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A crustoid graptolite lithoimmured inside a Middle Ordovician nautiloid conch from northern Estonia

Vinn Olev, Wilson Mark A., Toom Ursula

Annales Societatis Geologorum Poloniae

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2019

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Vol. 89, No. 3

285--290

EN

A light grey nautiloid conch has a dark brown colony attached to its internal surface. This colonial fossil resembles hederellids and bryozoans, but is in fact a crustoid graptolite (Hormograptus? sp.). The colony has been lithoimmured inside this nautiloid conch by early cementation. Crustoid graptolites were a part of the encrusting communities in the Middle Ordovician of Baltica, but their abundance among encrusters of biogenic substrates reached a peak in the middle Sandbian. The cryptic mode of life appeared very early in the evolution of the crus- toids. The discovery of this crustoid graptolite in a nautiloid conch indicates that the Baltic Middle Ordovician cryptic communities were taxonomically more diverse than was known previously. The nautiloid conch studied is sparsely encrusted with an encrustation density that is similar to those of other Middle Ordovician cryptic surfaces described from Estonia.

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Cephalopod fauna and stratigraphy of the Adnet type red deposits of the Krížna unit in the Western Tatra Mountains, Poland

Myczyński R., Jach R.

Annales Societatis Geologorum Poloniae

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2009

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Vol. 79, No 1

27-39

EN

The Lower Jurassic Adnet type red limestones and marlstones (Kliny Limestone Member, Huciska Limestone Formation) of the Krížna unit in the Tatra Mountains comprise cephalopod fauna represented by ammonites, belemnites and rarely by nautiloids. Ammonites belong to the families Phyloceratidae, Lytoceratidae, Hildoceratidae and Dactylioceratidae and indicate Early Toarcian Serpentinum Zone, Middle Toarcian Bifrons Zone (most probably Sublevisoni and Bifrons Subzones) and Late Toarcian Pseudoradiosa Zone. Hence, the age of Adnet type deposits may be estimated as Early Toarcian-Late Toarcian. Relatively moderate diversity of ammonite assemblage is noticed. Ammonites and nautiloids are preserved mainly as internal moulds, only some specimens display preserved calcified shells. Part of this macrofauna has resedimented character. Studied ammonite assemblage is closely related to that of the Mediterranean Province.

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The carbon and oxygen isotope records of Upper Bajocian-Bathonian calcareous fossils from the Polish Jura Chain

Wierzbowski H., Joachimski M.

Volumina Jurassica

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2006

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Vol. 4, no. 1

220-222

EN

A collection of stratigraphically well-dated calcitic and aragonitic fossils (belemnites, ammonites, nautiloids and oysters), derived from Upper Bajocian - Upper Bathonian clays from the Polish Jura Chain (central Poland), were studied for oxygen and carbon isotopes. The preservation state of the shell material was investigated by means of cathodoluminescence microscopy, trace element geochemistry and X-ray diffraction. Palaeotemperatures calculated from the oxygen isotope composition of calcitic shells (belemnites and oysters) are similar to each other despite the significant spread in 18O values (Fig. 1). The 18O values of calcitic fossils generally vary from -0.1 to +1.1‰ VPDB for the studied interval, which corresponds to palaeotemperatures between +7.9 and +12.4°C (calculated with the equation of Anderson & Arthur 1983). The palaeotemperatures derived from the oxygen isotope composition of aragonitic ammonoid and nautiloid shells are distinctly higher (Fig. 1) with most of the estimates ranging from 15 to 23°C (calculated with the equation of Grossman & Ku 1986). The observed temperature difference may have resulted from different depth habitats of the organisms. The ammonites and nautiloids might have lived in surface waters and the temperature contrast might represent a palaeotemperature gradient between thermally stratified surface and deep waters of the Late Bajocian - Late Bathonian sea in the Polish Jura Chain. The ?13C values for the Upper Bajocian - Upper Bathonian belemnite rostra do not indicate major secular variations (Fig. 1). However, the data show a significant scatter of about 1.5‰. Several oyster shells show considerable higher 13C values (around +3‰ VPDB) compared to coeval belemnite rostra (between 0 and +1.5‰ VPDB). This may point to a metabolic fractionation effect that resulted in disequilibrium fractionation of carbon isotopes within belemnite skeletons (cf. Wierzbowski 2002). The aragonitic ammonite and nautiloid shells show a significant variation in 13C with values ranging from -3.7 to +2.2‰ VPDB. The carbon isotope composition of the oysters and the belemnites may suggest that the ?13C value of ancient seawater bicarbonate (HCO3-) averaged +3‰ VPDB.

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Latest Campanian to Early Maastrichtian (Cretaceous) nautiloids from the white chalk of Kronsmoor, northern Germany

Wilmsen M., Esser K. J.

Acta Geologica Polonica

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2004

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Vol. 54, no. 4

489-498

EN

A well preserved and stratigraphically tightly constrained nautiloid fauna consisting of two species is described from the uppermost Campanian to Lower Maastrichtian white chalk section of Kronsmoor, northern Germany. Cymatoceras patens (KNER, 1848) occurs rather frequently in the Kronsmoor section; one specimen is from the Upper Campanian Micraster grimmensis/Cardiaster granulosus Zone, one from the upper Belemnella pseudobtusa to lowermost Belemnella obtusa Zone. The bulk of the material (nine specimens) is from the Early Maastrichtian B. obtusa and Belemnella sumensis zones. The species is known from the Upper Campanian to Lower Maastrichtian of northern Germany, The Netherlands, Poland, the Ukraine, and possibly Denmark. Cymatoceras loricatum (SCHLUTER, 1876) occurs in Kronsmoor (four specimens) in an interval comprising the Early Maastrichtian upper B. obtusa to B. sumensis zones.The species was hitherto only recorded from the uppermost Lower and Upper Campanian of Westphalia and Lower Saxony, Germany. Both species appear to be restricted to the Central European Subprovince of the temperate North European Province (Boreal Realm).

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Upper Maastrichtian ammonites and nannofossils and a Palaeocene nautiloid from Richards Bay, Kwa Zulu, South Africa

Klinger H.

Acta Geologica Polonica

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2001

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Vol. 51, nr 3

273-291

EN

Temporary exposures of Upper Maastrichtian to Palaeocene sediments of the Richard Bay area, Kwa Zulu yielded Maastrichtian and Danian cephalopod faunas. The lower Upper Maastrichtian assemblage, dated to nannofossil standard biozone CC25b, or UC20a^TP of BURNETT (1998), is: Anagaudryceras politissimum (KOSSMAT, 1895), Pseudophyllites indira (FORBES, 1846) (abundant), Desmophyllites diphylloides (FORBES, 1846) Pachydiscus (P.) australis HENDERSON & McNAMARA, 1985, Menuites fresvillensis (SEUNES, 1890), Diplomoceras cylindraceum (DEFRANCE, 1816), Baculites ambatryensis COLLIGNON, 1971, Eubaculites carinatus (MORTON, 1834), and E. latecarinatus (BRUNNSCHWEILER, 1966). The Danian yields a monospecific assemblage of Hercoglossa madagascariensis COLLIGNON, 1951. The Maastrichtian assemblage has strong similarities to the lower Upper Maastrichtian fauna of the Miria Formation of Western Australia, and is made up of cosmopolitan and latitudinally restricted taxa: there are no endemic elements.