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Squamate study places mosasaurs near to snakes, not varanids
New in PLoS ONE:
Tod W. Reeder, Ted M. Townsend, Daniel G. Mulcahy, Brice P. Noonan,
Perry L. Wood Jr., Jack W. Sites Jr. & John J. Wiens (2015)
Integrated Analyses Resolve Conflicts over Squamate Reptile Phylogeny
and Reveal Unexpected Placements for Fossil Taxa.
PLoS ONE 10(3): e0118199
Squamate reptiles (lizards and snakes) are a pivotal group whose
relationships have become increasingly controversial. Squamates
include >9000 species, making them the second largest group of
terrestrial vertebrates. They are important medicinally and as model
systems for ecological and evolutionary research. However, studies of
squamate biology are hindered by uncertainty over their relationships,
and some consider squamate phylogeny unresolved, given recent
conflicts between molecular and morphological results. To resolve
these conflicts, we expand existing morphological and molecular
datasets for squamates (691 morphological characters and 46 genes, for
161 living and 49 fossil taxa, including a new set of 81 morphological
characters and adding two genes from published studies) and perform
integrated analyses. Our results resolve higher-level relationships as
indicated by molecular analyses, and reveal hidden morphological
support for the molecular hypothesis (but not vice-versa).
Furthermore, we find that integrating molecular, morphological, and
paleontological data leads to surprising placements for two major
fossil clades (Mosasauria and Polyglyphanodontia). These results
further demonstrate the importance of combining fossil and molecular
information, and the potential problems of estimating the placement of
fossil taxa from morphological data alone. Thus, our results caution
against estimating fossil relationships without considering relevant
molecular data, and against placing fossils into molecular trees (e.g.
for dating analyses) without considering the possible impact of
molecular data on their placement.