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A review of Shamosuchus and Paralligator (Crocodyliformes, Neosuchia) from the Cretaceous of Asia.

Turner AH - PLoS ONE (2015)

Bottom Line: Rugosuchus and Batrachomimus are sister taxa to Paralligator.Paralligatoridae is closely related to Theriosuchus, hylaeochampsids and a speciose Allodaposuchus clade, which together are the sister group of Borealosuchus plus Crocodylia.These results support the presence of a diverse clade in eastern Asia and western North America throughout the Cretaceous with origins in the Late Jurassic.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomical Sciences, Stony Brook University, Stony Brook, New York, United States of America.

ABSTRACT
The crocodyliform Shamosuchus is known from numerous Late Cretaceous localities in southern and eastern Mongolia and fragmentary remains from Uzbekistan. Seven species of Shamosuchus have been named from six localities in Mongolia and three in Uzbekistan. Six species originally described as Paralligator were later referred to Shamosuchus. Only the type species, Shamosuchus djadochtaensis has been examined in detail. Many of the named species of Shamosuchus show striking similarity in size and cranial morphology but most are based on partial remains suggesting that the true species diversity is overestimated. A review of all species referred to Shamosuchus recognizes three valid taxa: Shamosuchus djadochtaensis, S. gradilifrons, and S. major. Shamosuchus sungaricus, S. borealis, and S. karakalpakensis are nomena dubia, whereas S. ancestralis, S. ulgicus, S. tersus, and S. ulanicus are junior subjective synonyms of S. gradilifrons. Phylogenetic analysis of 318 phenotypic characters recovers a Paralligatoridae clade consisting of Shamosuchus, Rugosuchus, Batrachomimus, Glen Rose Form, and Wannchampsus. Shamosuchus is non-monophyletic: S. djadochtaensis is near the base of Paralligatoridae whereas S. gradilifrons + S. major are the most deeply nested. The name Paralligator is resurrected for this clade. Rugosuchus and Batrachomimus are sister taxa to Paralligator. Paralligatoridae is closely related to Theriosuchus, hylaeochampsids and a speciose Allodaposuchus clade, which together are the sister group of Borealosuchus plus Crocodylia. These results support the presence of a diverse clade in eastern Asia and western North America throughout the Cretaceous with origins in the Late Jurassic.

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Reduced strict consensus of 108 equally optimal trees recovered from maximum parsimony analysis of 101 ingroup taxa and 318 phenotypic characters.Trees rooted on Gracilisuchus stipanicicorum. Two equally optimal positions of Bernissartia fagesii shown with dotted line (length = 1662, CI = 0.239, RI = 0.700).
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pone.0118116.g014: Reduced strict consensus of 108 equally optimal trees recovered from maximum parsimony analysis of 101 ingroup taxa and 318 phenotypic characters.Trees rooted on Gracilisuchus stipanicicorum. Two equally optimal positions of Bernissartia fagesii shown with dotted line (length = 1662, CI = 0.239, RI = 0.700).

Mentions: Maximum parsimony analysis recovered 108 optimal trees with a length of 1662 steps (CI = 0.239, RI = 0.700). A reduced strict consensus of the trees (Fig. 14) deviates from the results of previous versions of this dataset [5,35,52] as well as many recent morphological analysis of Neosuchia [36,47,64]. Here paralligatorids and hylaeochampsids are not successive sister taxa to Crocodylia but instead form a speciose clade that is itself the sister to Crocodylia. Isisfordia and Susisuchus are recovered in a basally diverging position within Neosuchia, outside of the Goniopholididae node, not near the crown-group as in most previous analysis. Conversely Theriosuchus and Alligatorium are not recovered as basal neosuchians but instead nest within the paralligatorid + hylaeochampsid clade, as the sister group to Paralligatoridae. The monophyly of the three Shamosuchus species is not supported. Shamosuchus major and S. gradilifrons are sister taxa and sit in a derived position within Paralligatoridae. Shamosuchus djadochtaensis is near the base of Paralligatoridae with Rugosuchus nonganensis and Batrachomimus pastosbonensis more closely related to S. major and S. gradilifrons than to S. djadochtaensis (Fig. 14). I propose that the name Paralligator be reapplied to S. major and S. gradilifrons.


A review of Shamosuchus and Paralligator (Crocodyliformes, Neosuchia) from the Cretaceous of Asia.

Turner AH - PLoS ONE (2015)

Reduced strict consensus of 108 equally optimal trees recovered from maximum parsimony analysis of 101 ingroup taxa and 318 phenotypic characters.Trees rooted on Gracilisuchus stipanicicorum. Two equally optimal positions of Bernissartia fagesii shown with dotted line (length = 1662, CI = 0.239, RI = 0.700).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4340866&req=5

pone.0118116.g014: Reduced strict consensus of 108 equally optimal trees recovered from maximum parsimony analysis of 101 ingroup taxa and 318 phenotypic characters.Trees rooted on Gracilisuchus stipanicicorum. Two equally optimal positions of Bernissartia fagesii shown with dotted line (length = 1662, CI = 0.239, RI = 0.700).
Mentions: Maximum parsimony analysis recovered 108 optimal trees with a length of 1662 steps (CI = 0.239, RI = 0.700). A reduced strict consensus of the trees (Fig. 14) deviates from the results of previous versions of this dataset [5,35,52] as well as many recent morphological analysis of Neosuchia [36,47,64]. Here paralligatorids and hylaeochampsids are not successive sister taxa to Crocodylia but instead form a speciose clade that is itself the sister to Crocodylia. Isisfordia and Susisuchus are recovered in a basally diverging position within Neosuchia, outside of the Goniopholididae node, not near the crown-group as in most previous analysis. Conversely Theriosuchus and Alligatorium are not recovered as basal neosuchians but instead nest within the paralligatorid + hylaeochampsid clade, as the sister group to Paralligatoridae. The monophyly of the three Shamosuchus species is not supported. Shamosuchus major and S. gradilifrons are sister taxa and sit in a derived position within Paralligatoridae. Shamosuchus djadochtaensis is near the base of Paralligatoridae with Rugosuchus nonganensis and Batrachomimus pastosbonensis more closely related to S. major and S. gradilifrons than to S. djadochtaensis (Fig. 14). I propose that the name Paralligator be reapplied to S. major and S. gradilifrons.

Bottom Line: Rugosuchus and Batrachomimus are sister taxa to Paralligator.Paralligatoridae is closely related to Theriosuchus, hylaeochampsids and a speciose Allodaposuchus clade, which together are the sister group of Borealosuchus plus Crocodylia.These results support the presence of a diverse clade in eastern Asia and western North America throughout the Cretaceous with origins in the Late Jurassic.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomical Sciences, Stony Brook University, Stony Brook, New York, United States of America.

ABSTRACT
The crocodyliform Shamosuchus is known from numerous Late Cretaceous localities in southern and eastern Mongolia and fragmentary remains from Uzbekistan. Seven species of Shamosuchus have been named from six localities in Mongolia and three in Uzbekistan. Six species originally described as Paralligator were later referred to Shamosuchus. Only the type species, Shamosuchus djadochtaensis has been examined in detail. Many of the named species of Shamosuchus show striking similarity in size and cranial morphology but most are based on partial remains suggesting that the true species diversity is overestimated. A review of all species referred to Shamosuchus recognizes three valid taxa: Shamosuchus djadochtaensis, S. gradilifrons, and S. major. Shamosuchus sungaricus, S. borealis, and S. karakalpakensis are nomena dubia, whereas S. ancestralis, S. ulgicus, S. tersus, and S. ulanicus are junior subjective synonyms of S. gradilifrons. Phylogenetic analysis of 318 phenotypic characters recovers a Paralligatoridae clade consisting of Shamosuchus, Rugosuchus, Batrachomimus, Glen Rose Form, and Wannchampsus. Shamosuchus is non-monophyletic: S. djadochtaensis is near the base of Paralligatoridae whereas S. gradilifrons + S. major are the most deeply nested. The name Paralligator is resurrected for this clade. Rugosuchus and Batrachomimus are sister taxa to Paralligator. Paralligatoridae is closely related to Theriosuchus, hylaeochampsids and a speciose Allodaposuchus clade, which together are the sister group of Borealosuchus plus Crocodylia. These results support the presence of a diverse clade in eastern Asia and western North America throughout the Cretaceous with origins in the Late Jurassic.

Show MeSH
Related in: MedlinePlus