Coeluridae is a historically unnatural group of generally small,

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

s from the late

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

Period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

. For many years, any small Jurassic or Cretaceous

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

that did not belong to one of the more specialized families recognized at the time was classified with the coelurids, creating a confusing array of 'coelurid' theropods that were not closely related. Although they have been traditionally included in this family, there is no evidence that any of these primitive

coelurosaur Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, tyrann ...

s form a natural group with ''

Coelurus ''Coelurus'' ( ) is a genus of coelurosaurian dinosaur from the Late Jurassic period (mid-late Kimmeridgian faunal stage, 155–152 million years ago). The name means "hollow tail", referring to its hollow tail vertebrae (Greek κοῖλο� ...

'', the namesake of Coeluridae, to the exclusion of other traditional coelurosaur groups.

Classification

Before the use of phylogenetic analyses, Coeluridae and

Coelurosauria Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, tyrann ...

were taxonomic wastebaskets used for small theropods that did not belong to other groups; thus, they accumulated many

dubious Doubt is a mental state in which the mind remains suspended between two or more contradictory propositions, unable to be certain of any of them. Doubt on an emotional level is indecision between belief and disbelief. It may involve uncertainty, ...

genera. As late as the 1980s, popular books recognized over a dozen "coelurids", including such disparate forms as the

noasaurid Noasauridae is an extinct family of theropod dinosaurs belonging to the group Ceratosauria. They were closely related to the short-armed abelisaurids, although most noasaurids had much more traditional body types generally similar to other ther ...

Laevisuchus ''Laevisuchus'' (, "light crocodile") is a genus of theropod dinosaur from the Late Cretaceous. Its remains were discovered by Charles Alfred Matley near Jabalpur in Maastrichtian deposits in the Lameta Formation in India, and were named and des ...

'' and the

oviraptorosauria Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or wit ...

n ''

Microvenator ''Microvenator'' (meaning "small hunter") is a genus of dinosaur from the Early Cretaceous Cloverly Formation in what is now south central Montana. ''Microvenator'' was an oviraptorosaurian theropod. The holotype fossil is an incomplete skeleton ...

'', and considered them descendants of the coelophysids. A wastebasket Coeluridae lingered into the early 1990s in some sources (and appears in at least one 2006 source) but since then it has only been recognized in a much reduced form. In 2003, O.W.M. Rauhut, using a

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...

analysis, found Coeluridae to include ''

'' (

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

, North America), ''

Compsognathus ''Compsognathus'' (; Greek ''kompsos''/κομψός; "elegant", "refined" or "dainty", and ''gnathos''/γνάθος; "jaw") is a genus of small, bipedal, carnivorous theropod dinosaur. Members of its single species ''Compsognathus longipes'' c ...

'' (Late Jurassic, Europe), ''

Sinosauropteryx ''Sinosauropteryx'' (meaning "Chinese reptilian wing", ) is a compsognathid dinosaur. Described in 1996, it was the first dinosaur taxon outside of Avialae (birds and their immediate relatives) to be found with evidence of feathers. It was covere ...

'' (

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

, Asia) and an unnamed ''

''-like form (Early Cretaceous, South America; this dinosaur has since been placed in the new genus ''

Mirischia ''Mirischia'' is a small (two meter-long) genus of compsognathid theropod dinosaur from the Albian stage ( Early Cretaceous Period) of Brazil. Discovery and naming In 2000 David Martill and Eberhard Frey reported the find of a small dinosaur ...

''). Rauhut considered coelurids to be a

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

group of basal

coelurosaurs Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, tyrann ...

, characterized by evolutionary reversals in some aspects of the vertebrae to the more primitive theropod condition. However, he and other authors have not since found this result. Phil Senter proposed in 2007 that ''Coelurus'' and ''Tanycolagreus'' were the only coelurids, and were actually

tyrannosauroids Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent be ...

. Coeluridae received a formal phylogenetic definition in 2015, when it was defined as all species more closely related to ''Coelurus fragilis'' than to ''Proceratosaurus bradleyi'', ''Tyrannosaurus rex'', ''Allosaurus fragilis'', ''Compsognathus longipes'', ''Ornithomimus edmontonicus'', or ''

Deinonychus antirrhopus ''Deinonychus'' ( ; ) is a genus of dromaeosaurid theropod dinosaur with one described species, ''Deinonychus antirrhopus''. This species, which could grow up to long, lived during the early Cretaceous Period, about 115–108 million ye ...

'' by Hendrickx, Hartman and Mateus. It remains unclear whether or not this group contains any species other than ''Coelurus'' itself, and while ''Tanycolagreus'' is often included, support for this relationship has been weak in most of the studies that recovered it.Brusatte, S. L., & Carr, T. D. (2016)
The phylogeny and evolutionary history of tyrannosauroid dinosaurs.
''Scientific Reports'', 6. Below is a cladogram placing ''Coelurus'' in Coelurosauria by Cau ''et al.'' in 2015.

References

{{Taxonbar, from=Q134155 Prehistoric tyrannoraptora Tyrannosaurs Prehistoric dinosaur families Kimmeridgian first appearances Late Jurassic extinctions Taxa named by Othniel Charles Marsh