Macrocollum Temporal range: Late Triassic, | |
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Restoration | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | † Sauropodomorpha |
Clade: | † Unaysauridae |
Genus: | † Macrocollum Müller et al., 2018 |
Species: | †M. itaquii |
Binomial name | |
†Macrocollum itaquii Müller et al., 2018 | |
Macrocollum is a genus of unaysaurid sauropodomorph dinosaur that lived during the Late Triassic period (early Norian) in what is now Brazil. It is one of the oldest dinosaurs known. [1]
Macrocollum was discovered in 2012 in Rio Grande do Sul, Brazil, at the Wachholz site of the Candelária Formation, Paraná Basin. [2] It was announced in a press conference on November 21, 2018. The generic name combines the Greek word μακρός (long) and the Latin word collum (neck), referring to the animal's elongated neck. The specific epithet honours José Jerundino Machado Itaqui, one of the main persons behind the creation of CAPPA/UFSM. [1]
Like most early dinosaurs, Macrocollum was relatively small, and walked on two legs.
The known remains of Macrocollum are relatively well preserved. The holotype specimen consists of an almost complete and articulated skeleton. The two paratype specimens are both articulated skeletons with one missing a skull and its cervical series. [1]
Macrocollum itaquii differs from all other known sauropodomorphs based on a unique combination of characters such as those found on the skull, which include an antorbital fossa perforated by a promaxillary fenestra, and a medial margin of the supratemporal fossa with a simple smooth curve at the frontal/parietal suture. [1]
Macrocollum, alongside Jaklapallisaurus and Unaysaurus , was found to belong to the clade Unaysauridae. [1]
Macrocollum lived between about 225.42 to 225 million years ago, in the Norian age of the late Triassic period. It was found in the south of Brazil, which at the time was connected to northwest Africa. At the time, most of the Earth's landmass was united into the supercontinent Pangaea, which was just starting to divide into Laurasia in the north, and Gondwana in the south. [3] [4] U-Pb (Uranium decay) dating found that the Caturrita Formation, close to the holotype locality, dates to around 225.42 million years ago, making it fewer than 10 million years younger than the Santa Maria and Ischigualasto Formations, from where the earliest dinosaurs are known. [5]
The ilia of one of the paratypes of Macrocollum (CAPPA/UFSM 0001b) were used as a model in a study on the taphonomical effects of sedimentary compression on the iliac morphology of early sauropodomorphs. [6]
Eoraptor is a genus of small, lightly built, basal sauropodomorph dinosaur. One of the earliest-known dinosaurs and one of the earliest sauropodomorphs, 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.
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.
Unaysaurus is a genus of unaysaurid sauropodomorph herbivore dinosaur. Discovered in southern Brazil, in the geopark of Paleorrota, in 1998, and announced in a press conference on Thursday, December 3, 2004, it is one of the oldest dinosaurs known. It is closely related to plateosaurid dinosaurs found in Germany, which indicates that it was relatively easy for species to spread across the giant landmass of the time, the supercontinent of Pangaea.
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.
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.
Lewisuchus is a genus of archosaur that lived during the Late Triassic. As a silesaurid dinosauriform, it was a member of the group of reptiles most commonly considered to be the closest relatives of dinosaurs. Lewisuchus was about 1 metre (3.3 ft) long. Fossils have been found in the Chañares Formation of Argentina. It exhibited osteoderms along its back.
Sacisaurus is a silesaurid dinosauriform from the Late Triassic (Norian) Caturrita Formation of southern Brazil. The scientific name, Sacisaurus agudoensis, refers to the city where the species was found, Agudo in the Rio Grande do Sul state, whereas Sacisaurus refers to Saci, a famous one-legged creature from Brazilian mythology, because among the dozens of fossil material unearthed, 35 right femora were collected whereas only 1 left femur was found.
The Santa Maria Formation is a sedimentary rock formation found in Rio Grande do Sul, Brazil. It is primarily Carnian in age, and is notable for its fossils of cynodonts, "rauisuchian" pseudosuchians, and early dinosaurs and other dinosauromorphs, including the herrerasaurid Staurikosaurus, the basal sauropodomorphs Buriolestes and Saturnalia, and the lagerpetid Ixalerpeton. The formation is named after the city of Santa Maria in the central region of Rio Grande do Sul, where outcrops were first studied.
The Caturrita Formation is a rock formation found in Rio Grande do Sul, Brazil. Its sediments were deposited in the Paraná Basin. The formation is from the Upper Triassic and forms part of the Santa Maria Supersequence in the upper section of the Rosário do Sul Group.
Trucidocynodon is an extinct genus of ecteniniid cynodonts from the Upper Triassic (Carnian) of Brazil. It contains a single species, Trucidocynodon riograndensis. Fossils of Trucidocynodon were discovered in outcrops of the Upper Santa Maria Formation in Paleorrota Geopark, Agudo. Trucidocynodon is one of the most completely known Triassic cynodonts, as its holotype is a nearly complete and fully articulated skeleton.
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.
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.
Unaysauridae is a clade of basal sauropodomorphs from the Late Triassic of India and Brazil.
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.
The Candelária Formation, in other literature also referred to as Candelária Sequence, is a sedimentary formation of the Santa Maria Group in the Paraná Basin in Rio Grande do Sul, southeastern Brazil. The formation dates to the Carnian of the Late Triassic, locally referred to as Tuvalian, from 231.4 to approximately 222 Ma.
Gnathovorax is a genus of herrerasaurid saurischian dinosaur from the Santa Maria Formation in Rio Grande do Sul, Brazil. The type and only species is Gnathovorax cabreirai, described by Pacheco et al. in 2019.
Erythrovenator is a genus of basal theropod dinosaurs from the Late Triassic of Rio Grande so Sul, Brazil. The genus contains a single species, Erythrovenator jacuiensis.
Scalenodontoides is an extinct genus of Traversodontidae, a family of herbivorous cynodonts. It lived during the Late Triassic in what is now South Africa. Its type species is Scalenodontoides macrodontes. It was named in 1957 by A. W. Crompton and F. Ellenberger. Arctotraversodon plemmyrodon was originally classified as a species of Scalenodontoides, but was given its own genus in 1992. It is found in the Scalenodontoides Assemblage Zone of the Elliot Formation, which is named for it. It is one of the geologically youngest traversodontids, alongside the putative traversodontid Boreogomphodon. It is closely related to Exaeretodon and Siriusgnathus, but is distinguished by the presence of a shelf-like expansion of its parietal called the nuchal table. Though the largest known complete skull is only 248 millimetres (9.8 in) long, it may have been the largest non-mammalian cynodont, as an incomplete snout would have belonged to a specimen with an estimated skull length of 617 millimetres (24.3 in).
Maehary is an extinct genus of probable gracilisuchid pseudosuchian archosaurs from the Late Triassic (Norian) Caturrita Formation of Rio Grande do Sul, Brazil. The genus contains a single species, M. bonapartei, known from a partial skull and fragmentary postcrania. Maehary was originally described as the basalmost member of the Pterosauromorpha, but several subsequent studies have suggested pseudosuchian affinities are more likely. If this is correct, it would represent the youngest known member of the Gracilisuchidae.
Gamatavus is a genus of silesaurid dinosauriform from the Middle Triassic Santa Maria Formation of Dilermando de Aguiar Municipality, Brazil. The genus contains a single species, G. antiquus, known from a partial ilium. Gamatavus represents the oldest silesaurid known from South America.