The researchers believe the marks were made by mammals because they were created by opposing pairs of teeth -- a trait seen only in mammals from that time. They think they were most likely made by multituberculates, an extinct order of archaic mammals that resemble rodents and had paired upper and lower incisors. Several of the bones display multiple, overlapping bites made along the curve of the bone, revealing a pattern similar to the way people eat corn on the cob.So by the late Cretaceous, mammals were considering some dinosaurs food. There is a good deal of suspicion that these were done by scavenging rather than predation—a squirrel-sized rodent would not ordinarily take on a five-foot dinosaur with teeth.
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