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MIOCENE COMMUNITIES AND PALEOENVIRONMENTS OF SOUTHERN COSTA RICA
Author(s) -
Graham Alan
Publication year - 1987
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1987.tb12142.x
Subject(s) - mangrove , podocarpus , ecology , late miocene , biology , frugivore , paleontology , structural basin , pollen , habitat
Fossil palynomorphs representing 40 taxa have been recovered from lower(?) Miocene (Uscari sequence) deposits in southern Costa Rica. Three paleocommunities are suggested for the vicinity of the depositional basin—coastal mangrove ( Rhizophora ); some form of the lowland wet forest ( Phaeoceros, Cnemideria , Bombacaceae, Alchornea , cf. Glycydendrum , cf. Banisteriopsis, Hiraea , Myrtaceae ( Eugenia/Myrcia type), and Melastomataceae); and especially the midaltitude (1,000–2,000 m) cloud forest ( Lycopodium, Selaginella , cf. Hymenophyllum, Lophosoria, Pityrogramma, Pteris, Podocarpus (common), Ilex , Ericaceae ( Cavendishia type), and Lisiantehus ). Absent are members of higher altitude communities, and vegetation of drier to arid aspect. Savannahs, important in the interchange of mammalian faunas between North and South America, remain undetected in Gulf/Caribbean Tertiary floras. Paleoenvironments are estimated as wet tropical, similar to present‐day conditions, with a less diverse and insular paleophysiography accounting principally for differences between the early Miocene and modern life zones. This is in contrast to the Paraje Solo assemblage from Veracruz, Mexico, which reflects distinctly cooler climates in the late Miocene. These results are consistent with plate tectonic models for the Gulf/Caribbean region, and emerging global paleotemperature patterns derived from 18 O studies of marine invertebrates.