P.P

Marsupials have less specialized forelimbs than eutherians and tend to specialize their hindlimbs rather than their forelimbs. Recent studies have suggested the presence of a marsupial forelimb complex. This complex forms a constraint as a result of functional requirements of a metatherian newborn crawl to the teat. Because metatherian gestation is a lot shorter than eutherian gestation, immature neonate crawl to the teat limits the forelimb and limits the developmental morphology of the forelimb. This theory proposes the existence of an evolutionary constraint under the assumption that because the mammalian hindlimb is more important for propulsion than the forelimb, the forelimb should therefore exhibit a higher level of evolutionary flexibility and thus be more capable of specialization for diverse functions.