نتایج جستجو برای: miocene
تعداد نتایج: 6531 فیلتر نتایج به سال:
A total of 12 species of marine gastropods, among which two taxa are new, is reported for the first time from the Miocene deposits of Khavich section, south of Sirjan, Kerman. Gastropods assemblage in Khavich area indicates deposition in shallow, warm ramp-type carbonate platform. The Miocene and even Oligocene gastropod assemblages, relatively similar to Khavich section, reported from the othe...
There is a considerable controversy about whether western Amazonia was ever covered by marine waters during the Miocene [23 to 5 Ma (million years ago)]. We investigated the possible occurrence of Miocene marine incursions in the Llanos and Amazonas/Solimões basins, using sedimentological and palynological data from two sediment cores taken in eastern Colombia and northwestern Brazil together w...
Echinoids fauna are common and distributed in the Lower Miocene deposits of the Bagher Abad area, northeast Isfahan, Central Iran.There are six Echinoid taxa belonging to the Echinoidea Class that can be described as: Clypeaster intermedius, Prinocidaris sp. andspines related to: Eucidaris zaemays, Stylocidaris Polyacantha, Spatangoid sp. and Prinocidaris sp. Bivalves, Foraminifers,Bryozoans, B...
The Late Miocene development of faunas and environments in western Eurasia is well known, but the climatic and environmental processes that controlled its details are incompletely understood. Here we map the rise and fall of the classic Pikermian fossil mammal chronofauna between 12 and 4.2 Ma, using genus-level faunal similarity between localities. To directly relate land mammal community evol...
This study presents results from the Community Climate System Model 3 (CCSM3) forced with early to middle Miocene (;20–14 Ma) vegetation, topography, bathymetry, and modern CO2. A decrease in the meridional temperature gradient of 6.58C and an increase in global mean temperature of 1.58C are modeled in comparison with a control simulation forced with modern boundary conditions. Seasonal polewar...
The >>Open Source<< Perspective deals with the spatio-temporal distribution pattern of Miocene hominids and suggests a pan-African perspective on the evolution of bipedalism. The shrinking of the rainforest from the Middle Miocene resulted in a selection pressure that was similar along its wide-stretched margin. The earliest hominids might represent co-existing geographic variants.
Jaws and dentition closely resembling those of the extant tuatara (Sphenodon) are described from the Manuherikia Group (Early Miocene; 19-16 million years ago, Mya) of Central Otago, New Zealand. This material is significant in bridging a gap of nearly 70 million years in the rhynchocephalian fossil record between the Late Pleistocene of New Zealand and the Late Cretaceous of Argentina. It prov...
We present a kinematic model for the Himalayan thrust belt that satisfies structural and metamorphic data and explains recently reported late Miocene–Pliocene geochronologic and thermochronologic ages from rocks in the Main Central thrust zone in central Nepal. At its current exposure level, the Main Central thrust juxtaposes a hanging-wall flat in Greater Himalayan rocks with a footwall flat i...
Balaenidae (right and bowhead whales) are a key group in understanding baleen whale evolution, because they are the oldest surviving lineage of crown Mysticeti, with a fossil record that dates back ∼20 million years. However, this record is mostly Pliocene and younger, with most of the Miocene history of the clade remaining practically unknown. The earliest recognized balaenid is the early Mioc...
Jon E. Keeley and Philip W. Rundel US Geological Survey, Western Ecological Research Center, Sequoia-Kings Canyon Field Station, Three Rivers, CA 93271, USA Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095-1606, USA Center for Embedded Networked Sensing, University of California, Los Angeles, CA 90095-1606, USA *Correspondence: E-mail: jon_keeley@u...
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