''Pustula'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

brachiopod Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear e ...

s which lived during the

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

period. It is the type genus of the subfamily Pustulinae. Its fossils have been found in

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

, North America and northern Africa.

Description

Members of the genus ''Pustula'' had a subrectangular outline with a weak ventral sulcus, minimal trails and dorsal median folds. Like other echinoconchids, they had recumbent spines arranged in irregular concentric bands, with ''Pustula'' having elongated spine bases and weak spine differentiation. The dorsal face of this brachiopod was trifid, and the cardinal process was narrow. Marginal ridges and cardinal process pits are absent in this genus, while the cardinal ridges diminished towards the ears.

Classification

Brunton et al. (1995) deemed ''Pustula'' to be a primitive member of the Echinoconchidae family, a placement also supported by Muir-Wood & Cooper (1960). Leighton & Maples (2002) conducted multiple

phylogenetic analyses In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as Computational phylogenetics, phylogenetic inference. It infers the relationship among organ ...

which are strongly in agreement that the four subfamilies Buxtoniinae, Echinoconchinae, Pustulinae and Juresaniinae form the family Echinoconchidae. The

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

results of their phylogenetic analyses are displayed in the

below:

References

{{Taxonbar, from=Q122828027 Rhynchonellata