Recent news stories have claimed evidence for evolution.  But has evolution been observed or assumed?

Snake transitional form:  In Nature last week, Longrich et al. claimed fossil evidence for a transitional form between lizards and snakes.  The fossil, named Coniophus, was known since 1892 from fragments, but the authors claim newly-discovered skull and vertebral parts establish its ancestral position.  The authors call it, however, a “mosaic” of features with “synapomorphies,” which means in cladistics traits shared by two taxa and their most recent common ancestor.  Their diagrams show a lizard head, a snake head and the Coniophus reconstructed head, each looking distinctive.  If this is a transitional form, furthermore, it is rare: “Snakes are the most diverse group of lizards, but their origins and early evolution remain poorly understood owing to a lack of transitional forms,” they said.  Owing primarily to its small size and non-motile jaw, they believe, “Coniophis therefore represents a transitional snake, combining a snake-like body and a lizard-like head.” (Longrich et al., “A transitional snake from the Late Cretaceous period of North America,” Nature 488, 09 August 2012, pp. 205–208, doi:10.1038/nature11227).

There has been a long-standing debate between evolutionists whether snakes evolved in the ocean or on land.  The authors feel Coniophus suggests a land origin: “its small size and reduced neural spines indicate fossorial habits, suggesting that snakes evolved from burrowing lizards.”  It would seem, however, that one oddball does not justify the assumed evolutionary story that follows: “Subsequent to the evolution of a serpentine body and carnivory, snakes evolved a highly specialized, kinetic skull, which was followed by a major adaptive radiation in the Early Cretaceous period. This pattern suggests that the kinetic skull was a key innovation that permitted the diversification of snakes.”  Coniophus, however, lacked the kinetic skull.  The Editors’ Summary is tentative, saying that the study “has come up with some facts that favour a land-based genesis for snakes,” and “suggests that early snakes were burrowers that achieved their elongate form before evolving the characteristic highly mobile skull of modern snakes.”  There are, however, legless lizards; it is not clear why the authors did not comment on that possible interpretation of this fossil….

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