Nice snake, shame about the legs

Coates, Michael I.; Ruta, Marcello

doi:10.1016/s0169-5347(00)01999-6

Cited by 53 publications

(46 citation statements)

References 16 publications

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“…Specializations shared by snakes, amphisbaenians and dibamids include the loss, reduction and consolidation of skull bones; braincase enclosure; loss or reduction of limbs and girdles; and increased uniformity along the vertebral column (Coates & Ruta 2000). The terrestrial origin hypothesis agrees with data derived from the sensory system of living snakes and in particular with the peculiarities of their eyes (Walls 1940).…”

supporting

confidence: 77%

Molecular evidence for a terrestrial origin of snakes

Vidal¹,

Hedges

2004

Proc. R. Soc. Lond. B

144

123

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Biologists have debated the origin of snakes since the nineteenth century. One hypothesis suggests that snakes are most closely related to terrestrial lizards, and reduced their limbs on land. An alternative hypothesis proposes that snakes are most closely related to Cretaceous marine lizards, such as mosasaurs, and reduced their limbs in water. A presumed close relationship between living monitor lizards, believed to be close relatives of the extinct mosasaurs, and snakes has bolstered the marine origin hypothesis. Here, we show that DNA sequence evidence does not support a close relationship between snakes and monitor lizards, and thus supports a terrestrial origin of snakes.

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supporting

confidence: 77%

Molecular evidence for a terrestrial origin of snakes

Vidal¹,

Hedges

2004

Proc. R. Soc. Lond. B

144

123

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“…Anguis, the European Slow Worm), xenosaurs, the Gila Monster and Beaded Lizard (genus Heloderma), and the successful varanids (Monitor Lizards). Under current hypotheses of relationship, Anguimorpha also includes snakes (Rieppel, 1988 b;Caldwell & Lee, 1997;Lee, 1998;Coates & Ruta, 2000;Lee & Caldwell, 2000;Tchernov et al, 2000), but the highly specialized, burrowing dibamids and amphisbaenians are more problematic, with recent analyses linking them alternatively to snakes (e.g. Rieppel & Zaher, 2000 a, b), to gekkotans (Lee, 1998;Caldwell, 1999;Lee & Caldwell, 2000), or to teiids (Wu et al, 1993;Wu, Brinkman & Russell, 1996;Kearney, 1999).…”

Section: (C) Iguaniamentioning

confidence: 99%

“…Dal Sasso & Pinna, 1997;Lee & Caldwell, 2000;Caldwell & Albino, 2001). The phylogenetic position of this early snake material (basal or crown group) is still uncertain (Coates & Ruta, 2000).…”

Section: (E) Anguimorphamentioning

confidence: 99%

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At the feet of the dinosaurs: the early history and radiation of lizards

2003

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Lizards, snakes and amphisbaenians together constitute the Squamata, the largest and most diverse group of living reptiles. Despite their current success, the early squamate fossil record is extremely patchy. The last major survey of squamate palaeontology and evolution was published 20 years ago. Since then, there have been major changes in systematic theory and methodology, as well as a steady trickle of new fossil finds. This review examines our current understanding of the first 150 million years of squamate evolution in the light of the new data and changing ideas. Contrary to previous reports, no squamate fossils are currently documented before the Jurassic. Nonetheless, indirect evidence predicts that squamates had evolved by at least the middle Triassic, and had diversified into existing major lineages before the end of this period. There is thus a major gap in the squamate record at a time when key morphological features were evolving. With the exception of fragmentary remains from Africa and India, Jurassic squamates are known only from localities in northern continents (Laurasia). The situation improves in the Early Cretaceous, but the southern (Gondwanan) record remains extremely poor. This constrains palaeobiogeographic discussion and makes it difficult to predict centres of origin for major squamate clades on the basis of fossil evidence alone. Preliminary mapping of morphological characters onto a consensus tree demonstrates stages in the sequence of acquisition for some characters of the skull and postcranial skeleton, but many crucial stages--most notably those relating to the acquisition of squamate skull kinesis--remain unclear.

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“…Boas and pythons, as well as all more basal (more 'primitive') snakes (such as blind snakes, thread snakes, pipe snakes and shield tails) retain much-reduced pelvic and hind limb rudiments (Kley et al 2002). Placing the fossil snakes with well-developed hind limbs as advanced macrostomatans (i.e., with boas and pythons) raises the possibility that limbs were re-developed from rudiments in these fossil snakes (Greene and Cundall 2000;Tchernov et al 2000), something that many find biologically implausible (e.g., Coates and Ruta 2000;Rage and Escuillie´2003). Alternatively, this phylogenetic hypothesis might imply that limbs were lost more than once and/or that 'missing' fossil snake lineages might resolve this case of character conflict (see discussion in Rieppel et al 2003).…”

Section: 'Splitters' and 'Lumpers'mentioning

confidence: 99%

The Poverty of Taxonomic Characters

Rieppel

Kearney

2006

Biol Philos

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The theory and practice of contemporary comparative biology and phylogeny reconstruction (systematics) emphasizes algorithmic aspects but neglects a concern for the evidence. The character data used in systematics to formulate hypotheses of relationships in many ways constitute a black box, subject to uncritical assessment and social influence. Concerned that such a state of affairs leaves systematics and the phylogenetic theories it generates severely underdetermined, we investigate the nature of the criteria of homology and their application to character conceptualization in the context of transformationist and generative paradigms. Noting the potential for indeterminacy in character conceptualization, we conclude that character congruence (the coherence of character statements) relative to a hierarchy is a necessary, but not a sufficient, condition for phylogeny reconstruction. Specifically, it is insufficient due to the lack of causal grounding of character hypotheses. Conceptualizing characters as homeostatic property cluster natural kinds is in accordance with the empirical practice of systematists. It also accounts for the lack of sharpness in character conceptualization, yet requires character identification and re-identification to be tied to causal processes.

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Nice snake, shame about the legs

Cited by 53 publications

References 16 publications

Molecular evidence for a terrestrial origin of snakes

Molecular evidence for a terrestrial origin of snakes

At the feet of the dinosaurs: the early history and radiation of lizards

The Poverty of Taxonomic Characters

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