The marine dO record indicates precipitous cooling or significant expansion of Antarctic ice volume across the Eocene-Oligocene epoch boundary at 33.7 Ma. This climatic step is also found in estimates of decreased paleoprecipitation from paleosols in Oregon, Montana, and Nebraska but is only a part of a long-term decline across the Eocene-Oligocene transition rather than a sudden shift. This su...

Tropical South America has the highest plant diversity of any region today, but this richness is usually characterized as a geologically recent development (Neogene or Pleistocene). From caldera-lake beds exposed at Laguna del Hunco in Patagonia, Argentina, paleolatitude approximately 47 degrees S, we report 102 leaf species. Radioisotopic and paleomagnetic analyses indicate that the flora was ...

Introduction.-Following the discovery and description of a titanotherel in the Poway sands of San Diego County, continued excavation in this important Eocene horizon has produced small lots of mammalian remains. One of these included specimens of a tarsiid primate and a mixodectid. Worthy of mention is the fact that the former represents a third member of the Tarsiidae to be discovered in the e...

A new fossiliferous locality is discovered from the upper Eocene Aydim Formation, in Dhofar, Southern Sultanate of Oman. A left ulna of rsinoitherium is described, and cranial and postcranial specimens found in close proximity are referred to the same taxon. The locality is romising for the recovery of additional fossil specimens. Moreover, the presence of Arsinoitherium in Oman is of biogeogra...

The tectonic opening of the Tasmanian Gateway and Drake Passage represented crucial geographic requirements for Cenozoic development Antarctic Circumpolar Current (ACC). Particularly complexity has hampered exact dating deepening phases, consequential onset throughflow ACC. One obstacles is putting key regional events, recorded in southern Patagonian sediments, absolute time. For that purpose, ...

Opening of Southern Ocean gateways may have had a controlling influence on the evolution of global climate. The largest step in the history of Cenozoic climate, from an Eocene bGreenhouseQ toward the modern glaciated state, is correlated with opening of a deep water connection between the Southern Indian and Southern Pacific Oceans. This study synthesizes results from previous work, assesses th...

The rise of the Isthmus of Panama, linked to a number of climatic, paleoceanographic, and biological events, has been studied mostly from indirect, often distal, geochemical and biotic evidence. We have upgraded existing geologic mapping in central Panama with more than 2000 fi eld stations, over 40 petrographic analyses, and more than 30 new geochronological and thermo chrono logical analy ses...

In this study, the assemblage of calcareous nannofossils has been investigated in long and continuous deposits from a Kafaz section in Eastern Iran. A systematic study of calcareous nannofossils has indicated 39 nannofossils species. In order to the age determination of Kafaz's deposits, a revised zonation for the Eocene is used. Based on it, the Early-Middle Eocene deposits of Kafaz section is...

In 1974, Fiersline and Applegate described a new species of billfish, Xiphiorhynchus kimblalocki, based on a rostrum, two vertebrae, and two partial fin spines, from the Yazoo Clay For­ mation, late Eoccne, Mississippi, U.S.A. This was the first sub­ stantiated record of Xiphiorhynchus van Beneden, 1871, outside of western Europe. Since this initial discovery, there have been three other record...