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

Olori, Jennifer C.; Bell, Christopher J.

doi:10.1371/journal.pone.0032450

Cited by 42 publications

(69 citation statements)

References 48 publications

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“…Miniaturization, which is a process usually attributed to paedomorphosis, is frequently correlated with burrowing habits in squamate reptiles [31–33]. This process generates shortening of the gnathic complex and verticalization of the quadrate bone in cryptozoic macrostomatans [34], and thus a regression of the crucial osteological requirements for macrostomy analysed herein.…”

Section: Discussionmentioning

confidence: 99%

Postnatal ontogeny and the evolution of macrostomy in snakes

Scanferla¹

2016

R. Soc. open sci.

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Macrostomy is the anatomical feature present in macrostomatan snakes that permits the ingestion of entire prey with high cross-sectional area. It depends on several anatomical traits in the skeleton and soft tissues, of which the elongation of gnathic complex and backward rotation of the quadrate represent crucial skeletal requirements. Here, the relevance of postnatal development of these skull structures and their relationship with macrohabitat and diet are explored. Contrary to the condition present in lizards and basal snakes that occupy underground macrohabitats, elements of the gnathic complex of most macrostomatan snakes that exploit surface macrohabitats display conspicuous elongation during postnatal growth, relative to the rest of the skull, as well as further backward rotation of the quadrate bone. Remarkably, several clades of small cryptozoic macrostomatans reverse these postnatal transformations and return to a diet based on prey with low cross-sectional area such as annelids, insects or elongated vertebrates, thus resembling the condition present in underground basal snakes. Dietary ontogenetic shift observed in most macrostomatan snakes is directly linked with this ontogenetic trajectory, indicating that this shift is acquired progressively as the gnathic complex elongates and the quadrate rotates backward during postnatal ontogeny. The numerous independent events of reversion in the gnathic complex and prey type choice observed in underground macrostomatans and the presence of skeletal requirements for macrostomy in extinct non-macrostomatan species reinforce the possibility that basal snakes represent underground survivors of clades that had the skeletal requirements for macrostomy. Taken together, the data presented here suggest that macrostomy has been shaped during multiple episodes of occupation of underground and surface macrohabitats throughout the evolution of snakes.

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Section: Discussionmentioning

confidence: 99%

Postnatal ontogeny and the evolution of macrostomy in snakes

Scanferla¹

2016

R. Soc. open sci.

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“…Skull of the uropeltid snake Rhinophis drummondhayi (redrawn from Olori and Bell, ). ( A ) Left lateral view; ( B ) dorsal view.…”

Section: Discussionmentioning

confidence: 99%

“…Data for the rare snakes Anomochilus leonardi and Casarea dussumieri were obtained from the works of Rieppel and Maisano (2007) and Maisano and Rieppel (2007), respectively. Data on uropeltid snakes were complemented with the work of Olori and Bell (2012). A useful source of information was also the series of CT-derived animations available on DigiMorph.org for both lizards and snakes.…”

Section: Methodsmentioning

confidence: 99%

Primary homologies of the circumorbital bones of snakes

Palci

Caldwell

2013

Journal of Morphology

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Some snakes have two circumorbital ossifications that in the current literature are usually referred to as the postorbital and supraorbital. We review the arguments that have been proposed to justify this interpretation and provide counter-arguments that reject those conjectures of primary homology based on the observation of 32 species of lizards and 81 species of snakes (both extant and fossil). We present similarity arguments, both topological and structural, for reinterpretation of the primary homologies of the dorsal and posterior orbital ossifications of snakes. Applying the test of similarity, we conclude that the posterior orbital ossification of snakes is topologically consistent as the homolog of the lacertilian jugal, and that the dorsal orbital ossification present in some snakes (e.g., pythons, Loxocemus, and Calabaria) is the homolog of the lacertilian postfrontal. We therefore propose that the terms postorbital and supraorbital should be abandoned as reference language for the circumorbital bones of snakes, and be replaced with the terms jugal and postfrontal, respectively. The primary homology claim for the snake "postorbital" fails the test of similarity, while the term "supraorbital" is an unnecessary and inaccurate application of the concept of a neomorphic ossification, for an element that passes the test of similarity as a postfrontal. This reinterpretation of the circumorbital bones of snakes is bound to have important repercussions for future phylogenetic analyses and consequently for our understanding of the origin and evolution of snakes.

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“…) and in extant amphisbaenians and uropeltid snakes (Maisano et al . ; Olori & Bell ). The dorsal process, slightly medially inclined in Orovenator and D. limbatus , is also present in the Permian parareptiles Colobomycter pholeter (MacDougall et al .…”

Section: Descriptionmentioning

confidence: 98%

A redescription of Orovenator mayorum (Sauropsida, Diapsida) using high‐resolution μCT, and the consequences for early amniote phylogeny

Ford

Benson

2018

Papers in Palaeontology

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The earliest known neodiapsid Orovenator mayorum from the lower Permian of Oklahoma is redescribed using high‐resolution μCT, revealing remarkable details of the skull anatomy. Our findings are relevant to both palaeoecology (suggesting burrowing and nocturnality) and phylogeny. Orovenator and other sauropsids share at least 16 character states with varanopids, many of which were not recognized by previous studies. These include a rounded subnarial shelf of the premaxilla, a posterodorsal extension of the external naris, the asymmetrical bifurcation of the anterior vomer, and a prominent dorsomedial shelf of the surangular. This exceptional degree of similarity between Orovenator and varanopids (a nominally synapsid clade) questions our current understanding of relationships among early amniotes. We test this by including Orovenator in a phylogenetic data matrix used in an earlier study to differentiate between early diapsids and synapsids, and find a monophyletic clade of Orovenator + varanopids within Diapsida. Recent phylogenetic research on early amniote evolution has focused on resolving intra‐clade affiliations rather than the interrelationships of major taxonomic groups. Nevertheless, the relative incompleteness of existing phylogenetic character lists for early amniotes can only be remedied by detailed cross‐clade assessment. We therefore suggest that early amniote relationships require further scrutiny before we can confidently accept or reject our new phylogenetic hypothesis.

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

Cited by 42 publications

References 48 publications

Postnatal ontogeny and the evolution of macrostomy in snakes

Postnatal ontogeny and the evolution of macrostomy in snakes

Primary homologies of the circumorbital bones of snakes

A redescription of Orovenator mayorum (Sauropsida, Diapsida) using high‐resolution μCT, and the consequences for early amniote phylogeny

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