Apical region | anterior end of ceratolith, hence terms such as apical node. |
Arch | part of apical region connecting the two arms. |
Arm | rod-like extension back from apical region. |
Rod | rod-shaped structure attached to the nannolith, (e.g. Amaurolithus bizarrus). |
Spur | projection from apical region. |
Keel | lath-like structure running along an arm. Types: Dentate keel - keel formed of sub-parallel teeth. Smooth keel - keel without teeth. |
Tooth | rod-like sub-element of a keel. |
Wing | plate-like extension from main body of nannolith (e.g. Amaurolithus ninae). |
Central-area | portion of discoaster with rays in contact. |
Contact-surface | surface between adjacent elements. (Alternative term attachment surface, see appendix). |
Disc | main part of discoaster, excluding bosses or stems. |
Boss | low distal or proximal protrusion from centre of disc (alternative term knob, see appendix). |
Rosette-shaped | discoaster with short free rays (Text-fig. 10). |
Segment | ray and associated boss or stem elements. |
Stem | high distal or proximal protrusion from centre of disc (e.g. Discoaster kuepperi). |
Star-shaped | discoaster with long free rays (Text-fig. 10). |
Sutural ridge | ridge running along suture. |
Bar | structure crossing central opening. Types; |
Conjunct bar | developed from rim elements (e.g. H. carteri). (Alternative terms optically continuous bar, bar, bridge, see appendix). |
Disjunct bar | formed from elements discrete from the rim (e.g. H. intermedia). (Alternative terms optically discontinuous bar, bridge, bar, see appendix). |
Normally oriented bar | diagonal bar with dextral orientation; i.e. rotated to the right of the long axis in distal view/ anterior end on opposite side to the wing. |
Inversely oriented bar | diagonal bar with sinistral orientation; i.e. rotated to the left of the long axis in distal view/ anterior end on same side as wing. N.B. Use of the terms normal/inverse is a ubiquitous convention based on their relative abundances. |
Blanket | mass of elements forming distal cover. {Theodoridis 1984} |
Flange | rim structure of helicolith (shield is also used by some workers). |
Origin | location of first/shortest elements of flange on the proximal side. |
Proximal plate | inward radiate elements on proximal side of central-area. |
Spur | spike-like expansion of flange near its termination (e.g. H. recta). |
Termination | location of last elements of flange on the distal side. |
Wing | broad expansion of flange near its termination (e.g. H. carteri). |
Apical cycle | upper part of sphenolith, formed of most steeply inclined cycle of elements. Types: Monocrystalline formed of one crystal-unit; e.g. S. heteromorphosus, S. belemnos. Duocrystalline formed of two crystal-units; e.g. S. distentus, S. furcatulithoides. Compoundformed of several crystal-units; e.g. S. radians, S. abies. |
Apical spine | elongate extension of apical cycle. |
Base | all of sphenolith except the apical spine. |
Blade | one of three sub-parts of an element, only seen in well preserved material. |
Core | centre of radiation of elements. |
Element | basic component of sphenoliths, each element appears to be a single crystal-unit. |
Lateral cycles | cycles between apical and proximal cycles, not always present. |
Proximal cycle | lowermost cycle of elements. |
Upper/lower part | part above/below the core. |
Longitudinal | parallel to length of nannolith. |
Transverse | perpendicular to length of nannolith. |
Blade | one of the three main sub-parts of the nannolith. |
Dentate blade | blade with transverse sub-structure of rod-shaped teeth. |
Lateral blade | one of two broader blades nearly in the same plane (e.g. T. rugosus) |
Median blade | narrowest of three blades. |
Ridge | subsidiary longitudinal structure on a blade. E.g. T. challengeri. |
Wing | blade greatly extended in transverse direction. E.g. T. finifer. |
Tooth | rod-like part of a dentate blade. |
Block | zone of holococcolith that behaves in cross-polarized light as one unit. |
Cavity | open central part of holococcolith, not filled by crystallites (e.g. Calyptrosphaera, Zygosphaera). |
Crystallite | individual minute crystal (typically ca. 0.1 microns). |
Crystallite arrangement | pattern of crystallites visible on a surface. Types:
hexagonal - crystallites arranged in hexagonal array (with C-axes directed radially)
hexagonal meshwork - similar but with regular array of perforations due to omission of single crystals (e.g. Calyptrosphaera oblonga).
rhomboid - crystallites arranged in rhombohedral array (c-axes oblique to surface) (e.g. Syracolithus confusus). |
Depression | pit on surface, not opening into a cavity. |
Distal-cover | distal layer(s) of crystallites, covering cavity (may merge into rim or be discrete from it). |
Perforation | opening in wall the size of one crystallite. |
Plug | distally positioned block (e.g. Lucianorhabdus). |
Pore | opening in wall larger than one crystallite (e.g. Gliscolithus). |
Proximal flange | sub-horizontal protrusion from base of rim. |
Proximal-plate | proximal layer(s) of crystallites (nearly) covering base of coccolith. |
Proximal-ring | proximal layer(s) of crystallites confined to edge of coccolith. |
Rim | peripheral zone discrete in cross-polarized light from the main blocks (typically rim elements have radial c-axes). |
Septum | layer(s) of crystallites forming internal wall. |
Wall | layer(s) of crystallites forming sub-vertical structure. |
Calicalith | open cavate, without distal cover (e.g. Calicasphaera). {Kleijne 1991} |
Calyptrolith | domal cavate, with nearly continuous distal-cover (e.g. Calyptrosphaera). {Lohmann 1902} |
Crystallolith | disc-like solid holococcolith formed of one or two layers of crystallites, with low rim (e.g. Coccolithus pelagicus holococcoliths). {Braarud et al. 1955a} |
Flosculolith | cavate with distal opening partially closed by a vaulted distal-cover (e.g. Flosculosphaera). {Kleijne et al. 1991} |
Fragariolith | proximal plate directly surmounted by blade-like process. E.g. Anthosphaera fragaria). {Kleijne 1991} |
Gliscolith | cavate with bulbous distal part (e.g. Gliscolithus). {Norris 1985} |
Helladolith | similar to zygolith but with bridge expanded distally into double-layered leaf-like process (e.g. Helladosphaera). {Heimdal and Gaarder 1980} |
Laminolith | solid holococcolith formed of several (>2) horizontal layers of crystallites, with or without perforations/pores (e.g. Syracolithus catilliferus). {Heimdal and Gaarder 1980} |
Zygolith | with bridge-shaped distal-cover (e.g. Corisphaera). {Kamptner 1937} |
Central Opening | opening running longitudinally through the nannoconid. Types:
Canal narrow, <1 µm;
cavity - wide, >1 µm;
aperture - expression of the central opening at the ends of the specimen. {Kamptner 1931} |
Bulb | a distinct swelling of the outline (e.g. N. borealis - single, N. paskentiensis - double, N. multicadus - triple). {Trejo 1960} |
Constriction | external indentation of the wall, between bulbs. {Deflandre and Deflandre-Rigaud 1962} |
Flange | horizontal projection around the end of nannoconid. N.B. Flanges may be symmetrical or asymmetrical in end view, and may be present at one or both ends of the specimen. {Stradner and Grün 1973} |
Wall | structure enclosing the central opening. {Kamptner 1931} |
Plate | basic structural element of nannoconid, single sub-triangular platy crystal. (Alternative term wedge, see appendix). {Stradner and Grun 1973} |
Type A-cycle | cycle of plates inclined at a lower angle (angle a to the horizontal. These are birefringent in longitudinal view (Perch-Nielsen 1988). {van Niel1992} |
Type B-cycle | cycle of plates inclined at a higher angle (angle b) to the horizontal. These cycles are non-birefringent in longitudinal view and form the dark spiral lines observed in cross-polars in longitudinal view (Kamptner 1931, Deflandre and Deflandre-Rigaud 1962, Perch-Nielsen 1988). {van Niel 1992} |
Angle D | angle of the A cycle/B cycle contact to the horizontal. N.B. This is the only angle measurable by light microscopy. {van Niel 1992} |
Cycle spacing | repeat distance between cycles perpendicular to angle D, i.e. combined thickness of A and B cycles. |
Calcisphere | hollow, typically spherical, calcareous nannofossil. Whereas coccospheres are composite structures formed of numerous coccoliths calcispheres possess a continuous wall. |
Cyst | wall formed around dinoflagellate during non-motile, non-vegetative, stage. These often show paratabulation but are continuous structures, except for the archaeopyle if present. Most calcispheres are thought to be cysts, however, the thoracosphere of Thoracosphaera heimii is formed during the vegetative stage and so is not a cyst. |
Dinoflagellate | informal taxon-based term for member of the phylum Dinophyta. |
Theca | non-resistant organic wall of motile vegetative stage of dinoflagellates, composite structures formed of plates. |
Thoracosphere | informal taxon-based term for calcisphere formed by Thoracosphaera. N.B. T. heimii has a wall structure of large elements (ca. 1 µm) with their c-axes tangential to the wall, and randomly aligned. |