rudists?

[brus]

hi,i found this shells,is this rudists?

[JohnBrewer]

Yes, I think so

[abyssunder]

Sure they can be rudists. Could we know in which region of Croatia were they found ?

[brus]

Shure,i found it in Istra.

[abyssunder]

Istra (Istria) is the largest peninsula in the Adriatic Sea and belongs to the Adriatic Carbonate Platform. The southern part of the Istrian peninsula exposes Upper Cretaceous rocks, comprising pure carbonate platform sediments from the Albian to the Upper Santonian stages, bearing radiolitid to radiolitid - Vaccinites rudist assemblages. The most common specimens belong to the genus Gorjanovicia, but there are also other species like Medella zignana, Sauvagesia raricostata, S. tenuicostata, S. kueni, S. meneghiniana, Radiolites sp. and Praeradiolites sp., Plagioptychus sp. . According to THE RUDISTS OF SOUTHERN ISTRIA - AN EXAMPLE OF ENVIRONMENTALLY INDUCED SUCCESSION WITHIN SANTONIAN LIMESTONES - A. Moro, V. Cosovic http://riviste.unimi.it/index.php/RIPS/article/viewFile/5390/5439

" It may be concluded that radiolitids and Vaccinites occupied different biotopes within subtidal environments of the Adriatic Carbonate Platform. Vaccinites preferred more stable, deeper subtidal environments. "

From the Aptian of the Kanfanar–Dvigrad area (Kanfanar Formation) in western Istria, Toucasia rich beds were acknowledged, besides them numerous requieniids (Requienia) are present, also in the Aptian–Albian strata of Veli Brijun Island. More details and description of the species could be found in : Lower Aptian Rudist Faunas (Bivalvia, Hippuritoidea) from Croatia - Jean-Pierre MASSE et al. https://www.researchgate.net/publication/27189465_Lower_Aptian_Rudist_Faunas_Bivalvia_Hippuritoidea_from_Croatia

"Faunas from Kanfanar are dominated by low diversity (Requienia? zlatarskii, Toucasia) and low density assemblages associated with Bacinella dominated biotopes, in relatively restricted settings of the Adriatic Carbonate Platform interior. "

Reading the research of Darko TIBLJAŠ et al. in establishing the mineral composition and trace element content of the Turonian - Upper Santonian rudist remains from Southern Istria, I found (as stated there) that the rudist genera Durania, Radiolites and Praeradiolites lived during the Middle to Upper Turonian, Gorjanovicia lived in the time span from Upper Turonian to Santonian while Vaccinites specimens are of Santonian age (MORO, 1997; MORO & ĆOSOVIĆ, 2000).

Edited May 29, 2016 by abyssunder

[brus]

tnx a lot for very informative links