Zhou Y, Shearwin-Whyatt L, Li J, Song Z, Hayakawa T, Stevens D, Fenelon JC, Peel E, Cheng Y, Pajpach F, Bradley N, Suzuki H, Nikaido M, Damas J, Daish T, Perry T, Zhu Z, Geng Y, Rhie A, Sims Y, Wood J, Haase B, Mountcastle J, Fedrigo O, Li Q, Yang H, Wang J, Johnston SD, Phillippy AM, Howe K, Jarvis ED, Ryder OA, Kaessmann H, Donnelly P, Korlach J, Lewin HA, Graves J, Belov K, Renfree MB, Grutzner F, Zhou Q, Zhang G.

Nature. 2021 Jan 6. doi:10.1038/s41586-020-03039-0

Platypus and echidna genomes reveal mammalian biology and evolution.

The ancestral mammalian genome had 30 pairs of chromosomes.