'Remarkable' meat-eating dinosaur officially recognised after 30 years

James Marshall
January 26, 2020

The dinosaur lived in what is now western North America during the Late Jurassic Period between 152 and 157 million years ago.

Allosaurus was a fierce predator at the top of the dinosaur food chain millions of years before Tyrannosaurus rex claimed its "king of the dinosaurs" title and researchers have now discovered the earliest known species of Allosaurus.

Both species differ in their skeletal details, which is why A.jimmadseni has been described as a new species entirely.

Allosaurus itself translates from Greek to mean "different reptile". It's been named after James Madsen, Utah's first state paleontologist.

More than two decades after a unique two-legged carnivore was unearthed in Utah's Dinosaur National Monument, scientists have given the massive carnivore a name. Only the skeleton was missing a key feature: the skull. Also, when DINO 11541 became first found, the paleontologists also can no longer uncover its skull, however for the reason that head became mildly radioactive, it became at closing recovered in 1996 by Ramal Jones from the University of Utah, who primitive a radiation detector to smell-out the gamma rays emanating from the skull (radioactive fossils are a pure incidence).

An important fossil began to be displayed in the Utah Natural History Museum.

It enabled the skull to be recovered, along with the rest of the fossil. A helicopter was then brought in to fly out the 6,000-pound block.

This newly discovered species has unique features compared to the allosauroids that followed. Researchers at the Dinosaur National Monument needed seven years to prepare the bones for analysis. In comparison with A. fragilis, it had a weaker skull and a narrower stereoscopic self-discipline of peep. Fragilis came on the scene five million years later as a younger cousin. The new species has relatively longer legs and tail, and long arms with three pointed claws.

'Recognising a new species of dinosaur in rocks that have been intensely investigated for over 150 years is an outstanding experience of discovery, ' said Dr Daniel Chure, a retired palaeontologist at the Dinosaur National Monument in north-eastern Utah and co-lead author on the study. Low facial crests extended from the dinosaur's horns, arcing just in front the eyes stretching down the length of its nose. For the new study, paleontologist Mark Loewen from the Natural History Museum of Utah, along with his sole co-author Daniel Chure, a retired paleontologist from the Dinosaur National Monument in Utah, described A. jimmadseni based on two almost complete skeletons and various fossils collected over the years. "The skull of Allosaurus jimmadseni is more lightly built than its later relative Allosaurus fragilis, suggesting a different feeding behavior between the two". A mishmash of other Allosaurus bones were also included in the study, some of which were found to belong to the newly described species.

Specimen MOR 693 is more commonly known as "Big Al", and it was incorrectly thought to be A. fragilis. Because the youngest species of Allosaurus within the fossil memoir, it's shedding contemporary gentle on the evolution of this seriously essential neighborhood of carnivorous dinosaurs.

"I've been waiting for this paper for about 20 years now, ever since I started studying dinosaurs as an undergraduate and heard rumours of a new Allosaurus species from the western US", explained Brusatte. Allosaurus jimmadseni is a great example of just how much more we have to learn about the world of dinosaurs.

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