{"id":252800,"date":"2026-01-19T17:32:10","date_gmt":"2026-01-19T17:32:10","guid":{"rendered":"https:\/\/www.newsbeep.com\/ie\/252800\/"},"modified":"2026-01-19T17:32:10","modified_gmt":"2026-01-19T17:32:10","slug":"study-finds-tyrannosaurus-rex-did-not-reach-full-size-until-age-40","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ie\/252800\/","title":{"rendered":"Study finds Tyrannosaurus rex did not reach full size until age 40"},"content":{"rendered":"

The study used a new statistical approach that considered growth records from different specimens to better estimate the growth trajectory of the species across all stages of life<\/p>\n

By Will Dunham \/ Reuters, WASHINGTON<\/p>\n

There is no question that Tyrannosaurus rex got big. In fact, this fearsome dinosaur may have been Earth\u2019s most massive land predator of all time. But the question of how quickly T. rex achieved its maximum size has been a matter of debate.<\/p>\n

A new study examining bone tissue microstructure in the leg bones of 17 fossil specimens concludes that Tyrannosaurus took about 40 years to reach its maximum size of roughly 8 tons, some 15 years more than previously estimated. As part of the study, the researchers identified previously unknown growth marks in these bones that could be seen only using polarized light.<\/p>\n

\u201cThis growth trajectory is more gradual than expected,\u201d said paleohistologist Holly Woodward of the Oklahoma State University Center for Health Sciences, lead author of the study published this week in the journal PeerJ. \u201cRather than T. rex ratcheting up to adult size quickly, it spent a lot of its life at juvenile to subadult sizes.\u201d<\/p>\n

<\/p>\n

Photo: Reuters<\/p>\n

The researchers scrutinized annual growth rings \u2014 akin to those present in tree trunks \u2014 in the Tyrannosaurus leg bones from the various specimens, which ranged from smaller juveniles to massive adults.<\/p>\n

\u201cWe also found that growth-ring spacing in individual T. rex was variable. T. rex had a flexible growth pattern. Some years it didn\u2019t grow much, while other years it grew a lot,\u201d Woodward said.<\/p>\n

\u201cThis likely depended on resource \u2014 food \u2014 availability or environmental conditions. In other words, if conditions weren\u2019t great, it didn\u2019t spend energy on growing, but when conditions were good, it could grow larger. This flexibility allowed it to survive harsh times while growing larger than other carnivores, so it could outcompete others for resources. Ultimately, T. rex was only competing against other T. rex for food,\u201d Woodward added.<\/p>\n

<\/p>\n

Photo courtesy of Wikimedia Commons<\/p>\n

Tyrannosaurus prowled western North America during the Cretaceous Period at the twilight of the age of dinosaurs before an asteroid struck Mexico\u2019s Yucatan Peninsula 66 million years ago. This calamity doomed the dinosaurs and wiped out three-quarters of Earth\u2019s species.<\/p>\n

T. rex reached more than 12.3 meters long, possessed a massive head and tremendous bite strength, walked on two strong legs, and bore puny arms with just two fingers.<\/p>\n

Previous research had pointed to a Tyrannosaurus lifespan of somewhere around 30 years. The new study, according to paleontologist and study co-author Jack Horner of Chapman University in California, suggests a lifespan more like 45 to 50 years.<\/p>\n

This study involved more Tyrannosaurus specimens \u2014 many of them held at the Museum of the Rockies in Montana \u2014 than previous research into the life history of this species. The authors also said they used a new statistical approach that considered growth records from different specimens to better estimate the growth trajectory of the species across all stages of life, producing a different conclusion than previous work.<\/p>\n

\u201cWe don\u2019t know for certain which of these estimates are more accurate since we don\u2019t have living T. rexes to measure, but these new estimates make more sense logically and statistically, considering the size these dinosaurs attain,\u201d Horner said.<\/p>\n

Tyrannosaurus preyed on various plant-eating dinosaurs, including duckbilled ones such as Edmontosaurus and horned ones such as Triceratops as well as, in the southern part of its range, the enormous long-necked dinosaur Alamosaurus.<\/p>\n

\u201cUnfortunately we can\u2019t know the evolutionary advantage of any particular characteristic, but a lengthened growth with an intervening growth hiatus allows the younger individuals a different food strategy than the older, larger individuals,\u201d Horner said.<\/p>\n

\u201cAnd, independent of this current paper, I think the older adults were much more opportunistic \u2014 utilizing more scavenging \u2014 than the younger, smaller individuals. The extended growth period would provide a longer period of time for the younger individuals to possibly acquire more live prey,\u201d Horner added.<\/p>\n","protected":false},"excerpt":{"rendered":"The study used a new statistical approach that considered growth records from different specimens to better estimate the…\n","protected":false},"author":2,"featured_media":252801,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[61,60,82,9889,9888],"class_list":["post-252800","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-ie","tag-ireland","tag-science","tag-the-taipei-times","tag-9888"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/252800","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=252800"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/252800\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/252801"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=252800"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=252800"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=252800"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}