The systematic relationships of the snake genus Anomochilus

Cundall, David; Wallach, Van; Rossman, Douglas A.

doi:10.1111/j.1096-3642.1993.tb02536.x

Cited by 93 publications

(39 citation statements)

References 57 publications

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“…Homoplastic morphology frequently results from miniaturization of vertebrates because of similar problems and constrained solutions associated with size reduction [64]. That may be one reason why phylogenies based on osteology alone tend to group uropeltids and Anomochilus together [2], [4], while those based on molecular or combined evidence (osteology, plus molecular or soft tissue data) are more variable (e.g., [2], [6], [9], [11], ). Morphological features associated with burrowing and small size may be exacerbated in uropeltids and clades hypothesized to be their close relatives (e.g., Anomochilus ) if those features were overprinted on existing modifications retained from an earlier period of fossoriality and size-reduction hypothesized to have played a role in the origin of snakes [55], [65].…”

Section: Discussionmentioning

confidence: 99%

“…Based on morphological data, the clade was hypothesized to be the sister taxon to either Anomochilus [2]–[6] or Anilius ([7]; Cylindrophis and Anomochilus were not included), or along with Cylindrophis , Anomochilus , and Anilius , to be part of a series of successive outgroups to all other alethinophidian snakes [2], [5], [6]. Hypotheses based on molecular data are more variable, with uropeltids placed as the sister taxon to Calabaria [8], Tropidophis and Casarea [9], Caenophidia [10], Liotyphlops [7], Cylindrophis [6], [9], [11]–[13], or Cylindrophis and Anomochilus [14].…”

Section: Introductionmentioning

confidence: 99%

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Comparative Skull Morphology of Uropeltid Snakes (Alethinophidia: Uropeltidae) with Special Reference to Disarticulated Elements and Variation

Olori

Bell²

2012

PLoS ONE

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Uropeltids form a diverse clade of highly derived, fossorial snakes that, because of their phylogenetic position among other alethinophidian lineages, may play a key role in understanding the early evolution of cranial morphology in snakes. We include detailed osteological descriptions of crania and mandibles for eight uropeltid species from three nominal genera (Uropeltis, Rhinophis, and Brachyophidium) and emphasize disarticulated elements and the impact of intraspecific variation on previously proposed morphological characters used for phylogenetic analysis. Preliminary analysis of phylogenetic relationships strongly supports a clade composed exclusively of species of Plectrurus, Uropeltis, and Rhinophis. However, monophyly of each of those genera and Melanophidium is not upheld. There is moderate support that Sri Lankan species (e.g., Rhinophis and Uropeltis melanogaster) are monophyletic with respect to Indian uropeltids. Previously proposed characters that are phylogenetically informative include the shape of the nasals, length of the occipital condyle, level of development of the posteroventral process of the dentary, and participation of the parietal in the optic foramen. Additionally, thirty new features that may be systematically informative are identified and described, but were not verified for their utility. Such verification must await availability of additional disarticulated cranial material from a larger sample of taxa. All characters require further testing through increased focus on sources and patterns of intraspecific variation, inclusion of broader taxonomic samples in comparative studies, and exploration of skeletal development, sexual dimorphism, and biogeographic patterns. Additionally, trends in the relative enlargement of the sensory capsules, reduction in cranial ossification and dentition, fusion of elements, and the appearance of novel morphological conditions, such as the structure and location of the suspensorium, may be related to fossoriality and miniaturization in some uropeltid taxa, and may complicate analysis of relationships within Uropeltidae and among alethinophidian snakes.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparative Skull Morphology of Uropeltid Snakes (Alethinophidia: Uropeltidae) with Special Reference to Disarticulated Elements and Variation

Olori

Bell²

2012

PLoS ONE

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“…In that study, the Booidea consists of Cylindrophiidae, Boidae, Bolyeriidae, Pythonidae, and Uropeltidae, as well as the monotypic families Anomochilidae, Calabariidae, Loxocemidae, Xenopeltidae, and Xenophiidae. The traditional Booidea, consisting of Boidae, Pythonidae, Loxocemidae, Xenopeltidae, and Tropidophiidae, represents a paraphyletic assemblage in this taxonomy, as it is in most cladistic analyses [32], [74]–[76], [78]–[80], [83], [84], [89]–[91]. Colubroidea retains the traditionally broad definition of all Caenophidia exclusive of Acrochordidae.…”

Section: Methodsmentioning

confidence: 99%

The Earliest Colubroid-Dominated Snake Fauna from Africa: Perspectives from the Late Oligocene Nsungwe Formation of Southwestern Tanzania

2014

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The extant snake fauna has its roots in faunal upheaval occurring across the Paleogene - Neogene transition. On northern continents, this turnover is well established by the late early Miocene. However, this transition is poorly documented on southern landmasses, particularly on continental Africa, where no late Paleogene terrestrial snake assemblages are documented south of the equator. Here we describe a newly discovered snake fauna from the Late Oligocene Nsungwe Formation in the Rukwa Rift Basin of Tanzania. The fauna is small but diverse with eight identifiable morphotypes, comprised of three booids and five colubroids. This fauna includes Rukwanyoka holmani gen. et sp. nov., the oldest boid known from mainland Africa. It also provides the oldest fossil evidence for the African colubroid clade Elapidae. Colubroids dominate the fauna, comprising more than 75% of the recovered material. This is likely tied to local aridification and/or seasonality and mirrors the pattern of overturn in later snake faunas inhabiting the emerging grassland environments of Europe and North America. The early emergence of colubroid dominance in the Rukwa Rift Basin relative to northern continents suggests that the pattern of overturn that resulted in extant faunas happened in a more complex fashion on continental Africa than was previously realized, with African colubroids becoming at least locally important in the late Paleogene, either ahead of or as a consequence of the invasion of colubrids. The early occurrence of elapid snakes in the latest Oligocene of Africa suggests the clade rapidly spread from Asia to Africa, or arose in Africa, before invading Europe.

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“…Considerations of morphological data have mostly hypothesized that Anilioidea is monophyletic (Rieppel 1988; Scanlon and Lee 2000; Tchernov et al. 2000; Lee and Scanlon 2002; Rieppel and Zaher 2000) or perhaps paraphyletic (Cundall et al. 1993; Greene 1997; Cundall and Greene 2000), but that they are collectively the proximate outgroup(s) to other (macrostomatan) alethinophidians (e.g.…”

Section: Previous Hypothesesmentioning

confidence: 99%

The phylogenetic position of Anomochilidae (Reptilia: Serpentes): first evidence from DNA sequences

Gower

Vidal

Spinks

et al. 2005

J Zoological System

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Previously, anilioids (Aniliidae, Anomochilidae, Cylindrophiidae and Uropeltidae) were considered the only extant, non-macrostomatan alethinophidian snakes. Although their monophyly and intrarelationships remained poorly established, their fossoriality, small gape, and inferred phylogenetic position have been important evidence in orthodox scenarios about early snake evolution. Recent molecular studies including aniliids, cylindrophiids and uropeltids indicate anilioid polyphyly, with the latter two families comprising a clade nested within Macrostomata. We carried out the first molecular phylogenetic analysis to include the very poorly known and seemingly rare Anomochilidae. Only partial sequences of 12S and 16S rRNA mitochondrial genes could be amplified from tissue collected from a single dead specimen of Anomochilus leonardi. Amplification failed for nuclear and other mitochondrial genes, and for all the investigated genes for the holotype and paratype of A. leonardi. Analyses recovered a para-or polyphyletic Anilioidea. Anomochilus is recovered as most closely related to Cylindrophis maculatus (rendering Cylindrophiidae possibly paraphyletic). The relatively small amount of available data produces only moderate levels of support, but the stability of taxa and agreement across different analytical methods and with larger analyses of snake phylogeny support the abandonment of Anilioidea as a natural taxon, and the recognition of a higher category for a clade comprising Asian anilioids (Anomochilidae, Cylindrophiidae and Uropeltidae).

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The systematic relationships of the snake genus Anomochilus

Cited by 93 publications

References 57 publications

Comparative Skull Morphology of Uropeltid Snakes (Alethinophidia: Uropeltidae) with Special Reference to Disarticulated Elements and Variation

Comparative Skull Morphology of Uropeltid Snakes (Alethinophidia: Uropeltidae) with Special Reference to Disarticulated Elements and Variation

The Earliest Colubroid-Dominated Snake Fauna from Africa: Perspectives from the Late Oligocene Nsungwe Formation of Southwestern Tanzania

The phylogenetic position of Anomochilidae (Reptilia: Serpentes): first evidence from DNA sequences

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