Life reconstruction of the pachycephalosaur particular person CMNFV 22039 in an surroundings typical of the Higher Maastrichtian Frenchman Formation. Picture credit score: Kaitlin Lindblad.
“Pachycephalosauria includes principally small (between 2 and 6 m lengthy), bipedal dinosaurs from the Santonian to Maastrichtian ages (85 to 66 million years in the past) of Asia and North America,” mentioned Carleton College paleontologist Bryan Moore and his colleagues.
“The clade is greatest identified for the fusion of its frontal and parietal bones into an inflated dome.”
“The encompassing cranial components are typically integrated into this construction and are sometimes adorned with nodes, spikes, and different ornaments.”
“As a result of the frontoparietal domes are probably the most taphonomically resistant elements of pachycephalosaur skeletons (apart from tooth), the pachycephalosaurian fossil file is dominated by these partial cranial stays.”
“In consequence, a lot of what’s identified about pachycephalosaur ontogeny and phylogeny is predicated largely on cranium morphology.”
Catalogued as CMNFV 22039, the newly-described pachycephalosaurian specimen is roughly 67 million years outdated (Maastrichtian age of the Late Cretaceous epoch).
The fossil was discovered inside the Frenchman Formation, the youngest of 5 Maastrichtian formations in southern Saskatchewan, Canada.
This dinosaur was probably lower than a yr outdated when it died, making it the youngest pachycephalosaur identified from skeletal stays.
“Regardless of its small dimension (estimated whole size of 90 cm, or 3 toes), the skeleton exhibits a number of characters diagnostic of Pachycephalosauria,” the paleontologists mentioned.
The findings present that most of the options scientists depend on to establish grownup pachycephalosaurs had been already current very early in life.
In addition they trace at how younger pachycephalosaurs moved: in contrast with adults, the juvenile’s hindlimbs had been proportionally lengthy, suggesting a extra cursorial, or speed-oriented, construct early in life.
Because the animals matured, their our bodies seem to have shifted towards the stockier proportions seen in adults, indicating a change in locomotion as they grew bigger and heavier.
“The comparatively lengthy hindlimbs of the juvenile in contrast with these of grownup pachycephalosaurs point out possible unfavourable ontogenetic allometry within the hindlimbs,” the researchers mentioned.
The group’s paper was printed on February 26 within the Journal of Vertebrate Paleontology.
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Bryan R.S. Moore et al. The ontogenetically youngest identified pachycephalosaur (Dinosauria: Ornithischia) postcranium. Journal of Vertebrate Paleontology, printed on-line February 26, 2026; doi: 10.1080/02724634.2026.2616325
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