Indian Veterinary Magazine (ISSN:3108-1398)

The placenta is a pivotal evolutionary innovation enabling prolonged intrauterine development and shaping reproductive strategies across vertebrate wildlife. In mammals, placentas exhibit striking diversity in gross morphology, interhaemal barrier structure, trophoblast invasion, decidualization, and microscopic exchange architecture. These structural differences align closely with life-history strategy, ecological context, and phylogenetic history. Phylogenomic analyses suggest that placental traits have undergone repeated transitions during mammalian diversification, challenging earlier linear models of increasing invasiveness. Molecular studies indicate that placental evolution is driven primarily by regulatory innovation and repeated co-option of endogenous retroviral genes involved in trophoblast fusion. Beyond mammals, placenta-like systems have evolved independently in reptiles, demonstrating strong convergent pressures favoring maternal–embryonic nutrient exchange. Integrating morphology, genomics, and ecology reveals that placental diversity reflects adaptive optimization under evolutionary constraint rather than progressive complexity. Understanding this diversity provides insight into reproductive resilience and evolutionary flexibility across wildlife taxa.