نتایج جستجو برای: devonian
تعداد نتایج: 2127 فیلتر نتایج به سال:
The new genus and species, Gondwanascorpio emzantsiensis, are described in Scorpiones incertae se dis on the basis of fragments from the Famennian (Late Devonian) Waterloo Farm locality near Grahams town, Eastern Cape, South Africa. This finding adds to the sparse record of Late Devonian scorpion taxa and provides the first evidence of Palaeozoic scorpions from Gondwana. Material includes a com...
Actinopterygians (ray-finned fishes) are the most diverse living osteichthyan (bony vertebrate) group, with a rich fossil record. However, details of their earliest history during the middle Palaeozoic (Devonian) 'Age of Fishes' remains sketchy. This stems from an uneven understanding of anatomy in early actinopterygians, with a few well-known species dominating perceptions of primitive conditi...
Depositional environment and source potential of the different organic-rich levels of Devonian age (up to 990m thick) from the onshore EC-1 well (Southern Tunisia) were investigated based on the analysis of more than 130 cutting samples by different geochemical techniques (Rock-Eval pyrolysis, GC-MS). The obtained results including Rock Eval Pyrolysis data and biomarker distribution (terpanes, ...
The Devonian marks a critical stage in the early evolution of vertebrates: It opens with an unprecedented diversity of fishes and closes with the earliest evidence of limbed tetrapods. However, the latter part of the Devonian has also been characterized as a period of global biotic crisis marked by two large extinction pulses: a "Big Five" mass extinction event at the Frasnian-Famennian stage b...
thirteen species of rugose corals, belonging to nine genera are described from the givetian and lower frasnian rocks of thekhoshyeilagh formation in the eastern alborz mountains (northeastern iran). glossophyllum ceratites (goldfuss), glossophyllum sp.,keriophyllum cf. maillieuxi (tsien), pseudozaphrentis sp., temnophyllum imperfectum coen-aubert, temnophyllum occidentale hilland jell, temnophy...
-Isotopic measurements (Sr, O, D) on formation waters from the Alberta Basin have been made, covering a stratigraphic range from Devonian to Upper Cretaceous. These measurements, combined with chemical compositional trends, give evidence for two distinct water regimes. One hydrological regime is composed of waters hosted in Devonian-Lower Cretaceous reservoirs, the other waters from Upper Creta...
The sedimentology and palaeogeography of some Devonian sedimentary rocks in southwest Ireland
Stearns, C. and Van der Voo, R., 1988. Dual polarity magnetizations from the Upper Devonian McAras Brook Formation, Nova Scotia, and their implications for the North American apparent polar wander path. Tectonophysics, 156: 179-191. Thermal demagnetization of 57 samples from four lava flows of the Upper Devonian McAras Brook Formation, sampled along the Northumberland Strait in northern Nova Sc...
Several fossil fish were discovered in 1994 in the Upper Devonian Chadakoin Formation, near Howard Falls, just outside of Edinboro, Erie County, Pennsylvania. These fossils are fragmentary in nature and have been described based on their morphology. They are identified as the median dorsal plate of the large arthrodire Dunkleosteus terrelli Newberry, 1873, and the spines of probable acanthodian...
A rare psammosteid heterostracan (Agnatha) occurrence in the Devonian of the Prague Basin is indicative of a dry land influence in the regional palaeogeography. This argument is strongly supported by the appearance of vascular plants, but the studied vertebrates allow us to presume a local brackish water environment. These conditions are considered to be related to a supposed land in the vicini...
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