The Polish tetrapod footprints indicate that four-limbed, digit-bearing vertebrates were walking nearly 20 million years earlier than previously thought based on the fossil record.
Notes on verification
Confirmed by original 2010 Nature paper and multiple independent contemporary news sources (CNN, ScienceDaily, Science News); figure slightly revised in 2018 follow-up study but original 18-million-year claim remains well documented and widely cited. [cascade flags: aggregator_dropped_primary_exists | tier=silver indep_score=0.95 clusters=3 claim_tier=notable]
Sources
- Oldest Land-Walker Tracks Found--Pushes Back Evolution (seed:science_and_space)
- https://www.cnn.com/2010/WORLD/europe/01/07/tetrapods.poland.evolution.discovery/index.html (corroboration)
- https://www.nature.com/articles/nature08623 (corroboration)
- https://www.sciencenews.org/article/footprints-could-push-back-tetrapod-origins (corroboration)