Abstract

A comparison of geographically extreme occurrences of calpionellids (southern Mexico, state of Oaxaca, and northeastern Caucasus) with Mediterranean faunas shows that faunal successions are practically identical. There are minor differences concerning the relative frequencies of individual species, but the same species are present throughout, no mutually exclusive endemic species could be observed. Detailed chronostratigraphic correlations over great distances, down to the level of standard subzones, are thus possible. Important palaeobiogeographic limitations do nevertheless exist, but these correspond rather to the total absence of calpionellids in strata of an age where they should be present. Calpionellids appeared first at the beginning of the late Tithonian in the Mediterranean realm and Cuba. From there they extended in successive spreads, reaching eastern Mexico in the early Calpionella Standard Zone (basal Berriasian) and southern Mexico and the Caucasus at the transition to the Calpionellopsis Standard Zone (mid Berriasian). The maximal spread is higher up in the Calpionellopsis Standard Zone (late Berriasian).

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