What are the primary groups of placental mammal?
placental mammals, infraclass eutheria (which means "True/Good Beast" in Greek) are the dominant group in mammals in general (classification, which also includes mangles and monotrems) and a dominant group of terrestrial vertebrates. This is the case since the extinction of Neaian dinosaurs 65.5 million years ago. Although placental mammals consist of fewer species (about 4,900 in total) than reptiles (8,200 species), amphibians (6,100 species) or birds (10,000 species), placental mammals are dominant in being the most honest, most terrestrial chains that are the highest chains. The highest is the highest position that is the highest, it is the highest position that is the highest attitudes that are the highest, in the highest attitudes that are the highest attitudes that are the highest attitudes that are the highest Counter -for example.
Placentary mammals consist of 20 orders contained in four nAD even: xenarthra (early placental mammal detachment includes Armadillos, sloths and avengera); Laurasiatheria (including most mammals), Afrothia (Smaller African-Pedestrian Group including TENRECS, Aardvarks, Hyraxes, Golden Moles, Elephants, Elephants and Manatees); and the Euarchontoglies (the sister group Laurasiatherie, which includes rabbits, hares, rodents, primates, treeshrews and Colugos). These superiors are based on various levels of support from molecular genetics and fossil evidence, although some are quite controversial and basically contradict the earlier classifications based on morphology.
The four largest orders of placental mammals are chiroptera (bats), rodentia (mice, rats), karnivora (dogs, cats, bears, other placental carnivores) and cetartiodactyla (all boots such as pigs and buffaloes and cectons that include karageny and dolfíny). In spite ofElky number of species is a rough morphological variation in the first two orders somewhat limited, but in the second two large. It is to imagine that pigs and goats are part of the same order as whales and dolphins, but it's true. These groups were divided about 60 million years ago, during the first main waves of placental mammalization diversification.
Today, most of all placental mammals are based on an individual number of people, our pets, livestock and animals adapted to live near us, especially rats and mice. In our short period of 200,000 years on the world scene, people radically transformed the picture of the biodiversity of placental mammals. Hundreds, not a thousand placental mammals, disappeared when people spread around the world, bring hunting tools such as spears and axes, which could not fully adapt to the biological world quickly enough. As a result, many impressive placental mammals of mammals from old, like saber and mammoth,He is now completely extinct. Numerous placental mammals will still extract due to destruction of the station and other factors.