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3 11, 2015

Deadly Dakotaraptor – Late Cretaceous Super Predator

By | November 3rd, 2015|General Teaching, Key Stage 3/4|Comments Off on Deadly Dakotaraptor – Late Cretaceous Super Predator

Scientists Report on Car-sized Raptor

The Hell Creek Formation of North America has provided scientists with fossils of some of the most iconic dinosaurs known.   These ancient sediments were once home to dinosaurs such as Triceratops and Tyrannosaurus rex, however, amongst the many thousands of fossils excavated from these Upper Cretaceous rocks, there were a number of large teeth, unmistakably from a huge Dromaeosaur (raptor), but no bones associated with them to provide a description.  All that has changed with the publication of a paper in the academic journal “Kansas University Paleontological Contributions”.

Terror of the Late Cretaceous of North America

Estimated to be around 5.5 metres in length.

Estimated to be around 5.5 metres in length.

Picture Credit:  Emily Willoughby

A team of scientists drawn from a number of top American institutions along with professional fossil collectors from the Black Hills Institute of South Dakota have described the partial and very fragmentary skeleton of a super-sized dromaeosaurid dinosaur that once co-existed with the likes of Triceratops and T. rex, sixty-six million years ago.  The fossils, including front limb bones and a huge, sickle-shaped toe claw were found in Harding County, South Dakota.  This dinosaur has been named Dakotaraptor steini.  Although, less than ten percent of the skeleton has been excavated, comparisons made between these bones and the fossils of more complete raptors such as the famous Velociraptor, suggest that Dakotaraptor measured more than five and half metres in length.  This makes it one of the largest dromaeosaurids known and the second largest from North America.  Only Utahraptor, a meat-eating dinosaur that roamed Utah some fifty million years or so before Dakotaraptor evolved, was bigger.

A Scale Drawing Showing the Estimated Size of Dakotaraptor

A scale drawing of Dakotaraptor.

A scale drawing of Dakotaraptor.

Picture Credit: Robert DePalma (Palm Beach Museum of Natural History)

The research team, led by Robert DePalma (Curator of Vertebrate Palaeontology at the Palm Beach Museum of Natural History (southern Florida), have speculated on where in the Hell Creek ecosystem, this agile predator may have fitted, after all, the apex predator was Tyrannosaurus rex.  It has been suggested that Dakotaraptor may have been a pack hunter and preyed on other types of herbivore and so it may not have been in direct competition with the Tyrannosaurs.

Important Skeletal Features Preserved

Described as being about the size of the “raptors” that featured in the Summer blockbuster “Jurassic World”, Dakotaraptor preserves two very intriguing anatomical features on its bones.  Firstly, there is the enormous sickle-shaped claw on the second toe.  It measures sixteen centimetres in length, but when the sweeping curvature of the outer curve of the claw is considered, the claw measures an impressive twenty-four centimetres in length.  That’s roughly the same size of the toe claw found in the much larger Utahraptor.  In addition, the ulna (bone in the forearm), preserves fifteen large and distinct ulnar papillae (quill knobs).  These depressions in the bone are the places of attachment for big, pennaceous feathers.  Dakotaraptor is the largest known dinosaur which had wing feathers.

A spokesperson from Everything Dinosaur commented:

“Fossil teeth had indicated that within the Hell Creek Formation strata, evidence for a substantial dromaeosaurid would be found.  This fascinating discovery adds another dimension in terms of niche partitioning to the fauna of this part of North America during the Late Cretaceous.”

3 11, 2015

Dakotaraptor a Giant Raptor

By | November 3rd, 2015|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page|0 Comments

Dakotaraptor steini and Niche Partitioning

An international research team which included scientists from the University of Kansas, Pete Larson (Black Hills Institute of Geological Research) and Bob Bakker (Houston Museum of Science and Nature) , have finally solved a hundred year mystery with the describing of a very large dromaeosaurid from fluvial deposits that form part of the famous Hell Creek Formation exposed in South Dakota.  Teeth, very typical of a dromaeosaurid, had been found in the Late Maastrichtian deposits indicating the presence of a very large “raptor”, however, no bones to link to the teeth were known.  However, a paper published in “Paleontological Contributions” describes Dakotaraptor (D. steini) and a new super-sized Dromaeosaur has been introduced to the world.

Dakotaraptor – A Fearsome Predator

Dakotaraptor steini

Dakotaraptor steini

Picture Credit: Emily Willoughby

At an estimated five and half metres in length, this new meat-eating dinosaur, known from fragmentary remains representing two individuals fills a niche within the food web of the fauna represented by the vertebrate fossils associated with the famous Hell Creek Formation.  A number of small Theropods are known as well as the super-sized Tyrannosaurs such as T. rex.  Dakotaraptor represents a sort of “halfway house” when it comes to the carnivores associated with Hell Creek.  Its limbs and body are very similar to the smaller dromaeosaurids known from this part of the world, dinosaurs such as Dromaeosaurus, (the first dromaeosaurid ever described), Saurornitholestes, and the recently named Acheroraptor but proportionately much larger.  Dakotaraptor was one “raptor” that actually did grow to be as big as the “Velociraptors” featured in the Jurassic Park franchise.

Commenting on the size and scale of Dakotaraptor, co-author of the publication and Kansas University palaeontologist, David Burnham said:

“This new predatory dinosaur also fills the body size gap between smaller Theropods and large Tyrannosaurs that lived at this time.”

The fossils were found in 2005, lead author of the research, Robert DePalma, (curator of vertebrate palaeontology at the Palm Beach Museum of Natural History) led the field expedition to Harding County (South Dakota) where the specimens were located.  At the time, he was a graduate student studying under former Kansas University professor and curator Larry Martin, who sadly passed away in 2014.

He explained:

“This Cretaceous period raptor would have been lightly built and probably just as agile as the vicious smaller Theropods such as Velociraptor.”

In addition to being roughly the size of the iconic “Raptors” from Jurassic Park, there are two very exciting skeletal features preserved in Dakotaraptor.  The paper describes a massive dromaeosaur sickle claw on the middle toe.  It measures 16 cm from top to bottom and 24 cm along the outer curve.  This was an impressively large raptorial claw, even for an animal this size.  The ulna, a bone in the forearm, bares 15 large and distinct quill knobs, or ulnar papillae, which are reinforced attachment points on the wings of birds and other dinosaurs where the large, pennaceous feathers attach.  This makes Dakotaraptor the largest known dinosaur with confirmed wings.

Reconstructed Dakotaraptor Wing and Proposed Plumage

The "wings" of Dakotaraptor.

The “wings” of Dakotaraptor.

Picture Credit: Robert DePalma

Dakotaraptor may not have competed directly with adult Tyrannosaurs.  Perhaps it adopted a different hunting strategy or specialised in attacking a different sort of prey.  By doing this it would have avoided direct competition between it and other large predatory dinosaurs. This is an example of niche partitioning.

When asked by Everything Dinosaur about this particular aspect of the research, Robert DePalma explained:

“Niche partitioning is a given, Dakotaraptor had to occupy a distinct ecological niche.  If it coexisted with the other large predators, had the same herbivores available to them, and did not out compete each other to extinction, then there had to be different strategies going on.”

Everything Dinosaur acknowledges the assistance of Kansas University and Robert DePalma in the compilation of this article.

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