![\"Fossils](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/09\/how-dinosaur-troodon-grew-1.jpg\")
<\/a>Reconstruction of\u00a0Troodon formosus. Credit: Clarissa Koos, CC-BY 4.0<\/a><\/p>\nDavid Varricchio of Montana State University and Heath Caldwell of North Carolina State University studied pelvic and hindlimb fossils linked to Troodon formosus. The findings appear in PLOS One on September 9, 2026.<\/p>\n
Troodontids were feathered theropods with long legs, large eyes, and relatively large brains. Fossils from the Late Cretaceous<\/a> show these dinosaurs<\/a> lived across parts of North America. Scientists have long struggled to understand their biology because most known remains are fragmentary.<\/p>\n The new sample comes from western Montana, from rocks in the Two Medicine Formation. During the Campanian stage, roughly 75 to 78 million years ago, the area formed part of a coastal plain. The fossils include individuals at several growth stages, from embryos to fully mature animals.<\/p>\n Together, the remains provide a near-complete record of pelvic and hindlimb development for T. formosus. The researchers found broad consistency in bone shape through growth. Most major skeletal features appear across the series, even in young animals.<\/p>\n Some changes still occurred as the dinosaurs grew. Bone strength, surface texture, and the fusion of skeletal parts shifted at set stages. The femur also became relatively longer compared with the tibia in adults. Such patterns point to a steady growth process with limited effects from changing conditions.<\/p>\n The fossils also show variation among adult animals. Some remains point to different adult body sizes within the species. Such differences might relate to individual variation or sex, though the fossil sample does not settle the cause.<\/p>\n Foot injuries and other bone changes stand out in the sample. Many bones from the feet show signs of possible pathology. Similar foot problems appear often in other troodontid fossils. The high rate of these changes adds more evidence for frequent foot injuries within the group.<\/p>\n The study also has a bearing on the name Troodon. For decades, a single tooth served as the type specimen for Troodon formosus. A type specimen serves as the main reference for a species name.<\/p>\n The researchers support replacing the tooth with a set of pelvic and hindlimb fossils from juvenile and adult animals. A larger bone sample gives scientists more anatomical features for comparing future fossils. Such a change could also help settle long-standing questions about whether Troodon represents a valid genus.<\/p>\n The proposed taxonomic change still awaits a decision from the International Commission of Zoological Nomenclature. Until then, the new fossil series provides a stronger basis for studying T. formosus.<\/p>\n The bones also offer a starting point for future work on how these dinosaurs moved. Researchers could use the pelvic and leg anatomy to study walking, running, foot injuries, and body mechanics. The broad growth series gives paleontologists a rare chance to link skeletal form with age in a North American troodontid.<\/p>\n Publication: Varricchio, D. J., & Caldwell, H. R. (2026). Pelvic and hindlimb osteology and ontogeny of a troodontid from the upper member of the Two Medicine Formation (Cretaceous) of Montana.\u00a0PloS One,\u00a021(9), e0356249. doi:10.1371\/journal.pone.0356249<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"Fossils from a bird-like dinosaur in Montana give researchers a rare view of growth from embryo to adult.…\n","protected":false},"author":2,"featured_media":767983,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[253580,2927,2928,59,90,56,54,55],"class_list":["post-767982","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-cretaceous-period","tag-dinosaur","tag-fossil","tag-gb","tag-science","tag-uk","tag-united-kingdom","tag-unitedkingdom"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/767982","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/comments?post=767982"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/767982\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media\/767983"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media?parent=767982"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/categories?post=767982"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/tags?post=767982"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"Fossils](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/09\/how-dinosaur-troodon-grew-3.jpg\")
<\/a>Embryonic pelvis and femur of Troodon formosus. Embryonic pelvic elements for Troodon (MOR 246\u221211) in lateral view. Abbreviations: fe, femur; il, ilium; isp, ischiadic peduncle; pp, pubic peduncle; ps, pubis. Credit: Varricchio, Caldwell, 2026, PLOS One, CC-BY 4.0<\/p>\n![\"Fossils](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/09\/how-dinosaur-troodon-grew-4.jpg\")
<\/a>The \u201ckilling claw\u201d (pedal ungual II) from Troodon from a juvenile (top) and adult (bottom). Credit: Varricchio, Caldwell, 2026, PLOS One, CC-BY 4.0<\/p>\n