''Horodyskia'' is a

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

ised organism found in rocks dated from to . Its shape has been described as a "string of beads" connected by a very fine thread. It is considered one of the oldest known eukaryotes. Horodyskia per Fedonkin 2003

Biology

Comparisons of different fossils in the same locations suggest that it rearranged itself into fewer but larger main masses as the sediment grew deeper round its base. It may also have had a series of holdfasts along the bottom of the thread. Dimple marks in offshore sandstone have been found in the same deposits as ''Horodyskia'', suggesting that they may be remnants of older holdfasts. Thin sections of ''Horodyskia'' have revealed a system of tubes within the beads, including connecting strings, and other tubes radiating outward from each bead. Partial burial and branching of these tubes suggest that it may have had a benthic sessile lifestyle. Members of the genus are distinguished by bead size and spacing, with the beads of ''H. moniliformi''s being larger and more spaced than ''H. williamsii.''

Distribution

Species of ''Horodyskia'' has been found in Western Australia, Southern China, and in parts of North America, They are found in siliciclastic rocks such as sandstone, often as casts or molds.

Classification

Like many Precambrian organisms, the biology of ''Horodyskia'' is still poorly understood. As a result, it is difficult to classify what type of organism it may have been. ''Horodyskia'' has been considered an early

metazoan Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in ...

, and a

colonial Colonial or The Colonial may refer to: * Colonial, of, relating to, or characteristic of a colony or colony (biology) Architecture * American colonial architecture * French Colonial * Spanish Colonial architecture Automobiles * Colonial (1920 au ...

foraminifera Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly ...

n. More recently it has been hypothesized that they are a type of '' Geosiphon''-like

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...

(

Glomeromycota Glomeromycota (often referred to as glomeromycetes, as they include only one class, Glomeromycetes) are one of eight currently recognized divisions within the kingdom Fungi, with approximately 230 described species. Members of the Glomeromyco ...

Archaeosporales Archaeosporales is an order of fungi best known as arbuscular mycorrhiza to vascular land plants (Tracheophyta). But also form free living endocyte symbioses with cyanobacteria. The free living forms have a Precambrian fossil record back 2.2 ...

), due to the similarity of ''Horodyskia’s'' bead-like structures to the bladders of early growth stage ''Geosiphons.''

Footnotes

{{Taxonbar, from=Q4040768 Fossils of China Precambrian life Glomeromycota

Biology

Distribution

Classification

See also

Footnotes