Although both subfamilies have been previously identified at different localities of the Neuquén Province (e.g. Six of them are provisionally referred to Metriorhynchinae indet. Metriorhynchids are also abundant (N= 15) and, contrary to ichthyosaur materials, most of them are diagnostic to a subfamily level. However, at least three specimens, based on forefin and pelvic morphologies, can be certainly identified as ophthalmosaurids. Most of them are represented by articulated vertebrae. At both sections, marine reptile findings are concentrated in beds assigned to the Corongoceras alternans Zone, late Tithonian Microcanthum to Durangites Zones).Preliminary results depict ichthyosaurs as the main component of fossil assemblages (N= 22).
#Mesozoica jurasico plus
Whilst at Arroyo Paulino, four in situ ichthyosaurus and five metriorhynchids have been found, plus one ex situ metriorhynchid. In consequence, marine reptiles were sampled in connection with an accurate ammonoid based biostratigraphic control at both sections.At Arroyo Durazno, 18 in situ marine reptiles were identified (14 ichthyosaurs, four metriorhynchid crocodylomorphs, and one eucryptodira turtle) and also four ex situ ichthyosaurs and five ex situ metriorhynchids coming from the same unit. noduliferum Andean Assemblage Zones Microcanthum to Occitanica Zones). While a late Tithonian-early Berriasian age span was proposed for the interval analyzed at Arroyo Paulino (Windhauseniceras internispinosum to A. Over the basis of bed-by-bed ammonoid sampling, an early to middle early Tithonian-early Berriasian age span was determined for the Vaca Muerta Formation beds studied at Arroyo Durazno (Virgatosphinctes andesensis to Argentiniceras noduliferum Andean Assemblage Zones Darwini/ Semiforme to Occitanica Zones). At both localities the Vaca Muerta Formation consists of an intercalation of organic-rich laminated marls and nodular to massive limestones. 220 m), outcropping on the right margin of the Paulino Creek, to the north. 260 m), located over the left margin of the El Durazno Creek, to the south, and Arroyo Paulino (c. Two cross-sections, 14 km apart, of the Vaca Muerta Formation were performed over the eastern flank of a NW-SE syncline: Arroyo Durazno (c. During the last two years, a new field survey for marine reptiles was carried out in the southern Mendoza sector of the Neuquén Basin. By contrast, exposures of the Vaca Muerta Formation in the northern sector of the Neuquén basin (Mendoza Province), though widely distributed, had not been prospected for marine reptiles since the middle of the XX century (e.g. Cerro Lotena, Los Catutos and Pampa Tril, in the Neuquén Province Gasparini and Dellapé, 1976 Pol and Gasparini, 2009 Gasparini and Fernández, 2011 Herrera et al., 2013).
Outcrops of this lithographic unit in the southern sector of the basin have proven to be highly fosiliferous in marine reptiles (e.g.
Most of them have been recorded at the Neuquén Basin (west-central Argentina) in sedimentites of the Vaca Muerta Formation (lower Tithonian-lower Valanginian). Jurassic marine reptiles from the southern margin of the Eastern Pacific have been documented since the XIX century.
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