Infaunal or semi‐infaunal bellerophont gastropods: analysis of Euphemites and functionally related taxa

Abstract

198501 15: Infaunal or semi-infaunal bellerophont gastropods:LETHAIA analysis of euphemites and functionally related taxa. Lethaia, Vol. 18, Oslo. ISSN 0024- 1164.Burrowing and plowing gastropods may have existed prior to the Mesozoic, contrary to the conservative tendency of categorizing Paleozoic archaeogastropods as herbivorous hardground dwellers. We propose that Euphemites and other bellerophontiform molluscs such as Praematuratroph and Beyrichidiscus make functional and paleoecological sense only if reconstructed with an internal shell adapted to an infaunal mode of life. Attributes diagnostic of a probable infaunal mode of life in fossil bellerophontiform molluscs include: (1) lack of apertural flare; (2) restricted aperture; (3) low rate of whorl expansion; (4) semi-radial aperture; (5) extensive secondary shell deposits; (6) absence of extensive collabral ornament; (7) dorsolateral or umbilical furrows; (8) color patterns indicative of mantle extension and retraction capabilities; (9) absence of shell breakage and repair; and (10) associated lithologies indicative of penetrable substrates such as mudstones. Niche diversity in the bellerophontacean molluscs was probably much greater than previously suspected. This is entirely consistent with their long geologic range. Most bellerophontaceans, particularly the Late Paleozoic forms, were probably either 'nestling' or semiinfaunal with the apertural margins enwrapped by mantle or mantle and foot. As such they may have been particularly susceptible to predation during the postulated Mesozoic increase in number of infaunal predatorsa factor which may have been contributory to the bellerophontacean demise. 0 Morphological analysis, Euphemites, Bellerophontacea, infaunal gastropods, Late Paleozoic.

Gradient and recurrence analyses of four marine zones in the Glenshaw Formation (Upper Pennsylvanian, Appalachian Basin)

“…Previous paleoecological interpretations of other Paleozoic gastropods based on the ecology of extant forms has resulted in the oversimplification of their mode of life (Harper and Rollins, 1985). Many Paleozoic gastropods, similar to the taxa in the present study, are found in dark, fine-grained sediments, which contradicts modern analogs that indicate non-predatory gastropods are strictly herbivores limited to clear water environments with firm substrates (Peel, 1978).…”

“…Paleoecological aspects of Paleozoic gastropods are not well understood (Aigen, 1974;Harper and Rollins, 1985;Anderson, 1986). In the present study gastropod guilds were based on shell morphology, with the exception of the bellerophontid gastropods, where interpretations of the mode of life of these planispiral gastropods do exist (e.g., Harper and Rollins, 1985).…”

“…Low-spired gastropods including Glabrocingulum, Trepospira, and Shansiella, which are thought to be epifaunal deposit feeding or herbivorous archaeogastropods (Aigen, 1974), were grouped in the pleurotomarid (PLEURO) guild. Planispiral gastropods were divided into the Euphemites (EUPHEM) guild, which is thought to be infaunal to semi-infaunal deposit feeding burrower or plower (Harper and Rollins, 1985), and the Bellerophontids (BELLERO) Bellerophon (Bellerophon), Knightites (Cymatospira), Knightites (Retispira), and Pharkidonotus which are thought to be active epifaunal deposit feeders and herbivores (Harper and Rollins, 1985).…”

Life in the arena: infaunal gastropods and the late Phanerozoic expansion of marine ecosystems into sand

“…). The best candidates for an infaunal habit in bellerophontoideans are species in such genera as Hispanosinuites , Praematuropsis and Euphemites , in which the shell is partially enveloped by either the mantle or the foot (Harper & Rollins ). Their shells, however, are globose, and not streamlined; and the inductural deposits laid down by the enveloping organ are sculptured.…”

Larval and juvenile gastropods from a Carboniferous black shale: palaeoecology and implications for the evolution of the Gastropoda

“…Autecology. -Linsley (1978) and Harper & Rollins (1985) reconstructed Euphemites with nearly the whole shell covered by tissue. It was interpreted as an active, probably burrowing, predator.…”