BILLINGS, Mont. (AP) - A noted Montana paleontologist is putting forward a theory that says up to a third of classified dinosaur species are really just juveniles or subadults of already known species.

Jack Horner, director of the Museum of the Rockies in Bozeman, recently published research co-authored with Mark Goodwin of the University of California, Berkeley, in the peer-reviewed online science journal PLoS ONE.

Horner says he and Goodwin focused on dome-headed dinosaurs and theorize that those dinosaurs went through vastly different forms of head hardware as they aged.

Horner says the changes occurred so dinosaurs could signal species difference to other dinosaurs as well as their sexual maturity. Horner says the dinosaur skulls appear so different at various ages that they were incorrectly classified as unique species.

Horner says CT scans of dinosaur skulls backs up the theory.

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Information from: Billings Gazette, http://www.billingsgazette.com.

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