Sigmoilina [SEP] parent taxon
, the only point of egress and ingress for the animal.
"Sigmoilina" is a protist, or proctoctist according to B.K. Sen Gupta, 1999, included in the miliolid family Hauerinidae (Loeblich & Tappan, 1988). It was previously assigned to the Miliolidae (Loeblich & Tappan, 1964) when foraminfera were regarded as comprising a suborder (Foraminiferida).
References.
- Alfred R. Loeblich Jr and Helen Tappan, 1964. Sarcodina Chiefly "Thecamoebians" and Foraminiferida; Treatise on Invertebrate Paleontology, Part C
Sigmoilina
Sigmoilina ia a miliolid genus, referring to the foraminiferal order Miliolida, characterized by an assymmetricall biconvex test formed by strongly overlapping chambers, one-half coil in length, that form a sigmoid (S-shaped) curve in cross section. The strongly overlapping chambers obliterate earlier ones from view resulting in the compressed biloculine appearance, differing from the squat, depressed biloculine form of "Pyrgo" and "Biloculina". The test, as for all Miliolida, is porcelaneous and imperphorate, the terminal aperture, with tooth