Eoleperditia is an extinct ostracod genus known chiefly from mineralised fossil material. The shell records some details directly, while age, classification and life habits require different kinds of evidence.
Its place among other fossil arthropods is explored in the ancient arthropod catalogue.
Quick facts
| Scientific name | Eoleperditia Swartz, 1949 |
|---|---|
| Type species | Cytherina fabulites Conrad, 1843 |
| Group | Arthropoda, Ostracoda, Leperditicopida, Leperditiidae |
| Main record | Ordovician marine carbonate deposits of North America and elsewhere |
| Shell | Two unequal valves with a hinge and diagnostic muscle-scar field |
| Measured examples | Published valve lengths include roughly 2.5–8.3 mm in a Kentucky sample |
| Main limit | The soft body and exact ecology are not preserved by the valves |
What can the fossils tell us?
Swartz established Eoleperditia in 1949 and selected Cytherina fabulites Conrad, 1843 as its type species. The name history includes older combinations and later synonymies that require comparison of the original descriptions.
The carapace has unequal valves and a hinge. Described features include a marginal rim and pits; the valve outlines can be measured, but they do not reveal the soft limbs inside.
The inner valve surface carries numerous small muscle-scar stigmata. Counts and patterns are observable on well-preserved material, though preservation can obscure their boundaries.
Published records occur in micritic and fine-grained carbonate rocks interpreted as shallow water. This constrains the depositional environment, not the exact position or behaviour of every animal.
A genus named from an older species
F. M. Swartz established Eoleperditia in 1949. Its type species is Cytherina fabulites, named by Timothy Abbott Conrad in 1843. Older literature therefore uses a different genus combination for the species that now anchors Eoleperditia.
Conrad's original material was presumed lost in the major 1984 revision by Jean M. Berdan, so later taxonomic work had to compare published descriptions and new specimens. The history also includes Leperditia josephiana, treated as a junior synonym of E. fabulites in that revision. Synonymy here records a taxonomic judgement about names and diagnostic characters, not proof that every specimen once given either name is identical.
Browse the ancient arthropod catalogue for other fossil groups whose hard parts preserve different amounts of anatomy.
Unequal valves and hinge
The animal's carapace consisted of two mineralised valves. The left valve is larger and overlaps the right around the free margin; the hinge joins the two along the dorsal edge. The exterior can carry a marginal rim and rows of small pits. Together, these features help distinguish Eoleperditia from other leperditicopid ostracods.
Berdan's revision describes four to six pits along the marginal area of some valves. Their count and preservation vary, so they are interpreted with the complete outline and internal features rather than used alone. A compressed or incomplete valve can lose a diagnostic edge.
Muscle scars and measured shells
The inner surface may preserve a striking field of minute muscle-scar stigmata, reported at roughly 150 to 200 in well-preserved examples. These impressions record attachment points associated with the animal's soft tissues. They do not preserve the muscles themselves or show how strongly the animal moved its valves.
Dimensions vary by species, locality and specimen. Berdan reported valves in a Kentucky sample measuring approximately 2.5 to 8.3 millimetres long. The 12.8 millimetre figure reported for a particular valve is a specimen measurement, not a universal maximum for the genus. A single largest published fossil is not enough to define the adult size range.
Ordovician carbonate settings
Eoleperditia occurs in marine carbonate deposits, including fine micritic limestones. Sediment texture and associated fossils have been used to interpret shallow-water environments. That is an interpretation of the beds where the valves accumulated; it does not mean every species occupied the same depth, salinity or substrate.
Ostracod shells can be transported after death or after moulting. A valve in a carbonate bed therefore gives stronger evidence for the depositional history than for the precise living position of the animal. The soft body, appendages and gut are not preserved in the material reviewed here.
What the shell can and cannot tell us
The valves establish the animal's bivalved arthropod carapace, its outline and overlap, and in favourable specimens the hinge, pits and muscle-scar field. Measurements support a millimetre-scale ostracod, but the published values apply to specimens and samples, not every member of the genus.
Movement, diet, reproductive biology and the function of each shell feature remain uncertain. Similar modern ostracods provide comparisons, but they cannot supply missing evidence for Eoleperditia. The safest reconstruction separates the directly observed shell from the inferred animal inside it.
Frequently asked questions
What is the type species of Eoleperditia?
The type species is Cytherina fabulites Conrad, 1843, later placed in the genus Eoleperditia.
How large was Eoleperditia?
Published measurements vary by species and sample. A Kentucky sample includes valves about 2.5 to 8.3 millimetres long; those values are not a universal size range.
What are the muscle-scar stigmata?
They are small impressions on the inner valve surface associated with muscle attachment. Counts of roughly 150 to 200 have been reported, but the muscles themselves are not preserved.
Did it live in shallow water?
Fine-grained carbonate deposits containing Eoleperditia have been interpreted as shallow marine settings. The sediments describe the depositional environment and do not locate every animal precisely.