The Kitchinites emscheris Zone comprises the Lower and Middle Santonian. The Upper Santonian corresponds to the Boehmoceras arculus Zone. The ammonite faunas are predominately endemic from the Upper Coniacian to the Middle Santonian. Uintacrinus socialis and Marsupites testudinarius . Sequence boundaries, followed by transgressive pulses, are identified in the uppermost Coniacian, with a subordinate event in the Middle Santonian, the most significant event in the basal Upper Santonian and the last in the Lower Campanian.
Ammonite occurrences are clearly related to the sequences recognized.
Top Sanmartinoceras aff. It is probably Late Aptian in age and represents the first evidence of the Aconeceratinae in North America. 11 species, belonging to nine genera, are treated. Tissotioides haplophyllum , Tongoboryceras cf. Yabeiceras manasoaense is described for the first time from Europe.