Fusulinidae

Part of speech: noun

Definitions

1. A family of extinct single-celled marine organisms characterized by complex shell structures, belonging to the larger group of foraminifera; known for their fossilized remains used in geological dating and paleoenvironmental studies; important indicators of late Paleozoic marine environments
2. A taxonomic grouping of fossil foraminifera distinguished by intricate calcareous shells; these ancient microorganisms contributed to sediment formation and serve as biostratigraphic markers in paleontology and stratigraphy; significant for reconstructing Earth’s historical climates and sea levels
3. A classification of prehistoric foraminiferal species notable for their elongate, chambered tests composed of calcium carbonate; their fossils are abundant in certain sedimentary rock layers, aiding in the study of Earth's deep past; utilized by scientists to interpret late Paleozoic marine ecosystems and geological timeframes

Etymology: Fusulinidae is the name of a family of extinct single-celled marine organisms, the foraminifera, whose shells are so distinctive that geologists use them to date Carboniferous and Permian rocks. The family name is a scientific coinage built on the genus "Fusulina," which was named in 1844 by Hermann von Meyer, and the "-idae" ending is the standard zoological suffix for animal families. Its root lies in the Latin "fusus," a spindle, a reference to the spindle-shaped, or fusiform, outline of the shells. Those shells were often no bigger than a grain of rice, yet they accumulated in enormous numbers on ancient sea floors. Their abundance and rapid evolution made them valuable index fossils, so a single specimen could tell a geologist roughly how old the surrounding rock was.