The Triassic saw the first of this lactating type of animal, evolving from creatures called synapsids
... Around 
20 million years later, a small group called the placozoa breaks away from... [DOC] [TLE] The Mammary Gland and Its Origin During Synapsid Evolution (PDF ... [PAR] The Mammary Gland and Its Origin During Synapsid Evolution ... 1st Olav T 
Oftedal ... Lactation appears to be an ancient reproductive trait that predates the 
origin of mammals.