The DNA revolution of the early 2000s produced comparatively few major changes in the taxonomy of mammals. Most of the orders survived intact. The biggest surprise was that the Cetacea (whales and dolphins) form a clade with the hippopotamuses: that is, these two groups are more closely related to each other than they are to other artiodactyls such as pigs and cattle. In consequence Cetacea is now subsumed under Artiodactyla, which is renamed Cetartiodactyla.
The big news was that the dozen or so traditional orders of Eutheria (placental mammals) could be grouped into four clades, three of them new. The Xenarthra, the mainly South American edentates, remained, and group alongside the other three as follows:
- Ferae: comprising Carnivora (cats, dogs, bears, seals, hyenas etc.) and Pholidota
- Cetartiodactyla: cattle, camels, deer, sheep/goats, pigs, hippopotamuses, whales, dolphins
- Perissodactyla: horses etc.
- Chiroptera: bats
- Eulipotyphla: hedgehogs, (European) shrews, moles
It was no surprise that the tree shrews and flying lemurs grouped with primates, nor that rodents and lagomorphs went together. At first it seemed the extended primate group would include bats as well, and that was called Archonta; then this turned out to be wrong, and the remainder was renamed Euarchonta (see eu-: "the good ones that are left when we take some out"). It had long been doubted whether the Microchiroptera (echo-locating bats) and Macrochiroptera (fruit bats) really do go together, or independently invented flight, but it seems they are indeed a clade together.
The big loser is Insectivora. It was disbanded after all sorts of 'shrews' and 'moles' and their protean Madagascan equivalents the tenrecs were removed from it, mostly into the impressively varied new clade Afrotheria. Under its new name Eulipotyphla it still contains the European shrews and moles. Basically, a 'shrew' isn't a kind of animal, it's what a mammal has always looked like if it hasn't changed into something sexy like an okapi or an ocelot. And lo and behold, the little and whimsically-named elephant shrew turns out to actually be closer to elephants than to shrews.
Unfortunately the otherwise very good Tree of Life website hasn't updated its Eutheria page in many years. They know they have to, but they seem to have just dried up. Richard Dawkins's book The Ancestor's Tale is a good popularization that is up-to-date enough to use the new phylogeny.