Poekilopleuron

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Poekilopleuron
Temporal range: Middle Bathonian, 167.7–166.1  Ma
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Poekilopleuron bucklandi.JPG
Cast of the holotype gastralia, Muséum National d'Histoire Naturelle
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family:† Megalosauridae
Subfamily:† Afrovenatorinae
Genus:† Poekilopleuron
Eudes-Deslongchamps, 1836
Type species
†Poekilopleuron bucklandii
Eudes-Deslongchamps, 1836
Synonyms [1]
Genus synonyms
Species synonyms
  • Poikilopleuron bucklandiOwen, 1842
  • Poecilopleurum bucklandiBronn, 1849
  • Poicilopleuron bucklandiLeidy, 1870
  • Megalosaurus bucklandiHulke, 1879
  • Megalosaurus poikilopleuron Huene, 1926
  • Poekilopleuron bucklandiWhite, 1973
  • Poecilopleuron bucklandiWelles & Long, 1974

Poekilopleuron (meaning "varied ribs") is a genus of tetanuran dinosaur, which lived during the middle Bathonian of the Jurassic, about 168 to 166 million years ago. The genus has been used under many different spelling variants, although only one, Poekilopleuron, is valid. The type species is P. bucklandii, named after William Buckland, and many junior synonyms of it have also been erected. Little material is currently known, as the holotype was destroyed in World War II, although many casts of the material still exist.

Discovery and naming

Geography of Normandy, France, where remains of Poekilopleuron have been found Falaise en Normandie.JPG
Geography of Normandy, France, where remains of Poekilopleuron have been found

Poekilopleuron is a genus of theropod with a long and complex history. The holotype was discovered in July 1835 near La Maladrerie and the genus was named and first described by Jacques Amand Eudes-Deslongchamps in a report published in 1836, [2] [3] based on holotype material that is now destroyed. In 1837, Eudes-Deslongchamps published a more detailed account of this discovery in a monograph [4] which was also inserted next year in volume 6 of the "Mémoires de la Société Linnéenne Normandie". [5]

The holotype, which was housed in Musée de la Faculté des Sciences de Caen and destroyed during World War II, included gastralia, phalanges, a left forelimb, caudal vertebrae, chevrons, ribs and a hindlimb. Of all the material, little is still preserved, although the gastralia, phalanges and forelimb were cast and now represent the plastotype, with casts in the Muséum National d'Histoire Naturelle (specimen MNHN 1897-2) and Yale Peabody Museum (specimen YPM 4938). The original material was uncovered in a layer of the Calcaire de Caen in Normandy, France. Poekilopleuron can be assigned to the middle Bathonian in age, [1] about 167.7 to 166 million years ago. [6]

Megalosauroid neural arch and spine referred by Owen to Poekilopleuron. Poekilopleuron neural spine.jpg
Megalosauroid neural arch and spine referred by Owen to Poekilopleuron.

In the same 1836 publication, Eudes-Deslongchamps also named the type species of Poekilopleuron, P. bucklandii. [2] [3] Eudes-Deslongchamps noted similarities with some material of Megalosaurus bucklandii and Poekilopleuron, and chose the species name bucklandii for Poekilopleuron, so that if the two genera were synonymized, only the genus name would be suppressed. [1] The generic name is derived from Greek ποίκιλος, poikilos, "varied", and πλευρών, 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.[ citation needed ]

Description

Size of Poekilopleuron compared to a human Poekilopleuron size.png
Size of Poekilopleuron compared to a human

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, Poekilopleuron's 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. [1]

The fossil of Poekilopleuron showed a rare complete set of gastralia: fourteen pair of belly ribs supported the body of the animal. [1]

Cau (2024) suggested that the contemporary Dubreuillosaurus (originally assigned to Poekilopleuron) may represent a junior synonym, attributing the skeletal differences as positional and individual variation, as seen in Allosaurus . Thus, Dubreuillosaurus would represent a less mature individual of Poekilopleuron. [7]

Classification

Poekilopleuron is a difficult taxon to classify, as its original material is lost, and few casts are known. Poekilopleuron has a history of being renamed under different species and genera, most of which are now its junior synonyms. [1]

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. [8] 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.[ citation needed ]

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.[ citation needed ]

Five other species would be named in the genus. In 1869 Edward Drinker Cope renamed Laelaps gallicus into Poekilopleuron gallicum. [9] In 1870 Joseph Leidy created a Poicilopleuron valens based on a fossil probably belonging to Allosaurus . [10] 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 . [11] 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. [12] This chimaera is a nomen dubium . A much later named species is Poekilopleuron valesdunensis created by Ronan Allain in 2002. [13] In 2005 it was renamed Dubreuillosaurus . [14]

Life restoration of two Poekilopleuron Poekilopleuron life restoration.png
Life restoration of two Poekilopleuron

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. [15] An earlier study found that it was a primitive allosauroid outside Sinraptoridae. [16] However, a recent analysis by Carrano et al. (2012), also used in subsequent studies of tetanuran theropods, recovered it as a Megalosauroid closely related to Afrovenator . [17] [18] However, the authors of that study state that this position is uncertain since "with a single additional step it can be recovered as a piatnitzkysaurid, elsewhere within Megalosauridae, or at several possible positions within Allosauria."

Paleobiology

The material of Poekilopleuron bucklandii includes two tail vertebrae with the chevron of one vertebra ankylosed to the centrum of the next within 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." Ralph Molnar considered the occurrence of three pathologies in one individual to be "noteworthy". The specimens cannot be examined further to determine the etiology of the pathologies because of their destruction during the British bombing raid in 1944. [19]

Related Research Articles

<i>Megalosaurus</i> Genus of Jurassic-aged theropod dinosaur

Megalosaurus is an extinct genus of large carnivorous theropod dinosaurs of the Middle Jurassic Epoch 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.

<i>Afrovenator</i> Extinct genus of dinosaurs

Afrovenator is a genus of megalosaurid theropod dinosaur from the Middle or Late Jurassic Period on the Tiourarén Formation and maybe the Irhazer II Formation of the Niger Sahara region in northern Africa. Afrovenator represents the only properly identified Gondwanan megalosaur, with proposed material of the group present in the Late Jurassic on Tacuarembó Formation of Uruguay and the Tendaguru Formation of Tanzania.

<i>Iliosuchus</i> Extinct genus of dinosaurs

Iliosuchus is a genus of theropod dinosaur known from Bathonian–age rocks of England. It was perhaps 2 metres (6.6 ft) long.

<span class="mw-page-title-main">Megalosauridae</span> Extinct family of dinosaurs

Megalosauridae is a monophyletic family of carnivorous theropod dinosaurs within the group Megalosauroidea. Appearing in the Middle Jurassic, megalosaurids were among the first major radiation of large theropod dinosaurs. 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.

<i>Piatnitzkysaurus</i> Extinct genus of dinosaurs

Piatnitzkysaurus is a genus of megalosauroid theropod dinosaur that lived approximately 179 to 177 million years ago during the lower 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.

<span class="mw-page-title-main">Megalosauroidea</span> Extinct superfamily of Dinosaurs

Megalosauroidea is a superfamily 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. They are possibly paraphyletic in nature with respect to Allosauroidea.

<i>Xuanhanosaurus</i> Extinct genus of dinosaurs

Xuanhanosaurus is a genus of theropod dinosaur that lived during the Middle Jurassic (Bathonian) of the Sichuan Basin, China, around 166 million years ago. This taxon represents one of the various non-coelurosaurian tetanuran taxa found on the Middle Jurassic of the region, uncovered in the Lower Shaximiao Formation. Although it has been known for more than 40 years, this taxon has been the subject of very few studies, although most seem to agree that it is a tetanuran, possibly a basal allosauroid, highlighting the fact that it has a vestigial fourth metacarpal.

<i>Magnosaurus</i> Extinct genus of dinosaurs

Magnosaurus was a genus of theropod dinosaur from the Middle Jurassic of England. It is based on fragmentary remains and has often been confused with or included in Megalosaurus.

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<span class="mw-page-title-main">Metriacanthosauridae</span> Extinct family of dinosaurs

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<i>Dubreuillosaurus</i> Extinct genus of dinosaurs

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.

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<i>Streptospondylus</i> Extinct genus of dinosaurs

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<i>Teleidosaurus</i> Genus of large reptiles

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<i>Duriavenator</i> Genus of theropod dinosaur

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<span class="mw-page-title-main">Marnes de Dives</span> Geological formation in Normandy, France

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The Calcaire de Caen or Calcaires de Caen Formation; French for Caen Limestone, is a geological formation in France. It dates back to the mid-Bathonian of the Jurassic. It was often quarried for building work and is referred to as Caen Stone.

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 1836.

<span class="mw-page-title-main">Sharp's Hill Formation</span>

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<span class="mw-page-title-main">Piatnitzkysauridae</span> Extinct family of dinosaurs

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References

  1. 1 2 3 4 5 6 Allain R.; Chure D. J. (2002). "Poekilopleuron bucklandii, the theropod dinosaur from the Middle Jurassic (Bathonian) of Normandy" (PDF). Palaeontology. 45 (6): 1107–1121. Bibcode:2002Palgy..45.1107A. doi: 10.1111/1475-4983.00277 .
  2. 1 2 Eudes-Deslongchamps J.-A. (1836). "Plusieurs parties d'un mémoire sur un très-grand animal fossile découvert, l'an dernier, dans les carrières de la Maladrerie à un quart de lieu de Caen". Analyse des Travaux de la Société Pendant l'Année Académique 1835–1836, Séance Publique de la Société Linnéenne de Normandie Tenue à Vire le 24 Mai 1836: 14–25.
  3. 1 2 Brignon A. (2018). "New historical data on the first dinosaurs found in France". BSGF - Earth Sciences Bulletin. 189 (4): 4. doi: 10.1051/bsgf/2018003 .
  4. ↑ Eudes-Deslongchamps J.-A. (1837) Mémoire sur le Poekilopleuron bucklandii, grand saurien fossile, intermédiaire entre les crocodiles et les lézards. A. Hardel, Caen, 114 p., 8 pl.
  5. ↑ Eudes-Deslongchamps J.-A. (1838). "Mémoire sur le Poekilopleuron bucklandii, grande saurien fossile, intermédiaire entre les crocodiles et les lézards, découvert dans les carrières de la Maladrerie, près Caen, au mois de juillet 1835". Mémoires de la Société Linnéenne Normandie. 6: 37–146, 8 pl.
  6. ↑ Holtz, T.R. Jr (2012). "Updated genus list for Holtz (2007) Dinosaurs" (PDF). University of Maryland. p. 8.
  7. ↑ Cau, Andrea (2024). "A Unified Framework for Predatory Dinosaur Macroevolution" (PDF). Bollettino della Società Paleontologica Italiana. 63: 1-19. doi:10.4435/BSPI.2024.08.
  8. ↑ Hulke J.W. (1879). "Note on Poekilopleuron bucklandi of Eudes Deslongchamps (père), identifying it with Megalosaurus bucklandi". Quarterly Journal of the Geological Society. 35 (1–4): 233–238. doi:10.1144/GSL.JGS.1879.035.01-04.10. S2CID   129449805.
  9. ↑ Cope, Edward (1869). "Synopsis of the Extinct Batrachia and Reptilia of North America. Part 1". Transactions of the American Philosophical Society. New Series. 14: 252.
  10. ↑ Leidy J (1870). "Remarks on Poicilopleuron valens, Clidastes intermedius, Leiodon proriger, Baptemys wyomingensis, and Emys stevensonianus". Proceedings of the Academy of Natural Sciences. 22 (1): 3–4. JSTOR   4624064.
  11. ↑ Seeley H.G. (1887). "On Aristosuchus pusillus Owen, being further notes on the fossils described by Sir R. Owen as Poikilopleuron pusillus Owen". Quarterly Journal of the Geological Society of London. 43 (1–4): 221–228. doi:10.1144/GSL.JGS.1887.043.01-04.22. S2CID   131237500.
  12. ↑ Kiprijanow W.A. (1883). "Studien über die Fossilen Reptilien Russlands. IV. Theil. Ordnung Crocodilia Oppel. Indeterminierte Fossile Reptilien". Mémoires de l'Académie Impériale des Sciences de Saint-Pétersbourg. VIIe série. 31 (7): 1–29.
  13. ↑ Allain R (2002). "Discovery of megalosaur (Dinosauria, Theropoda) in the Middle Bathonian of Normandy (France) and its implications for the phylogeny of basal Tetanurae". Journal of Vertebrate Paleontology. 22 (3): 548–563. doi:10.1671/0272-4634(2002)022[0548:DOMDTI]2.0.CO;2. S2CID   85751613.
  14. ↑ Allain R (2005). "The postcranial anatomy of the megalosaur Dubreuillosaurus valesdunensis (Dinosauria: Theropoda) from the Middle Jurassic of Normandy, France" (PDF). Journal of Vertebrate Paleontology. 25 (4): 850–858. doi:10.1671/0272-4634(2005)025[0850:TPAOTM]2.0.CO;2. S2CID   130620389.
  15. ↑ Benson, R.B.J., Carrano, M.T and Brusatte, S.L. (2010). "A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic". Naturwissenschaften. 97 (1): 71–78. Bibcode:2010NW.....97...71B. doi:10.1007/s00114-009-0614-x. PMID   19826771. S2CID   22646156.{{cite journal}}: CS1 maint: multiple names: authors list (link) Supporting Information
  16. ↑ Allain R (2001). "Redescription de Streptospondylus altdorfensis, le dinosaure théropode de Cuvier, du Jurassique de Normandie [Redescription of Streptospondylus altdorfensis, Cuvier's theropod dinosaur from the Jurassic of Normandy]" (PDF). Geodiversitas. 23 (3): 349–367. Archived from the original (PDF) on 2012-06-02. Retrieved 2011-02-24.
  17. ↑ Rauhut, Oliver W.M.; Hübner, Tom R.; Lanser, Klaus-Peter (2016). "A new megalosaurid theropod dinosaur from the late Middle Jurassic (Callovian) of north-western Germany: Implications for theropod evolution and faunal turnover in the Jurassic". Palaeontologia Electronica. 19 (2): 1–65. Retrieved 13 January 2022.
  18. ↑ Hui Dai; Roger Benson; Xufeng Hu; Qingyu Ma; Chao Tan; Ning Li; Ming Xiao; Haiqian Hu; Yuxuan Zhou; Zhaoying Wei; Feng Zhang; Shan Jiang; Deliang Li; Guangzhao Peng; Yilun Yu; Xing Xu (2020). "A new possible megalosauroid theropod from the Middle Jurassic Xintiangou Formation of Chongqing, People's Republic of China and its implication for early tetanuran evolution". Scientific Reports. 10 (1): Article number 139. Bibcode:2020NatSR..10..139D. doi: 10.1038/s41598-019-56959-x . PMC   6954265 . PMID   31924836.
  19. ↑ Molnar, R. E., 2001, Theropod paleopathology: a literature survey: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 337-363.
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