Trisha Shetty (Editor)

Cirquella

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Kingdom  Animalia
Suborder  Olenellina
Family  "Nevadiidae"
Rank  Genus
Class  Trilobita
Superfamily  "Nevadioidea"
Phylum  Arthropoda
Order  Redlichiida
Similar  Daguinaspis, Nevadella, Olenelloides

Cirquella is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the Atdabanian stage, in the former continent Laurentia.

Contents

Description

Only the thin and lightly calcified headshields (or cephalon) of Cirquella have ever been found. It is very flat, almost oval in outline, the length about 85% of the width. The central area of the cephalon (or glabella) is moderately tapered forward. The furrows dividing the glabella are only weakly developed. The back of the eye ridge is opposite the first lobe (L1) of the glabella in front of the band (or occipetal ring) at the back of the glabella. In Cirquella espinata there is no genal spine but a slight angularity of margin opposite first lobe in front of the occipetal ring. In Cirquella nummularia the rim of the cephalon is entirely rounded.

Distribution

C. nummularia is known from the earliest half of the Lower Nevadella Zone, in the Dogtooth Mountains, British Columbia, Canada, and in Nevada.
C. espinata lived at the same time in the Southern Canadian Rocky Mountains.
C. nelsoni is reported from the Fallotaspis-Judomia Faunule, Fallotaspis Biozone, Campito Formation, Inyo-White Mountains, Eastern California.

Habitat

Cirquella species were probably marine bottom dwellers, like all Olenellina.

References

Cirquella Wikipedia


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Daguinaspis
Nevadella
Olenelloides
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