Poekilopleuron
Encyclopedia
Poekilopleuron is an extinct genus
of large basal
tetanuran
theropod dinosaur, perhaps belonging to the clade
Allosauroidea
. It measured 9 metres (30 feet) long and 1 ton (1 tonne) in mass. It dates from the Bathonian
(Middle Jurassic
), 168 to 165 million years ago.
Poekilopleuron is known from a partial skeleton discovered by Jacques Amand Eudes-Deslongchamps
in July 1835 near La Maladrerie in Normandy
, France
, in a layer of the Calcaire de Caen Formation. This skeleton, part of the collection of the Musée de la Facultée des Sciences de Caen, was in 1944 destroyed during the Battle of Caen in World War II
, and the taxon has since had to be studied on the basis of cast replicas. One set is present in the Muséum National d'Histoire Naturelle
in Paris
with inventory number MNHN 1897-2, a second in the Yale Peabody Museum, YPM 4938. The remains consisted of caudal vertebrae, cervical ribs, ribs, gastralia or belly ribs, a forelimb and a hindlimb.
Eudes-Deslongchamps named the type species
Poekilopleuron bucklandii in 1837 or 1838. The generic name is derived from Greek poikilos, "varied", and pleuron, "rib", a reference to the three types of rib present. The specific name, honouring William Buckland
, was deliberately identical to that of Megalosaurus
bucklandii. Eudes-Deslongchamps thought the specimen might well be proven to belong to this earlier named species; if so, merely the generic name would have to be changed. Indeed, following 1879 Poekilopleuron was often subsumed under Megalosaurus bucklandii. Eudes-Deslongchamps' choice caused problems however, when Friedrich von Huene
in 1923 concluded it was part of Megalosaurus but as a separate species within that genus. As both species carried the same epithet bucklandii, they could no longer be distinguished. Von Huene therefore renamed the species into Megalosaurus poekilopleuron. Most later authors continued using the generic name Poekilopleuron.
Another problem was caused by the fact that the name was only partially latinised. In correct Greek it would have been "poikilopleuron", in Latin "poecilopleurum". This induced later writers to improve the spelling, leading to such variants as Poecilopleuron and Poikilopleuron (still used as late as 2006). However, the original name has priority and is valid.
Five other species would be named in the genus. In 1869 Edward Drinker Cope
renamed Laelaps
gallicus into Poekilopleuron gallicum. In 1870 Joseph Leidy
created a Poicilopleuron valens based on a fossil probably belonging to Allosaurus
. In 1876 Richard Owen
named a Poikilopleuron pusillus, in 1879 renamed by Cope to Poekilopleuron minor; in 1887 Harry Govier Seeley made it a separate genus: Aristosuchus
. In 1883 W.A. Kiprijanow created a Poekilopleuron schmidti, of which the specific name honours Friedrich Schmidt
, based on some indeterminate ribs and a sauropod metatarsal. This chimaera
is a nomen dubium
. A much later named species is Poekilopleuron valesdunensis created by Ronan Allain in 2002. In 2005 it was renamed Dubreuillosaurus
.
The most distinctive feature of Poekilopleuron were its forelimbs. Their length, about 60 cm, was a sign of this theropod's more original build. Unlike later Theropoda
, whose forelimbs tended toward reduction in length in proportion to the animals' size, Poekilopleurons were long and, by implication, potent. The length mostly resided in the elongated but powerfully muscled humerus. The antebrachia (forearms) were markedly short and robust, a characteristic shared with Poekilopleuron's slightly later and considerably larger American cousin Torvosaurus
. A unique feature is a lack of the olecranon process on the ulna.
The fossil of Poekilopleuron showed a rare complete set of gastralia: fourteen pair of belly ribs supported the body of the animal.
Because the original fossil was destroyed and no other remains of Poekilopleuron have since been found, and also because of its name change, there is much controversy surrounding its classification that cannot be resolved. Traditionally it has been assigned to the Megalosauridae, but some recent analyses showed a position in the Sinraptoridae
; others had as result it was a member of Megalosauroidea
, in a basal position or in the Eustreptospondylinae. Benson et al. (2010) found it and Lourinhanosaurus
to belong to Sinraptoridae
.
Poekilopleuron bucklandii has a tail vertebra with the chevron
of one vertebra ankylosed to the centrum
of the next with the development of an exostosis
. Two phalanges also preserve pathologies. One probable pedal phalanx
shows three low, irregular exostosis-like projections. A second probable manual phalanx exhibits a "low rounded projection resembling a callus
." Molnar considered the occurrence of three pathologies in one individual to be "noteworthy". Sadly the specimens can't be examined further to determine the etiology of the pathologies because they were destroyed during a British bombing raid near the send of the Second World War.
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 large basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
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, perhaps belonging to the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
Allosauroidea
Allosauroidea
Allosauroidea is a superfamily or clade of theropod dinosaurs which contains four families — the Sinraptoridae, Allosauridae, Carcharodontosauridae, and Neovenatoridae...
. It measured 9 metres (30 feet) long and 1 ton (1 tonne) in mass. It dates from the 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...
(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....
), 168 to 165 million years ago.
Poekilopleuron is known from a partial skeleton discovered by Jacques Amand Eudes-Deslongchamps
Jacques Amand Eudes-Deslongchamps
Jacques Amand Eudes-Deslongchamps was a French naturalist and palaeontologist.He was born at Caen in Normandy...
in July 1835 near La Maladrerie in Normandy
Normandy
Normandy is a geographical region corresponding to the former Duchy of Normandy. It is in France.The continental territory covers 30,627 km² and forms the preponderant part of Normandy and roughly 5% of the territory of France. It is divided for administrative purposes into two régions:...
, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, in a layer of the Calcaire de Caen Formation. This skeleton, part of the collection of the Musée de la Facultée des Sciences de Caen, was in 1944 destroyed during the Battle of Caen in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, and the taxon has since had to be studied on the basis of cast replicas. One set is present in the Muséum National d'Histoire Naturelle
Muséum national d'histoire naturelle
The Muséum national d'Histoire naturelle is the National Museum of Natural History in Paris, France.- History :The museum was formally founded on 10 June 1793, during the French Revolution...
in Paris
Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...
with inventory number MNHN 1897-2, a second in the Yale Peabody Museum, YPM 4938. The remains consisted of caudal vertebrae, cervical ribs, ribs, gastralia or belly ribs, a forelimb and a hindlimb.
Eudes-Deslongchamps named 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...
Poekilopleuron bucklandii in 1837 or 1838. The generic name is derived from Greek poikilos, "varied", and pleuron, "rib", a reference to the three types of rib present. The specific name, honouring William Buckland
William Buckland
The Very Rev. Dr William Buckland DD FRS was an English geologist, palaeontologist and Dean of Westminster, who wrote the first full account of a fossil dinosaur, which he named Megalosaurus...
, was deliberately identical to that of Megalosaurus
Megalosaurus
Megalosaurus is a genus of large meat-eating theropod dinosaurs of the Middle Jurassic period of Europe...
bucklandii. Eudes-Deslongchamps thought the specimen might well be proven to belong to this earlier named species; if so, merely the generic name would have to be changed. Indeed, following 1879 Poekilopleuron was often subsumed under Megalosaurus bucklandii. Eudes-Deslongchamps' choice caused problems however, when Friedrich von Huene
Friedrich von Huene
Friedrich von Huene was a German paleontologist who named more dinosaurs in the early 20th century than anyone else in Europe.-Biography:...
in 1923 concluded it was part of Megalosaurus but as a separate species within that genus. As both species carried the same epithet bucklandii, they could no longer be distinguished. Von Huene therefore renamed the species into Megalosaurus poekilopleuron. Most later authors continued using the generic name Poekilopleuron.
Another problem was caused by the fact that the name was only partially latinised. In correct Greek it would have been "poikilopleuron", in Latin "poecilopleurum". This induced later writers to improve the spelling, leading to such variants as Poecilopleuron and Poikilopleuron (still used as late as 2006). However, the original name has priority and is valid.
Five other species would be named in the genus. In 1869 Edward Drinker Cope
Edward Drinker Cope
Edward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of nineteen...
renamed Laelaps
Laelaps
The name Laelaps is a name attributed to the following:*Laelaps was a Greek mythological dog who never failed to catch what he was hunting.*Laelaps is a genus of mites which are ectoparasites of rodents...
gallicus into Poekilopleuron gallicum. In 1870 Joseph Leidy
Joseph Leidy
Joseph Leidy was an American paleontologist.Leidy was professor of anatomy at the University of Pennsylvania, and later was a professor of natural history at Swarthmore College. His book Extinct Fauna of Dakota and Nebraska contained many species not previously described and many previously...
created a Poicilopleuron valens based on a fossil probably belonging to 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...
. In 1876 Richard Owen
Richard Owen
Sir Richard Owen, FRS KCB was an English biologist, comparative anatomist and palaeontologist.Owen is probably best remembered today for coining the word Dinosauria and for his outspoken opposition to Charles Darwin's theory of evolution by natural selection...
named a Poikilopleuron pusillus, in 1879 renamed by Cope to Poekilopleuron minor; in 1887 Harry Govier Seeley made it a separate genus: Aristosuchus
Aristosuchus
Aristosuchus was a small coelurosaurian dinosaur, whose name was derived from the Greek ἄριστος and σουχος, the Ancient Greek corruption of the name of the Egyptian crocodile-headed god Sobek. It shared many characteristics with birds.Aristosuchus was a bipedal, meat-eating theropod dinosaur...
. In 1883 W.A. Kiprijanow created a Poekilopleuron schmidti, of which the specific name honours Friedrich Schmidt
Friedrich Schmidt
Friedrich Schmidt was Baltic German geologist and botanist in Russian Empire. He won the Wollaston Medal in 1902.- External links :*...
, based on some indeterminate ribs and a sauropod metatarsal. This chimaera
Chimaera
Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, ratfish , spookfish , or rabbitfishes...
is a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
. A much later named species is Poekilopleuron valesdunensis created by Ronan Allain in 2002. In 2005 it was renamed Dubreuillosaurus
Dubreuillosaurus
Dubreuillosaurus is a genus of carnivorous dinosaur from the middle Jurassic Period. It was a megalosaurid theropod. Its fossils were found in France....
.
The most distinctive feature of Poekilopleuron were its forelimbs. Their length, about 60 cm, was a sign of this theropod's more original build. Unlike later Theropoda
Theropoda
Theropoda is both a suborder of bipedal saurischian dinosaurs, and a clade consisting of that suborder and its descendants . Dinosaurs belonging to the suborder theropoda were primarily carnivorous, although a number of theropod groups evolved herbivory, omnivory, and insectivory...
, whose forelimbs tended toward reduction in length in proportion to the animals' size, Poekilopleurons were long and, by implication, potent. The length mostly resided in the elongated but powerfully muscled humerus. The antebrachia (forearms) were markedly short and robust, a characteristic shared with Poekilopleuron's slightly later and considerably larger American cousin Torvosaurus
Torvosaurus
Torvosaurus is a genus of large theropod dinosaur that lived during the Late Jurassic period...
. A unique feature is a lack of the olecranon process on the ulna.
The fossil of Poekilopleuron showed a rare complete set of gastralia: fourteen pair of belly ribs supported the body of the animal.
Because the original fossil was destroyed and no other remains of Poekilopleuron have since been found, and also because of its name change, there is much controversy surrounding its classification that cannot be resolved. Traditionally it has been assigned to the Megalosauridae, but some recent analyses showed a position in the Sinraptoridae
Sinraptoridae
Sinraptorids were a family of carnivorous theropod dinosaurs. They tended to be large predators, some growing to sizes of . Sinraptorids are carnosaurs, and many were initially classified within Megalosauridae or Allosauridae prior to recent analysis...
; others had as result it was a member of Megalosauroidea
Megalosauroidea
Megalosauroidea is a group of tetanuran theropod dinosaurs that lived from the Middle Jurassic to the Late Cretaceous period.-Classification:...
, in a basal position or in the Eustreptospondylinae. Benson et al. (2010) found it and Lourinhanosaurus
Lourinhanosaurus
Lourinhanosaurus was a carnivorous theropod dinosaur genus that lived during the Late Jurassic Period . Its first remains were found at Peralta, near Lourinhã, Portugal in 1982, but were not described until 1998, by Portuguese paleontologist Octávio Mateus.Its type species is L...
to belong to Sinraptoridae
Sinraptoridae
Sinraptorids were a family of carnivorous theropod dinosaurs. They tended to be large predators, some growing to sizes of . Sinraptorids are carnosaurs, and many were initially classified within Megalosauridae or Allosauridae prior to recent analysis...
.
Poekilopleuron bucklandii has a tail vertebra with the chevron
Chevron (anatomy)
A chevron is one of a series of bones on the ventral side of the tail in many reptiles, dinosaurs , and some mammals such as kangaroos and manatees....
of one vertebra ankylosed to the centrum
Centrum
Centrum means center in Latin.Centrum may refer to:* The central portion of a vertebra*Centrum , a Washington state performing arts organization* Centrum , metro station in Warsaw, Poland...
of the next with the development of an exostosis
Exostosis
An exostosis is the formation of new bone on the surface of a bone. Exostoses can cause chronic pain ranging from mild to debilitatingly severe, depending on where they are located and what shape they are....
. Two phalanges also preserve pathologies. One probable pedal phalanx
Phalanx
Phalanx, from Ancient Greek , may refer to:-Military:* Phalanx formation, in ancient Greek warfare* Phalanx CIWS, a U.S. Navy defense system to protect against an anti-ship missile-Politics:...
shows three low, irregular exostosis-like projections. A second probable manual phalanx exhibits a "low rounded projection resembling a callus
Callus
A callus is an especially toughened area of skin which has become relatively thick and hard in response to repeated friction, pressure, or other irritation. Rubbing that is too frequent or forceful will cause blisters rather than allow calluses to form. Since repeated contact is required, calluses...
." Molnar considered the occurrence of three pathologies in one individual to be "noteworthy". Sadly the specimens can't be examined further to determine the etiology of the pathologies because they were destroyed during a British bombing raid near the send of the Second World War.