Washington, March 21 : Paleontologists have formally described a creature, whose remains were discovered 14 years back in Canada, as one of the oldest and most complete plesiosaur fossils recovered in North America.
The plesiosaur has also been described as the oldest yet discovered from the Cretaceous Period, and representing a new genus of the prehistoric aquatic predator.
The fossil was discovered by machine operators Greg Fisher and Lorne Cundal in 1994 during routine mining operations at Syncrude's Base Mine, about 35 kilometres north of Fort McMurray near the Athabasca River in Canada.
Amazingly, the specimen was serendipitously exposed by one of Syncrude's 100-ton electric shovels approximately 60 metres below ground surface. It is complete except for its left forelimb and shoulder blade.
It was transported to the Royal Tyrrell Museum, where it was prepared for research observations and exhibit and studied by former U of C (University of Calgary) graduate student Patrick Druckenmiller and biological sciences professor Anthony Russell.
Known as "Nichollsia borealis", the dinosaur is one of the most complete and best-preserved North American plesiosaurs from the Cretaceous Period, that lived approximately 112-million years ago. ccording to Druckenmiller, "This specimen was preserved in sandstone and was not crushed as much as most specimens, which have typically been found in shale." Because of this, I was able to have its three-dimensional skull CT-scanned so we can see the details of the insides of its braincase. This has helped us understand this animal in more detail than almost any other plesiosaur ever found," he added.
Although not classified as dinosaurs, plesiosaurs lived in the seas at the same time that dinosaurs roamed the land throughout the Jurassic and Cretaceous Periods (205 million - 65 million years ago). They were a diverse group of carnivorous aquatic reptiles that reached lengths of over 12 metres.
Nichollsia is very significant because it fills a 40-million-year gap in the plesiosaur fossil record and greatly increases the understanding of the ancient seaway that once split North America in two and whose shores abounded with dinosaurs.
"This individual was a pioneer in the marine waters that would eventually become the Cretaceous Western Interior Seaway, which ran the length of North America during much of the Cretaceous and was home to one of the world's most diverse communities of marine reptiles," said Druckenmiller.
"It represents the oldest known forerunner of this amazing period in North American prehistory," he added.