TERMINOLOGY9. Nannolith shapes
TERMINOLOGY| Dibrachiate | consisting of two sub-parallel arms joined at one end. Includes horseshoe, arrow-head, and arcuate shapes (e.g. Ceratolithus, Amaurolithus, Ceratolithina, Ceratolithoides - except C. verbeekii). |
| Compact | more or less equidimensional nannoliths. Includes conical (e.g. Sphenolithus), obconical (i.e. inverted cone-shaped, e.g. Conusphaera), cylindrical (e.g. Fasciculithus) and cubic (e.g. Micula) shapes. |
| Rod-shaped | elongate, and apparently without a basal disc. Includes bladed (e.g. Lithraphidites quadratus, Triquetrorhabdulus carinatus) and (sub-)cylindrical (e.g. Microrhabdulus) shapes. |
| Radiate | with radial symmetry. N.B. the number of crystal-units may be larger or smaller than the number of rays. |
| Triradiate | threefold radial symmetry (e.g. Marthasterites, Trochasterites). |
| Tetraradiate | fourfold radial symmetry (e.g. Micula, Quadrum, Nannotetrina). |
| Pentaradiate | fivefold radial symmetry (e.g. Goniolithus, Braarudosphaera). |
| Multiradiate | more than fivefold radial symmetry (e.g. many Discoaster spp.). |
| Central body | core part of radiate nannolith where elements are in contact. |
| Free rays | parts of radiate nannolith extending beyond central body. |
| Short free rays | length of free rays is less than radius of central body, resulting in a rosette-shaped outline. |
| Long free rays | length of free rays is greater than radius of central body, resulting in a star-shaped outline. |
| Convex outline | without free rays (e.g. Braarudosphaera). Including e.g. triangular, square, and pentagonal shapes. |
| Stellate | with free rays (e.g. Micrantholithus, Discoaster). Including rosette and star-shaped. |
