Boltonocosta
| Order | Ephemeroptera (stem-group) |
| Age | ~310 Ma (Late Carboniferous) |
| Wingspan | ~8–10 cm |
| Diet | Unknown (adults may not have fed) |
| Fossil Sites | Mazon Creek and European deposits |
Boltonocosta is a large Carboniferous-era insect related to modern mayflies (Ephemeroptera). It had broad, veined wings and is among the earliest known representatives of the mayfly lineage, though it belongs to a stem group rather than being a direct ancestor of modern species.
Description
Boltonocosta had a wingspan of roughly 8-10 cm, making it large by modern mayfly standards (most living mayflies have wingspans of 1-4 cm). The wings were broad with a dense venation pattern. Like other early palaeodictyopteroid-grade insects, Boltonocosta could not fold its wings flat against its body.
Modern adult mayflies are famously short-lived, often surviving only hours to days in the adult stage, just long enough to mate and lay eggs. Whether Carboniferous proto-mayflies shared this extremely abbreviated adult life is unknown, but the anatomy suggests a similar lifecycle with aquatic larvae and short-lived winged adults.
Significance
Boltonocosta and related Carboniferous proto-mayflies demonstrate that the mayfly lineage is ancient, extending back over 300 million years. Mayflies (along with dragonflies) represent the most basal living lineages of winged insects, and their Carboniferous relatives help us understand the early evolution of insect flight.