Abstract
Teiid lizards are well represented in the fossil record and are common components of modern ecosystems in North and South America. Many fossils were referred to the cnemidophorine teiid group (whiptails, racerunners and relatives), particularly from North America. However, systematic interpretations of morphological features in cnemidophorines were hampered by the historically problematic taxonomy of the clade, and the biogeography and chronology of cnemidophorine evolution in North America is poorly understood from the fossil record. Few fossil cnemidophorines were identified with an apomorphy-based diagnosis, and there are almost no fossil cnemidophorines that could be used to anchor node calibrations. Here, I describe a cnemidophorine from the Miocene Ogallala Group of Nebraska and diagnose the fossil using apomorphies. In that process, I clarify the systematic utility of several morphological features of cnemidophorine lizards. I refer the fossil to the least inclusive clade containing Aspidoscelis, Holcosus and Pholidoscelis. The most conservative minimum age of the locality of the fossil is a fission-track date of 6.3 Ma, but mammal biochronology provides a more refined age of 9.4 Ma, which can be used as a minimum age for the crown cnemidophorine clade in divergence time analyses. The fossil indicates that a cnemidophorine lineage that does not live in Nebraska today inhabited the area during the Miocene. I refrain from naming a new taxon pending discovery of additional fossil material of the lineage to which the fossil belonged.
Highlights
Teiidae is a clade of diurnal and largely terrestrial lizards with a substantial Cenozoic fossil record from North and South America [1,2,3]
Extant Teiidae is divided into two clades, a clade containing the large-bodied tegus and their relatives (Tupinambinae), and Teiinae, a clade containing Dicrodon, Teius and a group known as the cnemidophorines
The fossil was identified using apomorphies grounded in a phylogenetic hypothesis based on analyses of targeted-sequence capture data [33,44]
Summary
Teiidae is a clade of diurnal and largely terrestrial lizards with a substantial Cenozoic fossil record from North and South America [1,2,3]. Borioteiioidea, a clade hypothesized to be the sister group of extant Teiidae ([4,5], but see [6,7,8,9,10]), is known royalsocietypublishing.org/journal/rsos R. Miocene (23–5.3 Ma) Pliocene (5.3–2.58 Ma) from the Cretaceous of North America and Eurasia Barbatteiidae, another potential sister clade of extant Teiidae, is known from the Cretaceous of Europe [11,12]. Extant Teiidae is divided into two clades, a clade containing the large-bodied tegus and their relatives (Tupinambinae), and Teiinae, a clade containing Dicrodon, Teius and a group known as the cnemidophorines (whiptails, racerunners and relatives). There are no cnemidophorines or other teiids known from the Palaeogene of North America
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