Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 1

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: Phylloceratidae

Sortuj według:

Ogranicz wyniki do:

Large-sized ammonites of the genus Calliphylloceras in the Middle Oxfordian of the Polish Jura Chain

Kin A.

Volumina Jurassica

2006

Vol. 4, no. 1

236-237

In the Middle Oxfordian (Plicatilis Zone: Patturatensis and Ouatius subzones) of the Polish Jura Chain, the present author found 12 large-sized phylloceratid specimens assigned the genus Calliphylloceras. Maximal diameter of the biggest specimen (nearly complete one coming from the Przybynów locality at Częstochowa) equals 730 mm. Genus Calliphylloceras is a characteristic element of the Mediterranean Province. In the Submediterranean Province comprising the area of the Polish Jura Chain, discoveries of such forms belong to rarities. Presence of phylloceratids, characterized by their large sizes, in the area of this province could have been caused by the postmortem drift of the shells. In contrast to the shells of small individuals, the large ones (>200 mm) had greater chance to be far transported in the sea (assuming postmortem phenomenon). The range of postmortem drift was connected with longer time-span of the buoyancy gases release, during ammonite soft-tissue decomposition. Empty phragmocone cameras were then successively filled with water, but before ammonite shell became sinking they could drifted of hundreds of kilometers. Genus Calliphylloceras is characterized by its largest shell diameters of all Jurassic representatives of the family Phylloceratidae. The occurrence of phylloceratid shells in deposits of Middle Oxfordian (especially of the Plicatilis Zone) both of “normal” sizes, as well as gigantic ones indicates free communication between the Mediterranean and Submediterranean provinces in the area of southern Poland.