The palaeobiology of marine driftwood with special reference to the wood-boring bivalves
Author(s)
Evans, Siân
Abstract
Review of wood-colonising groups through geological time has shown that the Teredinidae, a family of wood-boring bivalves, have formed the major component of xylic faunas since the Lower Cretaceous.
Extensive microstructural and ultrastructural studies of Recent teredinids have demonstrated that the internal construction of the pallet and the morphology of the apertural region of the boring lining holds valuable systematic information. These features may be used to recognise fossil teredinids present in wood preserved within concretions, a source of palaeontological information which has been largely overlooked. Using this information, the stratigraphical distribution of the Teredinidae has been reassessed. Lower Cretaceous Bankia and Upper Cretaceous Nausitora are recorded for the first time on the basis of pallets. Taxa with solid pallets and thickened boring apertures appear in the Lower Tertiary. This suggests that the construction of pallets of Bankia is the primitive condition from which the solid pallet construction has evolved, contrary to previous interpretations based on relationships between extant genera. The mud-dwelling teredinid Kuphus has been considered the primitive sister group of the wood-boring teredinids. It is suggested here that Kuphus is a derived teredinid which has secondarily lost specialisations associated with wood boring. This hypothesis is supported by preliminary cladistic analysis. There is no support for the hypothesis that the teredinids evolved within the mangrove environment. Not all modern representatives of genera present in the Cretaceous are restricted to mangrove environment. The first evidence of extant genera which are entirely restricted to mangroves occurs in the Eocene. This suggests that the early teredinids colonised driftwood and subsequently exploited the mangrove environment. Cladistic analysis would suggest that extant mangrove general form a clade. These mangrove specialists have distinctive pallets and boring linings, providing an important new palaeoenvironmental tool for identifying mangroves within the fossil record.
Extensive microstructural and ultrastructural studies of Recent teredinids have demonstrated that the internal construction of the pallet and the morphology of the apertural region of the boring lining holds valuable systematic information. These features may be used to recognise fossil teredinids present in wood preserved within concretions, a source of palaeontological information which has been largely overlooked. Using this information, the stratigraphical distribution of the Teredinidae has been reassessed. Lower Cretaceous Bankia and Upper Cretaceous Nausitora are recorded for the first time on the basis of pallets. Taxa with solid pallets and thickened boring apertures appear in the Lower Tertiary. This suggests that the construction of pallets of Bankia is the primitive condition from which the solid pallet construction has evolved, contrary to previous interpretations based on relationships between extant genera. The mud-dwelling teredinid Kuphus has been considered the primitive sister group of the wood-boring teredinids. It is suggested here that Kuphus is a derived teredinid which has secondarily lost specialisations associated with wood boring. This hypothesis is supported by preliminary cladistic analysis. There is no support for the hypothesis that the teredinids evolved within the mangrove environment. Not all modern representatives of genera present in the Cretaceous are restricted to mangrove environment. The first evidence of extant genera which are entirely restricted to mangroves occurs in the Eocene. This suggests that the early teredinids colonised driftwood and subsequently exploited the mangrove environment. Cladistic analysis would suggest that extant mangrove general form a clade. These mangrove specialists have distinctive pallets and boring linings, providing an important new palaeoenvironmental tool for identifying mangroves within the fossil record.
Version
Open Access
Date Awarded
1998
Copyright Statement
Attribution-Non Commercial-No Derivatives 4.0 International Licence (CC BY-NC-ND)
Advisor
Taylor, Paul
Shaw, Harry
Gale, Andy
Sponsor
NERC grant.
Grant Number
GT4/212/93
Publisher Department
Department of Life Sciences
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)