The life and death of living things is intimately connected, not just with the physical environment, but with the life of other species. These relationships are dynamic, and may continue for millions of years, as has the relationship between flowering plants and insects (pollination).<br>The gut contents, wing structures, and mouthparts of fossilized beetles and flies suggest that they acted as early pollinators. The association between beetles and angiosperms during the Lower Cretaceous period led to parallel radiations of angiosperms and insects into the late Cretaceous. The evolution of nectaries in Upper Cretaceous flowers signals the beginning of the mutualism between hymenopterans and angiosperms.