Cruxicheiros
Encyclopedia
Cruxicheiros is a genus
of tetanuran
theropod dinosaur
which lived in the Middle Jurassic
of England
. The type species
is C. newmanorum, described by Roger Benson and Jonathan Radley in 2010.
were discovered in the early 1960s in the Cross Hands Quarry, near Little Compton, in Warwickshire
in England. These fossils came from the Chipping Norton Limestone Formation, which is dated to the lower Bathonian
stage
of the Middle Jurassic
, about 167 ma (million years ago). The fossils were stored in the Birmingham Museum and Art Gallery until 2008 when they were transferred to the Warwickshire Museum Service; the transfer prompted closer study of the neglected fossils.
Unrecognized fossils of dinosaurs, many of them theropods, have been discovered in England at least as early as 1677. The larger theropod fossils had been attributed (without critical examination) to Megalosaurus
, while the smaller ones were assigned to Iliosuchus
. The 2010 paper recognized differences between the Cross Hands Quarry discovery and those attributed to Megalosaurus. These differences include lower and broader spines along the animal's back, and differences in leg and hip bones. The authors re-named the Cross Hands Quarry specimens Cruxicheiros newmanorum; the generic name Cruxicheiros comes from a mixture of Latin
and Greek
, Latin crux meaning "cross" and Greek cheiros meaning "hand," in reference to the Cross Hands Quarry locality where the fossils were discovered. The specific name newmanorum honors the Newman family, who own the quarry.
, cataloged as WARMS G15770, is a partial right femur
. Additional material from the site probably comes from the same individual as the holotype, based on examination of the matrix of sandy limestone and calcite which make up all the fossils. The additional material consists of "an anterior dorsal or posterior cervical vertebra; a dorsal neural arch; a partial dorsal vertebra; the anterior half of a middle-distal caudal vertebra; a partial right scapulocoracoid; a partial left ilium; the proximal end of a left pubis; [and] numerous rib and bone fragments".
, a member of the dinosaur group Tetanurae which also includes theropods such as Tyrannosaurus
and Spinosaurus
. The describers did not place Cruxicheiros in any family. They performed a cladistic analysis which rendered three equally probable positions for Cruxicheiros: as the most basal neotetanuran (the line which gave rise to dinosaurs like Allosaurus
and bird
s), as the most basal megalosauroid (the line which led to Megalosaurus
and Spinosaurus
), or as the most basal member of the Tetanurae, whose earliest members must have predated the split between these theropod groups. In view of the uncertainties they classified Cruxicheiros as Tetanurae incertae sedis
.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of tetanuran
Tetanurae
Tetanurae, or "stiff tails", is a clade that includes most theropod dinosaurs, as well as birds. Tetanurans first appear during the early or middle Jurassic Period.-Definition:...
theropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
which lived in the Middle Jurassic
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
of England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
is C. newmanorum, described by Roger Benson and Jonathan Radley in 2010.
Discovery
The remains of the holotypeHolotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
were discovered in the early 1960s in the Cross Hands Quarry, near Little Compton, in Warwickshire
Warwickshire
Warwickshire is a landlocked non-metropolitan county in the West Midlands region of England. The county town is Warwick, although the largest town is Nuneaton. The county is famous for being the birthplace of William Shakespeare...
in England. These fossils came from the Chipping Norton Limestone Formation, which is dated to the lower Bathonian
Bathonian
In the geologic timescale the Bathonian is an age or stage of the Middle Jurassic. It lasted from approximately 167.7 Ma to around 164.7 Ma...
stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
of the Middle Jurassic
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
, about 167 ma (million years ago). The fossils were stored in the Birmingham Museum and Art Gallery until 2008 when they were transferred to the Warwickshire Museum Service; the transfer prompted closer study of the neglected fossils.
Unrecognized fossils of dinosaurs, many of them theropods, have been discovered in England at least as early as 1677. The larger theropod fossils had been attributed (without critical examination) to Megalosaurus
Megalosaurus
Megalosaurus is a genus of large meat-eating theropod dinosaurs of the Middle Jurassic period of Europe...
, while the smaller ones were assigned to Iliosuchus
Iliosuchus
Iliosuchus is a genus of theropod dinosaur known from Bathonian–age rocks of England. It was perhaps long....
. The 2010 paper recognized differences between the Cross Hands Quarry discovery and those attributed to Megalosaurus. These differences include lower and broader spines along the animal's back, and differences in leg and hip bones. The authors re-named the Cross Hands Quarry specimens Cruxicheiros newmanorum; the generic name Cruxicheiros comes from a mixture of Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
and Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
, Latin crux meaning "cross" and Greek cheiros meaning "hand," in reference to the Cross Hands Quarry locality where the fossils were discovered. The specific name newmanorum honors the Newman family, who own the quarry.
Description
Cruxicheiros was a large theropod, but the known material is very limited. The holotypeHolotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
, cataloged as WARMS G15770, is a partial right femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
. Additional material from the site probably comes from the same individual as the holotype, based on examination of the matrix of sandy limestone and calcite which make up all the fossils. The additional material consists of "an anterior dorsal or posterior cervical vertebra; a dorsal neural arch; a partial dorsal vertebra; the anterior half of a middle-distal caudal vertebra; a partial right scapulocoracoid; a partial left ilium; the proximal end of a left pubis; [and] numerous rib and bone fragments".
Phylogeny and Classification
Cruxicheiros was a tetanuranTetanurae
Tetanurae, or "stiff tails", is a clade that includes most theropod dinosaurs, as well as birds. Tetanurans first appear during the early or middle Jurassic Period.-Definition:...
, a member of the dinosaur group Tetanurae which also includes theropods such as Tyrannosaurus
Tyrannosaurus
Tyrannosaurus meaning "tyrant," and sauros meaning "lizard") is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex , commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, with a much wider range than other...
and Spinosaurus
Spinosaurus
Spinosaurus is a genus of theropod dinosaur which lived in what is now North Africa, from the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. This genus was first known from Egyptian remains discovered in 1912 and described by German...
. The describers did not place Cruxicheiros in any family. They performed a cladistic analysis which rendered three equally probable positions for Cruxicheiros: as the most basal neotetanuran (the line which gave rise to dinosaurs like Allosaurus
Allosaurus
Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...
and bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s), as the most basal megalosauroid (the line which led to Megalosaurus
Megalosaurus
Megalosaurus is a genus of large meat-eating theropod dinosaurs of the Middle Jurassic period of Europe...
and Spinosaurus
Spinosaurus
Spinosaurus is a genus of theropod dinosaur which lived in what is now North Africa, from the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. This genus was first known from Egyptian remains discovered in 1912 and described by German...
), or as the most basal member of the Tetanurae, whose earliest members must have predated the split between these theropod groups. In view of the uncertainties they classified Cruxicheiros as Tetanurae incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
.