نتایج جستجو برای: Triassic
تعداد نتایج: 3848 فیلتر نتایج به سال:
—A global database of gastropod sizes from the Permian through the Middle Triassic documents trends in gastropod shell size and permits tests of the suggestion that Early Triassic gastropods were everywhere unusually small. Analysis of the database shows that no specimens of unambiguous Early Triassic age larger than 2.6 cm have been reported, in contrast to common 5– 10-cm specimens of both Pe...
The presence of gigantic apex predators in the eastern Panthalassic and western Tethyan oceans suggests that complex ecosystems in the sea had become re-established in these regions at least by the early Middle Triassic, after the Permian-Triassic mass extinction (PTME). However, it is not clear whether oceanic ecosystem recovery from the PTME was globally synchronous because of the apparent la...
Triassic tetrapod tracks have long been studied, including classic ichnofaunas such as those of the lower Newark Supergroup of eastern North America and the Bundsandstein of central Europe. They are known from all seven continents and encompass five archetypal vertebrate ichnofacies for nonmarine environments (Chelichnus, Grallator, Batrachichnus, Brontopodus, Characichnos), all of which are pr...
The facies changes, tectonics and magmatism across the Triassic–Jurassic boundary in the southern Tethyan margin have been studied in Egypt, Sudan, Jordan and Saudi Arabia. In Saudi Arabia and Jordan an unconformable contact is recognized between the Upper Triassic and Lower Jurassic rocks. This unconformity surface is marked by the truncation of the fluvial clastics of the uppermost Triassic b...
Ornithischian dinosaurs are one of the most taxonomically diverse dinosaur clades during the Mesozoic, yet their origin and early diversification remain virtually unknown. In recent years, several new Triassic ornithischian taxa have been proposed, mostly based upon isolated teeth. New discoveries of skeletal material of some of these tooth taxa indicate that these teeth can no longer be assign...
The Permian ended with the largest of known mass extinctions in the history of life. This signal event has been difficult to recognize in Antarctic non-marine rocks, because the boundary with the Triassic is defined by marine fossils at a stratotype section in China. Late Permian leaves (Glossopteris) and roots Vertebraria), and Early Triassic leaves (Dicroidium) and vertebrates (Lystrosaurus) ...
Triassic vertebrate tracks are known from the beginning of the 19th century and have a worldwide distribution. Several Triassic track ichnoassemblages and ichnotaxa have a restricted stratigraphic range and are useful in biochronology and biostratigraphy. The record of Triassic tracks in the Iberian Peninsula has gone almost unnoticed although more than 25 localities have been described since 1...
The rise of archosaurs during the Triassic and Early Jurassic has been treated as a classic example of an evolutionary radiation in the fossil record. This paper reviews published studies and provides new data on archosaur lineage origination, diversity and lineage evolution, morphological disparity, rates of morphological character change, and faunal abundance during the Triassic–Early Jurassi...
Carbon cycle disturbance associated with mass extinction at the end of the Permian Period continued through the Early Triassic, an interval of approximately 5 million years. Coincidence of carbon cycle stabilization with accelerated Middle Triassic biotic recovery suggests a link between carbon cycling and biodiversity, but the cause of Early Triassic carbon isotope excursions remains poorly un...
The Permian-Triassic bottleneck has long been thought to have drastically altered the course of echinoid evolution, with the extinction of the entire echinoid stem group having taken place during the end-Permian mass extinction. The Early Triassic fossil record of echinoids is, however, sparse, and new fossils are paving the way for a revised interpretation of the evolutionary history of echino...
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