Fusulina and Miliolina Lecture 8 Suborders Fusulina and Miliolina

Suborder Fusulina The Fusulina contains those foraminifera with non-laminar, calcareous, microgranular walls. The group was largerly Paleozoic in age, becoming extinct in the Triassic , although its descendants are extant in the hyaline Suborder Rotaliina.

The Fusulinacea includes the extinct fusulines "larger" forms which also had microgranular perforate tests, but with chambers arranged planispirally in a discoidal to fusiform plan. Two kinds of wall structure are found. The ancestral, fusulind wall is primarily two-layered with a dark, partly organic outer tectum and an inner, clear diaphanotheca. Secondary deposition of a dark epitheca within the chamber may give the inner walls a four-layered appearance. The schwagerinid wall lacks this secondary thickening and the mural pores are much enlarged to form alveoli. This gives the cleare inner layer a fibrous appearance termed keriotheca. The schwagerinid walls is typical of the lager fusulines of the later Pennsylvanian (Upper Carboniferous) and Permian periods. It includes many genera as Endothyra, Profusulinela, Fusulina, Schwagerina, and Neoschwagerina.

Fusulinid wall Schwagerinid wall

Suborder Miliolina The Miliolina have imperforate calcareous tests of porcelaneous appearance with a planispirally coiled proloculus. Subsequent growth may continue planispirally (Cyclogyra), uncoil and develop uniserially (Nubeculinella) or coil streptospirally. Streptospiral coiling here involves the addition of tubular chambers (generally half a whorl in length) arranged lengthwise about a growth axis. When added in the same plane (at 180 to one another) the arrangement is called spiroloculine if the chambers are evolute and biloculine if they are involute. More chambers are added at angles of 144 leaving five chambers visible from the outside (quinqueloculine, e.g. Quinqueloculina). In Triloculina, the chambers are visible from outside the test (triloculine). Such streptospiral growth forms may later "unroll" to uniserial, as in Articulina.

Growth series in Quniqueloculina and Massilina Chamber arrangement and dentition in the Miliolidae Growth series in Quniqueloculina and Massilina

Soritidae Alveolinidae Broeckina orbitolitoides Borelis pulchra

The Soritidae have thrived in reefal and carbonate habitats since the Late Triassic period. Coiling is basically discoidal planispiral, further modified to cyclical, fan-shaped (flabelliform) or straight uniserial in the later stages of growth (Peneroplis). Interseptal septulae subdivided the chambers into chamberlets in genera as Archaias. The all-emberacing, annular chamber addition in forms like Orbitiolites.

Peneroplis pertusus Archaias angulatus

The Alveolinidae also have imperforate test with a perforate proloculus (Fasciolites). Coiling is fusiform to ovate planispiral. The chambers are divided by septulae into numerous tubular chamberlets arranged in one or more rows. This group exhibits remarkable convergence with the Paleozoic fusulines but in much younger, ranging from Early Cretaceous to Recent times.

Alveolinid morphology and terminology

Peneroplis Archaias Orbitolites