Lucianovenator

Lucianovenator is an extinct genus of coelophysoid theropod dinosaur which lived in Argentina during the Triassic.[1] 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.[1]

Lucianovenator
Temporal range: Late Norian-Rhaetian
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Coelophysidae
Genus: Lucianovenator
Martinez & Apaldetti, 2017
Type species
Lucianovenator bonoi
Martinez & Apaldetti, 2017

Discovery

The holotype (PVSJ 906) of Lucianovenator bonoi was found in the "Quebrada del puma" locality of the Quebrada del Barro formation in Argentina, which is estimated to be from the late Norian to Rhaetian in age, approximately 210 to 202 million years ago. PVSJ 906 represents an articulated vertebral sequence from the third cervical to fourth dorsal vertebra, as well as a sacrum and a partial pelvis. In addition, three more specimens were referred to Lucianovenator. These include PVSJ 899 (a sacrum and partial pelvis), PVSJ 1013 (a sacrum), and PVSJ 1084 (a sacrum and partial pelvis). PVSJ 1004, the proximal end of a right tibia, may also belong to the species.[1]

Description

As with other neotheropods, the cervical vertebrae of Lucianovenator possess a complex system of fossae (pits) and laminae (ridges) that connect the main body of each vertebrae (centra), front and rear joint plates (pre- and post-zygapophyses), and top and bottom rib facets (diapophyses and pleurapophyses) to each other. Although the cervicals of Lucianovenator possess many fossae, four particular examples of paired fossae (four on each side of the vertebrae) can be used to distinguish it from other neotheropods.

The first of these is deep pit located directly at the base of each prezygapophysis, and the second is a larger pit is located immediately behind it. These two pits are obscured by a ridge known as a prezygapophyseal centrodiapophyseal lamina, which connects each prezygapophysis to the each diapophysis, and each diapophysis to the rear portion of the centrum. A third fossa is located at the rear portion of the vertebra. It too is obscured from the side, this time by the centropostzygapophyseal lamina which connects each postzygapophysis to the rear portion of the centrum. Each of the third fossae connects to a pair of large internal cavities which lie adjacent to the canal for the spinal cord. This combination of features is unique to Lucianovenator, as no other coelophysoid possesses all of these features at once. The first and third pairs of fossae are similar to those of "Syntarsus" kayentakatae, but the second pair is not. The third pair does connect to internal cavities in Coelophysis bauri, but so does the first pair, unlike the case in Lucianovenator. Another of Lucianovenator's distinguishing traits is that the anterior cervical ribs are very long (more than five times as long as the cervical centra).[1]

The fourth diagnostic pair of cervical fossae in Lucianovenator is also the only autapomorphy (unique distinguishing trait) of the genus. Lucianovenator is unique in the fact that the edge of each centrodiapophyseal lamina (which connects each diapophysis to the centrum) acquires a long and deep pit, which becomes progressively longer and deeper towards the base of the neck. In cervical 9, the pit is nearly the entire length of the centrodiapophyseal lamina, and is so deep that it is not completely visible from the side.[1]

Classification

A phylogenetic analysis published along with the description of Lucianovenator assigned it to the Coelophysidae, in a clade with Coelophyis rhodesiensis and Camposaurus. This clade is supported by a single feature, the fact that the zygapophyses of the sacral vertebrae are fused. The authors of the paper suggested that the relative rarity of theropods in Rhaetian deposits compared to Norian deposits may be the result of taphonomic bias rather than a decline in diversity.[1]

See also

References

  1. ^ a b c d e f Martínez, Ricardo N.; Apaldetti, Cecilia (2017). "A late Norian-Rhaetian coelophysid neotheropod (Dinosauria, Saurischia) from the Quebrada del Barro Formation, northwestern Argentina". Ameghiniana. 54 (5): 488–505. doi:10.5710/AMGH.09.04.2017.3065.
Anchisauria

The Anchisauria were a clade of sauropodomorph dinosaurs that lived during the Late Triassic and Early Jurassic. The name Anchisauria was first used by Galton and Upchurch in the second edition of The Dinosauria. Galton and Upchurch assigned two families of dinosaurs to the Anchisauria: the Anchisauridae and the Melanorosauridae. The more common prosauropods Plateosaurus and Massospondylus were placed in the sister clade Plateosauria.

However, recent research indicates that Anchisaurus is closer to sauropods than traditional prosauropods; thus, Anchisauria would also include Sauropoda.The following cladogram simplified after an analysis presented by Blair McPhee and colleagues in 2014.

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.

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.

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.

Haya griva

Haya is an extinct genus of basal neornithischian dinosaur known from Mongolia.

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.

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.

Raeticodactylidae

Raeticodactylidae is a family of eudimorphodontoid eopterosaurian pterosaurs that lived in Switzerland during the Late Triassic. The family includes Caviramus, and the type genus Raeticodactylus, which are both known from the Kössen Formation, around 205 mya. Raeticodactylidae was first used in 2014 by Andres et al., as a group of all pterosaurs closer to Raeticodactylus than Eudimorphodon. The following phylogenetic analysis follows the topology of Andres et al. (2014).

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).

Thescelosaurinae

Thescelosaurinae is a subfamily of ornithischian dinosaurs from the Early Cretaceous of Asia and the Late Cretaceous of North America.

Unaysauridae

Unaysauridae is a family of basal sauropodomorphs from the Late Triassic of India and Brazil.

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.

Yueosaurus

Yueosaurus is an extinct genus of basal ornithopod dinosaur known from Zhejiang Province, China.

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