Camposaurus

Camposaurus (/ˌkæmpoʊˈsɔːrəs, -pə-/ KAMP-o-SOR-əs) is a coelophysoid 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 neotheropod.

Camposaurus
Temporal range: Late Triassic, 220 Ma
Camposaurus holotype ankle
Lower leg and ankle bones of the holotype in multiple views
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Coelophysidae
Genus: Camposaurus
Hunt et al., 1998
Type species
Camposaurus arizonensis
Hunt et al., 1998

Description

Camposaurus arizonensis
Reconstruction based on Coelophysis

Camposaurus is a small, carnivorous, theropod dinosaur. Its approximate length and weight cannot be reliably estimated because of the sparse material that is known from this genus. Camposaurus is known from partial lower leg bones, holotype UCMP 34498 (which includes distal tibiae, distal fibulae, and astragalocalcanea), and other fragmentary material. Like other coelophysids, it has fused tibio-tarsals and fibulo-tarsals. Unlike its relatives, the area of the tibia that fits with the fibula has a distinct ridge at the back. Another unique feature is the lack of a large medial condyle on the astragalus.[1] The type species, C. arizonensis, was formally named and described by Adrian Hunt, Spencer G. Lucas, Andrew B. Heckert, Robert M. Sullivan and Martin Lockley in 1998.[2] As the species name suggests, it was found in Arizona, in the United States.

Discovery

The holotype specimen UCMP 34498 was discovered in the Placerias quarry of the Bluewater Creek Formation of Arizona, from the Norian stage of the Late Triassic period.

Classification

Camposaurus is considered to be the oldest known neotheropod dinosaur. Camposaurus was originally placed in the clade Ceratosauria based on the analysis of Long and Murray (1995).[3] It is morphologically similar to, and was incorrectly considered for some time to be a species of, Coelophysis. In 2000, Downs examined Camposaurus and concluded that it is a junior synonym of Coelophysis, because of its similarity to some of the Coelophysis Ghost Ranch specimens.[4] The review by Nesbitt et al. in 2007, revealed that a specific feature of the ankle (the ventral astragalar margin) was found to be straight, and is indistinguishable from that of Coelophysis bauri. Based on this Nesbitt et al. (2007) concluded that the two genera were synonymous.[5] In 2011, it was entered into a phylogenetic analysis and found to be a close relative of Coelophysis rhodesiensis.[1] The lack of material has led many paleontologists to reject it as a nomen dubium.[1][6] A reassessment of the holotype UCMP 34498 of Camposaurus arizoniensis by Ezcurra and Brusatte revealed two autapomorphies, thereby firmly establishing this material as a valid genus and species. This analysis also demonstrated that Camposaurus is definitely a neotheropod, and based on phylogenetic analysis its closest known relative is Coelophysis rhodesiensis, because they share similarities in the tibia, and ankle.[1] Spielman et al. (2007) assigned Camposaurus to the family Coelophysidae.[7]

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 and Brusatte (2011), Camposaurus can be distinguished based on the following features:[1]

  • the caudal ridge of the tibia articular surface on the fibula is prominent, taking the form of a sharp longitudinal ridge, the medial surface having a strongly developed, rostrally bowed, diagonal tuberosity
  • the astragalus is without a strong cranial projection of the medial condyle of the astragalar body, resulting in a sub-rectangular astragalar body in the distal aspect, and a ventral margin that is incipiently concave in the cranial aspect

References

  1. ^ a b c d e Ezcurra, M.D.; Brusatte, S.L. (2011). "Taxonomic and phylogenetic reassessment of the early neotheropod dinosaur Camposaurus arizonensis from the Late Triassic of North America". Palaeontology. 54 (4): 763–772. doi:10.1111/j.1475-4983.2011.01069.x.
  2. ^ A.P. Hunt, S.G. Lucas, A.B. Heckert, R.M. Sullivan and M.G. Lockley, 1998, "Late Triassic dinosaurs from the western United States", Géobios 31(4): 511-531
  3. ^ Long and Murray, 1995. Late Triassic (Carnian and Norian) tetrapods from the Southwestern United States. New Mexico Museum Nat. History Sci. Bull. 4, 1-254.
  4. ^ Downs, 2000. Coelophysis bauri and Syntarsus rhodesiensis compared, with comments on the preparation and preservation of fossils from the Ghost Ranch Coelophysis quarry. in Lucas and Heckert (eds.), 2000. Dinosaurs of New Mexico. NMMNH Bulletin 17. 33-37.
  5. ^ Nesbitt, Irmis and Parker, 2007. A critical re-evaluation of the Late Triassic dinosaur taxa of North America. Journal of Systematic Palaeontology. 5(2), 209–243.
  6. ^ R. B. Irmis. 2005. The vertebrate fauna of the Upper Triassic Chinle Formation in northern Arizona. In S. J. Nesbitt, W. G. Parker, & R. B. Irmis (eds.), Guidebook to the Triassic Formations of the Colorado Plateau in Northern Arizona: Geology, Paleontology, and History. Mesa Southwest Museum Bulletin 9:63-88
  7. ^ J. A. Spielmann, S. G. Lucas, L. F. Rinehart, A. P. Hunt, A. B. Heckert and R. M. Sullivan. 2007. Oldest records of the Late Triassic theropod dinosaur Coelophysis bauri. In S. G. Lucas & J. A. Spielmann (eds.), The Global Triassic. New Mexico Museum of Natural History and Science Bulletin 41:384-401
Averostra

Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs that have a promaxillary fenestra (fenestra promaxillaris), an extra opening in the front outer side of the maxilla, the bone that makes up the upper jaw. Two groups of averostrans, the Ceratosauria and the Orionides, survived into the Cretaceous period. When the Cretaceous–Paleogene extinction event occurred, ceratosaurians and two groups of orionideans within the clade Coelurosauria, the Tyrannosauroidea and Maniraptoriformes, were still extant. Only one subgroup of maniraptoriformes, Aves, survived the extinction event and persisted to the present day.

Avetheropoda

Avetheropoda, or "bird theropods", is a clade that includes carnosaurians and coelurosaurs to the exclusion of other dinosaurs.

Cerapoda

Cerapoda ("ceratopsians and ornithopods") is a clade of the dinosaur order Ornithischia.

Charles Lewis Camp

Charles Lewis Camp (March 12, 1893 Jamestown, North Dakota – August 14, 1975 San Jose, California) was a palaeontologist and zoologist, working from the University of California, Berkeley. He took part in excavations at the 'Placerias Quarry', in 1930 and the forty Shonisaurus skeleton discoveries of the 1960s, in what is now the Berlin-Ichthyosaur State Park. Camp served as the third director of the University of California Museum of Paleontology from 1930 to 1949, and coincidentally as chair of the UC Berkeley Paleontology Department between 1939 and 1949. Camp named a number of species of marine reptiles such as Shonisaurus and Plotosaurus, as well as the dinosaur Segisaurus.

Camp was also an important bibliographer and historian of Western America. This aspect of his career is represented most notably by two works. The first is his biography of American pioneer James Clyman, which Bernard De Voto called "one of the half-dozen classics in the field." The second work was the third edition of The Plains and the Rockies, published in 1953, which Camp annotated heavily. He was the 1970 recipient of the California Historical Society's Henry Raup Wagner Memorial Award.

The theropod Camposaurus was named in Camp's honour in 1998.

Coelophysidae

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 Coelophysidae are characterized by long, slender skulls and light skeletons built for speed. One member, Coelophysis, displays the earliest known furcula in a dinosaur.Under cladistic analysis, Coelophysidae was first defined by Paul Sereno in 1998 as the most recent common ancestor of Coelophysis bauri and Procompsognathus triassicus, and all of that common ancestor's descendants. However, Tykoski (2005) has advocated for the definition to change to include the additional taxa of "Syntarsus" kayentakatae and Segisaurus halli. Coelophysidae is part of the superfamily Coelophysoidea, which in turn is a subset of the larger Neotheropoda clade. As part of Coelophysoidea, Coelophysidae is often placed as sister to the Dilophosauridae family, however, the monophyly of this clade has often been disputed. The older term "Podokesauridae", named 14 years prior to Coelophysidae (which would normally grant it priority), is now usually ignored, since its type specimen was destroyed in a fire and can no longer be compared to new finds.

Coelophysis rhodesiensis

Coelophysis rhodesiensis is an extinct species of coelophysid theropod dinosaur that lived approximately 188 million years ago during the early part of the Jurassic Period in what is now Africa. The species was a small to medium-sized, lightly built, ground-dwelling, bipedal carnivore, that could grow up to 3 m (9.8 ft) long. It was formerly called Syntarsus, but that name was already taken by a beetle, and was subsequently given the name Megapnosaurus by Ivie, Ślipiński & Węgrzynowicz, in 2001, though many subsequent studies have classified it in the genus Coelophysis.

Dinosauriformes

Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs and a partially to fully perforated acetabulum, the hole in the hip socket traditionally used to define dinosaurs. The oldest known member is Asilisaurus, dating to about 245 million years ago in the Anisian age of the middle Triassic period.

Jeholosauridae

Jeholosaurids were herbivorous neornithischian dinosaurs from the Cretaceous Period (Aptian - Santonian, with a possible Campanian record) of Asia. The family was first proposed by Han et al. in 2012. The jeholosaurids were defined as those ornithischians more closely related to Jeholosaurus shangyuanensis than to Hypsilophodon foxii, Iguanodon bernissartensis, Protoceratops andrewsi, Pachycephalosaurus wyomingensis, or Thescelosaurus neglectus. The Jeholosauridae includes the type genus Jeholosaurus and Yueosaurus.

Jingshanosaurus

Jingshanosaurus (meaning "Jingshan lizard") is a genus of sauropodomorph dinosaurs from the early Jurassic period.

Lepidus praecisio

Lepidus is a genus of extinct coelophysoidean theropod from the Upper Triassic of the United States. It lived in the Otis Chalk localities of the Dockum Group in Texas, around 223 million years ago.

List of the prehistoric life of Arizona

This list of the prehistoric life of Arizona contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Arizona.

Lucianovenator

Lucianovenator is an extinct genus of coelophysoid theropod dinosaur which lived in Argentina during the Triassic. The genus name Lucianovenator translates to "Luciano's hunter", in reference Don Luciano Leyes, who first reported the remains. The species name bonoi refers to Tulio del Bono, a local scientific authority who collaborated on the describers' research. It is one of the few neotheropods known from South America.

Melanorosauridae

The Melanorosauridae were a family of sauropodomorph dinosaurs which lived during the Late Triassic and Early Jurassic. The name Melanorosauridae was first coined by Friedrich von Huene in 1929. Huene assigned several families of dinosaurs to the infraorder "Prosauropoda": the Anchisauridae, the Plateosauridae, the Thecodontosauridae, and the Melanorosauridae. Since then, these families have undergone numerous revisions. Galton and Upchurch (2004) considered Camelotia, Lessemsaurus, and Melanorosaurus members of the family Melanorosauridae. A more recent study by Yates (2007) indicates that the melanorosaurids were instead early sauropods.

Neotheropoda

Neotheropoda (meaning "new theropods") is a clade that includes coelophysoids and more advanced theropod dinosaurs, and the only group of theropods who survived the Triassic–Jurassic extinction event. Yet all of the neotheropods became extinct during the early Jurassic period except for Averostra.

Orionides

Orionides is a clade of tetanuran theropod dinosaurs from the Middle Jurassic to the Present. The clade includes most theropod dinosaurs, including birds.

Orodrominae

Orodrominae is a subfamily of parksosaurid dinosaurs from the Cretaceous of North America and Asia.

Panguraptor

Panguraptor ("Pangu [a Chinese god] plunderer") is a genus of coelophysid theropod dinosaur known from fossils discovered in Lower Jurassic rocks of southern China. The type and only known species is Panguraptor lufengensis. The generic name refers to the deity Pangu but also to the supercontinent Pangaea for which in a geological context the same characters are used: 盘古. Raptor means "seizer", "robber" in Latin. The specific name is a reference to the Lufeng Formation.The holotype specimen was recovered on 12 October 2007 from the Lufeng Formation of Yunnan, which is noted for sauropodomorph fossils. It was described in 2014 by You Hai-Lu and colleagues.

Riojasauridae

Riojasauridae is a family of sauropod-like dinosaurs from the Upper Triassic. It is known primarily from the genera Riojasaurus and Eucnemesaurus. Sites containing Riojasauridae include the Lower Elliot Formation of Orange Free State, South Africa (where fossils of Eucnemesaurus have been found), and Ischigualasto, in La Rioja Province, Argentina ( where fossils of Riojasaurus have been recovered).

Xixiposaurus

Xixiposaurus is a genus of prosauropod dinosaur which existed in what is now Lower Lufeng Formation, China during the lower Jurassic period. It was first named by Sekiya Toru in 2010 and the type species is Xixiposaurus suni.

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