© 2026 ABC News

The sediments that trapped the specimen were extremely toxic, the researchers said. The water contained no oxygen, but hydrogen sulphide -- described as not only \"stinky\" but deadly -- was dissolved in the water, the researchers said.

An unusual chemical alchemy may have been responsible for the unique way Sue was fossilized, the researchers hypothesized.

About 85% of the animals on Earth today are arthropods -- including shrimps, lobsters, spiders, mites, millipedes and centipedes, the paper stated.

The downside to Sue's unique fossilization is it makes it hard to compare the specimen with other fossils of similar species of the time.

\"So it remains a mystery how she fits into the evolutionary tree of life,\" according to the researchers.

","canonicalUrl":"https://abcnews.com/International/scientists-discover-legless-headless-predated-dinosaurs/story?id=120330636","legacySlug":"/news/story/scientists-discover-legless-headless-predated-dinosaurs-120330636","noIndexNoFollow":false},"publishTime":"22:01","publishDate":"03-31-2025","updatedTime":"22:16","updatedDate":"03-31-2025","socialImage":{"alt":"A 444 million-year-old specimen of a primitive marine anthropod was fossilized “inside-out,” with its muscles and guts preseserved in ancient sediment, scientists say.\n","credit":"University of Leicester\n\n","ratio":"16x9","url":"https://s.abcnews.com/images/International/fossil-ht-er-250331_1743453471968_hpMain_16x9_1600.jpg","width":992,"height":558},"datePublished":"3/31/2025 22:01:00 GMT","video":{"live":false,"id":120330636,"headline":"Fossil of 'legless, headless wonder' discovered","mediaAssetTitle":"SCIENTISTS DISCOVER ‘LEGLESS, HEADLESS WONDER' THAT PRE-DATED THE DINOSAURS","description":"The 444 million-year-old creature fossilized inside-out, researchers say.","duration":"1:52","posterImg":{"url":"https://s.abcnews.com/images/GMA/default-img-undefined.png","width":608,"height":342},"video":{"feed":"https://service-pkgabcnews.akamaized.net/opp/hls/abcnews/2024/08/240813_wn_ender_726_,500,800,1200,1800,2500,3200,4500,.mp4.csmil/playlist.m3u8"},"playlist":["137060236","137028746","136712647"]},"relatedItems":[{"contentType":"video","date":"October 7, 2026","headline":"French protests as hundreds of schools partially shut down this week","section":"News","slug":"/video/137060236","id":"137060236","image":{"alt":"VIDEO: French protests as hundreds of schools partially shut down this week","credit":"ABCNews.com","ratio":"1x1","url":"https://s.abcnews.com/images/GMA/261007_gma_burridge_france1_713_hpMain_1x1_608.jpg","width":384,"height":384},"images":{"alt":"VIDEO: French protests as hundreds of schools partially shut down this week","credit":"ABCNews.com","crops":[{"16x9":{"small":"https://s.abcnews.com/images/GMA/261007_gma_burridge_france1_713_hpMain_16x9_608.jpg","medium":"https://s.abcnews.com/images/GMA/261007_gma_burridge_france1_713_hpMain_16x9_992.jpg","large":"https://s.abcnews.com/images/GMA/261007_gma_burridge_france1_713_hpMain_16x9_1600.jpg"}},{"9x16":{"small":"https://s.abcnews.com/images/GMA/261007_gma_burridge_france1_713_hpMain_9x16_608.jpg","medium":"https://s.abcnews.com/images/GMA/261007_gma_burridge_france1_713_hpMain_9x16_992.jpg","large":"https://s.abcnews.com/images/GMA/261007_gma_burridge_france1_713_hpMain_16x9_1600.jpg"}},{"1x1":{"small":"https://s.abcnews.com/images/GMA/261007_gma_burridge_france1_713_hpMain_1x1_608.jpg","medium":"https://s.abcnews.com/images/GMA/261007_gma_burridge_france1_713_hpMain_1x1_992.jpg","large":"https://s.abcnews.com/images/GMA/261007_gma_burridge_france1_713_hpMain_1x1_1600.jpg"}}]}},{"contentType":"video","date":"October 6, 2026","headline":"How abandoned mines across America are wreaking havoc on homeowners","section":"News","slug":"/video/137028746","id":"137028746","image":{"alt":"VIDEO: How abandoned mines across America are wreaking havoc on homeowners","credit":"ABCNews.com","ratio":"1x1","url":"https://s.abcnews.com/images/GMA/261006_gma_job_mines1_741_hpMain_1x1_608.jpg","width":384,"height":384},"images":{"alt":"VIDEO: How abandoned mines across America are wreaking havoc on homeowners","credit":"ABCNews.com","crops":[{"16x9":{"small":"https://s.abcnews.com/images/GMA/261006_gma_job_mines1_741_hpMain_16x9_608.jpg","medium":"https://s.abcnews.com/images/GMA/261006_gma_job_mines1_741_hpMain_16x9_992.jpg","large":"https://s.abcnews.com/images/GMA/261006_gma_job_mines1_741_hpMain_16x9_1600.jpg"}},{"9x16":{"small":"https://s.abcnews.com/images/GMA/261006_gma_job_mines1_741_hpMain_9x16_608.jpg","medium":"https://s.abcnews.com/images/GMA/261006_gma_job_mines1_741_hpMain_9x16_992.jpg","large":"https://s.abcnews.com/images/GMA/261006_gma_job_mines1_741_hpMain_16x9_1600.jpg"}},{"1x1":{"small":"https://s.abcnews.com/images/GMA/261006_gma_job_mines1_741_hpMain_1x1_608.jpg","medium":"https://s.abcnews.com/images/GMA/261006_gma_job_mines1_741_hpMain_1x1_992.jpg","large":"https://s.abcnews.com/images/GMA/261006_gma_job_mines1_741_hpMain_1x1_1600.jpg"}}]}},{"contentType":"video","date":"September 24, 2026","headline":"Tracking the Nor'easter impacting the East Coast ","section":"News","slug":"/video/136712647","id":"136712647","image":{"alt":"VIDEO: Tracking the Nor'easter impacting the East Coast and hurricane heading for Hawaii","credit":"ABCNews.com","ratio":"1x1","url":"https://s.abcnews.com/images/GMA/260924_gma_zee_storm1_hpMain_1x1_608.jpg","width":384,"height":384},"images":{"alt":"VIDEO: Tracking the Nor'easter impacting the East Coast and hurricane heading for Hawaii","credit":"ABCNews.com","crops":[{"16x9":{"small":"https://s.abcnews.com/images/GMA/260924_gma_zee_storm1_hpMain_16x9_608.jpg","medium":"https://s.abcnews.com/images/GMA/260924_gma_zee_storm1_hpMain_16x9_992.jpg","large":"https://s.abcnews.com/images/GMA/260924_gma_zee_storm1_hpMain_16x9_1600.jpg"}},{"9x16":{"small":"https://s.abcnews.com/images/GMA/260924_gma_zee_storm1_hpMain_9x16_608.jpg","medium":"https://s.abcnews.com/images/GMA/260924_gma_zee_storm1_hpMain_9x16_992.jpg","large":"https://s.abcnews.com/images/GMA/260924_gma_zee_storm1_hpMain_16x9_1600.jpg"}},{"1x1":{"small":"https://s.abcnews.com/images/GMA/260924_gma_zee_storm1_hpMain_1x1_608.jpg","medium":"https://s.abcnews.com/images/GMA/260924_gma_zee_storm1_hpMain_1x1_992.jpg","large":"https://s.abcnews.com/images/GMA/260924_gma_zee_storm1_hpMain_1x1_1600.jpg"}}]}}],"relatedContentSection":"news","schemaContent":{"name":"Fossil of 'legless, headless wonder' discovered","description":"The 444 million-year-old creature fossilized inside-out, researchers say.","duration":"1:52","uploadDate":"03-31-2025","publication":"03-31-2025","images":"https://s.abcnews.com/images/GMA/default-img-undefined.png","url":"https://service-pkgabcnews.akamaized.net/opp/hls/abcnews/2024/08/240813_wn_ender_726_,500,800,1200,1800,2500,3200,4500,.mp4.csmil/playlist.m3u8","contentUrl":"https://service-pkgabcnews.akamaized.net/opp/hls/abcnews/2024/08/240813_wn_ender_726_,500,800,1200,1800,2500,3200,4500,.mp4.csmil/playlist.m3u8","link":"https://www.goodmorningamerica.com/news/story/scientists-discover-legless-headless-predated-dinosaurs-120330636"}},"playlist":[{"id":"137443017","contentType":"story","section":"news"},{"id":"136253720","contentType":"story","section":"news"},{"id":"137220313","contentType":"story","section":"news"},{"id":"137234817","contentType":"story","section":"news"},{"id":"137147457","contentType":"story","section":"news"},{"id":"137132187","contentType":"story","section":"news"},{"id":"136945841","contentType":"story","section":"news"},{"id":"136945748","contentType":"story","section":"news"},{"id":"136930796","contentType":"story","section":"news"},{"id":"136874802","contentType":"story","section":"news"},{"id":"136841854","contentType":"story","section":"news"},{"id":"136766868","contentType":"story","section":"news"},{"id":"136694294","contentType":"story","section":"news"},{"id":"136682772","contentType":"story","section":"news"},{"id":"136631130","contentType":"story","section":"news"},{"id":"136644492","contentType":"story","section":"news"},{"id":"136623234","contentType":"story","section":"news"},{"id":"136614308","contentType":"story","section":"news"},{"id":"136605272","contentType":"story","section":"news"},{"id":"136553132","contentType":"story","section":"news"}],"kvps":{"pgtyp":"article","lang":"en","sp":"goodmorningamerica","programmatic":"true","bundleId":"com.abcnews"}},"analytics":{"accountID":"wdgnewwdgnewgmaweb","ns":"gma","pageName":"gma:news:video","pageType":"video","globalSpecVersion":"v1.08","siteDifferentiator":"gma:site","tagID":"g_page01","userABCookie":"0","section":"news","title":"Fossil of 'legless, headless wonder' discovered","pubTime":"18:01","pubDate":"03-31-2025","modTime":"18:16","modDate":"03-31-2025","taxonomyTags":"none","id":120330636,"editorialOtherSubjects":"","wordCount":"none","columns":"none","authors":"","authorsUnit":"none","authorsBureau":"none","subBrand":"Good Morning America","provider":"Good Morning America","videoName":"Fossil of 'legless, headless wonder' discovered","mediaAssetTitle":"SCIENTISTS DISCOVER ‘LEGLESS, HEADLESS WONDER' THAT PRE-DATED THE DINOSAURS","videoId":120330636,"mediaOnPage":"video","legacySlug":"/news/story/scientists-discover-legless-headless-predated-dinosaurs-120330636"},"taboola":{}},"request":{"headers":{},"httpVersion":"1.1","method":"GET","url":"/video/120330636","vary":{"host":"www.goodmorningamerica.com","cached":true,"path":"/video/120330636","forwarded-proto":"https","device":"desktop","userab":"0"}},"viewport":{"width":1260,"height":0},"user":{}};