%0 Journal Article
%A Sandoval Gabarrón, José
%A Henriques, María Helena Paiva
%A Chandler, Robert B.
%A Ureta Gil, María Soledad
%T Latest Toarcian-earliest Bajocian (Jurassic) Grammoceratinae (Hildoceratidae,Ammonitina) of the western Tethys: Their palaeobiogeographic andphylogenetic significance
%D 2012
%@ 0016-6995
%U https://hdl.handle.net/20.500.14352/42337
%X Grammoceratinae (Hildoceratidae, Ammonitina) abound in the Toarcian strata of many western Tethyanlocalities, especially the Subbetic and Lusitanian basins (of southern Spain and central western Portugal,respectively). They decline through the Aalenian and disappear by the lowermost Bajocian. The generaAsthenoceras, Vacekia (subgenera Vacekia and Nadorites) and Fontannesia are traditionally considered asthe last Grammoceratinae, with species of Osperleioceras occurring in the uppermost Toarcian.Grammoceratinae are common in the eastern Pacific, especially Oregon and Alaska where Asthenoceras isabundant. They also occur in the eastern Tethys (Thailand). Although studies of Toarcian to earlyBajocian Subbetic and Lusitanian grammoceratins already exist, new material from these and otherpalaeogeographic areas (England, Portugal and Spain) is revised here. A new genus, Linaresites nov. gen.(for Fontannesia montillanensis Linares and Sandoval) and two new species (Vacekia striata Henriques,and Asthenoceras taverai Sandoval) are described. Another form, ‘‘Asthenoceras’’ sp. A is described and letin open nomenclature. Temporal analysis of Aalenian to early Bajocian Grammoceratinae demonstratesa progressively more evolute morphology through time, sometimes coupled with size reduction.Palaeogeographic evidence suggests that during the early Middle Jurassic, western Tethys and easternPacific were temporarily well connected, possibly through the Hispanic Corridor, as demonstrated by thesimilarity between Tethyan and eastern Pacific Grammoceratinae.
%~