Contribution
'Hammer oysters' as secondary soft bottom dwellers
Seilacher, A.
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen Band 164 Heft 1-2 (1982), p. 245 - 250
7 références bibliographiques
publié: Dec 22, 1982
DOI: 10.1127/njgpa/164/1982/245
ArtNo. ESP155016401052, Prix: 29.00 €
Abstract
The basic organization of the pelecypods has evolved from monoplacophoran ancestors with the transition to a burrowing, infaunal mode of life (Vogel & Gutmann, 1980). Secondarily, several lineages returned to an epifaunal life habit by neotenic retention of the post-larval byssus and reduction of the locomotive foot (STANLEY, 1972). Some of these groups have replaced the byssal attachment by an oyster-like cementation to hard or rocky substrates. In our present project, studying and comparing the evolutionary return from rocky to soft bottom environments, the non-cemented, byssally attached groups present some difficulties: 1. The neotenic processes of byssus retention and foot reduction can be reversed (secondary burrowers in the Arcidae; Stanley, 1972). 2. Free lying forms can evolve directly from endo- or epibyssate soft bottom dwellers, leaving out the intermediate rocky bottom stage necessary in cemented forms (Stanley, 1972). Thus adaptive pathways in byssate pelecypods are not oneway streets, so that phylogenetic lineages may be read in different directions. The present study refers to such a controversial case.
Mots-clefs
pelecypods • byssus • locomotive foot • epibyssate • endobyssate