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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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Related in: MedlinePlus

PIN 3458/501, Shamosuchus ulgicus (= Paralligator gradilifrons).A, skull in right lateral view; B, skull in posterior view; C, partial skull table dorsal view; D, frontal with partial prefrontals and lacrimals in dorsal view; E, posterior portion of mandible in medial view; F, posterior portion of mandible in lateral view; G, dorsal osteoderms in dorsal view.
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pone.0118116.g009: PIN 3458/501, Shamosuchus ulgicus (= Paralligator gradilifrons).A, skull in right lateral view; B, skull in posterior view; C, partial skull table dorsal view; D, frontal with partial prefrontals and lacrimals in dorsal view; E, posterior portion of mandible in medial view; F, posterior portion of mandible in lateral view; G, dorsal osteoderms in dorsal view.

Mentions: As with S. gradilifrons, Konzhukova [6] distinguished S. ancestralis from other crocodyliforms mostly on the grounds of skull ornamentation. The interorbital crest on the frontal was described as short and gradually widening anteriorly. This seems little different from most other Shamosuchus species. Unlike S. gradilifrons, there are no lateral (orbital margin) crests in S. ancestralis (Fig. 8G, H). The preorbital crest possesses a deep furrow (Fig. 7B), but this too seems more widespread among Shamosuchus species (Figs. 7 and 8 and 9D). Konzhukova also noted that the postero-internal edge of the nasals is concave medially and that the back teeth on the lower jaw are blunted and clove shaped.


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

Turner AH - PLoS ONE (2015)

PIN 3458/501, Shamosuchus ulgicus (= Paralligator gradilifrons).A, skull in right lateral view; B, skull in posterior view; C, partial skull table dorsal view; D, frontal with partial prefrontals and lacrimals in dorsal view; E, posterior portion of mandible in medial view; F, posterior portion of mandible in lateral view; G, dorsal osteoderms in dorsal view.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0118116.g009: PIN 3458/501, Shamosuchus ulgicus (= Paralligator gradilifrons).A, skull in right lateral view; B, skull in posterior view; C, partial skull table dorsal view; D, frontal with partial prefrontals and lacrimals in dorsal view; E, posterior portion of mandible in medial view; F, posterior portion of mandible in lateral view; G, dorsal osteoderms in dorsal view.
Mentions: As with S. gradilifrons, Konzhukova [6] distinguished S. ancestralis from other crocodyliforms mostly on the grounds of skull ornamentation. The interorbital crest on the frontal was described as short and gradually widening anteriorly. This seems little different from most other Shamosuchus species. Unlike S. gradilifrons, there are no lateral (orbital margin) crests in S. ancestralis (Fig. 8G, H). The preorbital crest possesses a deep furrow (Fig. 7B), but this too seems more widespread among Shamosuchus species (Figs. 7 and 8 and 9D). Konzhukova also noted that the postero-internal edge of the nasals is concave medially and that the back teeth on the lower jaw are blunted and clove shaped.

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