Меловой период

Keutgen, N., Remin, Z., Jagt, J.W.M. (2017). The late Maastrichtian Belemnella kazimiroviensis group (Cephalopoda, Coleoidea) in the Middle Vistula valley (Poland) and the Maastricht area (the Netherlands, Belgium) – taxonomy and palaeobiological implications // Palaeontologia Electronica 20.2.38A: 1-29. https://doi.org/10.26879/671

palaeo-electronica.org/content/2017/1931-belemnites-around-the-ktb