Dinnetherium Temporal range: Sinemurian ~ | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Synapsida |
Clade: | Therapsida |
Clade: | Cynodontia |
Clade: | Mammaliaformes |
Order: | † Morganucodonta |
Family: | † Megazostrodontidae |
Genus: | † Dinnetherium Jenkins, Crompton & Downs, 1983 |
Species: | †D. nezorum |
Binomial name | |
†Dinnetherium nezorum Jenkins, Crompton & Downs, 1983 | |
Dinnetherium is an extinct genus of morganucodont mammaliaform that is part of the monotypic order Dinnetheria [1] and is also part of the monotypic family Dinnetheriidae. [1] The type species, D. nezorum, was named in 1983. [2] It was discovered in a Sinemurian layer of the Kayenta Formation, [3] within the Gold Spring Quarry 1, in Arizona. The holotype is MNA V3221, which is a partial right mandible. [1]
The Phanerozoic is the current and the latest of the four geologic eons in the Earth's geologic time scale, covering the time period from 538.8 million years ago to the present. It is the eon during which abundant animal and plant life has proliferated, diversified and colonized various niches on the Earth's surface, beginning with the Cambrian period when animals first developed hard shells that can be clearly preserved in the fossil record. The time before the Phanerozoic, collectively called the Precambrian, is now divided into the Hadean, Archaean and Proterozoic eons.
A tetrapod is any four-limbed vertebrate animal of the superclass Tetrapoda. Tetrapods include all extant and extinct amphibians and amniotes, with the latter in turn evolving into two major clades, the sauropsids and synapsids. Some tetrapods such as snakes, legless lizards, and caecilians had evolved to become limbless via mutations of the Hox gene, although some do still have a pair of vestigial spurs that are remnants of the hindlimbs.
Amniotes are tetrapod vertebrate animals belonging to the clade Amniota, a large group that comprises the vast majority of living terrestrial and semiaquatic vertebrates. Amniotes evolved from amphibian ancestors during the Carboniferous period and further diverged into two groups, namely the sauropsids and synapsids. They are distinguished from the other living tetrapod clade — the non-amniote lissamphibians — by the development of three extraembryonic membranes, thicker and keratinized skin, and costal respiration.
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Hans-Dieter Sues is a German-born American paleontologist who is Senior Scientist and Curator of Vertebrate Paleontology at the National Museum of Natural History of the Smithsonian Institution in Washington, DC.
Robert Rafael Reisz is a Canadian paleontologist and specialist in the study of early amniote and tetrapod evolution.
The La Boca Formation is a geological formation in Tamaulipas state, northeast Mexico. It was thought to date back to the Early Jurassic, concretely the Pliensbachian stage epoch. Although, the latest studies had proven that the local Vulcanism, related to the aperture of the Atlantic Ocean and the several Rift Events, that continue until the Bajocian, while the unit itself was likely deposited between the earliest Pliensbachian, as proven by zircon with the fossil taxa deposited on the rocks above, likely of Late Pliensbachian-Lower Toarcian age, and the upper section of Late Toarcian-Late Aalenian age. Due to successions of Aalenian depositional sistems on the upper layers of the Huizachal Canyon, has been delimited the formation to the Toarcian stage, being the regional equivalent of the Moroccan Azilal Formation. Deposits of Late Triassic Age referred to this unit have been reclassified in a new formation, El Alamar Formation. In North America, La Boca Formation was found to be a regional equivalent of the Eagle Mills redbeds of southern United States, the Todos Santos Formation of southern Mexico and the Barracas Group of the Sonora desert region.
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The McCoy Brook Formation is a geological formation dating to roughly between 200 and 190 million years ago and covering the Hettangian to Sinemurian stages. The McCoy Brook Formation is found in outcrops around the Bay of Fundy, Nova Scotia.
Uatchitodon is an extinct genus of Late Triassic reptile known only from isolated teeth. Based on the structure of the teeth, Uatchitodon was probably a carnivorous archosauromorph. Folded grooves on the teeth indicate that the animal was likely venomous, with the grooves being channels for salivary venom. The teeth are similar to those of living venomous squamates such as Heloderma and venomous snakes. Uatchitodon is the earliest known venomous reptile.
Kayentavenator is a genus of small carnivorous tetanuran dinosaur that lived during the Early Jurassic Period; fossils were recovered from the Kayenta Formation of northeastern Arizona and were described in 2010.
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Sarahsaurus is a genus of basal sauropodomorph dinosaur which lived during the Early Jurassic period in what is now northeastern Arizona, United States.
The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. Tetrapods are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals. While most species today are terrestrial, little evidence supports the idea that any of the earliest tetrapods could move about on land, as their limbs could not have held their midsections off the ground and the known trackways do not indicate they dragged their bellies around. Presumably, the tracks were made by animals walking along the bottoms of shallow bodies of water. The specific aquatic ancestors of the tetrapods, and the process by which land colonization occurred, remain unclear. They are areas of active research and debate among palaeontologists at present.
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. It was originally named Syntarsus kayentakatae, but the genus Syntarsus was found to be preoccupied by a Colydiine beetle, so it was moved to the genus Megapnosaurus, and then to Coelophysis. A recent reassessment suggests that this species may require a new genus name.