Devonian-Carboniferous boundary is not clear in the Eastern Alborz Mountains. In the current study Tuyeh-Darvar section with about 170 m, thickness is selected. In this investigation, the primary goal is revision of Devonian/Carboniferous Boundary (known as DCB) and the other goal is the redefinition of the DCB as a famous necessity (based on ICS program in 2008 for defining the boundary and to...

Conodonts of Khoshyeilagh Formation, the most complete section of Devonian rocks in the Alborz Mountains, northern Iran, has been studied, and subspecies of the genera Icriodus, Bipennatus, Polygnathus, Pelekysgnathus, Ancyrodella, Palmatolepis, Bispathodus, Scaphignathus, Clydagnathus, Gnathodus, Scaliognathus and Dollymae have been obtained from the studied section. The faunas indicate an Eif...

abundance and multilateral extension of prominent genus and species of brachiopoda in the majority of sedimentation series of the late devonian have been observed in all parts of iran. the variability and rapid change in this respect has made it possible to delineate different lines of orthogenetism, biozonation and present biostratigraphical models at the sub-stage level. these characteristics...

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...

Four TOC-rich shale intervals spanning the Frasnian–Famennian (F–F) boundary were recovered in a drillcore (West Valley NX-1) from western New York (USA) and radiometrically dated using Re–Os. Two of the black shale intervals (WVC785 from ∼2.9 m below, and WVC754 from ∼6.4 m above the F–F boundary, respectively) yielded statistically overlapping ages with uncertainties of b1.1%. An interpolated...

An apparent absence of Silurian fishes more than half-a-metre in length has been viewed as evidence that gnathostomes were restricted in size and diversity prior to the Devonian. Here we describe the largest pre-Devonian vertebrate (Megamastax amblyodus gen. et sp. nov.), a predatory marine osteichthyan from the Silurian Kuanti Formation (late Ludlow, ~423 million years ago) of Yunnan, China, w...

During the Devonian, Svalbard Archipelago lay at low latitudes, occupying a paleogeographic position intersection of Caledonian and Ellesmerian orogens. Provenance analysis, including detrital zircon U-Pb age studies, Devonian (ca. 420–360 Ma) strata from Andrée Land Basin, Svalbard, help reconstruct sediment sources to understand assembly three basement provinces that make up which are present...

The Yukon-Tanana terrane in Yukon, Canada, records Late Devonian (ca. 366–360 Ma) rifting and the onset of latest Devonian–Carboniferous arc back-arc magmatism 360–325 Northern Cordillera. Detrital zircon U-Pb Hf isotope analyses indicate that metasedimentary basement was sourced northwestern Laurentia. Sandstones successions generally have robust Devonian–Mississippian age peaks, their signatu...