A discussion about Valanginian Neocomitinae from Central Poland, their ontogeny and possible origin

Abstract

In the Valanginian Wąwał section, Central Poland, ammonites are numerous and very well preserved, often with early whorls. This material provides new information and unique details for the study of the ontogeny and relationships within the Neocomitinae. The early ontogenetic stages of the genera Neohoploceras Spath, Karakaschiceras Thieuloy and Neocomites Uhlig from the Wąwał section have been studied in detail and, based on the similarity of the early stages, the close relationship between Neohoploceras Spath and Karakaschiceras Thieuloy is suggested. More distant from them is the genus Neocomites Uhlig, whose early ontogenetic stages are different. The earliest appearance of the genera Karakaschiceras Thieuloy and Neohoploceras Spath in the Wąwał section may suggest that the Polish Basin, with its intermediate character between the Tethyan and Boreal realms, could have been the best place for their early development and the beginning of their later evolutionary path.