Most of the cranial sutures that outline individual bones of the skull are not visible in the holotype, and are often obscured by cracks. However, the overall shape of Prodiplocynodon is similar to that of basal alligatoroids.[1] Many of the features seen in Prodiplocynodon are common among eusuchians. The skull is short and triangular, being around 50 centimetres (20 in) in length. The orbits, or eye sockets, are quite large and subtriangular. The teeth are short and somewhat sharp, and in comparison to modern crocodiles show little variation. The orbits face directly upwards, but this may have been the result of slight compression in the holotype skull. The external nasal aperture, the opening for the nostrils, is very large. There is a constriction at the point of contact between the premaxilla and maxilla which would have been an area of reception for a large mandibular tooth. In Prodiplocynodon, the constriction is not deep, being intermediate between that of Alligator and Crocodylus.[2]
Classificationedit
Mook suggested that Prodiplocynodon may be ancestral to alligatorids and crocodylids because it possessed features of both families. However, Mook also noted that some of the features observed in Prodiplocynodon that are also found in modern crocodylians may be the result of evolutionary convergence,[2] and thus Prodiplocynodon was also proposed to be an alligatorine.[3][4]
Phylogenyedit
Prodiplocynodon was not included in a phylogenetic study until 1996. In that study, Prodiplocynodon was excluded from the Alligatorinae because it lacked all seven of the unequivocal synapomorphies that were proposed for the clade. According to the 1996 study, characters that exclude Prodiplocynodon from Alligatorinae include the presence of a distinct lateral constriction between the premaxilla and maxilla, a contact between the nasal and lacrimal, and the lack of posterior massive crushing teeth. The 1996 analysis considered Prodiplocynodon to be the sister taxon to the Alligatorinae rather than the Crocodylinae because in Prodiplocynodon, the jugal-lacrimal suture is much shorter than the ventral border of the orbit. However, the authors of the study mentioned that this character is also seen in some derived crocodylines, and is lost in some ingroups of Alligatorinae.[5]
Successive phylogenetic studies have placed Prodiplocynodon as a basal member of Crocodyloidea along with Asiatosuchus,[6][7][8] as shown in the cladogram below:
*Note: Tomistominae, which includes the extant False Gharial, is sometimes considered to be a gavialoid lineage on the basis of genetic evidence.[9][10]
The below cladogram shows the results of the latest studies, which placed Prodiplocynodon outside of Crocodyloidea, as more basal than Longirostres (the combined group of crocodiles and gavialids).[11]
^ abBrochu, C. A. (2003). "Phylogenetic approaches toward crocodylian history" (PDF). Annual Review of Earth and Planetary Sciences. 31 (31): 357–97. Bibcode:2003AREPS..31..357B. doi:10.1146/annurev.earth.31.100901.141308.
^ abcdMook, C. C. (1941). "A new crocodilian from the Lance Formation" (PDF). American Museum Novitates (1128): 1–5.
^Steel, R. (1973). "Crocodilia". Handbuch der Paläoherpetologie. Stuttgart and Portland: Gustav Fischer Verlag. pp. 116pp.
^Carroll, R. L. (1988). Vertebrate Paleontology and Evolution. New York: W H. Freeman and Company. pp. 698pp. ISBN9780716718222.
^Wu, X.-C.; Brinkman, D. B.; Russell, A. P. (1996). (PDF). Palaeontology. 39 (2): 351–375. Archived from the original (PDF) on 2011-09-28.
^Brochu, C. A. (2000). "Phylogenetic relationships and divergence timing of Crocodylus based on morphology and the fossil record". Copeia. 2000 (3): 657–673. doi:10.1643/0045-8511(2000)000[0657:pradto]2.0.co;2. S2CID 85824292.
^Brochu, C. A.; Gingerich, P. D. (2000). "New tomistomine crocodylian from the middle Eocene (Bartonian) of Wadi Hitan, Fayum Province, Egypt" (PDF). Contributions from the Museum of Paleontology: The University of Michigan. 30: 251–268.
^Hua, S.; Jouve, S. (2004). "A primitive marine gavialoid from the Paleocene of Morocco" (PDF). Journal of Vertebrate Paleontology. 24 (2): 341–350. doi:10.1671/1104. S2CID 86497272.
^Densmore, L. D.; Owen, R. D. (1989). "Molecular systematics of the order Crocodilia". American Zoologist. 29 (3): 831–841. doi:10.1093/icb/29.3.831.
^Brochu, C. A. (2004). "A new Late Cretaceous gavialoid crocodylian from Eastern North America and the phylogenetic relationships of Thoracosaurs" (PDF). Journal of Vertebrate Paleontology. 24 (3): 610–633. doi:10.1671/0272-4634(2004)024[0610:anlcgc]2.0.co;2. S2CID 131176447.
^ abMichael S. Y. Lee; Adam M. Yates (27 June 2018). "Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil". Proceedings of the Royal Society B. 285 (1881). doi:10.1098/rspb.2018.1071. PMC6030529. PMID 30051855.
^Hekkala, E.; Gatesy, J.; Narechania, A.; Meredith, R.; Russello, M.; Aardema, M. L.; Jensen, E.; Montanari, S.; Brochu, C.; Norell, M.; Amato, G. (2021-04-27). "Paleogenomics illuminates the evolutionary history of the extinct Holocene "horned" crocodile of Madagascar, Voay robustus". Communications Biology. 4 (1): 505. doi:10.1038/s42003-021-02017-0. ISSN 2399-3642. PMC8079395. PMID 33907305.
prodiplocynodon, extinct, genus, basal, crocodyloid, crocodylian, only, crocodyloids, known, from, cretaceous, existed, during, maastrichtian, stage, only, species, type, species, langi, from, lance, formation, wyoming, known, only, from, single, holotype, sku. Prodiplocynodon is an extinct genus of basal crocodyloid crocodylian It is one of the only crocodyloids known from the Cretaceous and existed during the Maastrichtian stage 1 The only species of Prodiplocynodon is the type species P langi from the Lance Formation of Wyoming known only from a single holotype skull lacking the lower jaw 2 ProdiplocynodonTemporal range Late Cretaceous 70 66 Ma PreꞒ Ꞓ O S D C P T J K Pg N Scientific classificationDomain EukaryotaKingdom AnimaliaPhylum ChordataClass ReptiliaOrder CrocodiliaSuperfamily CrocodyloideaGenus ProdiplocynodonMook 1941Type species Prodiplocynodon langiMook 1941The skull was collected by the American Museum Expedition of 1892 from exposures near the Cheyenne River in Niobrara County It was described by Charles C Mook of the American Museum of Natural History in 1941 2 The generic name means before Diplocynodon because Mook saw close similarities between the holotype skull and that of the alligatoroid Diplocynodon from the Eocene of Europe Contents 1 Description 2 Classification 2 1 Phylogeny 3 References 4 External linksDescription editMost of the cranial sutures that outline individual bones of the skull are not visible in the holotype and are often obscured by cracks However the overall shape of Prodiplocynodon is similar to that of basal alligatoroids 1 Many of the features seen in Prodiplocynodon are common among eusuchians The skull is short and triangular being around 50 centimetres 20 in in length The orbits or eye sockets are quite large and subtriangular The teeth are short and somewhat sharp and in comparison to modern crocodiles show little variation The orbits face directly upwards but this may have been the result of slight compression in the holotype skull The external nasal aperture the opening for the nostrils is very large There is a constriction at the point of contact between the premaxilla and maxilla which would have been an area of reception for a large mandibular tooth In Prodiplocynodon the constriction is not deep being intermediate between that of Alligator and Crocodylus 2 Classification editMook suggested that Prodiplocynodon may be ancestral to alligatorids and crocodylids because it possessed features of both families However Mook also noted that some of the features observed in Prodiplocynodon that are also found in modern crocodylians may be the result of evolutionary convergence 2 and thus Prodiplocynodon was also proposed to be an alligatorine 3 4 Phylogeny edit Prodiplocynodon was not included in a phylogenetic study until 1996 In that study Prodiplocynodon was excluded from the Alligatorinae because it lacked all seven of the unequivocal synapomorphies that were proposed for the clade According to the 1996 study characters that exclude Prodiplocynodon from Alligatorinae include the presence of a distinct lateral constriction between the premaxilla and maxilla a contact between the nasal and lacrimal and the lack of posterior massive crushing teeth The 1996 analysis considered Prodiplocynodon to be the sister taxon to the Alligatorinae rather than the Crocodylinae because in Prodiplocynodon the jugal lacrimal suture is much shorter than the ventral border of the orbit However the authors of the study mentioned that this character is also seen in some derived crocodylines and is lost in some ingroups of Alligatorinae 5 Successive phylogenetic studies have placed Prodiplocynodon as a basal member of Crocodyloidea along with Asiatosuchus 6 7 8 as shown in the cladogram below Crocodyloidea Prodiplocynodon langiAsiatosuchus germanicusCrocodylus affinisDormaal crocodyloidCrocodylus acerBrachyuranochampsa eversolei Crocodylidae Tomistominae Crocodylinae Note Tomistominae which includes the extant False Gharial is sometimes considered to be a gavialoid lineage on the basis of genetic evidence 9 10 A 2018 tip dating study by Lee amp Yates simultaneously using morphological molecular DNA sequencing and stratigraphic fossil age data established the inter relationships within Crocodilia 11 which was expanded upon in 2021 by Hekkala et al using paleogenomics by extracting DNA from the extinct Voay 12 The below cladogram shows the results of the latest studies which placed Prodiplocynodon outside of Crocodyloidea as more basal than Longirostres the combined group of crocodiles and gavialids 11 Crocodylia Alligatoroidea nbsp Prodiplocynodon Asiatosuchus Crocodylus affinis Crocodylus depressifrons Crocodylus acer Brachyuranochampsa MekosuchinaeLongirostres Crocodyloidea Crocodylus megarhinus Crocodylidae nbsp Gavialoidea extinct basal Gavialoids Gavialidae Gavialis nbsp Tomistoma nbsp References edit a b Brochu C A 2003 Phylogenetic approaches toward crocodylian history PDF Annual Review of Earth and Planetary Sciences 31 31 357 97 Bibcode 2003AREPS 31 357B doi 10 1146 annurev earth 31 100901 141308 a b c d Mook C C 1941 A new crocodilian from the Lance Formation PDF American Museum Novitates 1128 1 5 Steel R 1973 Crocodilia Handbuch der Palaoherpetologie Stuttgart and Portland Gustav Fischer Verlag pp 116pp Carroll R L 1988 Vertebrate Paleontology and Evolution New York W H Freeman and Company pp 698pp ISBN 9780716718222 Wu X C Brinkman D B Russell A P 1996 A new alligator from the Upper Cretaceous of Canada and the relationships of early eusuchians PDF Palaeontology 39 2 351 375 Archived from the original PDF on 2011 09 28 Brochu C A 2000 Phylogenetic relationships and divergence timing of Crocodylus based on morphology and the fossil record Copeia 2000 3 657 673 doi 10 1643 0045 8511 2000 000 0657 pradto 2 0 co 2 S2CID 85824292 Brochu C A Gingerich P D 2000 New tomistomine crocodylian from the middle Eocene Bartonian of Wadi Hitan Fayum Province Egypt PDF Contributions from the Museum of Paleontology The University of Michigan 30 251 268 Hua S Jouve S 2004 A primitive marine gavialoid from the Paleocene of Morocco PDF Journal of Vertebrate Paleontology 24 2 341 350 doi 10 1671 1104 S2CID 86497272 Densmore L D Owen R D 1989 Molecular systematics of the order Crocodilia American Zoologist 29 3 831 841 doi 10 1093 icb 29 3 831 Brochu C A 2004 A new Late Cretaceous gavialoid crocodylian from Eastern North America and the phylogenetic relationships of Thoracosaurs PDF Journal of Vertebrate Paleontology 24 3 610 633 doi 10 1671 0272 4634 2004 024 0610 anlcgc 2 0 co 2 S2CID 131176447 a b Michael S Y Lee Adam M Yates 27 June 2018 Tip dating and homoplasy reconciling the shallow molecular divergences of modern gharials with their long fossil Proceedings of the Royal Society B 285 1881 doi 10 1098 rspb 2018 1071 PMC 6030529 PMID 30051855 Hekkala E Gatesy J Narechania A Meredith R Russello M Aardema M L Jensen E Montanari S Brochu C Norell M Amato G 2021 04 27 Paleogenomics illuminates the evolutionary history of the extinct Holocene horned crocodile of Madagascar Voay robustus Communications Biology 4 1 505 doi 10 1038 s42003 021 02017 0 ISSN 2399 3642 PMC 8079395 PMID 33907305 External links editProdiplocynodon in the Paleobiology Database nbsp Paleontology portal Retrieved from https en wikipedia org w index php title Prodiplocynodon amp oldid 1134967231, wikipedia, wiki, book, books, library,
