Acadialithus


Classification: Mesozoic -> Nannoliths inc sedis -> Nannoliths inc sed - radiate multielement -> Acadialithus
Sister taxa: Acadialithus, Assipetra, Hayesites, Phosterolithus, Rucinolithus, Sikoraea,

Distinguishing features: Squat tube-shaped nannoliths; wall formed of two vertically stacked cycles, with 6-7 elements per cycle; wide central opening; c-axes oblique


Daughter taxa: (blue => in age window 0-800Ma)

Acadialithus with 6 elements in each wall cycle


Acadialithus with 7 elements in each wall cycle

Taxonomy:

Citation: Acadialithus Howe 2017
Rank: Genus
Type species: Acadialithus valentinei Howe 2017
Notes & discussion: Varol & Bowman (2019) suggested that Acadialiuths was synyonym of Trapezopentus, the later genus, however, is poorly known and does not appear to show the distinctive two-tiered construction of Acadialithus

Farinacci & Howe catalog pages: Acadialithus

Distinguishing features: Squat tube-shaped nannoliths; wall formed of two vertically stacked cycles, with 6-7 elements per cycle; wide central opening; c-axes oblique


Morphology remarks: Calcareous nannofossil having a vertical wall with two cycles which are made up of six to seven elements. No structures were observed in the large central opening. The heights of the two cycles are approximately equal. The elements in the cycles of the wall are vertical to slightly inclined. The elements in the cycles of the wall are roughly L-shaped in plan view, with one end of the elements extending outward to form a lateral projection of the element, where two elements are joined. In plan view, the lateral projections of each element in the upper cycle project at the opposite end of each element, compared to the lateral projections of the underlying elements of the lower cycle.
From plan view observations with a quartz plate, the c-axes of the calcite crystal comprising each element are oblique at an angle of ~30° to the long axis of the element. [Howe 2017]

Evolution & Phylogeny: Acadialithus differs from members of the family Polycyclolithaceae by the orientation of the wall elements, and in the absence of a diaphragm.[Howe 2017]

Ecology & Biogeography: Acadialithus has been observed in Upper Tithonian sediments from offshore eastern Newfoundland, Canada (this study), from the Baltimore Canyon area, offshore of the northeast coast of the United States (Valentine, 1980), offshore in the eastern Gulf of Mexico (Rich Denne, Jim Pospichal pers. comm.), and from the Pernik District of Bulgaria (Sinnyovsky, 2005). [Howe 2017]

Geological Range:
Last occurrence (top): at top of Tithonian Stage (100% up, 145Ma, in Tithonian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Tithonian Stage (62% up, 147.7Ma, in Tithonian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Howe, R. W. (2017). Acadialithus, a new nannofossil genus from offshore Eastern Newfoundland, Canada. Journal of Nannoplankton Research. 37(1): 61-66. gs

Varol, O. & Bowman, A. R. (2019). Taxonomic revision of selected Late Jurassic (Tithonian) calcareous nannofossils and the application of mobile mounting. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen. 291: 65-87. gs


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Acadialithus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 12-12-2019

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10002 Go to Archive.is to create a permanent copy of this page - citation notes



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