Coelurosauria

A few fossil traces tentatively associated with the Coelurosauria date back as far as the late Triassic. What has been found between then and the earliest Middle Jurassic is fragmentary. The oldest known unambiguous members of Coelurosauria are the proceratosaurid tyrannosauroids Proceratosaurus and Kileskus from the late Middle Jurassic.[15][16] Many nearly complete fossil coelurosaurians are known from the Late Jurassic. Archaeopteryx (incl. Wellnhoferia) is known from Bavaria at 155-150 Ma. Ornitholestes, the troodontid Hesperornithoides, Coelurus fragilis and Tanycolagreus topwilsoni are all known from the Morrison Formation in Wyoming at about 150 Ma. Epidendrosaurus and Pedopenna are known from the Daohugou Beds in China at about 165-163 Ma. The wide range of fossils in the late Jurassic and morphological evidence shows that coelurosaurian differentiation was virtually complete before the end of the Jurassic.

In the early Cretaceous, a superb range of coelurosaurian fossils (including avians) are known from the Yixian Formation in Liaoning. All known theropod dinosaurs from the Yixian Formation are coelurosaurs. Many of the coelurosaurian lineages survived to the end of the Cretaceous period (about 66 Ma) and fossils of some lineages, such as the Tyrannosauroidea, are best known from the late Cretaceous. A majority of coelurosaur groups became extinct in the Cretaceous–Paleogene extinction event, including the Tyrannosauroidea, Ornithomimosauria, Oviraptorosauria, Deinonychosauria, Enantiornithes, and Hesperornithes. Only the Neornithes, otherwise known as modern birds, survived, and continued to diversify after the extinction of the other dinosaurs into the numerous forms found today.

There is consensus among paleontologists that birds are descended from coelurosaurs. Under modern cladistical definitions, birds are considered the only living lineage of coelurosaurs. Birds are classified by most paleontologists as belonging to the subgroup Maniraptora.[17]

A portion of a tail belonging to a juvenile coelurosaur was found in 2015, inside of a piece of amber.

The phylogeny and taxonomy of Coelurosauria has been subject to intensive research and revision. For many years, Coelurosauria was a 'dumping ground' for all small theropods. In the 1960s several distinctive lineages of coelurosaurs were recognized, and a number of new infraorders were erected, including the Ornithomimosauria, Deinonychosauria, and Oviraptorosauria. During the 1980s and 1990s, paleontologists began to give Coelurosauria a formal definition, usually as all animals closer to birds than to Allosaurus, or equivalent specifiers. Under this modern definition, many small theropods are not classified as coelurosaurs at all and some large theropods, such as the tyrannosaurids, were actually more advanced than allosaurs and therefore were reclassified as giant coelurosaurs. Even more drastically, the segnosaurs, once not even regarded as theropods, have turned out to be non-carnivorous coelurosaurs related to Therizinosaurus. Senter (2007) listed 59 different published phylogenies since 1984. Those since 2005 have followed almost the same pattern, and differ significantly from many older phylogenies.

Within Coelurosauria exists a slightly less inclusive clade named Tyrannoraptora. This clade was defined by Sereno (1999) as "Tyrannosaurus rex, Passer domesticus (the house sparrow), their last common ancestor, and all of its descendants". As tyrannosauroids are considered to be the most basal large group within Coelurosauria, this means that the common ancestor of tyrannosauroids and birds was an even more basal coelurosaurian. As a result, almost all coelurosaurians are also tyrannoraptorans, with the only exceptions being particularly basal species such as Zuolong salleei or Sciurumimus albersdoerferi. Within Tyrannoraptora exists a slightly less inclusive clade named Neocoelurosauria erected by Hendrickx, Mateus, Araújo and Choiniere (2019),[18] defining it as "the clade Compsognathidae + Maniraptoriformes", which can be more or less inclusive than Maniraptoromorpha depending on the topology.

The following family tree illustrates a synthesis of the relationships of the major coelurosaurian groups based on various studies conducted in the 2010s.[19]

• Feathered dinosaurs
• Origin of birds
• List of fossil birds

• Currie, Philip J. (2005). Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Indiana University Press. p. 368. ISBN 978-0-253-34595-0.
• Larsson, H.C.E. (2001). "Endocranial anatomy of Carcharodontosaurus saharicus (Theropoda: Allosauroidea) and its implications for theropod brain evolution". In Tanke, D. H.; Carpenter, K.; Skrepnick, M. W. (eds.). Mesozoic Vertebrate Life. Indiana University Press. pp. 19–33.
• Mayr, G., B. Pohl & D.S. Peters (2005). "A well-preserved Archaeopteryx specimen with theropod features". Science, 310(5753): 1483–1486.
• George Olshevsky. "Re: What are these dinosaurs". Archived from the original on 2007-12-09. Retrieved 2007-01-29. (on "Coelurosaurus")
• Padian, K (2004). "Basal Avialae". In Weishampel, D.B.; Dodson, P.; Osmólska, H. (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 210–231. ISBN 0-520-24209-2.
• Senter, P. (2007). "A new look at the phylogeny of Coelurosauria (Dinosauria: Theropoda)." Journal of Systematic Palaeontology, (doi:10.1017/S1477201907002143).
• Zanno, L.E., Gillette, D.D., Albright, L.B., and Titus, A.L. (2009). "A new North American therizinosaurid and the role of herbivory in 'predatory' dinosaur evolution." Proceedings of the Royal Society B, Published online before print July 15, 2009, doi:10.1098/rspb.2009.1029.
• First Dinosaur Tail Found Preserved in Amber. National Geographic, December 8, 2016.

Look up Coelurosauria in Wiktionary, the free dictionary.

• Paleobiology Database: Coelurosauria
• The Major Groups of Coelurosaurs
• Palaeos: Coelurosauria
• Tree of Life Web: Coelurosauria