Piveteausaurus

Piveteausaurus (meaning "Jean Piveteau's lizard") is a genus of theropod dinosaur known from a partial skull discovered in the Middle Jurassic Marnes de Dives formation of Calvados, in northern France.

Piveteausaurus
Temporal range: Middle Jurassic, 164 Ma
P1050190 - Piveteausaurus
Fossil holotype braincase, Musee d'Histoire Naturelle, Paris
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Megalosauridae
Genus: Piveteausaurus
Taquet & Welles, 1977
Species:
P. divesensis
Binomial name
Piveteausaurus divesensis
(Walker, 1964 [originally Eustreptospondylus])
Synonyms

Eustreptospondylus divesensis Walker, 1964

History and description

Piveteausaurus divesensis
Holotype

The partial braincase that became the type specimen of Piveteausaurus was first described in 1923 by French paleontologist Jean Piveteau in illustrations and photographs of the specimen (MNHN 1920-7). The braincase is comparable in size to that of a large Allosaurus,[1] and resembles that of another megalosauroid, Piatnitzkysaurus from Argentina.[2] Piveteau grouped this partial skull with other specimens found earlier in that locality and described in 1808 by French naturalist Georges Cuvier.[3] In 1861 English paleontologist Richard Owen assigned the fragments to the species Streptospondylus cuvieri, and Piveteau included the skull he found in the same species.[3]

MNHN 1920-7 was found by local collector Dutacq in rocks thought to be Oxfordian (Upper Jurassic), of the Vaches Noires cliffs near Dives in Normandy, France, and was after being reported by amateur geologist Cazenave in 1920 acquired by Professor Marcellin Boule for the Muséum national d'histoire naturelle.[4] Later these rocks were reevaluated as older (Upper Callovian, Middle Jurassic, ~164 million years old).[5]

Piveteausaurus divesensis jmallon
Hypothetical restoration

MNHN 1920-7 was reevaluated in 1964 by Alick Walker as part of his work on Ornithosuchus and the evolution of the Carnosauria.[3] He assigned MNHN 1920-7 to Eustreptospondylus as the holotype, or type specimen, of the new species E. divesensis.[3] The other bone fragments described by Cuvier and attributed to S. cuvieri by Owen were also transferred, as a "matter of convenience," but without conviction on the part of Walker, to the new species, E. divesensis.[3] It was given its own genus in 1977 by Philippe Taquet and Samuel Welles: Piveteausaurus, named after Piveteau. Taquet and Welles removed the postcranial bones, conveniently associated with the skull by Walker, from the species.[6] Later the braincase would be regarded by Gregory S. Paul as a species of Proceratosaurus (P. divesensis),[7] but this assignment was rejected by other researchers.[1][8]

While the braincase appears to be distinct, the limited remains mean Piveteausaurus has not been easy to classify. It has been compared to Ceratosaurus,[9] Eustreptospondylus,[3][8] and Proceratosaurus,[7] and was interpreted as a species of the latter two genera at various times.

Classification

Piveteausaurus was originally regarded as a megalosaurid as a "matter of convenience", as its describers did not want to name a new family for such fragmentary remains. Tom Holtz and colleagues (2004) considered it to be an indeterminate member of Tetanurae, though they did not include it in a phylogenetic analysis.[1] The first such analysis was performed by Benson in 2010. He found that while its exact placement was unresolved, it always grouped with a member of the clade Megalosauridae, and so most likely belonged to that family.[10]

The phylogenetic position of Piveteausaurus according to Carrano e.a. (2012) is shown by this cladogram:[11]

Megalosauroidea

Piatnitzkysauridae Piatnitzkysaurus floresi by Paleocolour

Megalosauria

Streptospondylus

Spinosauridae Spinosaurus by Joschua Knüppe

Megalosauridae
Eustreptospondylinae

Eustreptospondylus Eustrept1DB1 (Flipped)

Megalosaurinae

Duriavenator Duriavenator NT (Flipped)

Megalosaurus Megalosaurus silhouette by Paleogeek

Torvosaurus Torvosaurus tanneri Reconstruction (Flipped)

Afrovenatorinae

Afrovenator Afrovenator Abakensis by PaleoGeek

Dubreuillosaurus Dubreuillosaurus NT Flipped

Magnosaurus Magnosaurus (Flipped)

Leshansaurus

Piveteausaurus

References

  1. ^ a b c Holtz, Thomas R., Jr.; Molnar, Ralph E.; Currie, Philip J. (2004). Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 71–110. ISBN 0-520-24209-2.
  2. ^ Rauhut, 2004. Braincase structure of the Middle Jurassic theropod dinosaur Piatnitzkysaurus. Canadian Journal of Earth Science. 41, 1109-1122.
  3. ^ a b c d e f Walker, Alick D. (1964). "Triassic reptiles from the Elgin area: Ornithosuchus and the origin of carnosaurs". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 248: 53–134. Bibcode:1964RSPTB.248...53W. doi:10.1098/rstb.1964.0009.
  4. ^ Piveteau, Jean (1923). "L'arrière-crâne d'un dinosaurien carnivore de l'Oxfordien de Dives [The braincase of a carnivorous dinosaur from the Oxfordian of Dives]". Annales de Paléontologie (in French). 12: 115–123.
  5. ^ Weishampel, David B.; Barrett, Paul M.; Coria, Rodolfo A.; Le Loeuff, Jean; Xu Xing; Zhao Xijin; Sahni, Ashok; Gomani, Elizabeth M.P.; Noto, Christopher R (2004). "Dinosaur distribution". In David B. Weishampel; Peter Dodson; Halszka Osmólska (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. p. 540. ISBN 0-520-24209-2.
  6. ^ Taquet, Philippe; Welles, Samuel P. (1977). "Redescription du crâne de dinosaure théropode de Dives (Normandie) [Redescription of a theropod dinosaur skull from Dives (Normandy)]". Annales de Paléontologie (Vertébrés) (in French). 63 (2): 191–206.
  7. ^ a b Paul, Gregory S. (1988). Predatory Dinosaurs of the World. New York: Simon & Schuster. pp. 304–305. ISBN 0-671-61946-2.
  8. ^ a b Molnar, Ralph E.; Kurzanov, Sergei M.; Dong Zhiming (1990). "Carnosauria". In Weishampel David B.; Dodson, Peter; Osmólska, Halszka (eds.). The Dinosauria (First ed.). Berkeley: University of California Press. pp. 169–209. ISBN 0-520-06727-4.
  9. ^ Bakker, Robert T.; Kralis, Donald; Siegwarth, James; Filla, James (1992). "Edmarka rex, a new, gigantic theropod dinosaur from the middle Morrison Formation, Late Jurassic of the Como Bluff outcrop region". Hunteria. 2 (9): 1–24.
  10. ^ Benson, R.B.J. (2010). "A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods". Zoological Journal of the Linnean Society. 158: 882–935. doi:10.1111/j.1096-3642.2009.00569.x.
  11. ^ M.T. Carrano, R.B.J. Benson, and S.D. Sampson, 2012, "The phylogeny of Tetanurae (Dinosauria: Theropoda)", Journal of Systematic Palaeontology 10(2): 211-300

Sources

  • Glut, Donald F. (1997). "Piveteausaurus". Dinosaurs: The Encyclopedia. Jefferson, North Carolina: McFarland & Co. pp. 706–707. ISBN 0-89950-917-7.

External links

1977 in paleontology

Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1977.

Afrovenator

Afrovenator (; "African hunter") is a genus of megalosaurid theropod dinosaur from the middle Jurassic Period of northern Africa.

Allosaurus

Allosaurus () is a genus of carnivorous theropod dinosaur that lived 155 to 145 million years ago during the late Jurassic period (Kimmeridgian to late Tithonian). The name "Allosaurus" means "different lizard" alluding to its unique concave vertebrae (at the time of its discovery). It is derived from the Greek ἄλλος/allos ("different, other") and σαῦρος/sauros ("lizard / generic reptile"). The first fossil remains that could definitively be ascribed to this genus were described in 1877 by paleontologist Othniel Charles Marsh. As one of the first well-known theropod dinosaurs, it has long attracted attention outside of paleontological circles. Indeed, it has been a top feature in several films and documentaries about prehistoric life.

Allosaurus was a large bipedal predator. Its skull was large and equipped with dozens of sharp, serrated teeth. It averaged 9.5 metres (31 ft) in length, though fragmentary remains suggest it could have reached over 12 m (39 ft). Relative to the large and powerful hindlimbs, its three-fingered forelimbs were small, and the body was balanced by a long and heavily muscled tail. It is classified as an allosaurid, a type of carnosaurian theropod dinosaur. The genus has a complicated taxonomy, and includes an uncertain number of valid species, the best known of which is A. fragilis. The bulk of Allosaurus remains have come from North America's Morrison Formation, with material also known from Portugal and possibly Tanzania. It was known for over half of the 20th century as Antrodemus, but a study of the copious remains from the Cleveland-Lloyd Dinosaur Quarry brought the name "Allosaurus" back to prominence and established it as one of the best-known dinosaurs.

As the most abundant large predator in the Morrison Formation, Allosaurus was at the top of the food chain, probably preying on contemporaneous large herbivorous dinosaurs, and perhaps even other predators. Potential prey included ornithopods, stegosaurids, and sauropods. Some paleontologists interpret Allosaurus as having had cooperative social behavior, and hunting in packs, while others believe individuals may have been aggressive toward each other, and that congregations of this genus are the result of lone individuals feeding on the same carcasses.

Callovian

In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 166.1 ± 4.0 Ma (million years ago) and 163.5 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian.

Dubreuillosaurus

Dubreuillosaurus is a genus of carnivorous dinosaur from the middle Jurassic Period. It is a megalosaurid theropod. Its fossils were found in France. The only named species, Dubreuillosaurus valesdunensis, was originally described as a species of Poekilopleuron, Poekilopleuron? valesdunensis, which is still formally the type species of the genus. It was later renamed Dubreuillosaurus valesdunensis when, in 2005, Allain came to the conclusion that it was not part of the genus Poekilopleuron. Its type specimen, MNHN 1998-13, is only rivalled in the number of preserved elements in this group by that of Eustreptospondylus. Dubreuillosaurus is considered to be the sister species of Magnosaurus. It did not show signs of insular dwarfism even though it was uncovered on an island.

Eustreptospondylus

Eustreptospondylus ( yoo-STREPT-o-spon-DY-ləs; meaning "true Streptospondylus") is a genus of megalosaurid theropod dinosaur, from the Oxfordian stage of the Late Jurassic period (some time between 163 and 154 million years ago) in southern England, at a time when Europe was a series of scattered islands (due to tectonic movement at the time which raised the sea-bed and flooded the lowland).

Leshansaurus

Leshansaurus is a genus of theropod dinosaur from the Mid to Late Jurassic Dashanpu Formation of what is now China. It was described in 2009 by a team of Chinese paleontologists. The type species is Leshansaurus qianweiensis. Fossils of Leshansaurus were discovered in strata from the Shangshaximiao Formation, a formation rich in dinosaur fossils. Li et al. referred this taxon to Sinraptoridae – a group of carnosaurian theropods, but it may it belong to Megalosauridae instead.

List of European dinosaurs

Dinosaurs evolved partway through the Triassic period of the Mesozoic era, around 230 Ma (million years ago). At that time, the earth had one supercontinental landmass, called Pangaea, of which Europe was a part. So it remained throughout the Triassic. By the start of the Jurassic period, some 30 million years later, the supercontinent began to split into Laurasia and Gondwana. The largest inlet from Panthalassa, the superocean that surrounded Pangaea, was called the Tethys Ocean, and as this inlet cut deeper into the supercontinent, much of Europe was flooded.

By the Cretaceous, from 145 to 66 million years ago, the continents were beginning to approach their present shapes, but not their present positions, and Europe remained tropical. At times, it was a chain of island-microcontinents including Baltica and Iberia.

Europe is relatively rich in fossils from the Jurassic-Cretaceous boundary, and much of what is known about European dinosaurs dates from this time. During the Maastrichtian the end of the Cretaceous dinosaurs were dominating western and Central Europe as the Tremp Formation in Spain dates back to that age. Examples of dinosaurs from Maastrichtian Europe are Struthiosaurus and Canardia.

List of dinosaur genera

This list of dinosaurs is a comprehensive listing of all genera that have ever been included in the superorder Dinosauria, excluding class Aves (birds, both living and those known only from fossils) and purely vernacular terms.

The list includes all commonly accepted genera, but also genera that are now considered invalid, doubtful (nomen dubium), or were not formally published (nomen nudum), as well as junior synonyms of more established names, and genera that are no longer considered dinosaurs. Many listed names have been reclassified as everything from birds to crocodilians to petrified wood. The list contains 1559 names, of which approximately 1192 are considered either valid dinosaur genera or nomina dubia.

Magnosaurus

Magnosaurus (meaning 'large lizard') was a genus of basal tetanuran theropod dinosaur from the Middle Jurassic of England. It is based on fragmentary remains and has often been confused with or included in Megalosaurus.

Marnes de Dives

The Marnes de Dives is a geological formation in Europe. It dates back to the Middle Jurassic.

Megalosauridae

Megalosauridae is a monophyletic family of carnivorous theropod dinosaurs within the order Megalosauroidea, closely related to the family Spinosauridae. Some members of this family include Megalosaurus, Torvosaurus, Eustreptospondylus, and Afrovenator. Appearing in the Middle Jurassic, megalosaurids were among the first major radiation of large theropod dinosaurs, although they became extinct by the end of the Jurassic period. They were a relatively primitive group of basal tetanurans containing two main subfamilies, Megalosaurinae and Afrovenatorinae, along with the basal genus Eustreptospondylus, an unresolved taxon which differs from both subfamilies.The defining megalosaurid is Megalosaurus bucklandii, first named and described in 1824 by William Buckland after multiple finds in Stonesfield, Oxfordshire, UK. Megalosaurus was the first formally described dinosaur and was the basis for the establishment of the clade Dinosauria. It is also one of the largest known Middle Jurassic carnivorous dinosaurs, with the best-preserved femur at 805 mm and a proposed body mass of around 943 kg. Megalosauridae is recognized as a mainly European group of dinosaurs, based on fossils found in France and the UK. However, recent discoveries in Niger have led some to consider the range of the family. Megalosaurids appeared right before the split of the supercontinent Pangaea into Gondwana and Laurasia. These large theropods therefore may have dominated both halves of the world during the Jurassic.The family Megalosauridae was first defined by Thomas Huxley in 1869, yet it has been contested throughout history due to its role as a ‘waste-basket’ for many partially described dinosaurs or unidentified remains. In the early years of paleontology, most large theropods were grouped together and up to 48 species were included in the clade Megalosauria, the basal clade of Megalosauridae. Over time, most of these taxa were placed in other clades and the parameters of Megalosauridae were narrowed significantly. However, some controversy remains over whether Megalosauridae should be considered its own distinct group, and dinosaurs in this family remain some of the most problematic taxa in all Dinosauria. Some paleontologists, such as Paul Sereno in 2005, have disregarded the group due to its shaky foundation and lack of clarified phylogeny. However, recent research by Carrano, Benson, and Sampson has systematically analyzed all basal tetanurans and determined that Megalosauridae should exist as its own family.

Megalosauroidea

Megalosauroidea (meaning 'great/big lizard forms') is a superfamily (or clade) of tetanuran theropod dinosaurs that lived from the Middle Jurassic to the Late Cretaceous period. The group is defined as Megalosaurus bucklandii and all taxa sharing a more recent common ancestor with it than with Allosaurus fragilis or Passer domesticus. Members of the group include Spinosaurus, Megalosaurus, and Torvosaurus.

Megalosaurus

Megalosaurus (meaning "Great Lizard", from Greek μέγας, megas, meaning 'big', 'tall' or 'great' and σαῦρος, sauros, meaning 'lizard') is an extinct genus of large meat-eating theropod dinosaurs of the Middle Jurassic period (Bathonian stage, 166 million years ago) of Southern England. Although fossils from other areas have been assigned to the genus, the only certain remains of Megalosaurus come from Oxfordshire and date to the late Middle Jurassic.

The earliest possible fossils of the genus came from the Taynton Limestone Formation. One of these was the lower part of a femur, discovered in the 17th century. It was originally described by Robert Plot as a thighbone of a Roman war elephant, and then as a biblical giant. The first scientific name given for it, in the 18th century, was Scrotum humanum, created by Richard Brookes as a caption; however, this is not considered valid today.

Megalosaurus was, in 1824, the first genus of non-avian dinosaur to be validly named. The type species is Megalosaurus bucklandii, named in 1827. In 1842, Megalosaurus was one of three genera on which Richard Owen based his Dinosauria. On Owen's directions a model was made as one of the Crystal Palace Dinosaurs, which greatly increased the public interest for prehistoric reptiles. Subsequently, over fifty other species would be classified under the genus, originally because dinosaurs were not well known, but even during the 20th century after many dinosaurs had been discovered. Today it is understood these additional species were not directly related to M. bucklandii, which is the only true Megalosaurus species. Because a complete skeleton of it has never been found, much is still unclear about its build.

The first naturalists who investigated Megalosaurus mistook it for a gigantic lizard of twenty metres length. In 1842, Owen concluded that it was no longer than nine metres, standing on upright legs. He still thought it was a quadruped, though. Modern scientists, by comparing Megalosaurus with its direct relatives in the Megalosauridae, were able to obtain a more accurate picture. Megalosaurus was about six metres long, weighing about seven hundred kilogrammes. It was bipedal, walking on stout hindlimbs, its horizontal torso balanced by a horizontal tail. Its forelimbs were short, though very robust. Megalosaurus had a rather large head, equipped with long curved teeth. It was generally a robust and heavily muscled animal.

Piatnitzkysaurus

Piatnitzkysaurus ( pee-ət-NYITS-kee-SOR-əs meaning "Piatnitzky's lizard") is a genus of megalosauroid theropod dinosaur that lived approximately 166 to 164 million years ago during the middle part of the Jurassic Period in what is now Argentina. Piatnitzkysaurus was a moderately large, lightly built, bipedal, ground-dwelling carnivore that could grow up to 6.6 m (21.7 ft) long.

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.

Streptospondylus

Streptospondylus (meaning "reversed vertebra") is a genus of tetanuran theropod dinosaur known from the Late Jurassic period of France, 161 million years ago. It was a medium-sized predator.

Torvosaurus

Torvosaurus () is a genus of carnivorous megalosaurid theropod dinosaurs that lived approximately 153 to 148 million years ago during the Late Jurassic Period (Kimmeridgian to Tithonian) in what is now Colorado and Portugal. It contains two currently recognized species, Torvosaurus tanneri and Torvosaurus gurneyi.

In 1979 the type species Torvosaurus tanneri was named: it was a large, heavily built, bipedal carnivore, that could grow to a length of about 10 m (33 ft). T. tanneri was among the largest carnivores of its time, together with Epanterias and Saurophaganax (which could be both synonyms of Allosaurus). Specimens referred to Torvosaurus gurneyi were initially claimed to be up to twelve metres long, but later shown to be smaller. Based on bone morphology Torvosaurus is thought to have had short but very powerful arms.

Wiehenvenator

Wiehenvenator is a genus of predatory megalosaurid theropod dinosaur from the Middle Jurassic (Callovian) of Germany.

Piatnitzkysauridae
Megalosauria

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