|Artist's impression of Guanlong wucaii|
Rauhut, Milner & Moore-Fay, 2010
Unlike the advanced tyrannosaurids but similar to primitive tyrannosauroids like Dilong, proceratosaurids were generally small (with the exception of the possible proceratosaurids Yutyrannus and Sinotyrannus) and had fairly long, three-fingered arms capable of grasping prey. In comparison to other members of Tyrannosauroidea, proceratosaurids can be distinguished by the following features according to phylogenetic analyses by Averianov et al. (2010) and Loewen et al. (2013) :
The family belongs to the tyrannosaur lineage. It was first named in 2010 by Oliver Rauhut and colleagues in their re-evaluation of the type genus, Proceratosaurus. Their study supported the idea that Proceratosaurus is a coelurosaur, a tyrannosauroid, and most closely related to the Chinese tyrannosauroid Guanlong. They defined the clade containing these two dinosaurs as all theropods closer to Proceratosaurus than to Tyrannosaurus, Allosaurus, Compsognathus, Coelurus, Ornithomimus, or Deinonychus. Later studies included the Russian Kileskus and the Chinese Sinotyrannus in the family. Recently, Proceratosauridae has been found to include Proceratosaurus, Guanlong, Kileskus, Sinotyrannus, and the genera Stokesosaurus, Juratyrant, and Dilong previously recognized as non-proceratosaurid tyrannosauroids. In their re-evaluation of Proceratosaurus, Rauhut et al. stated that tooth taxa from the Late Jurassic and Early Cretaceous previously assigned to the dromaeosaurid subfamily Velociraptorinae may instead be proceratosaurid in nature, due to the similarity between the teeth of the two groups and the fact that velociraptorines are otherwise unknown from the fossil record until the Late Cretaceous. This would mean that Nuthetes and other dubious genera are potential proceratosaurids.
Below is the cladogram by Loewen et al. in 2013.
An analysis by Brusatte et al. in 2016 provides both parsimony and Bayesian phylogenetic analyses, with Yutyrannus being placed within Proceratosauridae as a sister taxon to Sinotyrannus and Juratyrant and Stokesosaurus being placed as more advanced tyrannosauroids in each instance. The Bayesian analysis is shown below.
Alectrosaurus (; meaning "alone lizard") is a genus of tyrannosauroid theropod dinosaur that lived approximately 83 to 74 million years ago during the latter part of the Cretaceous Period in what is now Mongolia. It was a medium-sized, moderately-built, ground-dwelling, bipedal carnivore, with a body shape similar to its much larger relative, Tyrannosaurus rex, and could grow up to an estimated 5 m (16.4 ft) long.Bagaraatan
Bagaraatan (/'ba-ɣa-raa-tan/ meaning 'small' baɣa + 'carnivorous animal, beast of prey' araatan in Mongolian) is a genus of theropod dinosaur from the Late Cretaceous period. Its fossils were found in the Nemegt Formation of Mongolia. Bagaraatan may have been around 3 to 4 metres (9.8 to 13 ft) in length.
The type species, B. ostromi, was described by Osmolska in 1996. The post-cranial (ZPAL MgD-I/108) skeleton has been described as "bird-like", while the skull exhibits features of several different theropod groups.Ceratosaurus
Ceratosaurus (from Greek κέρας/κέρατος, keras/keratos meaning "horn" and σαῦρος/sauros meaning "lizard") was a carnivorous theropod dinosaur in the Late Jurassic period (Kimmeridgian to Tithonian). This 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.
The Garden Park specimen remains the most complete skeleton known from the genus, and only a handful of additional specimens have been described since. Two additional species, Ceratosaurus dentisulcatus and Ceratosaurus magnicornis, have been described in 2000 from two fragmentary skeletons from the Cleveland-Lloyd Quarry of Utah and from the vicinity of Fruita, Colorado. The validity of these additional species has been questioned, however, and all three skeletons possibly represent different growth stages of the same species. In 1999, the discovery of the first juvenile specimen was reported. Since 2000, a partial specimen was excavated and described from the Lourinhã Formation of Portugal, providing evidence for the presence of the genus outside of North America. Fragmentary remains have also been reported from Tanzania, Uruguay, and Switzerland, although their assignment to Ceratosaurus is currently not accepted by most paleontologists.
Ceratosaurus was a medium-sized theropod. The original specimen is estimated to be 5.3 m (17 ft) or 5.69 m (18.7 ft) long, while the specimen described as C. dentisulcatus was larger, at around 7 m (23 ft) long. Ceratosaurus was characterized by deep jaws that supported proportionally very long, blade-like teeth, a prominent, ridge-like horn on the midline of the snout, and a pair of horns over the eyes. The forelimbs were very short, but remained fully functional; the hand had four fingers. The tail was deep from top to bottom. A row of small osteoderms (skin bones) was present down the middle of the neck, back, and tail. Additional osteoderms were present at unknown positions on the animal's body.
Ceratosaurus gives its name to the Ceratosauria, a clade of theropod dinosaurs that diverged early from the evolutionary lineage leading to modern birds. Within the Ceratosauria, some paleontologists proposed it to be most closely related to Genyodectes from Argentina, which shares the strongly elongated teeth. The geologically older genus Proceratosaurus from England, although originally described as a presumed antecedent of Ceratosaurus, was later found to be unrelated. Ceratosaurus shared its habitat with other large theropod genera including Torvosaurus and Allosaurus, and it has been suggested that these theropods occupied different ecological niches to reduce competition. Ceratosaurus may have preyed upon plant-eating dinosaurs, although some paleontologists suggested that it hunted aquatic prey such as fish. The nasal horn was probably not used as a weapon as was originally suggested by Marsh, but more likely was used solely for display.Dilong paradoxus
Dilong (帝龍, which means 'emperor dragon') is a genus of basal tyrannosauroid dinosaur. The only species is Dilong paradoxus. It is from the Lower Cretaceous Yixian Formation near Lujiatun, Beipiao, in the western Liaoning province of China. It lived about 126 million years ago.Dryptosaurus
Dryptosaurus ( DRIP-toh-SOR-əs) is a genus of tyrannosauroid that lived approximately 67 million years ago during the latter part of the Cretaceous period in what is now New Jersey. Dryptosaurus was a large, bipedal, ground-dwelling carnivore, that could grow up to 7.5 m (25 ft) long. Although largely unknown now outside of academic circles, a famous painting of the genus by Charles R. Knight made it one of the more widely known dinosaurs of its time, in spite of its poor fossil record. First described by Edward Drinker Cope in 1866 and later renamed by Othniel C. Marsh in 1877, Dryptosaurus is among the first theropod dinosaurs known to science.Eotyrannus
Eotyrannus (meaning "dawn tyrant") is a genus of tyrannosauroid theropod dinosaur hailing from the Early Cretaceous Wessex Formation beds, included in Wealden Group, located in the southwest coast of the Isle of Wight, United Kingdom. The remains (MIWG1997.550), consisting of assorted skull, axial skeleton and appendicular skeleton elements, from a juvenile or subadult, found in a plant debris clay bed, were described by Hutt et al. in early 2001. The etymology of the generic name refers to the animals classification as an early tyrannosaur or "tyrant lizard", while the specific name honors the discoverer of the fossil.Guanlong
Guanlong (冠龍) is a genus of extinct proceratosaurid tyrannosauroid from the Late Jurassic of China. The taxon was first described in 2006 by Xu Xing et al., who found it to represent a new taxon related to Tyrannosaurus. The name is derived from Chinese, translating as "five colored crowned dragon". Two individuals are currently known, a partially complete adult and a nearly complete juvenile. These specimens come from the Oxfordian stage of the Chinese Shishugou Formation.Juratyrant
Juratyrant (meaning "Jurassic tyrant") is a tyrannosauroid dinosaur genus from the late Jurassic period (early Tithonian age) of England. The genus contains a single species, J. langhami.Kileskus
Kileskus (meaning lizard in the Khakas language) is a genus of tyrannosauroid dinosaur known from partial remains found in Middle Jurassic (Bathonian stage) Itat Formation of Krasnoyarsk Krai, Russia. Fossils recovered include the holotype maxilla, a premaxilla, a surangular, and a few bones from the hand and foot. The skull bones are similar to those of Proceratosaurus. The type species is K. aristotocus. Kileskus was named in 2010 by Averianov and colleagues.Megaraptora
Megaraptora is a clade of carnivorous theropod dinosaurs with elongated hand claws and controversial relations to other theropods.Megaraptorans are incompletely known, and no complete megaraptoran skeleton has been found. However, they still possessed a number of unique features. Their forelimbs were large and strongly built, and the ulna bone had a unique shape in members of the family Megaraptoridae, a subset of megaraptorans which excludes Fukuiraptor. The first two fingers were elongated, with massive curved claws, while the third finger was small. Megaraptoran skull material is very incomplete, but a juvenile Megaraptor described in 2014 preserved a portion of the snout, which was long and slender. Leg bones referred to megaraptorans were also quite slender and similar to those of coelurosaurs adapted for running. Although megaraptorans were thick-bodied theropods, their bones were heavily pneumatized, or filled with air pockets. The vertebrae, ribs, and the ilium bone of the hip were pneumatized to an extent which was very rare among theropods, only seen elsewhere in taxa such as Neovenator. Other characteristic features include opisthocoelous neck vertebrae and compsognathid-like teeth.The clade was originally named in 2010 as a subset of the family Neovenatoridae, a group of lightly-built allosauroids related to the massive carcharodontosaurids such as Giganotosaurus and Carcharodontosaurus. A 2013 phylogenetic analysis by Fernando Novas and his colleagues disagreed with this classification scheme, and instead argued that the megaraptorans evolved deep within Tyrannosauroidea, a superfamily of basal coelurosaurs including the famous Tyrannosaurus. Subsequent refinements to Novas's data and methodologies have supported a third position for the group, at the base of Coelurosauria among other controversial theropods such as Gualicho, but not within the Tyrannosauroidea. Regardless of their position, it is clear that megaraptorans experienced a large amount of convergent evolution with either Neovenator-like allosauroids or basal coelurosaurs.Megaraptorans were most diverse in the early Late Cretaceous of South America, particularly Patagonia. However, they had a widespread distribution. Fukuiraptor, the most basal ("primitive") known member of the group, lived in Japan. Megaraptoran material is also common in Australia, and the largest known predatory dinosaur from the continent, Australovenator, was a megaraptoran.Proceratosaurus
Proceratosaurus is a genus of small-sized (~3 metres (9.8 ft) long) carnivorous theropod dinosaur from the Middle Jurassic (Bathonian) of England. It was originally thought to be an ancestor of Ceratosaurus, due to the similar small crest on its snout. Now, however, it is considered a coelurosaur, specifically one of the earliest known members of the clade Tyrannosauroidea.The type specimen is held in the Natural History Museum in London and was recovered in 1910 at Minchinhampton while excavating for a reservoir.Raptorex
Raptorex is a dubious genus of tyrannosaurid dinosaur. Its fossil remains consist of a single juvenile specimen probably uncovered in Mongolia, or possibly northeastern China. The type species is R. kriegsteini, described in 2009 by Sereno and colleagues. The genus name is derived from Latin raptor, "robber", and rex, "king". The specific name honours Roman Kriegstein, a survivor of the Holocaust, whose son Henry Kriegstein donated the specimen to the University of Chicago for scientific study.While initially considered to have come from the Yixian Formation of China, dated to approximately 125 million years ago during the early Cretaceous period, later studies showed that such an early date for the fossil are unlikely, and given its extremely close similarity to juvenile tyrannosaurids of the late Cretaceous, it probably came from the Iren Dabasu or similar formation. Because the specimen is a juvenile, and the changes undergone by tyrannosaurids during growth are not yet well understood, many researchers now consider it to be a nomen dubium, because it cannot be confidently paired with an adult skeleton (though it is extremely similar to juvenile Tarbosaurus bataar skeletons of the same size and age).Sinotyrannus
Sinotyrannus (meaning "Chinese tyrant") is a genus of large basal proceratosaurid dinosaur, a relative of tyrannosaurids which flourished in North America and Asia during the Jurassic and early Cretaceous periods. Sinotyrannus is known from a single incomplete fossil specimen including a partial skull, from the Early Cretaceous Jiufotang Formation of Liaoning, China. Though it is not much younger than primitive tyrannosauroids such as Dilong, it is similar in size to later forms such as Tyrannosaurus. It was much larger than contemporary tyrannosauroids; reaching a total estimated length of 9–10 m (30–33 ft), it is the largest known theropod from the Jiufotang Formation. The type species is S. kazuoensis, described by Ji et al., in 2009.Stokesosaurus
Stokesosaurus (meaning "Stokes' lizard") is a genus of small (around 3 to 4 meters (10 to 13 ft) in length), carnivorous early tyrannosauroid theropod dinosaurs from the late Jurassic period of Utah, United States.Suskityrannus
Suskityrannus (meaning "coyote tyrant", suski meaning "coyote" in Zuni) is a genus of small tyrannosauroid theropod from the Late Cretaceous in southern Laramidia. It contains a single species, Suskityrannus hazelae, believed to have lived roughly 92 million years ago. The type specimen was found in the Turonian-age Moreno Hill Formation of the Zuni Basin in western New Mexico.Timeline of tyrannosaur research
This timeline of tyrannosaur research is a chronological listing of events in the history of paleontology focused on the tyrannosaurs, a group of predatory theropod dinosaurs that began as small, long-armed bird-like creatures with elaborate cranial ornamentation but achieved apex predator status during the Late Cretaceous as their arms shrank and body size expanded. Although formally trained scientists did not begin to study tyrannosaur fossils until the mid-19th century, these remains may have been discovered by Native Americans and interpreted through a mythological lens. The Montana Crow tradition about thunder birds with two claws on their feet may have been inspired by isolated tyrannosaurid forelimbs found locally. Other legends possibly inspired by tyrannosaur remains include Cheyenne stories about a mythical creature called the Ahke, and Delaware stories about smoking the bones of ancient monsters to have wishes granted.Tyrannosaur remains were among the first dinosaur fossils collected in the United States. The first of these was named Deinodon horridus by Joseph Leidy. However, as this species was based only on teeth the name would fall into disuse. Soon after, Edward Drinker Cope described Laelaps aquilunguis from a partial skeleton in New Jersey. Its discovery heralded the realization that carnivorous dinosaurs were bipeds, unlike the lizardlike megalosaurs sculpted for the Crystal Palace. Laelaps was also among the first dinosaurs to be portrayed artistically as a vigorous, active animal, presaging the Dinosaur Renaissance by decades. Later in the century, Cope's hated rival Othniel Charles Marsh would discover that the name Laelaps had already been given to a parasitic mite, and would rename the dinosaur Dryptosaurus.Early in the 20th century, Tyrannosaurus itself was discovered by Barnum Brown and named by Henry Fairfield Osborn, who would recognize it as a representative of a distinct family of dinosaurs he called the Tyrannosauridae. Tyrannosaur taxonomy would be controversial for many decades afterward. One controversy centered around the use of the name Tyrannosauridae for this family, as the name "Deinodontidae" had already been proposed. The name Tyrannosauridae came out victorious following arguments put forth by Dale Russell in 1970. The other major controversy regarding tyrannosaur taxonomy was the family's evolutionary relationships. Early in the history of paleontology, it was assumed that the large carnivorous dinosaurs were all part of one evolutionary lineage ("carnosaurs"), while the small carnivorous dinosaurs were part of a separate lineage (coelurosaurs). Tyrannosaurid anatomy led some early researchers like Matthew, Brown, and Huene, to cast doubt on the validity of this division. However, the traditional carnosaur-coelurosaur division persisted until the early 1990s, when the application of cladistics to tyrannosaur systematics confirmed the doubts of early workers and found tyrannosaurs to be large-bodied coelurosaurs.Another debate about tyrannosaurs would not be settled until the early 21st century: their diet. Early researchers were so overwhelmed by the massive bulk of Tyrannosaurus that some, like Lawrence Lambe, were skeptical that it was even capable of hunting down live prey and assumed that it lived as a scavenger. This view continued to be advocated into the 1990s by Jack Horner but was shown false by Kenneth Carpenter, who reported the discovery of a partially healed tyrannosaur bite wound on an Edmontosaurus annectens tail vertebra, proving that T. rex at least sometimes pursued living victims.Tyrannosauroidea
Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent beginning in the Jurassic Period. By the end of the Cretaceous Period, tyrannosauroids were the dominant large predators in the Northern Hemisphere, culminating in the gigantic Tyrannosaurus. Fossils of tyrannosauroids have been recovered on what are now the continents of North America, Europe, Asia, South America and Australia.
Tyrannosauroids were bipedal carnivores, as were most theropods, and were characterized by numerous skeletal features, especially of the skull and pelvis. Early in their existence, tyrannosauroids were small predators with long, three-fingered forelimbs. Late Cretaceous genera became much larger, including some of the largest land-based predators ever to exist, but most of these later genera had proportionately small forelimbs with only two digits. Primitive feathers have been identified in fossils of two species, and may have been present in other tyrannosauroids as well. Prominent bony crests in a variety of shapes and sizes on the skulls of many tyrannosauroids may have served display functions.Xiongguanlong
Xiongguanlong ("Grand Pass dragon") is a genus of tyrannosauroid dinosaur that lived in the Early Cretaceous of what is now China. The type species is X. baimoensis, described online in 2009 by a group of researchers from China and the United States, and formally published in January 2010. The genus name refers to the city of Jiayuguan, a city in northwestern China. The specific name is derived from bai mo, "white ghost", after the "white ghost castle", a rock formation near the fossil site. The fossils include a skull, vertebrae, a right ilium and the right femur. The rocks it was found in are from the Aptian to Albian stages of the Cretaceous, between 125 and 100 million years ago.Yutyrannus
Yutyrannus (meaning "feathered tyrant") is a genus of tyrannosauroid dinosaurs which contains a single known species, Yutyrannus huali. This species lived during the early Cretaceous period in what is now northeastern China. Three fossils of Yutyrannus huali—all found in the rock beds of Liaoning Province—are currently the largest-known dinosaur specimens that preserve direct evidence of feathers.