Koparion Temporal range: Late Jurassic, | |
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Holotype tooth | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Family: | † Troodontidae |
Genus: | † Koparion Chure, 1994 |
Type species | |
Koparion douglassi Chure, 1994 |
Koparion is a genus of small coelurosaurian theropod dinosaur, from the late Jurassic Period (Kimmeridgian stage), of Utah. It contains the single named species Koparion douglassi which is known only from a single isolated tooth.
In 1993, Daniel Chure and Brooks Britt reported the discovery of small theropod remains, found by screenwashing large amounts of earth in the Rainbow Park near Dinosaur National Monument in Uintah County, Utah. [1] In 1994, Chure named and described a unique tooth as the type specimen of the new species Koparion douglassi. The generic name Koparion comes from the Ancient Greek κοπάριον, "small surgical knife", in reference to the small size of the tooth. The specific name honors Earl Douglass, who, in the early twentieth century, excavated the Dinosaur National Monument quarry. [2]
The holotype specimen, DINO 3353, was found in the Brushy Basin Member of the Morrison Formation dating from the late Kimmeridgian, about 151 million years old. [2] The taxon is thus present in stratigraphic zone 6 of the Morrison Formation. [3] The specimen consists of a single maxillary (upper cheek) tooth crown (the root is missing). It cannot be determined whether it represents a left or a right tooth. [2]
The tooth is two millimeters tall and very recurved, with a strongly convex front edge and a nearly vertical back edge. The tooth is stout, with a maximum fore-aft length of 1.9 millimeters. Both edges are serrated, showing low rectangular denticles (individual serrations). The twelve denticles on the rear edge are much higher than the fourteen on the front edge, which cover only the nearly horizontal upper part of the front edge. The tooth base, though very wide, is constricted. The base is asymmetrical, with the right side in front view protruding much further than the left side; because it is not known whether it is a left or right tooth, it cannot be established what is the inner and what the outer side. The denticles are separated by "blood grooves", and "blood pits" are also present. The back denticles point obliquely upwards but have no hooked upper corners. [2]
Chure assigned Koparion to the Troodontidae based on the anatomy of the tooth. At that time, it was the oldest known troodontid, and is the first of that group discovered from the Jurassic. A troodontid presence in the Jurassic was predicted by the standard theory regarding the origin of birds, claiming that birds and troodontids are closely related (Chure suggested that they may even have been sister taxa, though this is not currently supported). [2] Within this context, Koparion could be used to refute the temporal paradox argument, that such a close relationship were unlikely because the then oldest known bird, Archaeopteryx , lived much earlier than the Deinonychosauria, i.e. the Troodontidae and the Dromaeosauridae; [4] later also non-fragmentary Jurassic troodontid material was reported, from China. [5] [6]
Troodontidae is a clade of bird-like theropod dinosaurs. 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.
Deinonychosauria is a clade of paravian dinosaurs which lived from the Late Jurassic to the Late Cretaceous periods. Fossils have been found across the globe in North America, Europe, Africa, Asia, South America, and Antarctica, with fossilized teeth giving credence to the possibility that they inhabited Australia as well. This group of dinosaurs are known for their sickle-shaped toe claws and features in the shoulder bones.
Aviatyrannis is a genus of coelurosaurian theropod dinosaur, possibly a tyrannosauroid, from the Oxfordian-Tithonian stages of the Late Jurassic found in Portugal.
Ceratosaurus was a carnivorous theropod dinosaur that lived in the Late Jurassic period. The genus was first described in 1884 by American paleontologist Othniel Charles Marsh based on a nearly complete skeleton discovered in Garden Park, Colorado, in rocks belonging to the Morrison Formation. The type species is Ceratosaurus nasicornis.
Torvosaurus is a genus of large megalosaurine theropod dinosaur that lived approximately 165 to 148 million years ago during the Callovian to Tithonian ages of the late Middle and Late Jurassic period in what is now Colorado, Portugal, Germany, and possibly England, Spain, Tanzania, and Uruguay. It contains two currently recognized species, Torvosaurus tanneri and Torvosaurus gurneyi, plus a third unnamed species from Germany.
Ornitholestes is a small theropod dinosaur of the late Jurassic of Western Laurasia.
Saurophaganax, also known as Allosaurus maximus or Saurophagus maximus, is a genus of large allosaurid dinosaur from the Morrison Formation of Late Jurassic Oklahoma, United States. Some paleontologists consider it to be a junior synonym and species of Allosaurus. Saurophaganax represents a very large Morrison allosaurid characterized by horizontal laminae at the bases of the dorsal neural spines above the transverse processes, and "meat-chopper" chevrons. It was the largest terrestrial carnivore of North America during the Late Jurassic, reaching 10.5 metres (34 ft) in length and 2.7–3.8 metric tons in body mass.
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.
Marshosaurus is a genus of medium-sized carnivorous theropod dinosaur, belonging to the Megalosauroidea, from the Late Jurassic Morrison Formation of Utah and possibly Colorado.
Hesperornithoides is a genus of troodontid theropod dinosaur that lived in North America during the Late Jurassic period.
Xixiasaurus is a genus of troodontid dinosaur that lived during the Late Cretaceous Period in what is now China. The only known specimen was discovered in Xixia County, Henan Province, in central China, and became the holotype of the new genus and species Xixiasaurus henanensis in 2010. The names refer to the areas of discovery, and can be translated as "Henan Xixia lizard". The specimen consists of an almost complete skull, part of the lower jaw, and teeth, as well as a partial right forelimb.
Uteodon is a genus of herbivorous iguanodontian dinosaur. It is a basal iguanodontian which lived during the late Jurassic period in what is now Uintah County, Utah. It is known from the middle of the Brushy Basin Member, Morrison Formation. The genus was named by Andrew T. McDonald in 2011 and the type species is U. aphanoecetes.
Xiaotingia is a genus of anchiornithid theropod dinosaur from Middle Jurassic or early Late Jurassic deposits of western Liaoning, China, containing a single species, Xiaotingia zhengi.
Aorun (pron.:"AW-roon") is an extinct genus of carnivorous theropod dinosaur first discovered in 2006, with its scientific description published in 2013. It is one of the oldest known coelurosaurian dinosaurs and is estimated to have lived ~161.6 million years ago during the Late Jurassic Period. It is the fifth theropod discovered from Wucaiwan, China.
Gobivenator is an extinct genus of troodontid theropod dinosaur known from the late Campanian Djadokhta Formation of central Gobi Desert, Mongolia. It contains a single species, Gobivenator mongoliensis. G. mongoliensis is known from a single individual, which represents the most complete specimen of a Late Cretaceous troodontid currently known.
This timeline of troodontid research is a chronological listing of events in the history of paleontology focused on the troodontids, a group of bird-like theropod dinosaurs including animals like Troodon. Troodontid remains were among the first dinosaur fossils to be reported from North America after paleontologists began performing research on the continent, specifically the genus Troodon itself. Since the type specimen of this genus was only a tooth and Troodon teeth are unusually similar to those of the unrelated thick-headed pachycephalosaurs, Troodon and its relatives would be embroiled in taxonomic confusion for over a century. Troodon was finally recognized as distinct from the pachycephalosaurs by Phil Currie in 1987. By that time many other species now recognized as troodontid had been discovered but had been classified in the family Saurornithoididae. Since these families were the same but the Troodontidae named first, it carries scientific legitimacy.
Anchiornithidae is a family of eumaniraptorans which could be the basalmost family of birds in the clade Avialae. Anchiornithids have been classified at varying positions in the maniraptoran tree, with some scientists classifying them as a distinct family, a basal subfamily of Troodontidae, members of Archaeopterygidae, or an assemblage of dinosaurs that are an evolutionary grade within Avialae or Paraves.