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- monotreme reproductive biology is discussed on pp. 76,
389-391 in Vaughan et al. and on pp. 101,
192, 209, 218-219 in Feldhamer et al..
- short gestation
- egg tooth
- extended lactation
- mammae lack nipples
- female urogenital system [Fig. 5-4]
- male urogenital system
- abdominal testes (no scrotum)
- cervical ribs
- uncoiled cochlea
girdle with precoracoids, coracoids, and interclavicle [Fig.
- epipubic bones in both sexes
- sprawling forelimb posture
- rhinarium covered with
- reduced to absent dentition in extant monotremes
- homeothermic, but Tbody = 32
- males bear horny spurs on ankles
- fossil record includes the early Cretaceous of Australia and Paleocene of Argentina