A combined evidence phylogenetic analysis of Anguimorpha (Reptilia: Squamata)

Abstract

Anguimorpha is a clade of limbed and limbless squamates with ca. 196 extant species and a known fossil record spanning the past 130 million years. Morphology-based and molecule-based phylogenetic analyses disagree on several key points. The analyses differ consistently in the placements of monstersaurs (e.g. Gila Monsters), shinisaurs (Crocodile Lizards), the anguid Anniella (American Legless Lizards), carusioids (Knobby Lizards), and the major clades within Varanus (Monitor Lizards). Given different data sources with such different phylogenetic hypotheses, Anguimorpha is an excellent candidate for a combined phylogenetic analysis. We constructed a data matrix consisting of 175 fossil and extant anguimorphs, and 2281 parsimony-informative characters (315 morphological characters and 1969 molecular characters). We analysed these data using the computer program TNT using the ''new technology search'' with the ratchet. Our result is novel and shows similarities with both morphological and molecular trees, but is identical to neither. We find that a global combined evidence analysis (GCA) does not recover a holophyletic Varanoidea, but omission of fossil taxa reveals cryptic molecular support for that group. We describe these results and others from global morphological analysis, extant-only morphological analysis, molecular data-only analyses, combined evidence analysis of extant taxa, and GCA.

Lizards and amphisbaenians (Reptilia, Squamata) from the late Eocene of Sossís (Catalonia, Spain)

“…The material described herein is housed at the Institut Català de Paleontologia Miquel Crusafont, labelled IPS followed by the corresponding number. Higher-level relationships within squamates are still not resolved, with a conflict between morphology based trees (e.g., Estes et al, 1988;Conrad, 2008;Gauthier et al, 2012) and those based on molecular or combined data sets (e.g., Townsend et al, 2004;Vidal and Hedges, 2005;Wiens et al, 2006Wiens et al, , 2010Wiens et al, , 2012Conrad et al, 2010;Müller et al, 2011). However, most of these analyses support the monophyly of the same major squamate groups: Iguania, Gekkota, Dibamidae, Scincoidea, Anguimorpha, Serpentes, and Lacertiformes, the latter clade encompassing Amphisbaenia in molecular (e.g., Townsend et al, 2004;Wiens et al, 2012) and combined evidence (Wiens et al, 2006(Wiens et al, , 2010Müller et al, 2011) trees, but not those derived from morphology alone (e.g., Estes et al, 1988;Conrad, 2008;Gauthier et al, 2012).…”

“…considered Dopasia to be a synoym of Ophisaurus, as suggested by Sullivan et al (1999), but later (Klembara and Green, 2010) maintained Dopasia for some Oligocene species. Conrad et al (2010) also separated Dopasia harti and Pseudopus apodus from Ophisaurus. Anguine relationships thus remain incompletely resolved, and this complicates referral of new fossil material.…”

Osteology of Gobiderma pulchrum (Monstersauria, Lepidosauria, Reptilia)

“…However, Monstersauria is a stable clade and Estesia mongoliensis is a very Heloderma-like animal based on our observations, a recent combined-evidence analysis of anguimorphs (which included data from the new specimen) (Conrad et al, 2011), and the analysis of the current paper (see below).…”

“…Today, monstersaurs are represented only by two species of Heloderma, known from the southwest of the United States and from western Central America. However, the clade was previously much more speciose (Estes, 1983;Gao and Norell, 2000;Nydam, 2000;Bhullar and Smith, 2008;Conrad, 2008;Conrad et al, 2011). Unfortunately, nearly all fossil monstersaurs are known from very incomplete material, often associated based on size and general similarity of nonoverlapping parts (e.g., Eurheloderma gallicum, Paraderma bogerti, and Primaderma nessovi among others) (Hoffstetter, 1957;Estes, 1964Estes, , 1983Nydam, 2000).…”

“…Monstersauria is an ancient clade of anguimorph lizards that has been distinct at least since the earliest Late Cretaceous (Nydam, 2000;Conrad, 2008;Conrad et al, 2011). Today, monstersaurs are represented only by two species of Heloderma, known from the southwest of the United States and from western Central America.…”