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The Major Clades of Living Snakes: Morphological Evolution, Molecular Phylogeny, and Divergence Dates
Ist Teil von
Reproductive Biology and Phylogeny of Snakes, 2011, p.67-108
Ort / Verlag
United States: CRC Press
Erscheinungsjahr
2011
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Snakes are among the most charismatic and highly-studied organisms
(Greene 1997), yet our understanding of their early evolution and
phylogeny remains in a state of flux. Extensive anatomical information
(e.g., Underwood 1967; McDowell 1974, 1975, 1979), analyzed using
quantitative phylogenetic methods (e.g., Kluge 1991; Cundall et al. 1993),
had led to a broad consensus on relationships among living snakes (Lee
and Scanlon 2002; Rieppel et al. 2003). The tiny, burrowing, worm-like
blindsnakes (scolecophidians) were considered the most basal clade of
living snakes, followed by other small burrowing taxa with restricted gapes
(pipesnakes and shieldtail snakes). The partly surface-active, and moderategaped sunbeam snakes (Xenopeltis and Loxocemus) were transitional forms,
while the typical, generally surface-active and large-gaped snakes (such
as pythons, boas, and colubroids) were inferred to represent a single,
derived radiation (“core macrostomatans”). This phylogeny implied
that snake evolution involved consistent trends towards greater surface
activity, increased body size, and enlarged gape (e.g., Underwood 1967;
Rodríguez-Robles et al. 1999). However, some studies of primitive fossil
snakes with large body size and extensive gapes did not support this
scenario, although the exact phylogenetic position of these fossils remains
debated (e.g., Caldwell 2007; Wilson et al. 2010). Most recently, increasingly
large molecular sequence datasets have further challenged the traditional
scenario (Slowinski and Lawson 2002; Wilcox et al. 2002; Lawson et al. 2005;
Vidal et al. 2007a, 2007b; Wiens et al. 2008; Burbrink and Crother 2010).