Temporal range: Early Permian - Cenomanian
Hohenegger and Piller, 1977
Involutinida is an order of Foraminifera found in the fossil record from the early Permian to early Late Cretaceous (Cenomanian) in which the proloculus, the initial chamber, is followed by an enrolled tubular second chamber. The test wall is calcareous, perforate, radiate, originally aragonitic but commonly recrystallized to homogeneous microgranular structure, with lamellar thickenings or pillar-like structures in umbilical region of one or both sides.
Four families are included in Involutinida, three of which, the Involutinidae, Hirsutospirellidae, and Planispirillinidae all have undivided tubular second chambers. The fourth, the Ventrolaminidae has numerous chambers following the proloculus. All four are represented by planispiral or trochospiral forms.
The concept of the Involutinida seems to have developed over the years, beginning perhaps with the Involutinidae as described in the Treatise on Invertebrate Paleontology Part C, 1964, which then was included in the Cassidulinacea, Rotaliina. This was expanded to the superfamily Involutinacea, named by Zaninetti, 1975, so accommodating additional families. Later, Hohenegger and Piller, 1977, the Involutinacea was redefined as the suborder Involutinina, now the Involutinida.[original research?]
- Alfred R. Loeblich Jr & Helen Tappan,1988. Forminiferal Genera and their Classification. Van Nostrand Reinhold.
- Alfred R. Loeblich Jr and Helen Tappan, 1964. Sarcodina Chiefly "Thecamoebians" and Foraminiferida; Treatise on Invertebrate Paleontology, Part C Protista 2. Geological Society of America and University of Kansas Press.