Image from the Biodiversity Heritage Library.
Contributed by Museum of Vertebrate Zoology, University of California, Berkeley.
| www.biodiversitylibrary.org
Transcription
(Course American fauna was evolved largely insitu)
2 tropical units evolved independently since Pleocene
End of Pleocene isthmus link submerged
re-established in Pliocene - Somillions yrs.)
South American element (evolution during
Cenozoic, trapped S. of isthmus)
(e.g. Lepistates, Neutivateres)
Middle Amer. element (trop. types occurred
N. of isthmus when link destroyed in E. Eocene)
(e.g. Geosaurus, Iguana, Basiliscus.)
Occurred further North (eg Colorado, Montana)
during Eocene but @ present time forms
with N. limit in Guatemala
(corresponds to Arcto-PA. Geoflora)
Old Northern element (typical warmers in Eocene
occurred in Oak-Quercus forest to N of
Cayman + Mexico) (eg. Ranids,
sieved lizard)
Geoflora & few groups moved down partly later, (eg. Iguanas)
eg. Melanocatur
+ became associate w/ M. Amer. el. during
Eocene
Young Northern element (genus + species
groups whose derived from trop. Ancestors -
became adapted to xeric condition of S.
+ Mex. Plateau)
Environment developed in middle to late
Cenozoic - evolved north
e.g. Crotalus
Sceloporus
Uranidophorus