Provenance Record

Well-structured News article at 765 words, within the 400–1200 word range for the category. The article covers two companion Nature papers coherently, correctly frames the evolutionary significance of both discoveries, and provides appropriate scientific context. The writing is clear and accessible without sacrificing accuracy.

Source 1 (https://www.nature.com/articles/s41586-026-10125-2): Nature.com returns HTTP 303 (paywall redirect); the DOI s41586-026-10125-2 is confirmed as the Eosteus chongqingensis paper by phys.org, which cites this exact DOI. The paper details (species, age 436 Ma, size 3 cm, IVPP/CAS authorship) are corroborated by all other sources. Source 2 (https://phys.org/news/2026-03-oldest-bony-fish-fossils-uncover.html): Fetched successfully. Confirms Eosteus chongqingensis at 436 Ma, 3 cm; Megamastax amblyodus at 423 Ma (vs article's '425 Ma'), over 1 m, published Nature 4 March 2026, IVPP/CAS researchers Zhu Min, Lu Jing, Zhu You'an. Source 3 (https://theconversation.com/new-fossil-reveals-the-weird-tooth-cushions-of-an-apex-predator-from-425-million-years-ago-274122): Fetched successfully. Confirms Megamastax amblyodus, 425 Ma (matches article's figure), ~1 m length, 17 cm jaw, Kuanti Formation, Yunnan, bony tooth cushions with clusters of sharp fangs, Brian Choo (Flinders University) and Jing Lu (CAS), Nature 4 March 2026. DOI 10.1038/s41586-025-10008-y confirmed. Source 4 (https://phys.org/news/2026-03-fossil-reveals-weird-tooth-cushions.html): Fetched successfully. Confirms Megamastax 425 Ma, 1 m, 17 cm jaw, tooth cushions description, same authors, Nature March 2026. Also confirms Eosteus at 435 Ma (vs article's 436 Ma — rounding difference). CAS press release (https://english.cas.cn/newsroom/cas-in-media/202603/t20260306_1151839.shtml): Fetched successfully. Confirms both species, ages (Eosteus 436 Ma, Megamastax 423 Ma), sizes, IVPP/CAS authorship, and the '10 million years earlier' claim.

Core facts verified: Eosteus chongqingensis at 436 Ma, 3 cm, oldest articulated bony fish — confirmed by phys.org and CAS. Megamastax amblyodus at ~1 m, 17 cm jaw, Silurian apex predator, bony tooth cushions — confirmed by The Conversation and phys.org. Published Nature 4 March 2026 — confirmed. IVPP/CAS — confirmed. '10 million years earlier' claim — confirmed by CAS press release. One minor discrepancy: the article uses '425 million years ago' for Megamastax, which matches The Conversation's figure; phys.org and the CAS press release use '423 million years ago.' This is a minor rounding variation across secondary sources and does not constitute an error — The Conversation (a cited primary secondary source) uses 425 Ma. No hallucinated quotes; no fabricated species characteristics detected. Pectoral fin spines and median dorsal plates described for Eosteus are consistent with what is described in the supporting secondary sources.

APPROVE. All key claims are verified against multiple sources. The minor age discrepancy for Megamastax (425 vs 423 Ma) reflects variation among secondary sources, with the article correctly citing the figure given by The Conversation. The two Nature paper DOIs are confirmed. The article is accurate, well-sourced, appropriately toned, and within category word-count guidelines.