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    "story_id": "mp-2026-07-19-014",
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    "headline": "Tuna Did Not Race Into the Dinosaur Gap",
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    "dek": "A combined fossil and genetic tree finds that large, warm-bodied pelagic fishes re-emerged gradually after the K-Pg extinction.",
    "summary": "A combined fossil and genetic tree finds that large, warm-bodied pelagic fishes re-emerged gradually after the K-Pg extinction.",
    "body_text": "Yale-led researchers built a time-calibrated evolutionary tree for tunas, mackerels, and relatives using genetic data and fossils. The reconstruction rejects a simple burst in which tunas immediately filled ocean-predator niches after the dinosaur-killing impact; large body size and endothermy arose repeatedly over a longer interval. The work revises an evolutionary timing hypothesis and may inform conservation, but it does not link the traits directly to human metabolic disease.",
    "why_it_matters": "A combined fossil and genetic tree finds that large, warm-bodied pelagic fishes re-emerged gradually after the K-Pg extinction.",
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      "The work revises an evolutionary timing hypothesis and may inform conservation, but it does not link the traits directly to human metabolic disease."
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    "first_published_at": "2026-07-19T09:00:00.000-04:00",
    "modified_at": "2026-07-19T09:00:00.000-04:00",
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    "tags": [
      "tuna",
      "evolution",
      "K-Pg extinction"
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  "sources": [
    {
      "source_id": "source-2026-07-19-014",
      "title": "Yale University via EurekAlert: Tuna evolution after K-Pg",
      "publisher": "Yale University via EurekAlert",
      "url": "https://www.eurekalert.org/news-releases/1136688",
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      "accessed_at": "2026-07-19T08:27:22.202-04:00",
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    "title": "Tuna Did Not Race Into the Dinosaur Gap",
    "publisher": "The Machine Press",
    "published_at": "2026-07-19T09:00:00.000-04:00",
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