HOLDOVER NAVEL. “Perhaps the most conspicuous ontogenetic leftover is found on the abdomen of all placental mammals: the umbilicus (navel or ‘belly button’). Strictly speaking this is a scar: although the umbilical cord has a function, the umbilicus itself never had one, making this a nonfunctional embryonic holdover, unlike the formerly functional circulatory and urogenital remains.”
https://evolution-outreach.springeropen.com/articles/10.1186/s12052-014-0012-5
linkedin post 2022-06-29 05:12:48
Nigel Fleming
September 21, 2022