Revision of the Middle Jurassic ammonite fauna from Csóka-hegy, Vértes Hills (Transdanubian Hungary)

In the Vertes Hills, a part of the Transdanubian Central Range, exposures of Middle Jurassic rocks are limited to some spots. The best-known occurrence is that on the Csoka-hegy, of which fauna was briefly described in 1960. The depositional and faunal features indicated a revision, what was made on the basis of the original materiai. The sediments are re-interpreted as fissure-filling materials of Middle Jurassic neptunian dykes, where a Bajocian and a Bathonian ammonite assemblage was recognized. The Bathonian fauna indicating the Oxycerites orbis Zone is richer and more interesting, because it contains forms which are interpreted here as cryptogenetic homoeomorphs. These previously less-known or unrecognized forms (e.g. “Morphoceras"gignouxi, ?“Dimorphinites" nodifer, special Epistrenoceras sp., etc.) were preserved here in this locality because the fissure-filling materia! escaped the normal sedimentologic and diagenetic processes which were general in the area of overwhelming radiolaritic deposition. In addition to these general conclusions, the paper gives short descriptions and figures of the characteristic Bajocian and Bathonian ammonites