belonged to big Ichthyosaur, very similar to a Shastasaurid Shonisaurus. These marine reptiles, with bodies similar to tuna or mackerel, are touted one of the fastest fish in the ocean, according to scholars at UC Berkeley.

Artist rendering of the ichthyosaur Shonisaurus in life and its skeletal reconstruction.

"This bone belonged to a giant", said University of Manchester paleontologist Dean Lomax.

Meanwhile, a separate study out today in PLOS One tells a much bigger ichthyosaur story: A partial jawbone from the other side of England - specifically the Somerset coast, in the southwest - appears to be evidence of one of the largest animals ever to grace Earth with its presence.

Judging from the size of the shastasaurid's jawbone, researchers estimate the animal must have been more than 85 feet (26 meters) long, which would make it the largest ichthyosaur on record - up to 25 percent larger than the previous record holder, Shonisaurus sikanniensis, a 69-foot-long (21 m) individual previously discovered in British Columbia.

Paul de la Salle, a fossil collector and co-author of the study, found the bone on the beach at Lilstock, Somerset, in May 2016. They also can't determine how big this big guy was, but the jawbone appears to be about 25 percent larger than that of Shonisaurus...if its jaw-to-body proportions are the same, it could be 25 meters (about 82 feet) long, putting it in the same category as the blue whale, now the largest animal on the planet.

In 1850, a large bone was found at Aust Cliff below the Severn Bridge in Gloucestershire.

De la Salle said that initially the bone just looked like a piece of rock, but when he recognized a groove and bone structure he thought it might be part of a jaw from an ichthyosaur.

This is a jaw bone called a surangular of a giant ichthyosaur found in England.

It's very hard to accurately estimate the animal's size because we only have a large piece of its jaw. Four other similarly incomplete bones were also discovered and described, two of which are now missing and presumed destroyed.

"Of course, such estimates are not entirely realistic because of differences between species", Lomax said in a statement.

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

Scientists have been unable to work-out whether the fossil and several other large bones found at the site came from a dinosaur or from a mystery reptile. But this kind of simple scaling is a common way of estimating size in palaeontology, especially when there aren't many samples to compare.

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.