Latenivenatrix Temporal range: Campanian, | |
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Hind part of assigned skull TMP 1982.019.0023, Royal Tyrrell Museum | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Family: | † Troodontidae |
Subfamily: | † Troodontinae |
Genus: | † Latenivenatrix |
Type species | |
†Latenivenatrix mcmasterae van der Reest and Currie, 2017 |
Latenivenatrix, meaning "hiding huntress", is a genus of large troodontid known from a single species, L. mcmasterae. Along with the contemporary Stenonychosaurus , it is known from non-tooth fossils that were formerly assigned to the now potentially dubious genus Troodon . Although described as separate, it has been considered a junior synonym of Stenonychosaurus. [1]
The type specimen, or holotype, of Latenivenatrix (CMN 12340) was originally described in 1969 by Dale Alan Russell and referred by him to the genus Stenonychosaurus . In 1987, it was referred to Troodon . It was collected in 1968 by Irene Vanderloh in the Dinosaur Park Formation strata from Alberta, Canada. The specimen has preserved some skull bones, such as the frontals, parietals, postorbital, basioccipital, and basisphenoid, four vertebrae, four ribs, some chevrons, gastralia, a fairly complete arm, and incomplete legs. [2]
Moreover, three additional specimens from the same locality are referred to L. mcmasterae. These include UALVP 55804 (a partial pelvis), TMP 1982.019.0023 (a partial skull), and TMP 1992.036.575 (a right dentary and several left metatarsals). [2]
Latenivenatrix was suggested to be distinguishable from Stenonychosaurus due to the structure of its frontals and metatarsal III, [2] although later analyses found these characters to be individually variable, and also present in specimens of Stenonychosaurus. [1]
With an estimated skull length of 45 centimetres (18 in) and a full body length of 3–3.5 metres (9.8–11.5 ft), Latenivenatrix is the largest troodontid known. It was described as distinguishable from other troodontids thanks to the following diagnostic (autapomorphic) traits residing in the pelvis: the pubis is retroverted forming a 17° angle; the pubic shaft is anteriorly curved; a large muscle scar on the lateral surface of the pubic shaft is present, slightly proximal to the pubic boot (this is seen also in dromaeosaurid Hesperonychus ). [2]
Other traits argued to further distinguish Latenivenatrix from other derived troodontids (particularly its close relative Stenonychosaurus) are: the triangular shape of each frontal bone which also does have a single deep groove in the frontonasal contact surface; a concave anterior surface of metatarsal III. While this trait appears to be absent in other derived troodontids such as Saurornithoides , Talos, and Urbacodon , it appears to be present in Philovenator as well and not clearly verifiable in several species. [2]
A later re-analysis of the stratigraphic positions of known specimens of Latenivenatrix and Stenonychosaurus (including specimens not included in the initial description of L. mcmasterae) also found stratigraphic overlap between the two proposed taxa. Due to this stratigraphic overlap, as well as the lack of definitive diagnostic characters, the variable presence of characters originally described as autapomorphic of Latenivenatrix in specimens of Stenonychosaurus, and the extensive overlap of frontals of both in morphospace, L. mcmasterae was considered to be a junior synonym of S. inequalis. [1]
Latenivenatrix was found to be a derived troodontid (part of the newly defined Troodontinae), probably related to coeval Asian forms such as Linhevenator and Philovenator . [2]
Latenivenatrix was the largest known troodontid, with a maximum total body length estimated to 3.5 m (11.5 ft). As a derived troodontid, it was probably a semi-omnivorous biped with loss of the skills of a primitive flyer.
A parietal bone catalogued as TMP 79.8.1 bears a "pathological aperture". In 1985, Phil Currie hypothesized that this aperture was caused by a cyst. Tanke and Rothschild interpreted it as a possible bite wound in 1999. One hatchling specimen may have suffered from a congenital defect, which resulted in the front part of its jaw being twisted. [3]
Troodontidae is a clade of bird-like theropod dinosaurs from the Late Jurassic to Late Cretaceous. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil discoveries of complete and articulated specimens, have helped to increase understanding about this group. Anatomical studies, particularly studies of the most primitive troodontids, like Sinovenator, demonstrate striking anatomical similarities with Archaeopteryx and primitive dromaeosaurids, and demonstrate that they are relatives comprising a clade called Paraves.
Troodon is a former wastebasket taxon and a potentially dubious genus of relatively small, bird-like theropod dinosaurs definitively known from the Campanian age of the Late Cretaceous period. It includes at least one species, Troodon formosus, known from Montana. Discovered in October 1855, T. formosus was among the first dinosaurs found in North America, although it was thought to be a lizard until 1877. Several well-known troodontid specimens from the Dinosaur Park Formation in Alberta were once believed to be members of this genus. However, recent analyses in 2017 have found this genus to be undiagnostic and referred some of these specimens to the genus Stenonychosaurus some to the genus Latenivenatrix, and some to the genus Pectinodon. The genus name is Ancient Greek for "wounding tooth", referring to the teeth, which were different from those of most other theropods known at the time of their discovery. The teeth bear prominent, apically oriented serrations. These "wounding" serrations, however, are morphometrically more similar to those of herbivorous reptiles, and suggest a possibly omnivorous diet.
Stenonychosaurus is a genus of troodontid dinosaur from the Late Cretaceous Dinosaur Park Formation of Alberta, Canada, as well as possibly the Two Medicine Formation. The type and only species, S. inequalis, was named by Charles Mortram Sternberg in 1932, based on a foot, fragments of a hand, and some caudal vertebrae from the Late Cretaceous of Alberta. S. inequalis was reassigned in 1987 by Phil Currie to the genus Troodon, which was reverted by the recognition of Stenonychosaurus as a separate genus from the possibly dubious Troodon in 2017 by Evans et al. and also later in the same year by Van der Reest and Currie.
Saurornitholestes is a genus of carnivorous dromaeosaurid theropod dinosaur from the late Cretaceous of Canada (Alberta) and the United States.
Saurornithoides is a genus of troodontid maniraptoran dinosaur, which lived during the Late Cretaceous period. These creatures were predators, which could run fast on their hind legs and had excellent sight and hearing. The name is derived from the Greek stems saur~ (lizard), ornith~ (bird) and eides (form), referring to its bird-like skull.
Byronosaurus is a genus of troodontid dinosaur from the Late Cretaceous Period of Mongolia.
Monolophosaurus is an extinct genus of tetanuran theropod dinosaur from the Middle Jurassic Shishugou Formation in what is now Xinjiang, China. It was named for the single crest on top of its skull. Monolophosaurus was a mid-sized theropod at about 5–5.5 metres (16–18 ft) long and weighed 475 kilograms (1,047 lb).
Orodromeus is a genus of herbivorous orodromine thescelosaurid dinosaur from the Late Cretaceous of North America. Only one species is known, the type species Orodromeus makelai.
Sinornithoides is a genus of troodontid theropod dinosaurs containing the single species Sinornithoides youngi. S. youngi lived during the Early Cretaceous. It measured approximately one meter long (3.3 ft). It lived in Inner Mongolia, China, and probably ate invertebrates and other small prey. They lived in what is now Mongolia, which was part of Laurasia.
Polyodontosaurus is a potentially dubious genus of troodontid dinosaur named in 1932 by Charles W. Gilmore for a left dentary from the Dinosaur Park Formation. It had been considered a synonym of Stenonychosaurus or Troodon for a significant time, before being declared a nomen dubium. The only known species is the type, P. grandis.
Sinovenator is a genus of troodontid dinosaur from China. It is from the early Cretaceous Period.
Sinusonasus is a genus of dinosaurs from the Early Cretaceous Period, recovered from the Yixian Formation. It lived in what is now the Liaoning Province of China. Sinusonasus was a theropod, specifically a troodontid dinosaur.
Zanabazar is a genus of large troodontid dinosaurs from the Late Cretaceous of Mongolia. The genus was originally named by Rinchen Barsbold as the new species Saurornithoides junior. In 2009 it was reclassified as its own genus and species, Zanabazar junior, named after Zanabazar, the first spiritual figurehead of Tibetan Buddhism in Mongolia. The holotype includes a skull, vertebrae, and right hindlimb. Zanabazar was one of the largest and most derived troodontids.
Qiupalong is an extinct genus of ornithomimosaurian theropod that was discovered in the Late Cretaceous Qiupa Formation of Henan, China. The genus contains a single species, Q. henanensis, the specific epithet for which was named for the province of Henan. Uniquely, Qiupalong is one of the few Late Cretaceous non-avian dinosaurs known from both Asia and Laramidia. Specimens from Russia and Alberta have been referred to the genus without being assigned to the type species.
Linhevenator is a genus of short-armed troodontid theropod dinosaur from the Late Cretaceous (Campanian) Bayan Mandahu Formation of Bayan Mandahu, Inner Mongolia, China.
Philovenator is an extinct genus of troodontid paravian dinosaurs from the Wulansuhai Formation of Inner Mongolia, China. Its specific name honors Phillip J. Currie.
Coronosaurus is a genus of centrosaurine ceratopsian dinosaurs which lived in the Late Cretaceous, in the middle Campanian stage. Its remains, two bone beds, were discovered by Phillip J. Currie in the Oldman Formation of Alberta, Canada, and its type and only species, Coronosaurus brinkmani, was first described in 2005, as a new species within the genus Centrosaurus. Later studies questioned the presence of a direct relationship, and in 2012 it was named as a separate genus. Coronosaurus means "crowned lizard", coming from "corona", Latin for crown, and "sauros", Greek for lizard; this name refers to the unique, crown-like shape of the horns on the top of its frill.
Murusraptor is a genus of carnivorous megaraptoran theropod dinosaur from the Sierra Barrosa Formation, part of the Neuquén Group of Patagonia, in Argentina, South America. It is known from a single specimen that consists of a partial skull, ribs, partial pelvis, leg and other assorted skeletal elements.
Jianianhualong is a genus of troodontid theropod dinosaur from the Early Cretaceous of China. It contains a single species, Jianianhualong tengi, named in 2017 by Xu Xing and colleagues based on an articulated skeleton preserving feathers. The feathers at the middle of the tail of Jianianhualong are asymmetric, being the first record of asymmetrical feathers among the troodontids. Despite aerodynamic differences from the flight feathers of modern birds, the feathers in the tail vane of Jianianhualong could have functioned in drag reduction whilst the animal was moving. The discovery of Jianianhualong supports the notion that asymmetrical feathers appeared early in the evolutionary history of the Paraves.
Citipes is an extinct genus of caenagnathid theropod from the Late Cretaceous Dinosaur Park Formation in Alberta, Canada. The genus contains only one species, the type species, C. elegans. The generic name of Citipes is Latin for "fleet-footed", and the specific epithet "elegans" is Latin for "elegant". The type specimen of Citipes has a convoluted taxonomic history, and has been previously assigned to the genera Ornithomimus, Macrophalangia, Elmisaurus, Chirostenotes, and Leptorhynchos before being given its own genus in 2020.