The Evolution and Classification of the Crocodilia

Mook, Charles Craig

doi:10.1086/624165

Cited by 32 publications

(20 citation statements)

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“…four individuals are less than 0.8 m in length and considered to be juvenile. Robust scutes present in life across the dorsal and ventral sides are still present, regardless of size (Mook 1934;Mueller-Töwe 2006).…”

Section: Methodsmentioning

confidence: 99%

Float or sink: modelling the taphonomic pathway of marine crocodiles (Mesoeucrocodylia, Thalattosuchia) during the death–burial interval

Beardmore

Orr

Manzocchi

et al. 2012

Palaeobio Palaeoenv

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A taphonomic model is erected for a dataset of 19 Steneosaurus (Mesoeucrocodylia; Thalattosuchia) from the Toarcian Posidonienschiefer Formation (Lower Jurassic) of Germany. These were deposited in a quiet-water, marine, basin. Their taphonomy is compared with that of an additional seven thalattosuchians from other Jurassic localities (Peterborough and Yorkshire, UK; Nusplingen, Germany). The skeletal taphonomy of the specimens is assessed in terms of the articulation and completeness of nine skeletal units. Steneosaurus from the Posidonienschiefer Formation exhibit variable levels of articulation in the nine units. Completeness also varies but the head, neck and dorsal units are complete in all specimens. Carcasses reached the sediment-water interface shortly after death. Loss of fidelity occurred primarily as individuals lay on the sediment, and disarticulated elements tended to remain in the vicinity of the carcass. Those elements absent from specimens are the smaller, more distal, bones of the limbs and tail; these were removed preferentially by weak bottom currents. Smaller specimens are consistently less complete. Specimens from other localities broadly follow the same taphonomic pathway, suggesting a consistent pattern for the skeletal taphonomy of the carcasses of marine crocodiles. Loss of completeness in some specimens is more exacerbated, the result of stronger current activity at the sediment-water interface.

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Section: Methodsmentioning

confidence: 99%

Float or sink: modelling the taphonomic pathway of marine crocodiles (Mesoeucrocodylia, Thalattosuchia) during the death–burial interval

Beardmore

Orr

Manzocchi

et al. 2012

Palaeobio Palaeoenv

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“…rostral length; paired external nares; relatively small supratemporal fenestrae; slenderness of the limbs and the peculiar limb ratios; absence or reduction of dermal armour; enlarged anterior maxillary teeth; antorbital fenestrae reduced or absent; squamosal not bent ventrally; and dental hypertrophy absent (Nopcsa 1928;Mook 1934;Kalin 1955;Kuhn 1968;Steel 1973;Clark 1985Clark , 1986Buscalioni and Sanz 1988). Currently, four valid genera are included in this family: Theriosuchus, Alligatorium, Alligatorellus and Montsecosuchus.…”

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confidence: 99%

Atoposaurid crocodyliforms from the Khorat Group of Thailand: first record of Theriosuchus from Southeast Asia

et al. 2010

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“…Some favor a close relationship of gavials with crocodylids (1,6,9,11), whereas others place them in a separate family/lineage (12).…”

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Generic affinities among crocodilians as revealed by DNA fingerprinting with a Bkm-derived probe.

Aggarwal

Majumdar

Lang

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

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Genetic fingerprint profiles have been succesfublly used for estabishing biological relationships, in linkage analysis, and in studies ofpopulato structure but have not so far been used for ascertalning phylogenetic relationships among related groups of species and genera. This Is largely because these proffles are thought to evolve too rapidly to be informative over large time intervals. However, we show here that among the Crocodilla, whose phylogeny is a debated Issue, these profiles can provide phylogenetically useful formation.By using the probe Bkm-2(8), DNA gerprints with distinct bands distributed in the size range 0.5-23.0 kb were obtained for individuals of 18 species belonging to seven of the eight genera of crocodiflans. These genetic profiles showed hidividual-, species-, and restriction enzyme-specific patterns. In addition, string differences were observed in the copy number of Bkm-related sequences in genomes of different crocodiflan species. The qualitative data from DNA flngirpit proffles, and quantitae data on copy number variation in Bkm-related sequences, suggest that these genera belong to two distinct groups, one of which includes Aligator, Paeosuchuis, and Caiman; the other incudes Crocodylus, Osteolkemus, Tomistoma, and Gavialis. A close relationship between Tomistoma and Gabals is also suggested by these results.Crocodilians are the sole living reptilian representatives of the subclass Archosauria, a highly successful group in the Mesozoic era both in numbers and in diversity. At present, only 8 of the 124 described genera have survived and all of these belong to the same suborder, Eusuchia (1). According to most systematists, there are only 21 extant species, 11 of which belong to Crocodylus, which is by far the largest genus.The natural affinities among living crocodilians have so far been determined primarily on the basis of comparative morphology and paleontological records. However, the resolving power of these approaches has not been adequate to solve certain problematic and confusing relationships within the order Crocodilia. The commonality in life-style of many of the crocodilian taxa may have led to similar adaptative strategies-e.g., convergent skull morphology and head shape. Such convergence in characters, although considered phylogenetically important, has made interpretation of the systematic relationships in crocodilians difficult (2). This has led to the use of other approaches such as cytogenetic parameters (3, 4), analysis ofcoevolving crocodilian-parasite lineages (5), biochemical and immunological studies of proteins (6-8), and Southern blot and DNA sequence analyses of mitochondrial and nuclear ribosomal DNA (9-11) to resolve the natural affinities and evolutionary history of the living crocodilians.On the basis of the approaches described above, there is general agreement in aing Osteolaemus with Crocodylus and the caimans (Caiman, Melanosuchus, Paleosuchus) as the nearest sister taxa ofAlligator, whereas opinion is divided on the affinities of the two gha...

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The Evolution and Classification of the Crocodilia

Cited by 32 publications

References 0 publications

Float or sink: modelling the taphonomic pathway of marine crocodiles (Mesoeucrocodylia, Thalattosuchia) during the death–burial interval

Float or sink: modelling the taphonomic pathway of marine crocodiles (Mesoeucrocodylia, Thalattosuchia) during the death–burial interval

Atoposaurid crocodyliforms from the Khorat Group of Thailand: first record of Theriosuchus from Southeast Asia

Generic affinities among crocodilians as revealed by DNA fingerprinting with a Bkm-derived probe.

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