\n
![\"EarthSnap\"\/](\"https:\/\/www.newsbeep.com\/il\/wp-content\/uploads\/2025\/12\/1766790432_598_earthsnap-banner-news.webp.webp\")
\n<\/a><\/p>\n
This finding reframes one of Earth\u2019s major climate shifts as a prolonged reshaping of life in the sea rather than a single moment of collapse.<\/p>\n
Reconstructing a complex timeline<\/p>\n
Across 161 rock sections and drill cores, fossil records capture how marine species changed unevenly through time rather than disappearing all at once.\u00a0<\/p>\n
By reconstructing this global sequence, Junxuan Fan at Nanjing University (NJU<\/a>) documented distinct patterns of loss and stability tied directly to where organisms lived in the ocean.\u00a0<\/p>\n Surface and shallow-water species held steady before declining abruptly, while deeper communities followed a delayed and more gradual trajectory.\u00a0<\/p>\n That divergence in timing shows the transition cannot be explained by a single shared cause, pointing instead to multiple overlapping environmental pressures.<\/p>\n Life at different depths<\/p>\n The main actors were foraminifera, tiny shell-building single<\/a>-celled marine organisms, whose remains pile up by the billions on the seafloor.<\/p>\n Some floated near the surface, some lived in warm shallow bottoms, and others occupied darker mud far below.<\/p>\n Because light, temperature, food, and oxygen differ sharply with depth, each group faced the same cooling in a different way.<\/p>\n That ecological split explains why the new record looks less like one collapse and more like an extended reshuffling.<\/p>\n Decline before the freeze<\/p>\n Long before Antarctica carried major ice sheets, the late Eocene already showed marine diversity thinning over millions of years.<\/p>\n Surface-floating and shallow-bottom forms stayed fairly steady initially, even as the broader background trend kept sliding downward.<\/p>\n Meanwhile, small bottom-dwellers briefly boomed during the early Priabonian, when more food seems to have reached deeper habitats.<\/p>\n That early burst is one reason the study rejects the older habit of flattening this interval into a single crisis.<\/p>\n Arrival of frozen conditions<\/p>\n The sharpest break came when Antarctica gained its first continent-scale ice sheet near the start of the Oligocene.<\/p>\n Sea-surface cooling trimmed warm-water species, and falling sea level squeezed shallow habitats where many larger species lived.<\/p>\n A broader climate record<\/a> places that turning point for Earth around 33.9 million years ago.<\/p>\n In the fossil curve, surface-floating and larger bottom-living forms lost species rapidly just as that colder world took hold.<\/p>\n Delayed collapse from below<\/p>\n Deep-sea communities did not crash at the same moment, and that delay is one of the record\u2019s clearest findings.<\/p>\n As oceans cooled, a stronger biological pump<\/a>, carbon sinking from surface waters, may have fed deeper seafloor species.<\/p>\n Only later did those small bottom-dwellers enter a long decline, likely as deep-water chemistry and food patterns kept changing.<\/p>\n That lag means the same global cooling could help one habitat for a while and still hurt it later.<\/p>\n Divergence of climate impact<\/p>\n When the team matched diversity against climate data, the groups lined up with different parts of the Earth system.<\/p>\n Surface and shallow-bottom species tracked sea-surface temperature and global sea level<\/a> more closely than deep-sea forms did.<\/p>\n Small bottom-dwellers instead followed changes tied to deep-ocean temperature and carbon cycling, which fits their darker, food-limited setting.<\/p>\n That split turns a vague extinction story into a map of who was exposed to which stress first.<\/p>\n Old suspects fade<\/p>\n Two late Eocene asteroid impacts have long tempted scientists looking for a single trigger, but the timing does not line up.<\/p>\n The small bottom-dweller slide began before the big ice-sheet pulse, while surface groups showed no matching impact-time collapse.<\/p>\n Later volcanism in the Afar-Arabian province could have worsened deep<\/a>-ocean stress, but evidence for that link stays tentative.<\/p>\n No lone disaster neatly explains every biological turn in time, even though several environmental changes overlapped.<\/p>\n Fossil clock intelligence<\/p>\n A new evolutionary algorithm, a search method that improves by variation and selection, made the sharper history possible.<\/p>\n Fan and colleagues at NJU designed the program to stitch patchy local fossil ranges into one timeline.<\/p>\n Using about 40,000 occurrences from 1,269 species<\/a>, the program reached a timeline with steps of roughly 29,000 years.<\/p>\n That extra detail made the difference between one blended pattern and separate losses, pauses, and rebounds.<\/p>\n Rethinking extinction narratives <\/p>\n For decades, low-resolution summaries made the transition look like one marine extinction event followed by a simple recovery.<\/p>\n Chinese coverage of the study put it plainly: \u201cnot a collective extinction, but each group went its own way.\u201d<\/p>\n That distinction sharpens how scientists read other deep-time crises, because different habitats can fail on very different clocks.<\/p>\n It also gives NJU and its collaborators a template for rechecking old extinction<\/a> stories that were built from coarse bins.<\/p>\n Lessons from deep time<\/p>\n Seen at high resolution, the Eocene-Oligocene transition becomes a layered ecological event, not a single change happening everywhere at once.<\/p>\n That does not make today\u2019s warming a replay, but it does show why fast global change can sort winners and losers by habitat.<\/p>\n The study is published in the journal Nature Communications<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read?\u00a0Subscribe to our newsletter<\/a>\u00a0for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on\u00a0EarthSnap<\/a>, a free app brought to you by\u00a0Eric Ralls<\/a>\u00a0and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"A new analysis has revealed that a major global cooling event about 34 million years ago did not…\n","protected":false},"author":2,"featured_media":377001,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[85,46,141],"class_list":{"0":"post-377000","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-il","9":"tag-israel","10":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/377000","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/comments?post=377000"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/377000\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media\/377001"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media?parent=377000"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/categories?post=377000"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/tags?post=377000"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}