''Eucoelophysis'' (meaning "true
hollow form") is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of
silesaurid
Silesauridae is an extinct family of Triassic dinosauriforms. It is most commonly considered to be a clade of non-dinosaur dinosauriforms, and the sister group of dinosaurs. Some studies have instead suggested that most or all silesaurids compri ...
dinosauriform from the
Late Triassic
The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. ...
(
Norian)
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 ...
Chinle Formation of
New Mexico
)
, population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano)
, seat = Santa Fe
, LargestCity = Albuquerque
, LargestMetro = Tiguex
, OfficialLang = None
, Languages = English, Spanish ( New Mexican), Navajo, Ke ...
. It was assumed to be a
coelophysid
Coelophysidae is a family of primitive carnivorous theropod dinosaurs. Most species were relatively small in size. The family flourished in the Late Triassic and Early Jurassic periods, and has been found on numerous continents. Many members of C ...
upon description, but a study by
Nesbitt ''et al.'' found that it was actually a close relative of ''
Silesaurus'', which was independently supported by Ezcurra (2006), who found it to be the
sister group to
Dinosauria, and ''Silesaurus'' as the next most basal
taxon
In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...
.
However, the relationships of ''Silesaurus'' are uncertain.
Dzik found it to be a
basal dinosauriform (the group of
archosaurs from which the dinosaurs evolved), but did not rule out the possibility that it represents a primitive
ornithischian
Ornithischia () is an extinct order of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name ''Ornithischia'', or "bird-hipped", reflects this similarity and is derived from the Greek st ...
.
References
External links
William Parker's reaction to Ezcurra (2006), from the Dinosaur Mailing List.
Silesaurids
Late Triassic archosaurs of North America
Taxa named by Spencer G. Lucas
Fossil taxa described in 1999
{{paleo-archosaur-stub