Paleogen e Land Mammal Faunas of South America; a Respo nse to Global Climatic Change s and Indigen ous Floral Diversity

WOODBURNE, M.O.; GOIN FRANCISCO J.; BOND, M.; CARLINI, A.A.; GELFO, J.; LÓPEZ, G.; IGLESIAS, A.; ZIMICZ ANA N.

JOURNAL OF MAMMALIAN EVOLUTION

SPRINGER

Lugar: New York; Año: 2014 vol. 21 p. 1 - 73

1064-7554

An apprai sal of Paleoge ne flor al and land mam-mal faunal dynam ics in So uth Am erica sugges ts that both biotic elem ents respon ded at rate and extent general ly com-parabl e to that portrayed by the global clima te patt ern of the interval. A maj or difference in the So uth Ameri can record is the initial as well as subseq uent much greater diver sity of b ot h Ne ot ro pi ca l a nd Aus t r al f lo ra s r ela t i ve t o N o r th Ameri can counte rparts. Converse ly, the concurrent mam mal faunas in So uth Ameri ca did no t match, much less exceed, the diver sity seen to the north. It appears unlikely that this difference is solel y due to the virtual absence of immig rants subsequent to the i nit i al d ispersal o f m ammals to So uth Ameri ca, and cannot be explain ed solely by the different collecti ng hist ories of the two regions. Possible roles played by non-mamm alian verte brates in niche exp loitation remain to be explor ed. The Paleogene floras of Patagonia and Chile show a cli-matic pattern that approximates that of North America, with an increase in both Mean Annual Temperature (MAT) and Mean Annual Precipitation (MAP) from the Paleocene into the Early Eocene Climatic Optimum (EECO), although the Paleocene-Eocene Thermal Maximum (PETM) is not recog-nized in the available data set. Post-EECO temperatures de-clined in both regions, but more so in the north than the south, which also retained a higher rate of precipitation. The So uth Ameri can Paleoge ne mam mal faunas devel-oped gradual , but distinct, changes in compo sition and di-versity as the EECO was approac hed, but actually dec lined some what during its peak, contr ary to the record in North Ameri ca. At abou t 40 Ma, a post-E ECO decline was recov-ered in bo th hemispher es, but the So uth Ameri can record achiev ed its greatest diversity then, rather than at the peak of the EECO as in the north. This post-E ECO faunal turno ver apparen tly was a response to the changing condit ions when global climat e was de terior ating toward the Oligocen e. Unde r the p rogressive ly more tem perate to season ally arid condit ions in South Am erica, this turno ver refl ected a major change from the more a rchaic, and more tropical to subtro pical-adapt ed mam mals, to the beginn ing of the ulti-mately modern South American fauna, achieved compl etely by the Eoc ene-Oligocen e t ransition. Inte restingly, hy pso-donty was ach ieved by South Ameri can cursorial mam mals about 15 ? 20 m.y. earli er than in Nor th Ameri ca. In addition to being compo sed of essent ially different groups of mam-mals, those of the South Ameri can conti nent seem to have respon ded to the climati c changes a ssociated with the ECCO and subsequent conditions i n a patter n t hat was init ially compa rable to, but subseq uently different from , their North Ameri can coun terparts.