FIGURE 1. Oesolcucumaria eostre Botting and Muir, 2012, Darriwilian, middle Ordovician of Bach-y-Graig, Llandrindod, Wales. 1-4, NHM EE8734, latex cast of showing the structure of the oral ring. 2, SEM micrograph of the body wall showing fine acicular cruciform spicules. 3, SEM micrograph of body fossil. 4, SEM micrograph of part of the perioral ring (inset shows the complete ring); note the lack of regular structure. 5, NHM EE8739, SEM micrograph of the perioral ring; general view and detail showing granular microstructure. All specimens housed in the Natural History Museum, London. Scale bars: 1=1 mm; 4 = 200 μm.
FIGURE 2. Comparison of rod- and cruciform-like sclerites of sponges (1, 11-12) and holothurians (2-10); 1, fossil isolated tylostyl (Demospongea), Eocene: Ypresian, Wobbanz, Isle of Rügen, Germany, GZG.001251/19 [from Ansorge and Reich, 2004]; 2, 4, 6, 8, Recent Laetmogone violacea Théel (Elasipodida: Laetmogonidae), North Atlantic Ocean, water depth 1,015 m, SMNH.110035/110036; 3, Recent Echinocucumis hispida (Barrett) (Dactylochirotida: Ypsilothuriidae), Norwegian Sea, water depth 100-300 m, SMNH.110122/110124; 5, Recent Trochodota purpurea (Lesson) (Apodida: Chiridotidae), southern Atlantic Ocean, water depth 11-13 m, SMNH.110131/110132; 7, Recent Chiridota pisanii Ludwig (Apodida: Chiridotidae), South Atlantic Ocean, water depth 10 m, SMNH.110126/110128; 9, Recent Elpidia heckeri Baranova (Elasipodida: Elpidiidae), Arctic Ocean, water depth 2,700 m, SMNH.110012/10013; 10, fossil cross-shaped table of Tribrachiodemas ordovicicus Reich (Aspidochirotida: Synallactidae), Late Ordovician (Katian/Hirnantian), Sweden, GZG.INV.20072 [from Reich, 2010b]; 11-12, fossil isolated pentactines (Hexactinellida), early Silurian (Telychian), Sweden, GZG.INV.24436, 24706 [from Maletz and Reich, 1997]. Abbreviations: GZG, Geoscience Centre, Georg-August University of Göttingen, Germany; MHI, Muschelkalk-Museum Ingelfingen, Germany; ROM, Royal Ontario Museum, Toronto, Canada; SMNH, Swedish Museum of Natural History, Stockholm, Sweden.
FIGURE 3. Holothurian body fossils, showing the preserved calcareous ring of 'standard architecture' with 5 radial and 5 interradial plates, and stereom structure of single elements. 1-2, Undescribed apodid holothurian body fossil with calcareous ring and body wall ossicles in situ, late Pennsylvanian Mazon Creek fossil Lagerstätte, Illinois, USA; 1, GZG.INV.50000 showing the calcareous ring and the body outline, 2, ROM.58481 showing the calcareous ring with stereom structure; 3, Undescribed aspidochirotid calcareous ring (Holothuriidae) with well-preserved radial and interradial elements, from a Triassic obrution deposit Lagerstätte in southern Germany, Upper Muschelkalk (Ladinian) MHI.1230 [from Reich, 2004, detail]. Abbreviations as in Figure 2.
FIGURE 4. Morphology of modern and fossil holothurian calcareous ring elements showing the typical stereo architecture; 1, outer view of right dorsolateral radial element, Recent Myriotrochus rinkii Steenstrup (Apodida: Myriotrochidae), Arctic Ocean, water depth 22 m, SMNH.110016/110019; 2, inner oblique view of an radial element, Recent Laetmogone violacea Théel (Elasipodida: Laetmogonidae), North Atlantic Ocean, water depth 1,015 m, SMNH.110035/110037; 3, outer view of an radial (left) and interradial element (right), Recent Chiridota pisanii Ludwig (Apodida: Chiridotidae), South Atlantic Ocean, water depth 10 m, SMNH.110126/110128; 4, inner view of an interradial element Eupyrgus scaber Lütken (Molpadiida: Eupyrgidae), North Atlantic Ocean, water depth 30-80 m, SMNH.110029/110031; 5, undescribed fossil radial element (stem group Apodida), inner view, middle Ordovician (early Darriwilian), Germany/Sweden, GZG.INV.20001; 6, undescribed fossil radial element (Apodida), outer view, late Silurian (Ludfordian), Gotland, Sweden, GZG.INV.13251; 7, undescribed fossil interradial element (stem group Apodida), inner view, late Silurian (Ludfordian), Gotland, Sweden, GZG.INV.40710; 8, undescribed fossil radial element (Aspidochirotida), inner view, late Silurian (Ludfordian), Gotland, Sweden, GZG.INV.13255. Scale: 1.0 mm (1-2); 0.5 mm (3-8). Abbreviations as in Figure 2.
