. Advances in herpetology and evolutionary biology : essays in honor of Ernest E. Williams. Williams, Ernest E. (Ernest Edward); Herpetology; Evolution. Figure 11. Suggested area of origin (stippled) and later dispersals (arrows) in Anguidae. Glyptosaur movement was in the Eocene. Date of diploglossine dispersal to South America not known. Ophisaurs not shown. Map data as in Figure 3. Dates at end of arrows represent earliest known pre-Pleistocene fossils of the group in the area. See text for further explanation. have originated subsequent to the early diversification of anguids in the Creta-
. Advances in herpetology and evolutionary biology : essays in honor of Ernest E. Williams. Williams, Ernest E. (Ernest Edward); Herpetology; Evolution. Figure 11. Suggested area of origin (stippled) and later dispersals (arrows) in Anguidae. Glyptosaur movement was in the Eocene. Date of diploglossine dispersal to South America not known. Ophisaurs not shown. Map data as in Figure 3. Dates at end of arrows represent earliest known pre-Pleistocene fossils of the group in the area. See text for further explanation. have originated subsequent to the early diversification of anguids in the Creta- ceous. The anniellines are North Ameri- can endemics, first appearing in the Early Eocene, and again suggest a North Ameri- can origin for Anguidae. The extinct varanoid necrosaurs oc- curred with true varanids in the Late Cretaceous of North America and Central Asia (different genera appear to be in- volved and the Asian forms have just re- cently been described by Borsuk- BiaJynicka, 1982). In the Early Cenozoic there are two derived forms in Europe (Fig. 12). Necrosaurs may have origi- nated in Asia, from varanoid ancestors, and dispersed across the Bering connec- tion together with the true varanids dur- ing the Late Cretaceous, but it is not pos- sible to falsify an origin in North America or Asiamerica, perhaps from a common stem with the helodermatids. The Eo- cene European necrosaurs are derived with respect to the North American Late Cretaceous genus Parasaniwa, and prob- ably reached Europe after its emergence in the very early Cenozoic. The helodermatids (Fig. 12), now iso- lated in southwestern North America, were once more widely distributed; they occur in the Late Faleogene of Nebraska and Colorado {Heloderma), and had un- doubted members in the Faleogene of France (Eurheloderma). Fossible helo- dermatids occur in the Late Cretaceous of Wyoming (Paraderma), and if this record is correctly referred, the group had a long North American history. Renous (1979) suppos
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Keywords: ., bookauthorharvarduniver, bookcentury1900, booksubjectherpetology
