Palaeobiology of Silurian Leptaeninae (Brachiopoda) from Gotland, Sweden

[摘要] Leptaenine brachiopods are common and widespread on Gotland.Lepidoleptaena poulseniandLeptaena rhomboidalisretained a functional apical pedicle throughout ontogeny, and both had strong adductor muscles and robust ornamentation, allowing them to occupy shallow water and high energy environments. A pedicle-shortening muscle is present within the pedicle tube ofLeptaena rhomboidalis.Leptaena sperion,L. depressa visbyensis, andL. depressa latainhabited low energy environments, retaining very slender pedicles.L. depressa depressaandL. parvorugataatrophied the pedicle early and then lived ambitopically in deeper water. The presence or absence of the apical pedicle strongly influenced the cardinal process morphology. Leptaenine shells had a small gape. The lophophore was simple, similar to productids andLeptaenoidea. In closed valves, the inner epithelium of leptaenine trails remained exposed to the sea. This was probably important in gas exchange. The life position of pedically attached species was with the disc vertical. Some ambitopic specimens may have retained a similar attitude. Shells ofL. depressa depressaandLepidoleptaena poulsenicommonly are encrusted by epibionts, apparently without problems for larger shells. Small shells are shown to have been killed by bryozoan epizoans. Repaired shell damage is rare on the disc but is common along the commisure.

[学科分类] 生物技术