| Daughter taxa (time control age-window is: 0-800Ma) | ||||
| | | | Wisea sanjuanensis |
Taxonomy:
Farinacci & Howe catalog pages: Wisea *
Morphology: A cretarhabdacean with a broad distal shield, which is mod- erately birefringent and apparently lacking an outer cycle. The distal shield elements of the rim are relatively broad, showing little imbrication, and are fewer in number than in other cretarhabdids. The rim is marked by four distinctive, sharp, thin black sutures, arranged in a ‘V’ shape at each end of the ellipse. An axial cross is present in the central area.
Differentiation: Wisea differs from other cretarhabdaceans in having no visible outer cycle in the distal shield, in having relatively few rim elements that do not appreciably imbricate, and in possessing distinctively sharp and narrow extinction lines that do not curve. In other cretarhabdacean genera, the extinction lines are diffuse, and curved to some degree. The axial cross also distinguishes it from most other cretarhabdaceans.
| Tags | LITHS: placolith, elliptical, CA: cross-axial, ca_disjunct, closed, |
| Metrics | Lith size: 0->0µm; |
Geological Range:
Last occurrence (top): within Coniacian Stage (86.26-89.77Ma, top in Coniacian stage). Data source:
First occurrence (base): within Turonian Stage (89.77-93.90Ma, base in Turonian stage). Data source:
Plot of occurrence data:
References:
 |
Wisea compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 14-4-2021
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=11389 Go to Archive.is to create a permanent copy of this page - citation notes |