Bournonia excavata d'Orbigny 1842
Creators: name: Săsăran, Liana
name: Săsăran, Emanoil
name: Bucur, Ioan I.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Bivalvia
Hippuritida
Radiolitidae
Bournonia
Bournonia excavata

description: Bournonia excavata d'Orbigny, 1842   
Fig. 7 a-b  
 1842 Radiolites excavata - d’Orbigny, p. 156, 185.   
 1850 Radiolites excavata d’Orbigny- p. 215, pl. 556.   
 1907 Bournonia excavata (d’Orbigny) - Toucas, p. 27, pl. 2, figs. 11-13a.   
 1912 Bournonia excavata (d’Orbigny) - Parona, p. 285, fig. 4.   
 1968 Bournonia excavata (d’Orbigny) - Pejović, pl. 5, fig. 2.   
 1989 Bournonia excavata (d’Orbigny) - Cestari and Sirna, p.145, fig.3.   
 1992 Bournonia excavata (d’Orbigny) - Vicens, p. 185, pl. 74, fig. 1.   
 1995 Bournonia excavata (d’Orbigny) - Caffau and Pleničar, p. 230; pl. 7, figs. 2, 2a; pl. 12, fig.3.   
 1995 Bournonia excavata (d’Orbigny) - Cestari and Sartorio, p.136.   
 1995 Bournonia excavata (d’Orbigny) - Scott, p. 303, pl.2, figs. 3-4; text-fig. 6-D.   
1999 Bournonia excavata (d’Orbigny) - Sirna & Paris, p.51, pl. X, fig. 3.  
 2002 Bournonia excavata (d’Orbigny) - Caffau, p. 92-94, figs.2-3.   
 2005 Bournonia excavata (d’Orbigny) - Pleničar, p. 80, pl.28 figs. 1-2.   
 2007 Bournonia excavata (d’Orbigny) - Macé-Bordy, p. 99-100, fig. 9D-E.   
 2008 Bournonia excavata (d’Orbigny) - Pons and Vicens, p. 230, fig. 14C.   
Material: one RV (24078-BBU-MPS).  
 Description: Lower attached RV is conical, height up to 55 mm (incomplete) (Fig. 7 a-b). The ornamentation of the shell as well as the outer shell layer from the anterior side of RV is entirely removed probably due to erosion. In ventral side only Pb is visible as a prominent costa that corresponds to downfolds of the laminae of the outer shell layer. Vb is broken but its location can be easily recognized. Vb and Pb are separated by a narrow furrow, 9 mm wide, concav (Ib). In the transverse section, the contour of the RV is oval to quadrangular, with a flat posteroventral side, having a diameter of about 30 mm antero-posterior and 40 mm dorsal-ventral (Fig. 7a). The elements of the myocardinal apparatus are visible (pm) and (am) and the (at) and (pt) (Fig. 7a); the ligamental ridge is absent. Transverse sections of the RV indicate two well defined layers. The inner layer is less 1 mm thick and is represented by calcite spar. The thickness of the outer shell layer varies from 3-4 mm in dorsal and posterior side to 10 mm in area of Pb. The outer shell layer has a prismatic structure, typical for the Bournonia genus.   
 Remarks: Specimens very similar with Bournonia excavata d’Orbigny have been reported by Douvillé (1910, 1913, 1915) and recently by Abdel-Gawad et al. (2011) from Turonian deposits in Egypt. This fact has a great implication extending to Turonian stratigraphical ranges of species B. excavata Also, detailed taxonomical studies on small shelled species of B. fourtaui and B. africana are required, because of their morphological similarities with B. excavata (Steuber, 1999). If these three species formed a single species (Steuber, 1999) thus Bournonia excavata (d’Orbigny, 1850) has priority according to the rules of International Commission on Zoological Nomenclature (ICZN, Ride et al., 1999).   
Age: middle Santonian in Spain (Vicens et al, 1998; Pons and Vicens, 2008) and France (Toucas, 1907); late Santonian–early Campanian in Croatia (Polšac and Mamuzic, 1969), Italy (Sirna and Paris, 1999), Romania (Lupu, 1976), Slovenia (Pleničar, 2005); late CampanianMaastrichtian in southern Italy (Cestari and Sirna, 1989) and Guatemala - Carribean Province (Scott, 1995); Maastrichtian in Montenegro (Pejović, 1968)
description: Published as part of Săsăran, Liana, Săsăran, Emanoil & Bucur, Ioan I., 2018, Upper Cretaceous Rudist-Bearing Mixed Siliciclastic-Carbonate And - Volcanoclastic Deposits From Strâmturii Valley, Borod Basin, Northern Apuseni Mountains: Description, Microfacies And Depositional Environments, pp. 3-20 in Acta Palaeontologica Romaniae 14 (1) on page 9, DOI: 10.5281/zenodo.13190185