(1) Six genera have Panthalassan records in Early Triassic (Palaeoneilo, Pinna, Bakevellia, Leptochond ria, Scythentolium and Permophorus), four have Tethyan records (Bakevellia, Leptochondria, Scythentolium and Astartella), one from the boreal (Plagiostoma), and three are known exclusively from Pakistan, at least during the Olenekian
(Eobuchia, Dimorphoconcha and Pseudocorbula).
RESULTS--Quaternary deposits are situated unconformably above the Lower Triassic (Olenekian
) Shnabkaib Member of the Moenkopi Formation.
Welles (1993) referred the trematosauroid cranial remains to the slender-snouted lonchorhynchine Cosgriffius, which was first reported from the Wupatki Member of the Moenkopi Formation (of Olenekian
age) in Arizona.
The age determination of the Montseny-Llobregat domain by palynomorphs revealed an Anisian age for the major part of siliclastic sediments of the domain (Sole de Porta, 1987; Calvet and Marzo, 1994; Dinares-Turell et al., 2005), although magnetostratigraphic work in the lower part of the Riera de Sant Jaume section revealed the presence of the Lower Triassic (Olenekian
) (Dinares-Turell et al., 2005).
Type genus: Chauliodites Heer, 1864 with 11 species from the Severodvinian--Olenekian of Russia, Induan of Mongolia, Olenekian
of Germany, Anisian of France and Middle Triassic of China (Aristov, 2003, 2004b, 2008).
Transitional forms from Neospathodus to Paragondolella are known in the basal Olenekian
and from Neospathodus to Neogondolella in the latest Olenekian
and basal Anisian (Kozur 1990a; 1990b).
Their reconstructions are based on the integration of paleontological, stratigraphic, and sedimentological data from published works and original analyses on the studied succession, spanning from the Early Permian (Cisuralian) to the Olenekian
. The authors attempt to integrate their observations in a coherent scenario, but their conclusions are largelly biased by the incorrect preconception that climatically-controlled sedimentary features should be necessarily synchronous, even if in contrast with biostratigraphic evidence.
Consequently, according to this age assessment, in Spain (Castilian Branch and Minorca), SE France (Provence), Sardinia (Nurra) and Bulgaria (NW Prebalkan and Kraishte), where the presence of ventifacts and their potential value as indicators of an arid period has been emphasized by Durand (2006), this author maintains that, in our current state of knowledge, this dry climatic regime generally started from the late Induan to early Olenekian
Successively, from the base to the top: 242 [+ or -] 7, 173 [+ or -] 5, 206 [+ or -] 6, 248 [+ or -] 8, 248 [+ or -] 8 Ma, i.e Anisian, Aalenian, Norian, and Olenekian
; because of a probable rejuvenation of the K/Ar system during the late tectonosedimentary events.
The name of Scythian was accepted as synonymous with the Lower Triassic and was divided into two stages: the Induan, whose name was derived from the Indus river in the Himalaya, and Olenekian
from the Olenek river in the south of Siberia.
However, on the basis of their stratigraphic position and wider correlation, attribution to an Induan-early Olenekian
time interval could be generally justified.
For almost all taxa, diversity is lowest at the beginning of the Triassic, in the Induan and Olenekian
. In some cases there is a notable drop from the Tatarian to the Induan.