A unique mammal for comparative studies
The unique suite of morphological and physiological characters of monotremes was
recognized very soon after their discovery. The first serious study of monotremes by
Caldwell (1884) demonstrated that their reproductive and developmental biology was
a mixture of reptilian and mammalian features (Griffiths 1968, 1978, 1999, Temple -
Smith 1974, Renfree 1993, 1995, Temple-Smith and Grant 2001, Lin and Jones
2001).