Palaeobiology of Silurian Leptaeninae (Brachiopoda) from Gotland, Sweden

Figure 8

Muscle systems and gape. Scale bar = 1 cm (= 0.5 cm in detail pictures). (a) L. rhomboidalis. NRM Br116301; Stuguklint, Stenkyrka parish; Högklint Formation; open foramen and large chilidium. (b) NRM Br138045 + NRM Br138048; Mulde Tegelbruk, Fröjel; Halla Formation; two valves posed to illustrate the relationship between the muscle scars in the two valves. (c), (d), and (j) L. depressa visbyensis. (c), (j) NRM Br116262; Norderstrand, Visby; Lower Visby Formation; dorsal interior and posterior view of cardinalia. (d) NRM Br137848; Nyhamn, Lummelunda; Lower Visby Formation; ventral interior. (e)-(f) L. sperion. Ansarve, Tofta; Högklint Formation; (e) NRM Br116273; dorsal muscle field, note cardinal pit and diverging cardinal process lobes (f) NRM Br116271; ventral muscle field, note relatively large adductor scars. (g)-(h) L. parvorugata. Valleviken 1, Rute; Slite Group; (g) NRM Br138049b; dorsal muscle field, note no cardinal pit and small, parallel cardinal process lobes. (h) NRM Br138049a; ventral muscle field, note small adductor scars and secondary shell filling the delthyrial cavity. (i) L. rhomboidalis. NRM Br116161; Östra Vi, Visby; Slite Group; posterior view of cardinal process lobes. (k) Lepidoleptaena poulseni NRM Br121588; Lau Backar, Lau; Eke Formation; dorsal interior showing muscle scars elevated on a platform, and very strong, diverging cardinal process lobes. (l) L. depressa depressa. PMU G1056; probably Mulde tegelbruk, Fröjel; very gerontic specimen with greatly thickened transmuscle ridges.