FIGURE 1. Phylogeny of Anguidae with tree topology adapted from Zheng and Wiens (2016). Branch lengths are arbitrary. The node calibrated in text is represented by the circle labelled Gerrhonotinae. The specimen UCMP 163737 is attached to the Elgaria panstem lineage. Character state changes are labelled by black bars, and parentheses around a change indicate that the state change was not present in all specimens examined. Abbreviations: a.Px.f = anterior premaxillary foramen; do.ap = dorsal ossification of the alveolar plate; pa.pr = palatal process; Px.br = premaxillary bridge.

FIGURE 2. Oldest fossil of Elgaria, UCMP 163737. All scale bars equal 1 mm. 1, UCMP 163737 in anterior view. 2, UCMP 163737 in posterior view. Anatomical abbreviations: a.Px.f = anterior premaxillary foramen; do.ap = dorsal ossification of the alveolar plate; pa.pr = palatal process.

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FIGURE 3. Premaxillae of extant gerrhonotines. All scale bars equal 1 mm. All images are in anterior view. 1, Elgaria multicarinata TMM 8988. 2, Elgaria kingii TMM M-8981. 3, Gerrhonotus parvus SRSU 5358. SRSU 5358 is an alcohol-preserved specimen that was scanned at the University of Texas High-Resolution CT facility (UTCT). Anatomical abbreviations: a.Px.f = anterior premaxillary foramen; Px.br = premaxillary bridge.

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FIGURE 4. UCMP 163012 in medial view. Scale bar equals 1 mm. Anatomical abbreviation: ims = intramandibular septum.

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