Eocypselus geminus
Eocypselus geminus
Summary
Eocypselus geminus was a small stem apodiform, part of the early radiation that ultimately produced swifts and hummingbirds. Eocypselids retained less extreme wing proportions than living swifts, showing that the highly specialised modern swift flight apparatus evolved after these early forms.
The bird was probably an agile flier that took small insects, but sustained open air feeding like a modern swift should not be assumed. Its ecology is reconstructed from the apodiform skeleton and close relatives rather than direct dietary evidence. It is known from associated London Clay skeletal material that allows separation from several closely related Eocypselus species.
Quick Identification
Look for: a small associated apodiform skeleton with Eocypselus type wing and shoulder bones. E. geminus is not safely identified from an isolated small wing fragment; species assignment depends on size, proportions and several osteological details together.
Diagnostic Features
- The skeleton has the characteristic early apodiform construction of Eocypselidae.
- The wing is less specialised and proportionally less extreme than in crown swifts.
- The species falls within the small Eocypselus size range and overlaps closely with E. vincenti.
- Separation from other London Clay Eocypselus species depends on the combined proportions of multiple associated bones.
- Species diagnosis should therefore use the published associated material rather than a single isolated measurement.
Fossil Details
Similar Species
Recorded Fossil Sites
No fossil-site occurrences have yet been recorded for this species.