6. Palaeontology of nematodes

Abstract

Cherts in Scotland. These 400 million year-old deposits were produced from hot springs and geysers that deposited silica in an opaline form called sinter around the fault zones. Silica molecules enter cells of organisms by permineralization and can provide excellent preservation of the internal tissues of small organisms such as nematodes. Trace fossilsTrace fossils are defined as any fossils showing the activity or growth of an organism. Those attributed to nematodes consist of trails or tracks left when movement occurs on a high viscosity surface. Sinuous, sinusoidal or traveling wave trails attributed to nematodes have been recorded in Mesozoic deposits, and it is possible (but not certain) that some of those attributed to the form genus Cochlichnus Hitchcock (Hantzschel 1975) were made by nematodes.Other possible nematode trace fossils are holes in foraminifera that resemble borings made by extant nematodes (Sliter 1971). CoprolitesEggs and other parasite stages of nematodes can occur in petrified coprolites. Care should be taken to make certain that the nematode stages recovered are not attributable to free-living, coprophagous nematodes that entered the dung after it was deposited. Human coprolites may contain a range of nematode stages, however, nematodes associated with human and animal remains during historic times are not covered here.