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Daniel Urban
Karen Sears Laboratory
Funded by the NSF
Biologists can never observe first-hand the evolutionary history of Earth’s diverse lifeforms. Instead, they play detective, examining the clues past processes have left behind to trace progressive changes in form and function. In this cross-section of an opossum skull, researchers can identify the similarity between the bone structure of the reptilian jaw and a developmental stage of mammalian middle ear bones. By studying middle ear development in mammals, we can better understand how the same bones used for chewing in a common ancestor became adapted for hearing in opossums and people.
