نتایج جستجو برای: upper triassic
تعداد نتایج: 208096 فیلتر نتایج به سال:
New evidence is presented on the Triassic–Jurassic boundary in northern Lusitanian Basin, Portugal, based miospore assemblages from a composite Upper Triassic to Lower Jurassic succession of Silves Group. The latter comprises, base top, Conraria, Penela, Castelo Viegas and Pereiros formations. Three informal palynological zones have been documented compared with coeval palynozones West South Eu...
—The small size of Early Triassic marine organisms has important implications for the ecological and environmental pressures operating during and after the end-Permian mass extinction. However, this “Lilliput Effect” has only been documented quantitatively in a few invertebrate clades. Moreover, the discovery of Early Triassic gastropod specimens larger than any previously known has called the ...
Triassic tetrapods are of key importance in understanding their evolutionary history, because several tetrapod clades, including most of their modern lineages, first appeared or experienced their initial evolutionary radiation during this Period. In order to test previous palaeobiogeographical hypotheses of Triassic tetrapod faunas, tree reconciliation analyses (TRA) were performed with the aim...
Outcrops of the Lower Triassic (Spathian) Virgin Limestone Member (Moenkopi Formation) in the southwestern United States contain the oldest known metazoan bioherms formed in the aftermath of the endPermian mass extinction. These small buildups, up to 1.0 m in diameter and 0.2 m high, were constructed by cementing bivalves. The bivalve bioherms accreted in a shallow, subtidal environment above s...
We report a new ichthyopterygian assemblage from Lower Triassic horizons of the Prida Formation at Fossil Hill in central Nevada. Although fragmentary, the specimens collected so far document a diverse fauna. One partial jaw exhibits isodont dentition with blunt tipped, mesiodistally compressed crowns and striated enamel. These features are shared with the Early Triassic genus Utatsusaurus know...
چکیده ندارد.
Coprolites are the least studied and most under-sampled vertebrate trace fossils. They are very common in some Triassic localities. We recognize six new coprolite ichnotaxa: Alococopros triassicus, A. indicus, Saurocopros bucklandi, Liassococopros hawkinsi, Malericopros matleyi and Falcatocopros oxfordensis. The distribution of coprolite ichnotaxa is: Permian Hyronocopros amphipolar and Heterop...
SYNOPSIS TheNorth American Triassic dinosaur record has been repeatedly cited as oneof themost complete early dinosaur assemblages. The discovery of Silesaurus from Poland and the recognition that Herrerasaurus and Eoraptor may not be theropods have forced a re-evaluation of saurischian and theropod synapomorphies. Here, we re-evaluate each purported Triassic dinosaur from North Americaonaspeci...
The current Triassic chronostratigraphic scale is a hierarchy of three series divided into seven stages, divided further into 15 substages. Ammonoid and conodont biostratigraphies provide the primary basis for chronostratigraphic definition based on global stratotype sections and points (GSSP). I propose that Triassic chronostratigraphic definition should rely entirely on ammonoid biochronologi...
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