Coelurosauria

Coelurus fragilis, a coelurosaur from the Late Jurassic of North America, pencil drawing, digital coloring

Coelurus fragilis, a coelurosaur from the Late Jurassic of North America, pencil drawing, digital coloring

Figure 1. Evolution of macroecological traits in Dinosauria. Large scale event in dinosaur evolution (a); the origin of dinosaurs (star), hyperthermals (volcano), the earliest fossil Avialae (bird), the earliest fossil angiosperm (flower), the Cretaceous/Palaeogene mass extinction (asteroid). Phylogeny of dinosaurs (b) redrawn from Sereno and adapted to the current consensus and upon which an ancestral state reconstruction of temperature niche (mean annual temperature) after Chiarenza et al. is plotted; Mesozoic palaeogeographies (c) for Triassic (T), Jurassic (J) and Cretaceous (K). Silhouette colours symbolize body mass for each of the taxa represented; information on dietary habits are plotted after Barrett and Zanno & Makovicky; numbers represent clades discussed through this study: 1, Ornithischia; 2, Thyreophora; 3, Ornithopoda; 4, Hadrosauroidea; 5, Marginocephalia; 6, Ceratopsia; 7, Saurischia; 8, Sauropodomorpha; 9, Sauropoda; 10, Theropoda; 11, Ceratosauria; 12, Tetanurae; 13, Coelurosauria; 14, Maniraptoriformes; 15, Maniraptora; 16, Deinonychosauria; 17, Avialae; 18, Ornithothoraces. Palaeogeographies modified from original plots via R package ‘mapast’ using plate models by Scotese.

Chinzorig et al. (2017)に掲載された、コエルロサウルス類内におけるエピオルニトミムスの類縁関係を示す厳密合意樹

Diagram illustrating the "Temporal paradox" in paleontology. First given it's nickname by Alan Feduccia, the paradox is made up by the fact that almost all feathered dinosaurs are dated to have lived millions of years after Archaeopteryx, the oldest bird (late Jurassic, believed to have existed about 150 million years ago). Only a few of the feathered dinosaurs/birdlike dinosaurs are given an older date than Archaeopteryx.

Разнообразие манирапторов.

Composite figure of various feathered maniraptorans: Archaeopteryx, Anchiornis, Microraptor and Zhenyuanlong

Montage of eight different representatives of coelurosaurian dinosaurs: (Clockwise from upper left) GIN 100/42 which may represent Citipati or a different oviraptorosaur, Sinosauropteryx prima, Nothronychus mckinleyi, Tyrannosaurus rex, Bambiraptor feinbergi, Passer domesticus, Struthiomimus altus, Microraptor gui. This is a collection of eight different works already found in Wikimedia Commons (see source field below).

Assortment of various Coelurosaurs

Diagram made to illustrate the debate over the hands of theropod dinosaurs and their alleged descendants, the birds ( Aves ). In the last years, the difference between the hands of theropods and birds have been an important thing when it comes question the theory that birds evolved from dinosaurs, even though some scientists may could refute it. In the diagram, a Neotheropoda ( 1 ), basal tetanurae ( 2 ), a coelurosaurian ( 3 ), the bird (?)Archaeopteryx ( 4 ) and modern bird ( 5 ). In 1997, birdexpert Alan Feduccia at University of North Carolina discovered that birds develop hands with the digits II, III and IV ( see The Cincinnati Enquirer, 25 - 10 - 1997 ). This is in contrast with the hands of tetanurae, which seems to have the digits I, II and III. This make it almost impossible for dinosaurs and birds to be closely related, according to Feduccia. Since the discovery by Feduccia, scientific research have came up with a possible explanation to the mystery of the dinosaur - bird hand difference, called The frame shift hypothesis ( see http://scienceblogs.com/tetrapodzoology/2009/06/limusaurus_is_awesome.php ). This hypothesis is based on a discovery which shows that although bird embryos develop the fingers II, III and IV, the genes which is coding for the external appearance of the digits seems to be from the fingers I, II and III. Based on this, scientists belive this: when neotheropods evolved into tetanurae, the losed digit I ( not digit IV, as earlier suggested ). During this process, the genes which coded for how the digits should looks like ( the number of phalanges, for example ) became refurnished ( see the color spots in th upper section in the diagram to understan ). The discovery of Limusaurus has been said to support this theory ( see https://www.livescience.com/animals/090617-dinosaur-hands.html ). One thing is that may can be used to refute that Limusaurus should support the Frame shift hypothesis is that Limusaurus was a ceratosaurian, and is dated to be much younger than the oldest tetanurae's. Also, some tetanure´s may had 4 digits' like the Archaeornithomimus ( see number 4 in the diagram ) ( see also http://dml.cmnh.org/1998Oct/msg00443.html and the Allosaurus hand in the image here: http://upload.wikimedia.org/wikipedia/commons/6/69/Allosaurus-mounted.jpg ). If this is the digits I, II, III and IV. If so, it shows that tetanurae had the digits I, II and III, and not II, II and IV, like birds. For more in this debate, see text section to my picture Raptor-Archaeopteryx-bird hands differens.JPG at http://commons.wikimedia.org/wiki/File:Raptor-Archaeopteryx-bird_hands_differens.JPG.

Cladogram of amniotes. Based on File:Cladogram Amniota A.jpg

Cladogram of the former "Reptilia" (red)

Pencil drawing of Coelurus, a coelurosaurian dinosaur that lived from the Late Jurassic period (North America).

Coelurus fragilis, a coelurosaur from the Late Jurassic of North America, pencil drawing, digital coloring

Six maniraptoran dinosaurs (top to bottom): the Zamyn Khondt oviraptorosaur, Sinornithosaurus, the Alaskan troodontid, Patagonykus, a short-tailed albatross, Nothronychus

Six exemplar coelurosaurs (clockwise from top left): Tyrannosaurus rex, Sinosauropteryx prima, Deinonychus antirrhopus, Archaeopteryx lithographica, an undescribed crested oviraptorid, and Passer domesticus. This is a collection of six different works which have been previously published on Wikimedia Commons (see source field below).