The Biostatistics of Aging

List of Illustrations

Chapter 1
1. Fig. 1. Map of Gotland (Sweden). About 98 per cent of the collected Telychian sponge specimens have been collected from the Gnisvärd/Blahäll area.
2. Fig. 2. Exposed pebble accumulations at the coast near Blåhäll/Tofta. View to the North (photo: Heilwig Leipnitz, Uelzen, Germany).
3. Fig. 3. Detail showing the heavily worn pebbles. The arrow indicates a specimen of Caryoconus gothlandicus (photo: Heilwig Leipnitz, Uelzen, Germany).
4. Fig. 4. Selection of characteristic acritarchs. A, Oppilatala insolita (Cramer & Diez, 1972). Scale bar 0.01 mm. B, Salopidium granuliferum (Downie, 1959). Scale bar 0.01 mm. C, Visbysphaera microspinosa Eisenack, 1954. Scale bar 0.01 mm. D, Nanocyclopia sp. Loeblich & Wicander, 1976. Scale bar 0.01 mm (photo: Dr. Zwier Smeenk, the Netherlands).
5. Fig. 5. Direction of ice movements in northern Gotland during the Weichselian glaciation (after Svantesson 1976, fig. 43). The limited area at the western coast, with ice direction perpendicular to the coast, coincides with the area of concentration of Telychian sponges.
6. Fig. 6. Terminology of sponge spicules. A, amphiarborescent or I-shaped dendroclone. B, triclonid or Y-shaped dendroclone. C, polyclonid dendroclone. D, rhizoclone. E, chiastoclone. F, tricranoclone. G, spheroclone. 1, shaft; 2, zygome; 3, ray, clone or arm; 4, clad; 5, centrum. Spicules not at scale.
7. Fig. 7. Example showing preservation of dermal layer (despite abrasion) in a sheltered constriction in Archaeosyphia annulata (NRM Sp10124, depicted in Pl. 2, fig. 5). Note the small specimen of Opetionella incompta n. sp. at left.
8. Fig 8. Schematic reconstruction of the unusual sphaeroclonid Caryoconus gothlandicus, the most frequently occurring species of lithistid in the assemblage.
9. Fig 9. Regular choanosomal skeleton in Caryoconus gothlandicus composed of spheroclones preserved in clear chalcedony. NRM Sp129 (photo: T. M. G. van Kempen).
10. Fig 10. Strands of spheroclones with elongated rays in the conus of Caryoconus gothlandicaus. NRM Sp4511 (photo: T. M. G. van Kempen).
11. Fig. 11. Early Silurian oceanic changes (after Jeppsson 1998). The arrow indicates the Snipklint Primo Episode, coeval with the Monograptus spiralis Graptolite Biozone and the sponge fauna.
12. Fig. 12. Example of overgrowth of the brachiopod Pentameroides subrectus by an orchocladinid, that is, Archaeoscyphia gislei (NRM Sp10204).