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a subfamily of extinct reptiles of the family Hadrosauridae, or duck-billed dinosaurs. The Lam-beosaurinae existed in the late Cretaceous epoch. Their body length measured about 5 m. There was a helmet-like crest on the skull, which was formed by the premaxillary and nasal bones and had cavities within that possibly served as a reservoir of air for breathing during underwater feeding. Skeletal remains of Lam-beosaurinae are numerous in North America and Asia, where they serve as index forms for stratigraphy. An almost complete skeleton of one of the Lambeosaurinae—the Procheneosaurus— was found near Tashkent.