''Coelophysis'' (
traditionally
A tradition is a belief or behavior (folk custom) passed down within a group or society with symbolic meaning or special significance with origins in the past. A component of cultural expressions and folklore, common examples include holidays o ...
; or , as heard more commonly in recent decades) is an
extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
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 ...
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 ...
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 ...
that lived approximately 228 to 201.3
million years ago
The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds.
Usage
Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...
during the latter part of the
Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
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 ...
from the Carnian and Rhaetian faunal stages in what is now the southwestern United States.
''
Megapnosaurus
''Megapnosaurus'' (meaning "big dead lizard", from Greek μεγα = "big", 'απνοος = "not breathing", "dead", σαυρος = "lizard") is an extinct genus of coelophysid theropod dinosaur that lived approximately 188 million years ago duri ...
'' was once considered a species within this genus,
[Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Jurassic, Africa)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 535–536. ] but this interpretation has been challenged since 2017 and the genus ''Megapnosaurus'' is now considered valid.
''Coelophysis'' was a small, slenderly-built, ground-dwelling,
bipedal
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' ...
carnivore
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 ...
that could grow up to long. It is one of the earliest known dinosaur genera. Scattered material representing similar animals has been found worldwide in some
Late Triassic
The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...
and
Early Jurassic
The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...
formations.
The
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
''C. bauri'', originally given to the genus ''
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 ...
'' by
Edward Drinker Cope
Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American zoologist, paleontologist, comparative anatomist, herpetologist, and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested ...
in 1887, was described by the latter in 1889. The names ''Longosaurus'' and ''Rioarribasaurus'' are synonymous with ''Coelophysis''. ''Coelophysis'' is one of the most specimen-rich dinosaur genera.
History of discovery
![Ghost Ranch Coelophysis Quarry](https://upload.wikimedia.org/wikipedia/commons/5/5c/Ghost_Ranch_Coelophysis_Quarry.jpg)
The type species of ''Coelophysis'' was originally named as a species of ''Coelurus''.
Edward Drinker Cope first named ''Coelophysis'' in 1889 to name a new genus, outside of ''Coelurus'' and ''
Tanystropheus
''Tanystropheus'' (Greek ~ 'long' + 'hinged') is an extinct archosauromorph reptile from the Middle Triassic, Middle and Late Triassic epochs. It is recognisable by its extremely elongated neck, which measured long—longer than its body and t ...
,'' which ''C. bauri'' was previously classified in, for ''C. bauri'', ''C. willistoni'' and ''C. longicollis''.
An amateur
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
collector working for Cope, David Baldwin, had found the first remains of the dinosaur in 1881 in the Chinle Formation in northwestern New Mexico.
Early in 1887, Cope referred the specimens collected to two new species, ''C. bauri'' and ''C. longicollis'' of the genus ''Coelurus''. Later in 1887 Cope reassigned the material to a yet another genus, ''Tanystropheus''. Two years later, Cope corrected his classification after realizing differences in the
vertebra
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...
e, and named ''Coelophysis'', with ''C. bauri'' as the
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
,
which was named for
Georg Baur
Georg Baur (1859–1898) was a German vertebrate paleontologist and Neo-Lamarckian who studied reptiles of the Galapagos Islands, particularly the Galápagos tortoises, in the 1890s. He is perhaps best known for his subsidence theory of the o ...
, a comparative anatomist whose ideas were similar to Cope's.
The name ''Coelophysis'' comes from the
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
words κοῖλος/koilos (meaning 'hollow') and φύσις/physis (meaning 'form'), together "hollow form", which is a reference to its hollow vertebrae.
However, the first finds were too poorly preserved to give a complete picture of the new dinosaur. In 1947, a substantial 'graveyard' of ''Coelophysis'' fossils was found by George Whitaker, the assistant of Edwin H. Colbert, in
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, Ker ...
, at the
Ghost Ranch
Ghost Ranch is a retreat and education center located close to the village of Abiquiú in Rio Arriba County in north central New Mexico, United States. It was the home and studio of Georgia O'Keeffe, as well as the subject of many of her painti ...
, close to the original find.
American Museum of Natural History
The American Museum of Natural History (abbreviated as AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. In Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 26 inter ...
paleontologist
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
Edwin H. Colbert
Edwin Harris "Ned" Colbert (September 28, 1905 – November 15, 2001)O'Connor, Anahad ''The New York Times'', November 25, 2001. was a distinguished American vertebrate paleontologist and prolific researcher and author.
Born in Clarinda, Iowa, he ...
conducted a comprehensive study
of all the fossils found up to that date and assigned them to ''Coelophysis''. The Ghost Ranch specimens were so numerous, including many well-preserved and fully articulated specimens, that one of them has since become the diagnostic, or
type specimen
In biology, a type is a particular wiktionary:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to a ...
, for the entire genus, replacing the original, poorly preserved specimen.
![Coelophysis bauri](https://upload.wikimedia.org/wikipedia/commons/b/bd/Coelophysis_bauri.jpg)
''"Syntarsus" rhodesiensis'' was first described by Raath (1969) and assigned to
Podokesauridae
Coelophysoidea were common dinosaurs of the Late Triassic and Early Jurassic periods. They were widespread geographically, probably living on all continents. Coelophysoids were all slender, carnivore, carnivorous forms with a superficial similar ...
.
[Raath (1969). "A new Coelurosaurian dinosaur from the Forest Sandstone of Rhodesia." Arnoldia Rhodesia. 4 (28): 1–25.] The taxon "Podokesauridae", was abandoned because its type specimen was destroyed in a fire and can no longer be compared to new finds. Over the years paleontologists assigned the genus to
Ceratosauridae
Ceratosauridae is an extinct family of theropod dinosaurs belonging to the infraorder Ceratosauria. The family's type genus, ''Ceratosaurus'', was first found in Jurassic rocks from North America. Ceratosauridae is made up of the genera ''Cerat ...
(Welles, 1984),
Procompsognathidae (Parrish and Carpenter, 1986) and
Ceratosauria
Ceratosaurs are members of the clade Ceratosauria, a group of dinosaurs defined as all theropods sharing a more recent common ancestor with ''Ceratosaurus'' than with birds. The oldest known ceratosaur, ''Saltriovenator'', dates to the earliest ...
(Gauthier, 1986). In 2004 "Syntarsus" was found to be synonymous with ''Coelophysis'' by Tykoski and Rowe (2004). Ezcurra and Novas (2007) and Ezcurra (2007) also concluded that "Syntarsus" was synonymous with ''Coelophysis''.
[Tykoski, R. S., and Rowe, T., 2004, Ceratosauria, Chapter Three: In: The Dinosauria, Second Edition, edited by Weishampel, D.B., Dodson, P., and Osmolska, H., California University Press, p. 47-70.] In a phylogenetic analysis by Ezcurra (2017), ''
Megapnosaurus
''Megapnosaurus'' (meaning "big dead lizard", from Greek μεγα = "big", 'απνοος = "not breathing", "dead", σαυρος = "lizard") is an extinct genus of coelophysid theropod dinosaur that lived approximately 188 million years ago duri ...
'' was recovered in a clade with ''
Segisaurus'' and ''
Camposaurus
''Camposaurus'' ( ) is a coelophysid dinosaur genus from the Norian stage of the Late Triassic period of North America. The pertinent fossil remains date back to the early to middle Norian stage, and is widely regarded as the oldest known neothe ...
'', supporting the generic distinction of ''Megapnosaurus''. This was supported by Barta and colleagues in 2018, noting that ''Coelophysis'' still bears the vestigial 5th metacarpal, a feature absent in ''Megapnosaurus''.
Description
![Coelophysis size](https://upload.wikimedia.org/wikipedia/commons/8/80/Coelophysis_size.jpg)
''Coelophysis'' is known from a number of complete fossil skeletons of the species ''C. bauri'': a lightly built dinosaur that measured up to in length
and was more than a meter tall at the hips. Paul (1988) estimated the weight of the gracile form at , and the weight of the robust form at ,
but later presented a higher estimate of . ''Coelophysis'' was a bipedal, carnivorous, theropod dinosaur and a fast and agile runner.
Despite being an early dinosaur, the evolution of the
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 ...
body form
A body plan, ( ), or ground plan is a set of morphological features common to many members of a phylum of animals. The vertebrates share one body plan, while invertebrates have many.
This term, usually applied to animals, envisages a "blueprin ...
had already advanced greatly from creatures like ''
Herrerasaurus
''Herrerasaurus'' is a genus of saurischian dinosaur from the Late Triassic period. This genus was one of the earliest dinosaurs from the fossil record. Its name means "Herrera's lizard", after the rancher who discovered the first specimen in ...
'' and ''
Eoraptor
''Eoraptor'' () is a genus of small, lightly built, basal sauropodomorph. One of the earliest-known dinosaurs, it lived approximately 231 to 228 million years ago, during the Late Triassic in Western Gondwana, in the region that is now northwest ...
''. The torso of ''Coelophysis'' conforms to the basic theropod body shape, but the
pectoral girdle
The shoulder girdle or pectoral girdle is the set of bones in the appendicular skeleton which connects to the arm on each side. In humans it consists of the clavicle and scapula; in those species with three bones in the shoulder, it consists of t ...
displays some special characteristics: ''C. bauri'' had a
furcula
The (Latin for "little fork") or wishbone is a forked bone found in most birds and some species of non-avian dinosaurs, and is formed by the fusion of the two pink
clavicles. In birds, its primary function is in the strengthening of the thoracic ...
(wishbone), the earliest known example in a dinosaur. ''Coelophysis'' also preserves the ancestral condition of possessing four digits on the hand (manus). It had only three functional digits, the fourth embedded in the flesh of the hand.
''Coelophysis'' had narrow hips, forelimbs adapted for grasping prey, and narrow feet.
[Tykoski, R.S. & Rowe, T. (2004). "Ceratosauria": In: ] Its neck and tail were long and slender.
The
pelvis
The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton).
The ...
and hindlimbs of ''C. bauri'' are also slight variations on the theropod body plan. It has the open
acetabulum
The acetabulum (), also called the cotyloid cavity, is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.
Structure
There are three bones of the ''os coxae'' (hip bone) that c ...
and straight ankle hinge that define the Dinosauria. The hindlimb ended in a three-toed foot (
pes
Pes (Latin for "foot") or the acronym PES may refer to:
Pes
* Pes (unit), a Roman unit of length measurement roughly corresponding with a foot
* Pes or podatus, a
* Pes (rural locality), several rural localities in Russia
* Pes (river), a river ...
), with a raised
hallux
Toes are the digits (fingers) of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being '' digitigrade''. Humans, and other animals that walk on the soles of their feet, are described as being '' pl ...
. The tail had an unusual structure within its interlocking
prezygapophysis
The articular processes or zygapophyses (Greek ζυγον = "yoke" (because it links two vertebrae) + απο = "away" + φυσις = "process") of a vertebra are projections of the vertebra that serve the purpose of fitting with an adjacent vertebr ...
of its vertebrae, which formed a semi-rigid lattice, apparently to stop the tail from moving up and down.
![Coelophysis-bauri head](https://upload.wikimedia.org/wikipedia/commons/3/3d/Coelophysis-bauri_head.jpg)
''Coelophysis'' had a long narrow head (approximately ), with large, forward-facing eyes that afforded it
stereoscopic
Stereoscopy (also called stereoscopics, or stereo imaging) is a technique for creating or enhancing the depth perception, illusion of depth in an image by means of stereopsis for binocular vision. The word ''stereoscopy'' derives . Any stere ...
vision and as a result excellent depth perception. Rinehart ''et al.'' (2004) described the complete
sclerotic ring
Sclerotic rings are rings of bone found in the eyes of many animals in several groups of vertebrates, except for mammals and crocodilians. They can be made up of single bones or multiple segments and take their name from the sclera. They are bel ...
found for a juvenile ''Coelophysis bauri'' (specimen NMMNH P-4200), and compared it to data on the
sclerotic rings
Sclerotic rings are rings of bone found in the eyes of many animals in several groups of vertebrates, except for mammals and crocodilians. They can be made up of single bones or multiple segments and take their name from the sclera. They are b ...
of reptiles and birds and concluded that ''Coelophysis'' was a
diurnal, visually oriented predator.
The study found that the vision of ''Coelophysis'' was superior to most lizards' vision, and ranked with that of modern birds of prey. The eyes of ''Coelophysis'' appear to be the closest to those of eagles and hawks, with a high power of accommodation. The data also suggested poor night vision, which would mean this dinosaur had a round rather than a split pupil.
''Coelophysis'' had an elongated snout with large
fenestrae
A fenestra (fenestration; plural fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomical st ...
which helped to reduce skull weight, while narrow struts of bones preserved the structural integrity of the skull. The neck had a pronounced
sigmoid
Sigmoid means resembling the lower-case Greek letter sigma (uppercase Σ, lowercase σ, lowercase in word-final position ς) or the Latin letter S. Specific uses include:
* Sigmoid function, a mathematical function
* Sigmoid colon, part of the l ...
curve. The braincase is known in ''Coelophysis bauri'' but little data could be derived because the skull was crushed.
Unlike some other theropods, the cranial ornamentation of ''Coelophysis'' was not located at the top of its skull. Low, laterally raised bony ridges were present on the dorsolateral margin of the nasal and lacrimal bones in the skull, directly above the
antorbital fenestra
An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with archosauriforms, first appearing during the Triassic Period. Among extant archosaurs, birds ...
.
Distinguishing anatomical features
A diagnosis is a statement of the anatomical features of an organism (or group) that collectively distinguish it from all other organisms. Some, but not all, of the features in a diagnosis are also autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to a given organism or group.
According to Ezcurra (2007), and Bristowe and Raath (2004) ''Coelophysis'' can be distinguished based on the following features: the absence of an offset rostral process of the maxilla; the quadrate is strongly caudally; a small external mandibular fenestra, which is 9–10% of the mandibular length;
and the anteroposterior length of the ventral lacrimal process is greater than 30% of its height.
Several paleontologists consider ''Coelophysis bauri'' to be the same dinosaur as ''Megapnosaurus rhodesiensis'' (formerly ''Syntarsus''), however this has been refuted by the following: Downs (2000) concluded that ''C. bauri'' differs from ''C. rhodesiensis'' in cervical length, proximal and distal hindlimb proportions and proximal caudal vertebral anatomy;
[Downs, A. (2000). "''Coelophysis bauri'' and ''Syntarsus rhodesiensis'' compared, with comments on the preparation and preservation of fossils from the Ghost Ranch Coelophysis quarry": In: ] Tykoski and Rowe (2004) concluded that ''C. bauri'' differs from ''M. rhodesiensis'' in that it lacks a pit at the base of the nasal process of the premaxilla;
Bristowe and Raath (2004) concluded that ''C. bauri'' differs from ''M. rhodesiensis'' in having a longer maxillary tooth row;
Barta ''et al''. (2018) concluded that ''C. bauri'' differed from ''M. rhodesiensis'' in that it bears its 5th metacarpal;
and several features in the musculature of the limbs according to Griffin (2018).
[Griffin, Christopher. (2018). Developmental patterns and variation among early theropods. Journal of Anatomy. 232. 604-640. 10.1111/joa.12775.]
Classification
''Coelophysis'' is a distinct taxonomic unit (genus), composed of one species; ''
C. bauri.'' Two additional originally described species, ''C. longicollis'' and ''C. willistoni'', are now considered dubious and undiagnostic.
''M. rhodesiensis'' was referred to ''Coelophysis'' for several years, but it is likely its own genus,
and is known from the early Jurassic of southern Africa. A third possible species is ''Coelophysis kayentakatae'', previously referred to the genus ''Megapnosaurus,'' from the
Kayenta Formation
The Kayenta Formation is a geological formation in the Glen Canyon Group that is spread across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah. Traditionally has been suggested ...
of the southwestern US. In recent phylogenetic analyses, ''"Syntarsus" kayentakatae'' has been shown to be distantly related to ''Coelophysis'' and ''Megapnosaurus'', suggesting that it belongs to its own genus.
In the early 1990s, there was debate over the diagnostic characteristics of the first specimens collected, compared to the material excavated at the Ghost Ranch ''Coelophysis'' quarry. Some paleontologists were of the opinion that the original specimens were not diagnostic beyond themselves and, therefore, that the name ''C. bauri'' could not be applied to any additional specimens. They therefore applied a different name, ''Rioarribasaurus'', to the Ghost Ranch quarry specimens.
![Coelophysis cast](https://upload.wikimedia.org/wikipedia/commons/f/f9/Coelophysis_cast.jpg)
Since the numerous well-preserved Ghost Ranch specimens were used as ''Coelophysis'' in most of the scientific literature, the use of ''Rioarribasaurus'' would have been very inconvenient for researchers, so a petition was given to have the type specimen of ''Coelophysis'' transferred from the poorly preserved original specimen to one of the well-preserved Ghost Ranch specimens. This would make ''Rioarribasaurus'' a definite synonym of ''Coelophysis'', specifically a junior objective synonym.
In the end, the
International Commission on Zoological Nomenclature
The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries.
Orga ...
(ICZN) voted to make one of the Ghost Ranch samples the actual type specimen for ''Coelophysis'' and dispose of the name ''Rioarribasaurus'' altogether (declaring it a ''nomen rejectum'', or "rejected name"), thus resolving the confusion. The name ''Coelophysis'' therefore became a ''nomen conservandum'' ("conserved name").
In a situation affecting many dinosaur taxa, some more recently discovered fossils were originally classified as new genera but may be species of ''Coelophysis''. For example, Prof.
Mignon Talbot
Mignon Talbot (August 16, 1869 – July 18, 1950) was an American paleontologist. Talbot recovered and named the only known fossils of the dinosaur ''Podokesaurus holyokensis'', which were found near Mount Holyoke College in 1910, and published ...
's 1911 discovery
which she named ''Podokesaurus holyokensis'', has long been considered to be related to ''Coelophysis'',
and some modern scientists consider ''Podokesaurus'' a synonym of ''Coelophysis''.
Another specimen from the
Portland Formation
The Portland Formation is a geological formation in Connecticut and Massachusetts in the northeastern United States.[Boston Museum of Science
The Museum of Science (MoS) is a science museum and indoor zoo in Boston, Massachusetts, located in Science Park, a plot of land spanning the Charles River. Along with over 700 interactive exhibits, the museum features a number of live presentat ...]
, has also been referred to ''Coelophysis''.
The specimen consists of sandstone casts of a pubis, tibia, three ribs, and a possible vertebra, and probably originated in a quarry in Middletown, Connecticut. However, both the type specimen of ''Podokesaurus'' and the Middletown specimen are typically considered indeterminate theropods today.
Sullivan & Lucas (1999) referred one specimen from Cope's original material of ''Coelophysis'' (AMNH 2706) to what they thought was a newly discovered theropod, ''
Eucoelophysis
''Eucoelophysis'' (meaning "true hollow form") is a genus of silesaurid dinosauriform from the Late Triassic ( Norian) period Chinle Formation of New Mexico. It was assumed to be a coelophysid upon description, but a study by Nesbitt ''et al. ...
''.
However, subsequent studies have shown that ''Eucoelophysis'' was misidentified, and is actually a primitive, non-dinosaurian
ornithodira
Avemetatarsalia (meaning "bird metatarsals") is a clade of diapsid reptiles containing all archosaurs more closely related to birds than to crocodilians. The two most successful groups of avemetatarsalians were the dinosaurs and pterosaurs. Dinos ...
n closely related to ''
Silesaurus
''Silesaurus'' is a genus of silesaurid dinosauriform from the Late Triassic, of what is now Poland.
Discovery
Fossilized remains of ''Silesaurus'' have been found in the Keuper Claystone in Krasiejów near Opole, Silesia, Poland, which is al ...
''.
The genus ''Syntarsus'' was named by Raath in 1969 for the type species ''
Syntarsus rhodesiensis'' from Africa, and later applied to the North American ''
Syntarsus kayentakatae
''Coelophysis''? ''kayentakatae'' is an extinct species of neotheropod dinosaur that lived approximately 200 - 196 million years ago during the early part of the Jurassic Period in what is now the southwestern United States. While originally a ...
''.
It was renamed by American entomologist Dr. Michael Ivie (
Montana State University
Montana State University (MSU) is a Public university, public land-grant university, land-grant research university in Bozeman, Montana. It is the state's largest university. MSU offers baccalaureate degrees in 60 fields, master's degrees in 6 ...
of
Bozeman
Bozeman is a city and the county seat of Gallatin County, Montana, United States. Located in southwest Montana, the 2020 census put Bozeman's population at 53,293, making it the fourth-largest city in Montana. It is the principal city of th ...
), Polish Australian Dr. Adam Ślipiński, and Polish Dr. Piotr Węgrzynowicz (Muzeum Ewolucji Instytutu Zoologii PAN of
Warsaw
Warsaw ( pl, Warszawa, ), officially the Capital City of Warsaw,, abbreviation: ''m.st. Warszawa'' is the capital and largest city of Poland. The metropolis stands on the River Vistula in east-central Poland, and its population is officia ...
), the three scientists who discovered that the
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
name ''Syntarsus'' was already taken by a
colydiine beetle
Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
described in 1869. Many paleontologists did not like the naming of ''Megapnosaurus'', partially because taxonomists are generally expected to allow original authors of a name to correct any mistakes in their work. Raath was aware of the homonymy between the dinosaur ''Syntarsus'' and beetle ''Syntarsus'', but the group who published ''Megapnosaurus'' were led to believe Raath was deceased and therefore unable to correct his mistake, and proceeded accordingly. Mortimer (2012) pointed out that "Paleontologists might have reacted more positively if the replacement name (''Megapnosaurus'') hadn't been facetious, translating to "big dead lizard". Yates (2005) analyzed ''Coelophysis'' and ''Megapnosaurus'' and concluded that the two genera are almost identical, and suggested that ''Megapnosaurus'' was possibly synonymous with ''Coelophysis''.
In 2004, Raath co-authored two papers in which he argued that ''Megapnosaurus'' (formerly ''Syntarsus'') was a junior synonym of ''Coelophysis''.
''
Megapnosaurus
''Megapnosaurus'' (meaning "big dead lizard", from Greek μεγα = "big", 'απνοος = "not breathing", "dead", σαυρος = "lizard") is an extinct genus of coelophysid theropod dinosaur that lived approximately 188 million years ago duri ...
'' was regarded by Paul (1988) and Downs (2000) as being
congeneric
Congener may refer to:
* A thing or person of the same kind as another, or of the same group.
* Congener (biology), organisms within the same genus.
* Congener (chemistry), related chemicals, e.g., elements in the same group of the periodic table. ...
with ''Coelophysis''.
Then in 1993, Paul suggested that ''Coelophysis'' should be placed in ''Megapnosaurus'' (then known as ''Syntarsus'') to get around the above-mentioned
taxonomic
Taxonomy is the practice and science of categorization or classification.
A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
confusion.
[Paul G.S. (1993). "Are ''Syntarsus'' and the Whitetaker theropod the same genus?": In: ] Downs (2000) examined ''Camposaurus'' and concluded that it was a junior synonym of ''Coelophysis'', because of its similarity to some of the ''Coelophysis'' Ghost Ranch specimens.
However, a reassessment of the ''Camposaurus'' holotype by Martin Ezcurra and Stephen Brusatte published in 2011 revealed a pair of
autapomorphies
In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...
in the holotype, indicating that ''C. arizonensis'' was not a synonym of ''C. bauri'', although it was a close relative of ''M. rhodesensis''.
Barta ''et al''. (2018) concluded that ''C. bauri'' differed from ''M. rhodesiensis'' in that it bears its 5th metacarpal
and several features in the musculature of the limbs according to Griffin (2018).
Paleobiology
Feeding
![Coelophysis with crocodylomorph bones AMNH](https://upload.wikimedia.org/wikipedia/commons/6/67/Coelophysis_with_crocodylomorph_bones_AMNH.jpg)
The teeth of ''Coelophysis'' were typical of predatory dinosaurs, blade-like, recurved, sharp and jagged with fine serrations on both the
anterior
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
and
posterior edges. Its dentition shows that it was carnivorous, probably preying on the small, lizard-like animals that were discovered with it.
It may also have hunted in packs to tackle larger prey.
''Coelophysis bauri'' has approximately 26 teeth on the maxillary bone of the upper jaw and 27 teeth on the dentary bone of the lower jaw.
Carpenter (2002) examined the bio-mechanics of theropod forelimbs and attempted to evaluate their usefulness in predation. He concluded that the forelimb of ''Coelophysis'' was flexible and had a good range of motion, but its bone structure suggested that it was comparatively weak. The "weak" forelimbs and small teeth in this genus, suggested that ''Coelophysis'' preyed upon animals that were substantially smaller than itself. Rinehart ''et al.'' agreed that ''Coelophysis'' was a "hunter of small, fast-moving prey".
Carpenter also identified three distinct models of theropod forelimb use and noted that ''Coelophysis'' was a "combination grasper-clutcher" as compared to other dinosaurs that were "clutchers" or "long armed graspers".
![Coelophysis skeletons](https://upload.wikimedia.org/wikipedia/commons/4/4e/Coelophysis_skeletons.jpg)
It has been suggested that ''C. bauri'' was a
cannibal
Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is well documented, bo ...
, based on supposed juvenile specimens found "within" the abdominal cavities of some Ghost Ranch specimens.
However,
Robert J. Gay showed in 2002 that these specimens were misinterpreted. Several specimens of "juvenile coelophysids" were actually small
crurotarsan reptiles such as ''
Hesperosuchus
''Hesperosuchus'' is an extinct genus of crocodylomorph reptile that contains a single species, ''Hesperosuchus agilis''. Remains of this pseudosuchian have been found in Late Triassic (Carnian) strata from Arizona and New Mexico.Colbert, E. H. 1 ...
''.
Gay's position was lent support in a 2006 study by Nesbitt ''et al.''
In 2009, new evidence of cannibalism came to light when additional preparation of previously excavated matrix revealed regurgitate material in and around the mouth of ''Coelophysis'' specimen NMMNH P-44551. This material included tooth and jaw bone fragments that Rinehart ''et al.'' considered "morphologically identical" to a juvenile ''Coelophysis.''
In 2010, Gay examined the bones of juveniles found within the thoracic cavity of AMNH 7224, and calculated that the total volume of these bones was 17 times greater than the maximum estimated stomach volume of the ''Coelophysis'' specimen. Gay observed that the total volume would be even greater when considering that there would have been flesh on these bones. This analysis also noted the absence of tooth marks on the bones as would be expected in defleshing, and the absence of expected pitting by stomach acids. Finally, Gay demonstrated that the alleged cannibalized juvenile bones were deposited stratigraphically below the larger animal that had supposedly cannibalized them. Taken together these data suggested that the ''Coelophysis'' specimen AMNH 7224 was not a cannibal and that the bones of the juvenile and adult specimens were found in their final position as a result of "coincidental superposition of different sized individuals.
Pack behavior
![Coelophysis block](https://upload.wikimedia.org/wikipedia/commons/e/e8/Coelophysis_block.jpg)
The discovery of over 1000 specimens of ''Coelophysis'' at the Whitaker quarry at
Ghost Ranch
Ghost Ranch is a retreat and education center located close to the village of Abiquiú in Rio Arriba County in north central New Mexico, United States. It was the home and studio of Georgia O'Keeffe, as well as the subject of many of her painti ...
, has suggested gregarious behavior to researchers like Schwartz and Gillette.
There is a tendency to see this massive congregation of animals as evidence for huge packs of ''Coelophysis'' roaming the land.
No direct evidence for flocking exists; the deposits only indicate that large numbers of ''Coelophysis'', along with other Triassic animals, were buried together. Some of the evidence from the
taphonomy
Taphonomy is the study of how organisms decay and become fossilized or preserved in the paleontological record. The term ''taphonomy'' (from Greek , 'burial' and , 'law') was introduced to paleontology in 1940 by Soviet scientist Ivan Efremov t ...
of the site indicates that these animals may have been gathered together to feed or drink from a depleted water hole or to feed on a
spawning
Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquati ...
run of fish, and then became buried in a catastrophic
flash flood
A flash flood is a rapid flooding of low-lying areas: washes, rivers, dry lakes and depressions. It may be caused by heavy rain associated with a severe thunderstorm, hurricane, or tropical storm, or by meltwater from ice or snow flowing o ...
or a drought.
![CMNH Coelophysis Block](https://upload.wikimedia.org/wikipedia/commons/6/68/CMNH_Coelophysis_Block.jpg)
With 30 specimens of ''C. rhodesiensis'' found together in Zimbabwe some palaeontologists have suggested that ''Coelophysis'' was indeed gregarious. Again there is no direct evidence of flocking in this case and it has also been suggested that these individuals were also victims of flash flooding as it appears to have been commonplace during this period.
[G. Bond, 1965. Some new fossil localities in the Karroo System of Rhodesia. Arnoldia, Series of Miscellaneous Publications, National Museum of Southern Rhodesia 2(11):1–4][M. A. Raath, 1977. The Anatomy of the Triassic Theropod Syntarsus rhodesiensis (Saurischia: Podokesauridae) and a Consideration of Its Biology. Department of Zoology and Entomology, Rhodes University, Salisbury, Rhodesia 1–233]
Growth and sexual dimorphism
Rinehart (2009) assessed the
ontogenic
Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the stu ...
growth
Growth may refer to:
Biology
* Auxology, the study of all aspects of human physical growth
* Bacterial growth
* Cell growth
* Growth hormone, a peptide hormone that stimulates growth
* Human development (biology)
* Plant growth
* Secondary growth ...
of this genus using data gathered from the length of its upper leg bone (
femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...
) and concluded that ''Coelophysis'' juveniles grew rapidly, especially during the first year of life.
''Coelophysis'' likely reached sexual maturity between the second and third year of life and reached its full size, just above 10 feet in length, by its eighth year. This study identified four distinct growth stages: 1-year, 2-year, 4-year, and 7+ year.
It was also thought, that as soon as they were hatched, they would have to fend for themselves.
Two "morphs" of ''Coelophysis'' have been identified: a more
gracile
Gracility is slenderness, the condition of being gracile, which means slender. It derives from the Latin adjective ''gracilis'' (masculine or feminine), or ''gracile'' ( neuter), which in either form means slender, and when transferred for examp ...
form, as in specimen AMNH 7223, and a slightly more
robust
Robustness is the property of being strong and healthy in constitution. When it is transposed into a system, it refers to the ability of tolerating perturbations that might affect the system’s functional body. In the same line ''robustness'' ca ...
form, as in specimens AMNH 7224 and NMMNH P-42200. Skeletal proportions were different between these two forms;
the gracile form has a longer skull, a longer neck, shorter forelimbs, and has
sacral
Sacral may refer to:
*Sacred, associated with divinity and considered worthy of spiritual respect or devotion
*Of the sacrum
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spi ...
neural spines that are fused; and the robust form has a shorter skull, a shorter neck, longer forelimbs, and unfused sacral neural spines.
Historically, many arguments have been made that this represents some sort of dimorphism in the population of ''Coelophysis'', probably
sexual dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
.
[Gay, R. (2005). "Sexual Dimorphism in the Early Jurassic Theropod Dinosaur '']Dilophosaurus
''Dilophosaurus'' ( ) is a genus of theropod dinosaurs that lived in what is now North America during the Early Jurassic, about 193 million years ago. Three skeletons were discovered in northern Arizona in 1940, and the two best preserved ...
'' and a Comparison with Other Related Forms": In: Raath agreed that dimorphism in ''Coelophysis'' is evidenced by the size and structure of the forelimb.
Rinehart ''et al.'' studied 15 individuals, and agreed that two morphs were present, even in juvenile specimens, and suggested that sexual dimorphism was present early in life, prior to sexual maturity. Rinehart concluded that the gracile form was female and the robust form was male based on differences in the sacral vertebrae of the gracile form, which allowed for greater flexibility for egg laying.
Further support for this position was provided by an analysis showing that each morph comprised 50% of the population, as would be expected in a 50/50 sex ratio.
However, more recent research has found that ''C. bauri'' and ''C. rhodesiensis'' had highly variable growth between individuals, with some specimens being larger in their immature phase than smaller adults were when completely mature; this indicates that the supposed presence of distinct morphs is simply the result of individual variation. This highly variable growth was likely ancestral to dinosaurs but later lost, and may have given such early dinosaurs an evolutionary advantage in surviving harsh environmental challenges.
Reproduction
Through the compilation and analysis of a database of nearly three dozen birds and reptiles, and comparison with existing data about the anatomy of ''Coelophysis'' Rinehart ''et al.'' (2009) drew the following conclusions. It was estimated that average egg of ''Coelophysis'' was 31–33.5 millimeters across its minor diameter, and that each female would lay between 24 and 26 eggs in each clutch. The evidence suggested that some parental care was necessary to nurture the relatively small hatchlings during the first year of life, where they would reach 1.5 meters in length by the end of their first growth stage. ''Coelophysis bauri'' invested as much energy in reproduction as other extinct reptiles of its approximate size.
Paleopathology
In a 2001 study conducted by Bruce Rothschild and other paleontologists, 14-foot bones referred to ''Coelophysis'' were examined for signs of
stress fracture
A stress fracture is a fatigue-induced bone fracture caused by repeated stress over time. Instead of resulting from a single severe impact, stress fractures are the result of accumulated injury from repeated submaximal loading, such as running or ...
, but none were found.
[Rothschild, B.; Tanke, D.H. & Ford, T.L. (2001). "Theropod stress fractures and tendon avulsions as a clue to activity": In: ]
In ''C. rhodesiensis'', healed fractures of the
tibia
The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...
and
metatarsus
The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the med ...
have been observed, but are very rare. "
e supporting butresses of the second sacral rib" in one specimen of ''Syntarsus rhodesiensis'' showed signs of fluctuating asymmetry. Fluctuating
asymmetry
Asymmetry is the absence of, or a violation of, symmetry (the property of an object being invariant to a transformation, such as reflection). Symmetry is an important property of both physical and abstract systems and it may be displayed in pre ...
results from developmental disturbances and is more common in populations under stress and can therefore be informative about the quality of conditions a dinosaur lived under.
[Molnar, R. E., 2001, Theropod paleopathology: a literature survey: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 337-363.]
Ichnology
![PSM V66 D145 Carnivorous dinosaur tracks in high relief preserved in stone](https://upload.wikimedia.org/wikipedia/commons/f/fc/PSM_V66_D145_Carnivorous_dinosaur_tracks_in_high_relief_preserved_in_stone.png)
Edwin H. Colbert has suggested that the theropod footprints referred to the
ichnogenus
An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. ''Ichnotaxa'' comes from the Greek ίχνος, ''ichnos'' meaning ''track'' and ταξις, ''taxis'' meaning ...
''
Grallator
''Grallator'' GRA-luh-tor"is an ichnogenus (form taxon based on footprints) which covers a common type of small, three-toed print made by a variety of bipedal theropod dinosaurs. ''Grallator''-type footprints have been found in formations dating ...
'', located in the
Connecticut River Valley
The Connecticut River is the longest river in the New England region of the United States, flowing roughly southward for through four states. It rises 300 yards (270 m) south of the U.S. border with Quebec, Canada, and discharges at Long Island ...
across Connecticut and Massachusetts, may have been made by ''Coelophysis''.
The footprints are from the Late Triassic to Early Jurassic aged Newark Supergroup. They clearly show digits II III and IV but not I or V. That condition is strange for footprints of their age. The digits I and V were presumed to be stubby and ineffective, not touching the ground when the dinosaur was walking or running. They have been thought to be from an unidentified, primitive saurischian similar to ''Coelophysis'' by David B. Weishampel and L. Young more recently.
Skeletal remains resembling ''Coelophysis'' have also been found in the valley, supporting the idea that a species similar to ''Coelophysis'' is responsible for the footprints.
Paleoenvironment
![Coelophysis Jeff Martz](https://upload.wikimedia.org/wikipedia/commons/2/2a/Coelophysis_Jeff_Martz.jpg)
Specimens of ''Coelophysis'' have been recovered from the
Chinle Formation
The Chinle Formation is an Upper Triassic continental geological formation of fluvial, lacustrine, and palustrine to eolian deposits spread across the U.S. states of Nevada, Utah, northern Arizona, western New Mexico, and western Colorado. In Ne ...
of New Mexico and Arizona, more famously at the Ghost Ranch (Whitaker) quarry in the Rock Point member
among other quarries in the underlying Petrified Forest member, the sediments of which have been dated to approximately 212 million years ago, making them part of the middle
Norian
The Norian is a division of the Triassic Period. It has the rank of an age (geochronology) or stage (chronostratigraphy). It lasted from ~227 to million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.
Stratigraphic defi ...
stage of the Late Triassic,
but Thomas Holtz Jr. interpreted that it was during the
Rhaetian
The Rhaetian is the latest age of the Triassic Period (in geochronology) or the uppermost stage of the Triassic System (in chronostratigraphy). It was preceded by the Norian and succeeded by the Hettangian (the lowermost stage or earliest age ...
stage from approximately 204 to 201.6 million years ago.
[Holtz, Thomas R. Jr. (2012) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,']
Winter 2011 Appendix.
/ref>
''C. rhodesiensis'' has been recovered in the Upper Elliott Formation in the Cape
A cape is a clothing accessory or a sleeveless outer garment which drapes the wearer's back, arms, and chest, and connects at the neck.
History
Capes were common in medieval Europe, especially when combined with a hood in the chaperon. Th ...
and Free State provinces of South Africa as well as the Chitake River bonebed quarry at the Forest Sandstone Formation
The Forest Sandstone is a geological formation in southern Africa, dating to roughly between 200 and 190 million years ago and covering the Hettangian to Sinemurian stages of the Jurassic Period in the Mesozoic Era. As its name suggests, it cons ...
in Zimbabwe.
Ghost Ranch was located close to the equator over 200 million years ago, and had a warm, monsoon-like climate with heavy seasonal precipitation. Hayden Quarry, a new excavation site at Ghost Ranch, New Mexico, has yielded a diverse collection of fossil material that included the first evidence of dinosaurs and less-advanced dinosauromorphs from the same time period. The discovery indicates that the two groups lived together during the early Triassic period 235 million years ago.
Therrien and Fastovsky (2001) examined the paleoenvironment of ''Coelophysis'' and other early theropods from Petrified Forest National Park in Arizona, and determined that this genus lived in an environment that consisted of floodplains marked by distinct dry and wet seasons. There was a great deal of competition during drier times when animals struggled for water in riverbeds that were drying up.
In the upper sections of the Chinle Formation where ''Coelophysis'' is found, dinosaurs were rare; so far only ''Chindesaurus
''Chindesaurus'' ( ) is an extinct genus of basal saurischian dinosaur from the Late Triassic (213-210 million years ago) of the southwestern United States. It is known from a single species, ''C. bryansmalli'', based on a partial skeleton recovere ...
'' and ''Daemonosaurus
''Daemonosaurus'' is an extinct genus of possible theropod dinosaur from the Late Triassic of New Mexico. The only known fossil is a skull and neck fragments from deposits of the latest Triassic Chinle Formation at Ghost Ranch. ''Daemonosaurus'' ...
'' are known, the terrestrial fauna being dominated instead by other reptiles like the rhynchocephalia
Rhynchocephalia (; ) is an order of lizard-like reptiles that includes only one living species, the tuatara (''Sphenodon punctatus'') of New Zealand. Despite its current lack of diversity, during the Mesozoic rhynchocephalians were a diverse g ...
n ''Whitakersaurus
''Whitakersaurus'' is a genus of sphenodontid rhynchocephalian reptile dated to be late Triassic in age and is from the Ghost Ranch fossil quarry in New Mexico, USA. It is named after the discoverer of the Ghost Ranch quarry, George O. Whitaker ...
''; the pseudosuchian
Pseudosuchia is one of two major divisions of Archosauria, including living crocodilians and all archosaurs more closely related to crocodilians than to birds. Pseudosuchians are also informally known as "crocodilian-line archosaurs". Prior to ...
''Revueltosaurus
''Revueltosaurus'' ("Revuelto lizard") is an extinct genus of suchian pseudosuchian from Late Triassic (late Carnian to middle Norian stage) deposits of New Mexico, Arizona and North Carolina, United States. Many specimens, mostly teeth, have be ...
''; the aetosaur
Aetosaurs () are heavily armored reptiles belonging to the extinct order Aetosauria (; from Greek, (aetos, "eagle") and (, "lizard")). They were medium- to large-sized omnivorous or herbivorous pseudosuchians, part of the branch of archosaurs ...
s ''Desmatosuchus
''Desmatosuchus'' (, from Greek δεσμός ''desmos'' 'link' + σοῦχος ''soûkhos'' 'crocodile') is an extinct genus of archosaur belonging to the Order Aetosauria. It lived during the Late Triassic.
Description
''Desmatosuchus'' was a ...
'', ''Typothorax
''Typothorax'' is an extinct genus of typothoracine aetosaur that lived in the Late Triassic. Its remains have been found in North America. Two species are known: ''T. coccinarum'', the type species, and ''T. antiquum''.
Description
''Typothor ...
'' and '' Heliocanthus''; the crocodilomorph ''Hesperosuchus
''Hesperosuchus'' is an extinct genus of crocodylomorph reptile that contains a single species, ''Hesperosuchus agilis''. Remains of this pseudosuchian have been found in Late Triassic (Carnian) strata from Arizona and New Mexico.Colbert, E. H. 1 ...
''; the "rauisuchia
"Rauisuchia" is a paraphyletic group of mostly large and carnivorous Triassic archosaurs. Rauisuchians are a category of archosaurs within a larger group called Pseudosuchia, which encompasses all archosaurs more closely related to crocodilia
...
ns" ''Shuvosaurus
''Shuvosaurus'' (meaning "Shuvo's lizard") is a genus of beaked reptile from the Late Triassic of western Texas. Despite looking superficially similar to a theropod dinosaur, it is actually more closely related to crocodilians.
Discovery and cl ...
'',[Irmis, R.B. (2005). "The vertebrate fauna of the Upper Triassic Chinle Formation in northern Arizona": In: ] ''Effigia
''Effigia'' was an extinct genus of shuvosaurid known from the Late Triassic of New Mexico, south-western USA. With a bipedal stance, long neck, and a toothless beaked skull, ''Effigia'' and other shuvosaurids bore a resemblance to the ornithomim ...
'' and ''Vivaron
''Vivaron'' is a genus of rauisuchid known from the Late Triassic (middle Norian) Chinle Formation in New Mexico. It is the second rauisuchid known from the southwestern United States, and it highlights the wide biogeographic range similar rauisu ...
''; along other rare components like the dinosauriform
Dinosauromorpha is a clade of avemetatarsalian archosaurs (reptiles closer to birds than to crocodilians) that includes the Dinosauria (dinosaurs) and some of their close relatives. It was originally defined to include dinosauriforms and lager ...
''Eucoelophysis
''Eucoelophysis'' (meaning "true hollow form") is a genus of silesaurid dinosauriform from the Late Triassic ( Norian) period Chinle Formation of New Mexico. It was assumed to be a coelophysid upon description, but a study by Nesbitt ''et al. ...
'', and the amniote
Amniotes are a clade of tetrapod vertebrates that comprises sauropsids (including all reptiles and birds, and extinct parareptiles and non-avian dinosaurs) and synapsids (including pelycosaurs and therapsids such as mammals). They are disti ...
''Kraterokheirodon
''Kraterokheirodon'' ("cupped hand tooth") is an extinct genus of enigmatic tetrapod, that was possibly an amniote, from the Late Triassic Chinle Formation of Arizona. The type and only species is ''K. colberti''. Although it is known only from ...
''. In the waterways there are the phytosaur
Phytosaurs (Φυτόσαυροι in greek) are an extinct group of large, mostly semiaquatic Late Triassic archosauriform reptiles. Phytosaurs belong to the order Phytosauria. Phytosauria and Phytosauridae are often considered to be equivalent ...
''Machaeroprosopus
''Machaeroprosopus'' is an extinct genus of mystriosuchin leptosuchomorph phytosaur from the Late Triassic of the southwestern United States. ''M. validus'', once thought to be the type species of ''Machaeroprosopus'', was named in 1916 on the b ...
''; the archosauromorph
Archosauromorpha (Greek for "ruling lizard forms") is a clade of diapsid reptiles containing all reptiles more closely related to archosaurs (such as crocodilians and dinosaurs, including birds) rather than lepidosaurs (such as tuataras, liza ...
''Vancleavea
''Vancleavea'' is a genus of extinct, armoured, non- archosaurian archosauriforms from the Late Triassic of western North America. The type and only known species is ''V. campi'', named by Robert Long & Phillip A Murry in 1995. At that time, ...
;'' the amphibians ''Apachesaurus
''Apachesaurus'' is an extinct genus of metoposaurid temnospondyl amphibian from western North America.
Description and taxonomy
''Apachesaurus'' was described from the Late Triassic (late Norian-Rhaetian
The Rhaetian is the latest age of ...
'' and ''Koskinonodon
''Anaschisma'' is an extinct genus of large temnospondyl amphibians. These animals were part of the family called Metoposauridae, which filled the crocodile-like predatory niches in the late Triassic. It had large skull about long, and possi ...
''; and the fishes '' Reticulodus'', ''Arganodus
''Arganodus'' is an extinct genus of Ceratodontidae (lungfish). Its fossils have been found in the Redonda Formation, New Mexico, the Tacuarembó Formation of Uruguay, and the Cumnock Formation, North Carolina, although the North Carolinian s ...
'' and '' Lasalichthyes''.
Taphonomy
The multitude of specimens deposited so closely together at Ghost Ranch was probably the result of a flash flood, which swept away a large number of ''Coelophysis'' and buried them quickly and simultaneously. In fact, it seems that such flooding was commonplace during this period of the Earth's history
The history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by constant geologic ...
and, indeed, the Petrified Forest
Petrified wood, also known as petrified tree (from Ancient Greek meaning 'rock' or 'stone'; literally 'wood turned into stone'), is the name given to a special type of ''fossilized wood'', the fossilized remains of terrestrial vegetation. ''P ...
of nearby Arizona
Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
is the result of a preserved log jam of tree trunks that were caught in one such flood. Whitaker quarry at Ghost Ranch is considered a monotaxic site because it features multiple individuals of a single taxon. The quality of preservation and the ontogenic (age) range of the specimens helped make ''Coelophysis'' one of the best known of all genera. In 2009, Rinehart ''et al.'' noted that in one case the ''Coelophysis'' specimens were "washed into a topographic low containing a small pond, where they probably drowned and were buried by a sheet flood event from a nearby river."
The 30 specimens of ''C. rhodesiensis'' found together in Zimbabwe was also probably the result of a flash flood, which swept away a large number of ''Coelophysis'' and buried them quickly and simultaneously as well.
Cultural significance
''Coelophysis'' was the second dinosaur in space, following ''Maiasaura
''Maiasaura'' (from the Greek ''μαῖα'', meaning "good mother" and ''σαύρα'', the feminine form of ''saurus'', meaning "reptile") is a large herbivorous saurolophine hadrosaurid ("duck-billed") dinosaur genus that lived in the area curre ...
'' (STS-51-F
STS-51-F (also known as Spacelab 2) was the 19th flight of NASA's Space Shuttle program and the eighth flight of Space Shuttle ''Challenger''. It launched from Kennedy Space Center, Florida, on July 29, 1985, and landed eight days later on Aug ...
). A ''Coelophysis'' skull from the Carnegie Museum of Natural History
The Carnegie Museum of Natural History (abbreviated as CMNH) is a natural history museum in the Oakland neighborhood of Pittsburgh, Pennsylvania. It was founded by Pittsburgh-based industrialist Andrew Carnegie in 1896.
Housing some 22 millio ...
was aboard the Space Shuttle Endeavour
Space Shuttle ''Endeavour'' (Orbiter Vehicle Designation: OV-105) is a retired orbiter from NASA's Space Shuttle program and the fifth and final operational Shuttle built. It embarked on its first mission, STS-49, in May 1992 and its 25th and ...
mission STS-89
STS-89 was a Space Shuttle mission to the ''Mir'' space station flown by Space Shuttle Space Shuttle Endeavour, '' Endeavour'', and launched from Kennedy Space Center, Florida on 22 January 1998.
Crew
Crew notes
STS-89 was originally schedule ...
when it left the atmosphere on 22 January 1998. It was also taken onto the space station Mir
''Mir'' (russian: Мир, ; ) was a space station that operated in low Earth orbit from 1986 to 2001, operated by the Soviet Union and later by Russia. ''Mir'' was the first modular space station and was assembled in orbit from 1986 to&n ...
before being returned to Earth.
As being over 100 years old, ''Coelophysis'' is one of the best-known dinosaurs in literature. It was designated as the official state fossil of New Mexico in 1981, and is now the logo of the New Mexico Museum of Natural History.
References
External links
''Coelophysis''
in the Dino Directory
{{Portal bar, Paleontology, Dinosaurs
Coelophysoids
Late Triassic dinosaurs of North America
Chinle fauna
Triassic geology of New Mexico
Paleontology in New Mexico
Symbols of New Mexico
Fossil taxa described in 1889
Taxa named by Edward Drinker Cope