Dictionary of Human Evolution and Biology

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Tympanic Region Of The Temporal Bone

Bony ring that develops from dermal bone and supports the tympanic membrane in mammals; in primates a ringlike ectotympanic is found among some lemurs, whereas a tubular ectotympanic is present among the anthropoids and some prosimians. In catarrhines this bone becomes elongated, fuses with the tympanic plate, and forms a tube that helps form the external acoustic meatus. Because a tubular tympanic region is present in some of the basal primates, it is uncertain which trait is primitive. Sometimes referred to as the ectotympanic or tympanic bone.

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