Tagasi otsingusse
Carriker & Yochelson, 1968

Recent gastropod boreholes and Ordovician cylindrical borings

Carriker, M. R. Yochelson, E.
Aasta1968
AjakiriUSGS Professional Paper
Köide593B
LeheküljedB1-B26
Tüüpartikkel ajakirjas
Keelinglise
Id7864

Abstrakt

A comparative study of Recent predatory gastropod boreholes and a review of gastropod boring activity shows that shell penetration has certain characteristics, in part due to morphology of boring organisms, in part due to boring behavior of the predators, and in part due to structure of the prey shell. These points are considered briefly. Recent gastropod boreholes exhibit a broad spectrum of geometric form and size, but are distinctive in a statistical populational sense in possessing smooth walls, beveled outer edges, decreasing diameters with depth, and a general circularity and perpendicularity. To clarify the geometry of the holes, terminology is introduced. Cylindrically bored late Middle Ordovician brachiopods occur in collections from Ontario and Kentucky. The specimens from Kentucky provide new paleoecologic data on relative abundance of boring. One boring from the Pratt Ferry Formation of Cooper in Alabama and one from the Benbolt Formation of Cooper and Prouty in Virginia are also noted; these are the earliest reported borings of this kind (Porterfield Stage). All Middle Ordovician borings are new occurrences and all are similar to younger Paleozoic borings ascribed by previous workers to carnivorous gastropod attacks. Late Ordovician holes attributed to gastropods also have been reexamined. The Middle Ordovician borings show many of the features of Recent gastropod borings but seem to differ from Recent holes in being bored at an oblique angle to the shell surface and in being irregularly chamfered rather than truly tapered. Ordovician borings appear to be exceedingly rare. There is no obvious relationship between these borings and any particular fossil gastropod. The Ordovician holes need not have resulted from gastropod predation, for the physical evidence is equivocable. Several intrinsic features argue against such an early development of gastropod predation. As an alternative, it is suggested that these holes may be the result of activity of unknown and extinct soft-bodied organisms attaching to shells.

Viimati muudetud: 11/15/2022
KIKNATARCSARVTÜ Loodusmuuseumi geokogudEesti Loodusmuuseumi geoloogia osakond
Leheküljel leiduvad materjalid on enamasti kasutamiseks CC BY-SA litsensi alusel, kui pole teisiti määratud.
Portaal on osaks teadustaristust ning infosüsteemist SARV, majutab TalTech.
Open Book ikooni autor Icons8.