“the first evidence we have of an animal with legs and digits walking on land at that time”

This month’s Nature’s cover story of the discovery in southeast Poland of “a trackway and an isolated footprint that were made by early four-legged land vertebrates (tetrapods) almost 400 million years ago” – 18 million years older than the earliest known tetrapod body fossils, and 10 million years older than the oldest elpistostegids – prompts The Guardian’s Adam Rutherford to celebrate “the intellectual freedom of pure research that led them to this awesome discovery.” Which may be a bit of a stretch… The BBC report provides some of the detail from the Nature story. An earlier Guardian article adds

Ahlberg and his co-authors, mainly from the Polish Geological Institute in Warsaw, say their findings highlight how little we know of the earliest history of land vertebrates. They write that the prints “force a radical reassessment of the timing, ecology and environmental setting of the fish-tetrapod transition, as well as the completeness of the body fossil record”.

And from the NatureVideoChannel
The BBC report also has some graphics from Nature.

The trackway and analysis

397 million years old fossil footprints

And a detailed footprint

397 million-year-old fossil footprint