Earth's oldest liverworts—Metzgeriothallus sharonae sp. nov. from the Middle Devonian (Givetian) of eastern New York, USA

Metzgeriothallus sharonae specimens from Givetian strata of eastern New York provide a Middle Devonian liverwort body-fossil record; this occurrence is not a crown-Marchantiophyta divergence date or a phylum-wide first appearance.

Metzgeriothallus sharonae is represented by well-preserved thalloid gametophytes with a medial costa and bifurcation, plus an associated sporophyte capsule; these observations diagnose the fossil material but do not describe all Marchantiophyta.

Metzgeriothallus sharonae supports a liverwort body-fossil assignment, while older Ordovician spore masses only suggest and do not establish Marchantiophyta affinity.

The profiled body fossils come from Givetian eastern New York and do not establish the phylum’s global origin area or complete fossil distribution.

The thalloid plant is interpreted as a small terrestrial primary producer; exact substrate, moisture regime and life history were not directly observed.

Metzgeriothallus specimens preserve bifurcating thalloid gametophytes with a medial costa and an associated sporophyte capsule.

The profile uses the Givetian body-fossil record as its evidence-linked older bound; older cryptospores are not silently promoted to crown-liverwort fossils.