Assertion: platypus's ancestor | /r/HasProperty | oviparous
Facets:
Source sentences:
text: The presence of vitellogenin genes (a protein necessary for egg shell formation) is shared with birds; the presence of this symplesiomorphy suggests that the common ancestor of monotremes, marsupials, and placental mammals was oviparous, and that this trait was retained in monotremes but lost in all other extant mammal groups.