\n<\/p>\n
January 13, 2026<\/p>\n
2 min read<\/p>\n
Add Us On Google<\/span>Add SciAm<\/span><\/span><\/p>\n T. rex Never Stopped Growing, Dinosaur Bone Study Suggests<\/p>\n New clues hidden inside T. rex bones suggest that the carnivore lived longer lives than we thought<\/p>\n By Cody Cottier edited by Claire Cameron<\/span><\/p>\n Artist’s rendering of a Tyrannosaurus rex.<\/p>\n ROGER HARRIS\/SPL\/Getty Images<\/p>\n Dinosaur bones are like trees\u2014every year is represented by a new ring, and paleontologists can count those concentric circles to determine a fossil\u2019s age. But new research suggests that in the case of Tyrannosaurus rex, some growth rings have escaped detection until now. That means the king of the tyrant lizards lived longer than experts realized\u2014and never stopped growing larger.<\/p>\n Previous estimates put T. rex\u2019s lifespan at about 30 years, and the dinosaurs were thought to have reached their full size around age 20 to 25. The new research, published today in PeerJ, rewrites that life cycle: bones from 17 specimens indicate that these hulking predators actually stopped growing sometime between 35 and 40 years old and typically reached at least 8.8 tons.<\/p>\n \u201cIt took the prince a lot longer to grow into the king,\u201d says Steve Brusatte, a paleontologist at the University of Edinburgh, who was not involved in the new study.<\/p>\n If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.<\/p>\n The clues lay hidden in T. rex leg bones all along: while some growth rings can be seen with visible light, others, it turns out, only reveal themselves in cross-polarized light. Past research overlooked these fainter rings. Holly Woodward, a paleontologist at Oklahoma State University and lead author of the new study, almost did, too.<\/p>\n \u201cI sort of discounted it at first,\u201d she says, \u201cuntil I started looking at all these specimens and seeing it in a lot of them.\u201d<\/p>\n It\u2019s unclear what the subtler rings mean\u2014maybe a tapping of the growth brakes rather than a complete stop. But the team\u2019s analysis shows that they paint a fuller picture of T. rex\u2019s true age.<\/p>\n Counting growth rings isn\u2019t as simple as counting tree rings. As bones expand, \u201cthe earliest growth record gets destroyed,\u201d Woodward says, so only a record of the animal\u2019s later years is left behind. But she and her team had access to specimens of different ages, each capturing some fragment of the species\u2019 lifespan, which enabled them to mathematically nest smaller, younger bones within bigger, older ones. That analysis yielded a more complete reconstruction of the dinosaurs\u2019 growth.<\/p>\n Since the first study investigating T. rex growth in 2004, all the evidence pointed to a creature that surged toward adulthood, much like humans and other modern vertebrates. A more recent study from 2024 describes \u201cexplosive growth during the teenage years.\u201d In the absence of more data, many paleontologists had accepted those findings, but some weren\u2019t convinced.<\/p>\n \u201cThat seemed pretty quick,\u201d says Thomas Carr, a paleontologist at Carthage College, who was not involved in the PeerJ study. \u201cExtending the age … makes sense for such a large animal.\u201d<\/p>\n Experts say Woodward and her team\u2019s approach could force paleontologists to reevaluate how fast other dinosaurs and extinct animals grew. And there\u2019s more work to be done to understand the life cycle of T. rex, particularly because the fossil record has precious few juveniles.<\/p>\n Still, Lindsay Zanno, a paleontologist at the North Carolina Museum of Natural Sciences, who was not involved in the new study, describes the findings as a landmark for the field. \u201cWe finally have a growth curve for Tyrannosaurus that we can feel confident in,\u201d she says.<\/p>\n If you enjoyed this article, I\u2019d like to ask for your support. Scientific American<\/span> has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.<\/p>\n I\u2019ve been a Scientific American<\/span> subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm <\/span>always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.<\/p>\n If you subscribe to Scientific American<\/span>, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.<\/p>\n In return, you get essential news, captivating podcasts, brilliant infographics, can’t-miss newsletters, must-watch videos, challenging games, and the science world’s best writing and reporting. You can even gift someone a subscription.<\/p>\n There has never been a more important time for us to stand up and show why science matters. I hope you\u2019ll support us in that mission.<\/p>\n","protected":false},"excerpt":{"rendered":" January 13, 2026 2 min read Add Us On GoogleAdd SciAm T. rex Never Stopped Growing, Dinosaur Bone Study Suggests New clues hidden inside T. rex bones suggest that the carnivore lived longer lives than we thought By Cody Cottier edited by Claire Cameron Artist’s rendering of a Tyrannosaurus rex. ROGER HARRIS\/SPL\/Getty Images Dinosaur bones<\/p>\n","protected":false},"author":1,"featured_media":41612,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[58],"tags":[21634,10389,2266,16489,3951,188,3415],"class_list":{"0":"post-41611","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-bone","9":"tag-dinosaur","10":"tag-growing","11":"tag-rex","12":"tag-stopped","13":"tag-study","14":"tag-suggests"},"_links":{"self":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/41611","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=41611"}],"version-history":[{"count":0,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/41611\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/media\/41612"}],"wp:attachment":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=41611"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=41611"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=41611"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}On supporting science journalism<\/h2>\n
It\u2019s Time to Stand Up for Science<\/h2>\n