Dakotaraptor

Name: Dakotaraptor ‭(‬Dakota thief‭)‬.
Phonetic: Da-ko-tah-rap-tor.
Named By: Robert A.‭ ‬DePalma,‭ ‬David A.‭ ‬Burnham,‭ ‬Larry Dean Martin,‭ ‬Peter Lars Larson‭ & ‬Robert Thomas Bakker‭ ‬-‭ ‬2015.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Saurischia,‭ ‬Theropoda,‭ ‬Dromaeosauridae,‭ ‬Dromaeosaurinae.
Species: D.‭ ‬steini‭ (‬type‭)‬.
Diet: Carnivore.
Size: Estimated at about‭ ‬5.5‭ ‬meters long.
Known locations: USA,‭ ‬South Dakota‭ ‬-‭ ‬Hell Creek Formation.
Time period: Late Maastrichtian of the Cretaceous.
Fossil representation: Partial post cranial skeletal remains.

       The one thing that immediately stands out about Dakotaraptor at first glance is simply the large size of this dromaeosaurid dinosaur.‭ ‬Most dromaeosaurid dinosaurs measure in at under two meters in length,‭ ‬with a few genera ranging between two and three meters long.‭ ‬The Holotype individual of Dakotaraptor however has a reconstructed length of five and a half meters.‭ ‬At the‭ ‬time of the‭ ‬2015‭ ‬description,‭ ‬this makes Dakotaraptor the second largest dromaeosaurid dinosaur known,‭ ‬with the largest being Utahraptor.
       As far as comparison between Dakotaraptor and Utahraptor goes,‭ ‬Utahraptor lived in North America around Utah‭ (‬clue is in the name‭) ‬during the Early Cretaceous roughly one hundred and twenty-six million years ago.‭ ‬Dakotaraptor also lived in North America but around South Dakota towards the end of the Late Cretaceous some sixty-six million years ago.‭ ‬Not only are Dakotaraptor and Utahraptor separated by a wide temporal gulf,‭ ‬study of the known fossils of Dakotaraptor show that in body‭ ‬proportions‭ ‬this genus was actually more like genera such as Deinonychus and Dromaeosaurus than it was Utahraptor,‭ ‬making a direct link between Dakotaraptor and Utahraptor unlikely.
       Studies of dromaeosaurid dinosaurs going back to the late twentieth century indicate that dromaeosaurid dinosaurs almost certainly had feathers.‭ ‬These feathers were not necessarily all over the body,‭ ‬but were likely on the thorax and abdomen and almost certain on the arms.‭ ‬Dakotaraptor supports this theory in that fossils of the ulna‭ (‬one of the forearm bones‭) ‬show attachment points for large pennaceous feathers.‭ ‬It is unknown to what extent feathers would have covered Dakotaraptor,‭ ‬but smaller insulating feathers are known to‭ ‬have covered the body in even larger theropod dinosaurs such as the tyrannosaur Yutyrannus.‭ ‬However other dinosaurs living in North America during the late Cretaceous such as the ornithomimosaur Ornithomimus are known to‭ ‬have had small feathers on the back and sides of the body,‭ ‬but have legs that were devoid of feathers.‭ ‬The coverage of feathers on Dakotaraptor were likely a reflection of environmental factors first,‭ ‬and additional functions such as display and egg insulation second.
       In the early twenty-first century there has been a lot of debate concerning the relationship between dromaeosaurid dinosaurs and the evolution of birds,‭ ‬with the classic idea being that birds evolved from maniraptoran dinosaurs.‭ ‬There are now alternate theories that maniraptoran dinosaurs may have evolved from birds,‭ ‬or perhaps even to birds and back again,‭ ‬but the ideas are simply too long to explain and off topic for this article.‭ ‬The key point is that some dromaeosaurs may have had a limited flight ability even if only gliding as has been speculated for genera such as Microraptor.‭ ‬As far as Dakotaraptor is concerned,‭ ‬flight was almost certainly an impossibility,‭ ‬mainly for the simple fact that at about five and a half meters long Dakotaraptor would have simply been too big.‭ ‬There was also no way for Dakotaraptor to use its arms to generate anywhere near enough lift.‭ ‬The original study of the forearms of Dakotaraptor into wings,‭ ‬indicated the total‭ ‘‬wingspan‭’ ‬of Dakotaraptor would have been about one hundred and twenty centimetres,‭ ‬which is even less than what an average human adult could achieve if they held their arms out to the side.
       Although certainly too big to fly,‭ ‬Dakotaraptor was still no slouch on the ground.‭ ‬Proportions of the leg show that the lower leg bones of the tibia and fibula were longer than the femur which makes up the upper leg.‭ ‬This allows for a significantly longer stride of the leg which directly translates to an increase in speed and ability to run fast.‭ ‬The vertebrae of Dakotaraptor were also pneumatised,‭ ‬meaning that they had air spaces within them.‭ ‬This dramatically reduces the weight of the bone,‭ ‬and with this factor in mind,‭ ‬Dakotaraptor would have actually been quite lightweight for its size.‭ ‬Not only would this allow for larger size growth,‭ ‬but it would also allow Dakotaraptor to retain some of the speed and agility that dromaeosaurid dinosaurs are known for.
       At the original fossil site of Dakotaraptor,‭ ‬remains of more than one individual were found.‭ ‬The Holotype individual is the most complete of these,‭ ‬however there‭ ‬also seems to have been a notable difference in build between the holotype which is by far the most robust‭ (‬heavily built‭)‬,‭ ‬and the others which are more gracile‭ (‬lightly built‭)‬.‭ ‬All individuals seem to have been fully grown adults,‭ ‬so one train of thought is that these may represent a collection of male and female individuals.‭ ‬However that still does not make it certain which is which,‭ ‬as while in the animal kingdom males are usually the more robustly built,‭ ‬it is not unknown for females to have been the larger‭ (‬the moa bird Dinornis is a good example‭)‬.‭ ‬Only further study and fossil remains can tell us for sure.
       Dakotaraptor is the second dromaeosaurid dinosaur known from the Hell Creek Formation,‭ ‬with the first being the much smaller Acheroraptor.‭ ‬The only predator known to have been around at the same time and location and also be bigger than Dakotaraptor is the mighty Tyrannosaurus.‭ ‬Possible prey dinosaurs for Dakotaraptor could include anything from ceratopsian dinosaurs such as Triceratops and Leptoceratops,‭ ‬ankylosaurs and nodosaurs such as Ankylosaurus and Edmontonia,‭ ‬pachycephalosaurs such as Pachycephalosaurus,‭ ‬and hadrosaurs and‭ ‬ornithopods such as Edmontosaurus and Thescelosaurus.

Further reading
-‭ ‬The First Giant Raptor‭ (‬Theropoda:‭ ‬Dromaeosauridae‭) ‬from the Hell Creek Formation.‭ ‬Paleontological Contributions‭ (‬14‭)‬.‭ ‬-‭ ‬Robert A.‭ ‬DePalma,‭ ‬David A.‭ ‬Burnham,‭ ‬Larry Dean Martin,‭ ‬Peter Lars Larson‭ & ‬Robert Thomas Bakker‭ ‬-‭ ‬2015.



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