warm-blooded and ancestral to birds.[3] Its distinct nature and similarity to Dromaeosaurus led Ostrom to follow Edwin Colbert and Dale Russel's suggestion that the Dromaeosaurinae be regarded as its own family separate from the Deinodontidae.[4]
After Ostrom's initial research on Deinonychus, evidence continued to mount for a close evolutionary relationship between dromaeosaurids and birds.
Sinornithosaurus milennii, described in 1999 by Xu, Wang, and Wu, is a notable example as the fine-grained Chinese limestone from which it was collected preserved its life covering of feathers.[2] Discoveries of feathered dromaeosaurids continued into the 2000s. Xu, Zhou, and Wang named the new genus Microraptor in 2000.[6] Three years later, Xu and others would report a new species in this genus that exhibited a bizarre "four winged" body plan with long pennaceous flight feathers on both its front and hind limbs.[7]
The Crow people and other Native American groups inhabiting Montana used to use rocks from the Cloverly Formation to make red pigments. Since the red pigments are richest in the same layers of the formation that preserve dinosaur fossils, it is likely that Native Americans encountered Deinonychus fossils long before scientifically trained paleontologists.[1]
Deinonychus antirrhopus.[6] This description provided the scientific literature with its first detailed information about the anatomy of the dromaeosaurid body, as previous work focused on the skull.[2] He proposed that Deinonychus killed its prey with the enlarged, sharply curved claws on the second toe of its feet.[9]
Ostrom further described the anatomy of
Deinonychus antirrhopus, providing further details about the anatomy of its body.[2] Ostrom proposed that Deinonychus only walked on two of its toes.[9]
Adasaurus mongoliensis.[6] Unlike most dromaeosaurs, famous for the "killing claws" on their second toe, the second toe claw of A. mongoliensis was relatively small and not sharply curved. It is similar to those of troodontids.[9]
Osmolska challenged Kielan-Jaworowska and Barsbold's 1972 interpretation of an associated skeleton of Velociraptor and Protoceratops as being of two animals killed and preserved while locked in mortal combat. She reinterpreted the association as a Velociraptor that had been killed while scavenging an already dead Protoceratops.[9]
Currie followed Barsbold's division of Dromaeosauridae into Dromaeosaurinae and Velociraptorinae. However, he proposed differing definitions for these subfamilies and argued that they had different members than were included under Barsbold's classification scheme.[5]
Maxwell and Ostrom reported on the association of Deinonychus teeth and Tenontosaurus remains and argued that these provided further support for the hypothesis that Deinonychus was a pack hunter.[9]
Unwin and others followed the fighting-to-the-death interpretation of the fighting dinosaurs specimen.[9]
Chatterjee argued that dromaeosaurids lived in trees based on the anatomy of their hands and the backward orientation of the pubic bones in their pelvis.[9]
Reid examined histological sections of the bones of Saurornitholestes to see whether or not they were consistent with the idea that dromaeosaurids were
warm blooded. However, the results of his study were inconclusive.[9]
cold or warm-blooded animals. They found that the probable course of airflow through the snout of a living, breathing dromaeosaurid would have been more consistent with that of a cold blooded animal. However, the anatomical reconstructions the researchers used to draw these conclusions have been criticized for positioning the choana too far forward and for excluding the animals' secondary palate.[9]
D. L. Brinkman and others reinterpreted the association between several Deinonychus specimens and a Tenontosaurus as preserving the aftermath of an ancient feeding frenzy rather than as evidence of pack hunting behavior in Deinonychus as argued by Ostrom.[9]
Clark and others argued that it was impossible to know whether or not Velociraptor was a predator of Protoceratops based on the famous "fighting dinosaurs" specimen, since this was only one specimen.[9]
Xu, Wang, and Wu described the new genus and species
Sinornithosaurus millenii.[6] The specimen actually preserved the remains of the feathers that covered the animal in life. The presence of a feathery covering is consistent with the idea that dromaeosaurids were warm-blooded.[9] They also performed a cladistic analysis of the Dromaeosauridae, finding more support for dividing the family into Dromaeosaurinae and Velociraptorinae. The researchers found both groups to be monophyletic clades, with Sinornithosaurus milenii the sister group to both, and therefore the most primitive known dromaeosaurid.[10]
dentary referred to Saurornitholestes with tooth marks.[11] The specimen was preserved in the Dinosaur Park Formation.[12] Although a specific identification cannot be made, the shape of the preserved serration marks implicate a juvenile individual of one of the formation's tyrannosaurids, like Gorgosaurus, Daspletosaurus, or Aublysodon.[13] All of the marks on the jawbone seem to have been left by the same animal because the serration marks all share the same morphology.[14]
coelurosaur evolution is faulty or feathers evolved multiple times.[17]
Cladogram of feathered dinosaurs from Padian et al. 2001
Phil R. Bell & Philip J. Currie (2015). "A high-latitude dromaeosaurid, Boreonykus certekorum, gen. et sp. nov. (Theropoda), from the upper Campanian Wapiti Formation, west-central Alberta". Journal of Vertebrate Paleontology. 36: e1034359.
Czerkas, S. A.; Zhang, D.; Li, J; Li, Y (2002). "Flying dromaeosaurs". In Czerkas, S. J. (ed.). Feathered Dinosaurs and the Origin of Flight. Vol. 1. Blanding: The Dinosaur Museum. pp. 96–126.
Evans, DC; Larson, DW; Currie, PJ (2013). "A new dromaeosaurid (Dinosauria: Theropoda) with Asian affinities from the latest Cretaceous of North America". Naturwissenschaften. 100 (11): 1041–1049.
Horner, John R.; Weishampel, David B.; Forster, Catherine A. (2004). "Hadrosauridae". In Weishampel, D. B.; Dodson, P.; Osmolska, H. (eds.). The Dinosauria (2 ed.). Berkeley: University of California Press. pp. 438–463.
Jacobsen, A. R. (2001). "Tooth-marked small theropod bone: An extremely rare trace". In Tanke, D. H.; Carpenter, K. (eds.). Mesozoic Vertebrate Life. Life of the Past. Indiana University Press. pp. 58–63.
Lü, J.-C.; Xu, L.; Zhang, X.-L.; Ji, Q.; Jia, S.-H.; Hu, W.-Y.; Zhang, J.-M.; Wu, Y.-H. (2007). "New dromaeosaurid dinosaur from the Late Cretaceous Qiupa Formation of Luanchuan area, western Henan, China". Geological Bulletin of China. 26 (7): 777–786.
Makovicky, Peter J.; Norell, Mark A. (2004). "Troodontidae". In Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 184–195.
Makovicky, Peter J.; Apesteguía, Sebastián; Agnolín, Federico L. (2005). "The earliest dromaeosaurid theropod from South America". Nature. 437 (7061): 1007–1011.
Norell, M.A. & Makovicky, P.J. (2004). "Dromaeosauridae". In Weishampel, D.B.; Dodson, P. & Osmólska, H. (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 196–210.
Ostrom, John H. (1969). "Osteology of Deinonychus antirrhopus, an unusual theropod from the Lower Cretaceous of Montana". Peabody Museum of Natural History Bulletin. 30: 1–165.
Padian, K.; Ji, Qiang; Ji, Shu-An (2001). "Feathered dinosaurs and origin of flight". In Tanke, D. H.; Carpenter, K. (eds.). Mesozoic Vertebrate Life. Life of the Past. Indiana University Press. pp. 117–135.
Xu, X.; Wang, X.-L. (2004). "A New Dromaeosaur (Dinosauria: Theropoda) from the Early Cretaceous Yixian Formation of Western Liaoning". Vertebrata PalAsiatica. 42 (2): 11–119.
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