Juratyrant
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''Juratyrant'' (meaning "
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
tyrant") is a
tyrannosauroid 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 b ...
dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
from the late
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
period (early
Tithonian In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma (million years ago). It is preceded by the K ...
age) of
England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
. The genus contains a single species, ''Juratyrant langhami'', which was once classed as a species of ''
Stokesosaurus ''Stokesosaurus'' (meaning "Stokes' lizard") is a genus of small (around in length), carnivorous early tyrannosauroid theropod dinosaurs from the late Jurassic period of Utah, United States. History From 1960 onwards Utah geologist William L ...
''.


Discovery

The species is known from a single specimen consisting of an "associated partial skeleton represented by a complete pelvis" as well as a partially complete leg and neck, back and tail vertebrae. This skeleton was discovered in 1984 in Dorset. The specimen was mentioned in several papers, but was not formally described until 2008. The species was named in honor of commercial fossil collector Peter Langham, who uncovered the specimen. The specimen was discovered in strata of the
Kimmeridge Clay The Kimmeridge Clay is a sedimentary deposit of fossiliferous marine clay which is of Late Jurassic to lowermost Cretaceous age and occurs in southern and eastern England and in the North Sea. This rock formation is the major source rock for North ...
dating from the
Tithonian In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma (million years ago). It is preceded by the K ...
, the final stage of the
Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...
, and belonging to the '' Pectinatites pectinatus'' ammonite zone, indicating the fossil is between 149.3 and 149 million years old.


Description

Paul (2010) listed it at 5 meters (16 ft) and 300 kg (660 lbs). Another estimation gave a larger size of 6.7 meters (22 ft) and 760 kg (1,675 lbs). The holotype of ''Juratyrant'' is a partial skeleton composed of specimens OUMNH J.3311-1 through OUMNH J.3311-30. Its components include a cervical vertebra, five dorsal vertebrae, a complete
sacrum The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part ...
, five caudal vertebrae, a complete
pelvic girdle The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The p ...
, both
femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...
s, both
tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...
e, and various other fragments. Although initially considered a species of ''Stokesosaurus'' due to various traits of the ilium, subsequent review has shown that due to the limited amount of pelvic material for basal tyrannosauroids, these traits cannot be assumed to only be present in these two species and thus ''S. langhami'' must be placed in its own genera. Once separated from ''Stokesosaurus'', ''Juratyrant'' can be characterized by four
autapomorphies In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...
, as well as two assumed autapomorphies (which are difficult to assess due to preservation): * An ischial apron with a "folded" appearance. * A
fibula The fibula or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. Its upper extremity is ...
r flange that continues as a distinct low ridge to the proximal end of the tibia. * A convex tubercule on the ischium. * A deep lateral fossa on the pubis below the
acetabulum The acetabulum (), also called the cotyloid cavity, is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint. Structure There are three bones of the ''os coxae'' (hip bone) that c ...
. * A thin but prominent hyposphene on the fifth sacral vertebra (assumed). * A broad, concave extensor groove of the femur (assumed).


Classification

The species was originally assigned to the genus ''
Stokesosaurus ''Stokesosaurus'' (meaning "Stokes' lizard") is a genus of small (around in length), carnivorous early tyrannosauroid theropod dinosaurs from the late Jurassic period of Utah, United States. History From 1960 onwards Utah geologist William L ...
'', as ''Stokesosaurus langhami'', by Roger Benson in 2008. However, later studies showed that it was not necessarily a close relative of ''Stokesosaurus clevelandi'', the
type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
of that genus. It was formally re-classified in its own genus, ''Juratyrant'', by Benson and Stephen Brusatte in 2013 and placed as a sister taxon to ''Stokesosaurus clevelandi'' in a clade (also including ''Eotyrannus'') of basal tyrannosauroids more advanced than ''Dilong''. However, in 2013 Loewen ''et al.'' published a cladogram placing ''Juratyrant'' as a sister taxon to ''Stokesosaurus'' inside
Proceratosauridae Proceratosauridae is a Family (biology), family or clade of Tyrannosauroidea, tyrannosauroid theropod dinosaurs from the Middle Jurassic to the Early Cretaceous. Distinguishing features Unlike the advanced Tyrannosauridae, tyrannosaurids but s ...
due to sharing with ''
Sinotyrannus ''Sinotyrannus'' (meaning "Chinese tyrant") is a genus of large basal tyrannosauroid dinosaur, known from a single incomplete fossil specimen including a partial skull, from the Early Cretaceous Jiufotang Formation of Liaoning, China. Specifical ...
'' a narrow preacetabular notch. Many basal tyrannosauroids have incomplete or unknown ilia and this trait may be more widespread than currently known. This cladogram is shown below. However, a 2016 analysis by Brusatte and Carr utilizing both
parsimonious Occam's razor, Ockham's razor, or Ocham's razor ( la, novacula Occami), also known as the principle of parsimony or the law of parsimony ( la, lex parsimoniae), is the problem-solving principle that "entities should not be multiplied beyond neces ...
and
Bayesian Thomas Bayes (/beɪz/; c. 1701 – 1761) was an English statistician, philosopher, and Presbyterian minister. Bayesian () refers either to a range of concepts and approaches that relate to statistical methods based on Bayes' theorem, or a followe ...
phylogeny placed ''Stokesosaurus'' and ''Juratyrant'' as tyrannosauroids slightly more advanced than the
Proceratosauridae Proceratosauridae is a Family (biology), family or clade of Tyrannosauroidea, tyrannosauroid theropod dinosaurs from the Middle Jurassic to the Early Cretaceous. Distinguishing features Unlike the advanced Tyrannosauridae, tyrannosaurids but s ...
and ''Dilong''. In addition, ''
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 r ...
'' is recovered as a sister taxon of these genera in the parsimonious phylogeny. The find of this animal in Europe puts in question to the purported Asian origin for these animals along with North American Stokesosaurus and European Aviatyrannis arguing for a more complex biogeography for tyrannosauroids.


See also

*
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 Theropoda, theropod dinosaurs that began as small, long-armed bird-like creatures with ela ...


References

{{Taxonbar, from=Q2701043 Tyrannosaurs Tithonian life Late Jurassic dinosaurs of Europe Jurassic England Fossils of England Fossil taxa described in 2013 Taxa named by Stephen L. Brusatte