Lower boundary of the viable size of newborns in aquatic environmets

Range ~5 kg
Organism Mammals
Reference Smith et al., Body size evolution across the Geozoic, Annual Review of Earth and Planetary Sciences, Vol. 44 :523-553, 2016 DOI: 10.1146/annurev-earth-060115-012147 link p.527 3rd paragraph
Primary Source Downhower JF, Blumer LS. 1988. Calculating just how small a whale can be. Nature 335: 675 doi:10.1038/335675b0 link
Comments P.527 3rd paragraph: "The medium in which an organism lives also interacts with both size and physiology over both ecological and evolutionary timescales. For example, in mammals, the much higher rate of convective heat loss in aquatic habitats (as much as 90 times greater than in most terrestrial environments) effectively sets a lower boundary of ∼5 kg on the viable size of newborns because of the high cost of maintaining homeothermy in water (primary source)."
Entered by Uri M
ID 113315