Wyniki wyszukiwania

1

Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik

Lower Turonian record of belemnite Praeactinocamax from NW Siberia and its palaeogeographic significance

100%

Kostak M., Wiese F.

Acta Palaeontologica Polonica

|

2008

|

tom 53

|

nr 4

Specimens of the belemnitellid Praeactinocamax Naidin, 1964 are described from the Upper Cretaceous of NW Siberia (Taimyr Region, Lower Agapa River, Russia). The rostra determined as Praeactinocamax aff. plenus consist of an aragonitic anterior part and a calcitic posterior part with a sharp boundary in between. This boundary surface is referred to as the “alveolar fracture”, and it is a typical morphological feature of early belemnitellids and not a result of diagenetic processes. The occurrence of Praeactinocamax in Arctic areas shows a wider palaeobiogeographical distribution of the genus in the Late Cenomanian–Early Turonian interval than previously known. This finding suggests that migration of the late Cenomanian–early Turonian fauna occurred across Turgai channel. The geographic position of these new records may also explain the occurrence of Praeactinocamax in the Turonian of the US Western Interior Seaway, the origin of which has been hitherto unclear.

2

Paleobiogeography and migration in the Late Cretaceous belemnite family Belemnitellidae

80%

Christensen W. K.

Acta Palaeontologica Polonica

|

1997

|

tom 42

|

nr 4

457-495

The Late Cretaceous belemnite family Belemnitellidae Pavlow, 1914, which includes nine genera and two subgenera, occurs only in the Northern Hemisphere, that is in the North European and North American palaeobiogeographical Provinces of the North Temperate Realm, in addition to the northern margin of the Tethyan Realm in Europe. The North European Province is subdivided into the Central European, Central Russian and Baltoscandian Subprovinces. The centre of origin and dispersal of the belemnitellids lay in the North European Province and all known genera and subgenera occur there. The belemnitellids immigrated intermittently into the Tethyan Realm (at least nine times) and the North American Province (at least six times). The majority of the species occurring in the Tethyan Realm are conspecific with those from the North European Province, whereas the species occurring in the North American Province are endemic, with a few exceptions. The endemic species probably evolved by allopatric speciation from initial migrants. More than a score migrations have been recognized within the subprovinces of the North European Province. The palaeogeographical distribution and migration patterns of the belemnitellids were to a certain extent controlled by eustatic sea-level changes, cool or warm climatic phases and competition, although the cause of several migration events cannot be satisfactorily explained at present.

3

Fusiteuthis polonica, a rare and unusual belemnite from the Maastrichtian

80%

Christensen W. K.

Acta Palaeontologica Polonica

|

2002

|

tom 47

|

nr 4

A specimen of Fusiteuthis polonica, from the basal Maastrichtian of the “Saturn” chalk pit at Kronsmoor in northwest Germany, is described. It came from the uppermost part of the Belemnella lanceolata Zone, ca. 9.5 m above the base of the Maastrichtian as defined on belemnites. Fusiteuthis was very rare, but widely distributed. Single occurrences are known from northwest Germany, Poland and Crimea. It has been recorded only from the lowest and uppermost parts of the Maastrichtian; the longevity of this genus was thus slightly less than 6 myr. Fusiteuthis belongs to the Upper Cretaceous belemnite family Belemnitellidae.

Ograniczanie wyników

3 Acta Palaeontologica Polonica

2 Christensen W. K.

1 Kostak M.

1 Wiese F.

1 2008

1 2002

1 1997

Lower Turonian record of belemnite Praeactinocamax from NW Siberia and its palaeogeographic significance

Paleobiogeography and migration in the Late Cretaceous belemnite family Belemnitellidae

Fusiteuthis polonica, a rare and unusual belemnite from the Maastrichtian