Guaibasaurids Temporal range: Late Triassic, | |
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Fossil skeleton of Guaibasaurus candelariensis | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | † Sauropodomorpha |
Family: | † Guaibasauridae Bonaparte et al., 1999 |
Type species | |
† Guaibasaurus candelariensis | |
Subgroups | |
Guaibasauridae is a family of basal sauropodomorph dinosaurs, known from fossil remains of late Triassic period formations in Brazil, [1] Argentina [2] and India. [3]
The exact makeup and classification of the Guaibasauridae remain uncertain. The family was originally named by Jose Bonaparte and colleagues in 1999 to contain a single genus and species, Guaibasaurus candelariensis . [1] When the second specimen of Guaibasaurus was described from better remains in 2007, it became easier to compare it to other enigmatic early saurischians, which are often difficult to classify because they combine characteristics of the two major saurischian groups, Theropoda and Sauropodomorpha. Bonaparte and colleagues, in light of the information gained from this second specimen, found that the genus Saturnalia (which is anatomically very similar to Guaibasaurus) could also be assigned to the Guaibasauridae, though they did not conduct a phylogenetic analysis or define Guaibasauridae as a clade. The researchers also tentatively assigned the poorly understood genus Agnosphitys to this family. [4] However, the latter assignment was not supported by the results of the phylogenetic analyses of early dinosaurs that were carried out by Baron, Norman & Barrett (2017). [5]
Bonaparte and colleagues (2007) found that guaibasaurids have more characteristics in common with theropods than they do with early sauropodomorphs (or "prosauropods"). Because of this, according to Bonaparte, they are most likely either a very basal group on the stem leading toward sauropodomorphs or a group ancestral to both sauropodomorphs and theropods. Furthermore, the authors interpret this as evidence that the common ancestor of both saurischian lineages was more theropod-like than prosauropod-like. [4]
Ezcurra (2010) defined the subfamily Saturnaliinae for the clade containing Saturnalia and Chromogisaurus , which were found to be close relatives in several studies. [2] While they are sometimes found to be a subgroup of guaibasaurids, [6] other studies have found the saturnaliines to form an independent lineage at the very base of the sauropodomorph family tree. [7] Langer and colleagues (2019) recovered Pampadromaeus and Panphagia as relatives of Saturnalia and Chromogisaurus, elevating Saturnaliinae to family rank as Saturnaliidae. They recovered Guaibasaurus as a basal theropod. [8] Guaibasaurus has since been recovered as a sauropodomorph, possibly allied with Unaysauridae, with Saturnaliidae representing a group of more basal sauropodomorphs. [9] Among taxa at one point considered guaibasaurids, Agnosphitys has been reassigned to Silesauridae, and Eoraptor, Panphagia, Saturnalia and Chromogisaurus are considered basalmost sauropodomorphs possibly in a clade of their own. [10]
Eoraptor is a genus of small, lightly built, basal sauropodomorph dinosaur. One of the earliest-known dinosaurs and one of the earliest members of the sauropod family, it lived approximately 231 to 228 million years ago, during the Late Triassic in Western Gondwana, in the region that is now northwestern Argentina. The type and only species, Eoraptor lunensis, was first described in 1993, and is known from an almost complete and well-preserved skeleton and several fragmentary ones. Eoraptor had multiple tooth shapes, which suggests that it was omnivorous. Eoraptor was 1.5 feet (0.46 m) tall and 3 feet (0.91 m) long.
Sauropodomorpha is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had long necks and tails, were quadrupedal, and became the largest animals to ever walk the Earth. The prosauropods, which preceded the sauropods, were smaller and were often able to walk on two legs. The sauropodomorphs were the dominant terrestrial herbivores throughout much of the Mesozoic Era, from their origins in the Late Triassic until their decline and extinction at the end of the Cretaceous.
Staurikosaurus is a genus of herrerasaurid dinosaur from the Late Triassic of Brazil, found in the Santa Maria Formation.
Saturnalia is an extinct genus of basal sauropodomorph dinosaur known from the Late Triassic Santa Maria Formation of Rio Grande do Sul, southern Brazil. It contains one species, Saturnalia tupiniquim. It is one of the earliest known dinosaurs.
Herrerasauridae is a family of carnivorous dinosaurs, possibly basal to either theropods or even all of saurischians, or even their own branching from Dracohors, separate from Dinosauria altogether. They are among the oldest known dinosaurs, first appearing in the fossil record around 233.23 million years ago, before becoming extinct by the end of the Carnian stage. Herrerasaurids were relatively small-sized dinosaurs, normally no more than 4 metres (13 ft) long, although the holotype specimen of "Frenguellisaurus ischigualastensis" is thought to have reached around 6 meters long. The best known representatives of this group are from South America, where they were first discovered in the 1930s in relation to Staurikosaurus and 1960s in relation to Herrerasaurus. A nearly complete skeleton of Herrerasaurus ischigualastensis was discovered in the Ischigualasto Formation in San Juan, Argentina, in 1988. Less complete possible herrerasaurids have been found in North America and Africa, and they may have inhabited other continents as well.
Herrerasaurus is likely 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 1958 in South America. All known fossils of this carnivore have been discovered in the Ischigualasto Formation of Carnian age in northwestern Argentina. The type species, Herrerasaurus ischigualastensis, was described by Osvaldo Reig in 1963 and is the only species assigned to the genus. Ischisaurus and Frenguellisaurus are synonyms.
Guaibasaurus is an extinct genus of basal saurischian dinosaur known from the Late Triassic Caturrita Formation of Rio Grande do Sul, southern Brazil. Most analyses recover it as a sauropodomorph, although there are some suggestions that it was a theropod instead. In 2016 Gregory S. Paul estimated it at 2 meters and 10 kg, whereas in 2020 Molina-Pérez and Larramendi listed it at 3 meters and 35 kg.
Chindesaurus is an extinct genus of basal saurischian dinosaur from the Late Triassic of the southwestern United States. It is known from a single species, C. bryansmalli, based on a partial skeleton recovered from Petrified Forest National Park in Arizona. The original specimen was nicknamed "Gertie", and generated much publicity for the park upon its discovery in 1984 and airlift out of the park in 1985. Other fragmentary referred specimens have been found in Late Triassic sediments throughout Arizona, New Mexico, and Texas, but these may not belong to the genus. Chindesaurus was a bipedal carnivore, approximately as large as a wolf.
Dinosauromorpha is a clade of avemetatarsalians that includes the Dinosauria (dinosaurs) and some of their close relatives. It was originally defined to include dinosauriforms and lagerpetids, with later formulations specifically excluding pterosaurs from the group. Birds are the only dinosauromorphs which survive to the present day.
Saurischia is one of the two basic divisions of dinosaurs, classified by their hip structure. Saurischia and Ornithischia were originally called orders by Harry Seeley in 1888 though today most paleontologists classify Saurischia as an unranked clade rather than an order.
Anchisauria is an extinct clade of sauropodomorph dinosaurs that lived from the Late Triassic to the Late Cretaceous. The name Anchisauria was first used Haekel and defined by Galton and Upchurch in the second edition of The Dinosauria. It is a node-based taxon containing the most recent common ancestor of Anchisaurus polyzelus and Melanorosaurus readi, and all its descendants. Galton and Upchurch assigned a family of dinosaurs to the Anchisauria: the Melanorosauridae. The more common prosauropods Plateosaurus and Massospondylus were placed in the sister clade Plateosauria.
Panphagia is a genus of sauropodomorph dinosaur described in 2009. It lived around 231 million years ago, during the Carnian age of the Late Triassic period in what is now northwestern Argentina. Fossils of the genus were found in the La Peña Member of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin. The name Panphagia comes from the Greek words pan, meaning "all", and phagein, meaning "to eat", in reference to its inferred omnivorous diet. Panphagia is one of the earliest known dinosaurs, and is an important find which may mark the transition of diet in early sauropodomorph dinosaurs.
Phytodinosauria is a group of dinosaurs proposed in 1986, combining the Sauropodomorpha and Ornithischia as sister groups, conceptualized as a superorder of herbivorous dinosaurs excluding the carnivorous Theropoda. This hypothesis has been refuted by modern cladistic analysis, showing such a group to be polyphyletic. Modern studies either combine the Theropoda and Sauropodormorpha in the Saurischia or the Theropoda and Ornithischia in the Ornithoscelida.
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 comprised an early diverging clade or a paraphyletic grade within ornithischian dinosaurs. Silesaurids have a consistent general body plan, with a fairly long neck and legs and possibly quadrupedal habits, but most silesaurids are heavily fragmentary nonetheless. Furthermore, they occupied a variety of ecological niches, with early silesaurids being carnivorous and later taxa having adaptations for specialized herbivory. As indicated by the contents of referred coprolites, Silesaurus may have been insectivorous, feeding selectively on small beetles and other arthropods.
Chromogisaurus is an extinct genus of saturnaliid sauropodomorph which existed in Argentina during the Late Triassic (Carnian) period. It is from the Cancha de Bochas, Valle Pintado member of the Ischigualasto Formation. It was a herbivore about 2 metres in length, and was optionally quadrupedal.
Saturnaliidae is a family of basal sauropodomorph dinosaurs found in Brazil, Argentina and possibly Zimbabwe. It is not to be confused with Saturnalidae, a family of radiolarian protists.
Eodromaeus is an extinct genus of probable basal theropod dinosaurs from the Late Triassic of Argentina. Like many other of the earliest-known dinosaurs, it hails from the Carnian-age Ischigualasto Formation, within the Ischigualasto-Villa Unión Basin of northwestern Argentina. Upon its discovery, it was argued to be one of the oldest true theropods, supplanting its contemporary Eoraptor, which was reinterpreted as a basal sauropodomorph.
Pampadromaeus is an extinct genus of basal sauropodomorph dinosaurs known from the Late Triassic (Carnian) Santa Maria Formation of the Paraná Basin in Rio Grande do Sul, southern Brazil.
Buriolestes is a genus of early sauropodomorph dinosaurs from the Late Triassic Santa Maria Formation of the Paraná Basin in southern Brazil. It contains a single species, B. schultzi, named in 2016. The type specimen was found alongside a specimen of the lagerpetid dinosauromorph Ixalerpeton.
Nhandumirim is a genus of basal sauropodomorph dinosaur from the Carnian age of Late Triassic Brazil. It is currently considered a saturnaliid sauropodomorph. The type and only species, Nhandumirim waldsangae, is known from a single immature specimen including vertebrae, a chevron, pelvic material, and a hindlimb found in the Santa Maria Formation in Rio Grande do Sul.