Alternative spelling: Monotremati
Parent taxon: Australosphenida according to Z.-X. Luo et al. 2001
See also Archer et al. 1985, Averianov and Lopatin 2011, Bonaparte 1850, Carroll 1988, Flower 1883, Flower and Lydekker 1891, Gadow 1898, Gardiner 1982, Gill 1872, Gregory 1910, Griffiths et al. 1991, Huxley 1880, Jaekel 1911, Kielan-Jaworowska et al. 2004, Kirsch and Mayer 1998, McKenna 1975, Murray 1978, Nowak 1991, Rauhut et al. 2002, Rich et al. 2001, Rowe 1988, Rowe et al. 2008, Velazco et al. 2022, Wible 1991, Wilson and Reeder 2005 and Woodburne and Tedford 1975
Sister taxon: Ausktribosphenida
Subtaxa: Agathodonta Cacodonta Kollikodontidae Kryoryctes Ornithorhynchidae Patagorhynchus Platypoda Spondilocoelia Steropodontidae Stirtodon Tachyglossa Tachyglossidae Teinolophidae
Ecology: scansorial insectivore