"Spongiostromata" is an antiquated
form taxon that refers primarily to
fossil cyanobacteria
Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blu ...
. "Spongiostromate" is also used to describe
stromatolites and
oncolites that do not preserve clear tubules or other cellular microstructure.
Pia (1927) erected the group to contain calcareous algal fossils that contain no visible cellular structure but which he presumed represented cyanobacteria based on comparisons to modern examples. He divided the taxon into two groups: the ''
stromatolithi'' and the ''
oncolithi''.
Monty (1981) abolished the group as taxonomically uninformative but advocated for the use of "spongiostromata" to describe a form and texture of bacterial fossils. He defined a "spongiostromate" texture as follows:
"Spongiostromate microstructures result from the individualization of micritic, spongious, fenestral, sparitic, pelloidal, detrital, etc. laminae or films, variously grouped and organized. "
Throughout geologic history, spongiostromate stromatolites and oncolites have always seemed to vastly outnumber the
porostromate forms.
References
Paleobotany
Cyanobacteria
Stromatolites
Trace fossils
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