The Tithonian (Upper Jurassic) ammonite succession at Portada Covunco, Neuquén-Mendoza Basin, Argentina

The Tithonian rock succession (Vaca Muerta Fm.) of Portada Covunco consists of a lower part of little more than 100 m of shales and shaly limestones with ammonites of the genera “Lithacoceras”, Choicensisphinctes and Pseudolissoceras of the Mendozanus and Zitteli zones; the middle part consists of about 160 m of limestones and marly limestones with ammonites of the genera Aspidoceras and Catutosphinctes of the Proximus? and Internispinosum zones; ending with some 45 m of unfossiliferous mudstones and shaly marls. Catutosphinctes Leanza & Zeiss (Ataxioceratidae: Torquatisphinctinae), a genus widely distributed through all the Tithonian of the southern Neuquén-Mendoza Basin, occurs through the more calcareous upper part of the section, mainly the type species Catutosphinctes rafaeli Leanza & Zeiss.