Girvanella

Girvanella is a fossil thought to represent the calcified sheath of a filamentous cyanobacterium known from the Burgess Shale[1] and other Cambrian fossil deposits.[2]

Girvanella
Scientific classification
Kingdom:	Bacteria
Phylum:	Cyanobacteria
Family:	incertae sedis
Genus:	†Girvanella Nicholson & Etheridge, 1878

Girvanella was originally described as a foraminifera.[3] It was later assigned to the now-obsolete family porostromata.[4]

Girvanella is characterised by having flexing, tubular filaments with a uniform diameter usually between 10 and 30 microns (rarely up to 100 microns). The walls of these tubules are relatively thick and calcareous. These tubules are typically (but not always) twisted together into nodules, and often encrust other objects including foraminifera.[3]

Fossils of Girvanella are found from the Cambrian through the Cretaceous.[3]

Girvanella fossils are found in a wide range of environmental conditions, most commonly shallow-shelf carbonate facies, but also in nonmarine limestones. Recent caliche deposts in Barbados may be referable to Girvanella.[3]

References

1. Caron, Jean-Bernard; Jackson, Donald A. (October 2006). "Taphonomy of the Greater Phyllopod Bed community, Burgess Shale". PALAIOS. 21 (5): 451–65. doi:10.2110/palo.2003.P05-070R. JSTOR 20173022.
2. Riding, R. (1975). "Girvanella and other algae as depth indicators". Lethaia. 8 (2): 173–179. doi:10.1111/j.1502-3931.1975.tb01310.x.
3. "Calcareous algae, Volume 4 - 1st Edition". www.elsevier.com. Retrieved 2020-09-28.
4. Monty, C. L. (1981). Monty, Claude (ed.). "Spongiostromate vs. Porostromate Stromatolites and Oncolites". Phanerozoic Stromatolites. Berlin, Heidelberg: Springer: 1–4. doi:10.1007/978-3-642-67913-1_1. ISBN 978-3-642-67913-1.