Paleogene anguimorph lizards from the Western Interior of North America and extant morphological analogues.

(A) Peltosaurus granulosus† (Anguidae) skull in right lateral view, and B) right humerus in medial view (AMNH 42913), indicated by arrow, Orellan (33.9–31.8 Ma). (C) Gerrhonotus infernalis (Anguidae) skull and right mandible in right lateral view and (D) left humerus in medial view (FMNH 22452), extant. (E) Heloderma suspectum (Helodermatidae) skull and left mandible in left lateral view, reflected for continuity, and (F) left humerus in medial view (UCMP 117512), extant. (G) Helodermoides tuberculatus† (Anguidae) left mandible in lateral view, reflected for continuity, and (H) right humerus in medial view (UNSM 4511), Chadronian (37.0–33.9 Ma). (I) Helodermoides tuberculatus† skull, mandibles, and cervical osteoderms in right lateral view (USNM V 13869), Chadronian. A-I are oriented with anterior to the right. Scale bar = 1 cm. USNM V 13869 (I) image courtesy of the Smithsonian Institution.