graptolite


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graptolite

any extinct Palaeozoic colonial pelagic animal of the class Graptolithina. Branching forms are found in later strata and up to Carboniferous times.
References in periodicals archive ?
Between Narva and the Pakri Islands, in the klint and in the valleys cutting into the bedrock, graptolite argillite and phosphorite rich in U are exposed or spread beneath the Quaternary cover.
The base of the Upper Ordovician Series has been formally designated at the base of the Nemagraptus gracilis graptolite Biozone (Bergstrom et al.
Thus, the base of the Sixth Stage of the Ordovician System correlates with the lower to middle part of the Keila Stage in Baltoscandia, and is in close proximity to the foliaceous/clingani graptolite zonal boundary.
Knowlton and Jackson (1994) have argued that--far more often than generally acknowledged--the apparent plasticity of coral reef cnidarians reflects genetic differentiation, Indeed, the literature provides numerous hints of genetic controls on size and form: genetically based, species-level differences in colony form within the Montastraea annularis complex (Weil and Knowlton, 1994); differences in regeneration among clones of the reef coral Stylophora pistillata (Rinkevich, 2000); age effects on the survival of stony corals (Hughes and Connell, 1987); graptolites with highly determinate patterns of colony size (Mitchell, 1986); and botryllid tunicates that exhibit zooid and colony senescence (Rinkevich et al.
2), and with the Lumsden Dam, Feltzen, and Bear River formations, which contain graptolite and acritarch fossils of Tremadocian age (White et al.
A number of graptolite genuses were found by Almera (1891), Schriel (1929), and Riba (1949), who attributed the black series to the Silurian (Llandovery, Wenlock and Ludlow).
The boundary between the Hunneberg and Billingen "groups" (later referred to as stages, substages or series) was placed between the Megistaspis (Paramegistaspis) planilimbata and Megalaspides dalecarlicus trilobite biozones when established (Tjernvik 1956), coinciding with the lower boundary of the Phyllograptus densus graptolite Biozone.
However, there is another type of oil shale in Estonia known as graptolite argillite (the older term Dictyonema shale).