Crucibiscutum bastetanum Aguado in Aguado, Company, O'Dogherty, Sandoval & Martinez

Plant Fossil Names Registry Number: PFN001007

Act LSID: urn:lsid:plantfossilnames.org:act:1007

Author: R. Aguado Merlo

Rank: species

Reference: Aguado, R., Company, M., O'Dogherty, L., Sandoval, J. & Martinez, M. (2022): New insights into the Barremian–lower Aptian calcareous nannofossils of the Mediterranean Tethys: Chronostratigraphic and paleobiogeographic implications. – Marine Micropaleontology 173: 102114 (24 pp.).

Page of description: 16

Illustrations or figures: fig. 14 A–N

Types

Original diagnosis/description

Diagnosis: Small to medium-sized (3.4–5.5 μm) broadly elliptical to normally elliptical Crucibiscutum coccoliths with a relatively narrow central-area spanned by off-axial (slightly rotated) cross bars. The rim is bicyclic under cross polarized light microscopy, with the bright inner cycle being usually wider (~1 μm width) than the outer dark cycle.

Description: Under cross polarized light (XPL), the bright inner cycle of the rim has equal or greater width than the outer dark cycle. The central-area is nearly filled by a relatively thick cross which is slightly rotated with respect to the axes of the ellipse defined by the rim. The cross is bright (although not as bright as the inner cycle of the rim) under XPL when oriented at 45°, and dark when oriented to 0°. The long and short arms of the central cross usually have slightly different degree of rotation.

Dimensions: length = 3.4–5.5 (average 4.6) μm; width = 2.9–4.5 (average 3.8) μm; specimens measured: 22.

Holotype dimensions: length = 4.9 μm, width =3.9 μm.

Etymology

After the Bastetani, an old Iberian tribe that populated the southeastern part of the Iberian Peninsula, the type area of this species.

Stratigraphy

Cretaceous, Lower Cretaceous, Barremian
Uppermost Barremian, sample X.HA-2 (NC5E nannofossil Zone; upper part of Imerites giraudi ammonite Zone). This species has a short range. Its lowest occurrence (LO) was found near the top of the Gerhardtia sartousiana ammonite Zone, (upper part of the Hemihoplites feraudianus Subzone), which is equivalent to the uppermost part of NC5E Zone, and is slightly preceded by the LO of the primitive forms (elongated) of Hayesites irregularis. Its highest occurrence (HO) was recorded in the lower part of the Martelites sarasini ammonite Zone (lowermost part of the NC6A), slightly following the nannoconid decline event (Coccioni et al., 1992; Erba, 1994; Bralower et al., 1994; Bergen, 1998; Erba et al., 1999). Usually this species is a rare component of the assemblages, being more abundant from the upper part of the Imerites giraudi Zone to its LO, but shows a rather consistent record.

Locality

Spain
X.HA section (37.852 N; 2.589 W), Province of Granada, southeastern Spain.