acritarch

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acritarch

(ˈækrɪˌtɑːk)
n
a type of small fossil
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References in periodicals archive ?
The palynostratigraphy is established on the base of plants microfossils such as pollen, spores and acritarchs and correspond to two different assemblage biozones, i.e.
However, in collaboration with colleagues he has been studying various fossil groups such as chitinozoans, acritarchs, brachiopods, conodonts, early vertebrates, tabulate corals, stromatoporoids and other typical members of Palaeozoic faunas.
Acritarchs from the Hanford Brook Formation, New Brunswick, Canada: new biochrono-logical constraints on the Protolenus elegans Zone and the Cambrian Series 2-3 transition.
There are some reports of Mesoproterozoic fossils about the discovery of eukaryotes all over the world [7-10], including the acritarchs with circular excystment, multilayered walls, or ornamentation, multicellular filaments, and algal thallus [11], string-of-beads fossils named Horodyskia moniliformis and Horodyskia williamsii from shales in the 1.48 Ga lower Appekunny Argillite of Glacier National Park [12], diverse eukaryotic fossils like Tappania plana from the Early Mesoproterozoic Roper Group in Australia, and Horodyskia moniliformis from the Mesoproterozoic Bangemall Group [13].
A modified palynological preparation technique for the extraction of large Neoproterozoic Acanthomorph Acritarchs and other acid-insoluble microfossils.
Samples collected 8 m above the dinosaur-bearing horizon yielded dinoflagellate cysts, acritarchs, spores, and pollen (Appendix 1).
By the late Paleoproterozoic, organic-walled unicellular structures, collectively termed "acritarchs" (from the Greek akritos, "uncertain"), are present.
Palynology is the science that studies contemporary and fossil palynomorphs, including pollen, spores, orbicules, dinoflagellate cysts, acritarchs, chitinozoans and scolecodonts, together with particulate organic matter (POM) found in sedimentary rocks and sediments (Jansonius and McGregor 1996).
Most specimens consist of amorphous material of indeterminate origin, but a few are densely packed with sphaeromorphic acritarchs (Fig.
The scientists found that diverse assemblages of microscopic organic-walled fossils called acritarchs, which dominate the fossil record of this time, are present in lower rocks of the Chuar Group, but are absent from higher strata.
During the Proterozoic, the record additionally contains single-celled planktonic eukaryotes (acritarchs), dominantly preserved in shales and a few macroscopic remains.