From Newsgroup: sci.bio.paleontology

Traces of dipnoan fish document the earliest adaptations of vertebrates
to move on land

Abstract

A new trackway produced by crawling fishes, which includes imprints of
the trunk, snout, tail, body drag traces, and pectoral fins, was
discovered in the Lower Devonian (middlerCoupper Emsian) marginal marine deposits in the Holy Cross Mountains, Poland. The snout imprints are represented by a low-angle variant of the already described Osculichnus tarnowskae, which has generally been interpreted as a hunting trace of
fishes. However, in this case, it is considered an imprint of a fishrCOs snout, used for anchoring in the sediment during the locomotion of at
least partially emerged fish. This compound trackway provides the first evidence of the previously unknown life behaviour and locomotion
abilities of dipnoan fishes in the early stage of their evolution and documents a testing land mobility skills of vertebrates, predating by
about 10 million years fully terrestrial tetrapods locomotion traces.
Similar trackways are produced by extant lungfish during terrestrial locomotion. The trackway co-occurs with a new resting trace produced by
a dipnoan fish supporting itself with one or two pairs of fins on the
bottom.

Open access:
https://www.nature.com/articles/s41598-025-14541-8
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