Assertion: prolactin | /r/AtLocation | the oldest known vertebrates
Facets:
Source sentences:
text: Although it is perhaps best known for its role in lactation, prolactin already existed in the oldest known vertebrates—fish—where its most important functions were probably related to control of water and salt balance.
text: Prolactin also existed in the oldest known vertebrates — fish — most likely to control the balance between water and salt.