Monjurosuchus is a genus of choristoderanreptile that lived in what is now China and Japan during the Early Cretaceous. It has large eyes, a rounded skull, robust legs with short claws, and a long, thin tail. Fossils have been found that preserve soft tissue, showing that it had soft skin and webbed feet.
Monjurosuchus was first found in China as part of the Early Cretaceous Jehol Biota. Named in 1940, the type speciesM. splendens was the first reptile described from the Yixian Formation. The holotype specimen was lost during World War II but was replaced in 2000 by a recently discovered neotype preserving soft tissue.[1] In 2007, remains were described from the Okurodani Formation of the Tetori Group of Japan. The Japanese material represents a different species of Monjurosuchus that has not yet been named.[2]
Monjurosuchus was a small choristodere, reaching a total body length of 30–40 cm (0.98–1.31 ft).[3] Unlike related choristoderes, Monjurosuchus has a relatively short neck with eight vertebrae, one less than usual. The skull is rounded rather than pointed and is dorsoventrally flattened in all fossils. The eye sockets are large and prominent temporal regions extend from the back of the skull. The jaws are lined with small, sharp teeth, while the palate is covered in closely spaced tooth batteries.[1] One distinguishing feature of Monjurosuchus is the lack of a lower temporal fenestra, a hole in the back of the skull that is common in many other diapsid reptiles, including most choristoderes. Monjurosuchus is also distinct in having small spikes on the edge of the squamosal bone at the back of the skull.
Specimens from China preserve soft tissue, including scales and webbing between the toes of the feet. The scales of Monjurosuchus were small, giving the animal soft skin. Two rows of larger scutes run along its back. The rest of the scales on the back are small, while the scales on the underside are slightly smaller. The skin of Monjurosuchus has a similar appearance to the living Chinese crocodile lizardShinisaurus.[1]
The feet of Monjurosuchus are webbed, with skin covering all parts of the foot but the short claws. The limbs were robust and the hips are wide. The long, slender tail shows no adaptations for its presumed semi-aquatic lifestyle. Gastralia are present on the underside of Monjurosuchus and are much thinner than the ribs. Intestinal contents are preserved between the gastralia and ribs of one specimen. Most of the material is sediment, but there are also fragments of what may be arthropod cuticle, indicating that Monjurosuchus may have fed on invertebrates.[1]
Monjurosuchus is a basal choristodere that lies outside the more advanced Neochoristodera. When named in 1940, it was placed in its own family Monjurosuchidae. Unlike Monjurosuchus, neochoristoderes have small, dorsally facing eyes and long snouts. Philydrosaurus, another Early Cretaceous Chinese choristodere, was grouped with Monjurosuchus in Monjurosuchidae.[4] A 2007 phylogenetic analysis of choristoderes found only weak support for this family, as Philydrosaurus seemed to be a more basal choristodere than Monjurosuchus. A close relationship was found between Monjurosuchus and the Miocene Lazarussuchus, but this was only weakly supported.[2]
Phylogeny from the analysis of Dong and colleagues (2020):[5]
^ abcdGao, K.; Evans, S.; Ji, Q.; Norell, M.; Ji, S. (2000). "Exceptional fossil material of a semi-aquatic reptile from China: the resolution of an enigma". Journal of Vertebrate Paleontology. 20 (3): 417–421. doi:10.1671/0272-4634(2000)020[0417:efmoas]2.0.co;2. S2CID 86064702.
^ abMatsumoto, R.; Evans, S.E.; Manabe, M. (2007). "The choristoderan reptile Monjurosuchus from the Early Cretaceous of Japan" (PDF). Acta Palaeontologica Polonica. 52 (2): 329–350.
^Dudgeon, Thomas William (2019). The internal cranial anatomy of Champsosaurus lindoei and its functional implications(PDF). Earth Sciences (M.Sci.). Ottawa, Ontario: Carleton University.
^Gao, K.-Q.; Fox, R.C. (2005). "A new choristodere (Reptilia: Diapsida) from the Lower Cretaceous of western Liaoning Province, China, and phylogenetic relationships of Monjurosuchidae". Zoological Journal of the Linnean Society. 145 (3): 427–444. doi:10.1111/j.1096-3642.2005.00191.x.
^Dong, Liping; Matsumoto, Ryoko; Kusuhashi, Nao; Wang, Yuanqing; Wang, Yuan; Evans, Susan E. (2020-08-02). "A new choristodere (Reptilia: Choristodera) from an Aptian–Albian coal deposit in China". Journal of Systematic Palaeontology. 18 (15): 1223–1242. doi:10.1080/14772019.2020.1749147. ISSN 1477-2019. S2CID 219047160.
November 28, 2023
monjurosuchus, genus, choristoderan, reptile, that, lived, what, china, japan, during, early, cretaceous, large, eyes, rounded, skull, robust, legs, with, short, claws, long, thin, tail, fossils, have, been, found, that, preserve, soft, tissue, showing, that, . Monjurosuchus is a genus of choristoderan reptile that lived in what is now China and Japan during the Early Cretaceous It has large eyes a rounded skull robust legs with short claws and a long thin tail Fossils have been found that preserve soft tissue showing that it had soft skin and webbed feet MonjurosuchusTemporal range Early Cretaceous Hauterivian Aptian PreꞒ Ꞓ O S D C P T J K Pg NFossil specimen on display at the National Museum of Natural ScienceScientific classificationDomain EukaryotaKingdom AnimaliaPhylum ChordataClass ReptiliaOrder ChoristoderaGenus MonjurosuchusEndo 1940Species M splendens Endo 1940 type Description and history edit nbsp Restoration of a Japanese specimenMonjurosuchus was first found in China as part of the Early Cretaceous Jehol Biota Named in 1940 the type species M splendens was the first reptile described from the Yixian Formation The holotype specimen was lost during World War II but was replaced in 2000 by a recently discovered neotype preserving soft tissue 1 In 2007 remains were described from the Okurodani Formation of the Tetori Group of Japan The Japanese material represents a different species of Monjurosuchus that has not yet been named 2 Monjurosuchus was a small choristodere reaching a total body length of 30 40 cm 0 98 1 31 ft 3 Unlike related choristoderes Monjurosuchus has a relatively short neck with eight vertebrae one less than usual The skull is rounded rather than pointed and is dorsoventrally flattened in all fossils The eye sockets are large and prominent temporal regions extend from the back of the skull The jaws are lined with small sharp teeth while the palate is covered in closely spaced tooth batteries 1 One distinguishing feature of Monjurosuchus is the lack of a lower temporal fenestra a hole in the back of the skull that is common in many other diapsid reptiles including most choristoderes Monjurosuchus is also distinct in having small spikes on the edge of the squamosal bone at the back of the skull nbsp Fossil of Monjurosuchus splendens in the Hong Kong Science Museum Specimens from China preserve soft tissue including scales and webbing between the toes of the feet The scales of Monjurosuchus were small giving the animal soft skin Two rows of larger scutes run along its back The rest of the scales on the back are small while the scales on the underside are slightly smaller The skin of Monjurosuchus has a similar appearance to the living Chinese crocodile lizard Shinisaurus 1 The feet of Monjurosuchus are webbed with skin covering all parts of the foot but the short claws The limbs were robust and the hips are wide The long slender tail shows no adaptations for its presumed semi aquatic lifestyle Gastralia are present on the underside of Monjurosuchus and are much thinner than the ribs Intestinal contents are preserved between the gastralia and ribs of one specimen Most of the material is sediment but there are also fragments of what may be arthropod cuticle indicating that Monjurosuchus may have fed on invertebrates 1 Classification edit nbsp Juvenile specimen Beijing Museum of Natural HistoryMonjurosuchus is a basal choristodere that lies outside the more advanced Neochoristodera When named in 1940 it was placed in its own family Monjurosuchidae Unlike Monjurosuchus neochoristoderes have small dorsally facing eyes and long snouts Philydrosaurus another Early Cretaceous Chinese choristodere was grouped with Monjurosuchus in Monjurosuchidae 4 A 2007 phylogenetic analysis of choristoderes found only weak support for this family as Philydrosaurus seemed to be a more basal choristodere than Monjurosuchus A close relationship was found between Monjurosuchus and the Miocene Lazarussuchus but this was only weakly supported 2 Phylogeny from the analysis of Dong and colleagues 2020 5 Choristodera Cteniogenys sp Heishanosaurus pygmaeusCoeruleodraco jurassicusNeochoristodera Ikechosaurus pijiagouensisIkechosaurus sunailinaeTchoiria namsariTchoiria klauseniChampsosaurus C gigasC albertensisSimoedosaurus S lemoineiS dakotensis Allochoristodera Monjurosuchus splendensPhilydrosaurus P proseilusP proseilusLazarussuchus L inexpectatusLazarussuchus sp L dvorakiKhurendukhosaurus orloviHyphalosaurus sp Hyphalosaurus lingyuanensisShokawa ikoiReferences edit a b c d Gao K Evans S Ji Q Norell M Ji S 2000 Exceptional fossil material of a semi aquatic reptile from China the resolution of an enigma Journal of Vertebrate Paleontology 20 3 417 421 doi 10 1671 0272 4634 2000 020 0417 efmoas 2 0 co 2 S2CID 86064702 a b Matsumoto R Evans S E Manabe M 2007 The choristoderan reptile Monjurosuchus from the Early Cretaceous of Japan PDF Acta Palaeontologica Polonica 52 2 329 350 Dudgeon Thomas William 2019 The internal cranial anatomy ofChampsosaurus lindoeiand its functional implications PDF Earth Sciences M Sci Ottawa Ontario Carleton University Gao K Q Fox R C 2005 A new choristodere Reptilia Diapsida from the Lower Cretaceous of western Liaoning Province China and phylogenetic relationships of Monjurosuchidae Zoological Journal of the Linnean Society 145 3 427 444 doi 10 1111 j 1096 3642 2005 00191 x Dong Liping Matsumoto Ryoko Kusuhashi Nao Wang Yuanqing Wang Yuan Evans Susan E 2020 08 02 A new choristodere Reptilia Choristodera from an Aptian Albian coal deposit in China Journal of Systematic Palaeontology 18 15 1223 1242 doi 10 1080 14772019 2020 1749147 ISSN 1477 2019 S2CID 219047160 Retrieved from https en wikipedia org w index php title Monjurosuchus amp oldid 1140746801, wikipedia, wiki, book, books, library,
