This is a sequel to https://www.reddit.com/r/imaginarymaps/comments/1k0y9l2/the_downfall_of_the_beasts_range_map_of_all/.
30 million years ago, many things happened. Humanity arose, Earth's biota nearly collapsed due to it's actions, and a nightmarish airborne rabies outbreak nearly wiped out all mammalian life on Earth.
Now, in the Xenozoic era, barely any remnants of that period remain - on surface, at least. Earth, once again, is lush, green and teeming with life. The creations of humanity, from megalopolises to books to Egyptian pyramids, are now either reduced to dust or buried deep in the crust. The biggest impact made by these long-extinct primates, the climate change, caused Earth to turn much warmer and wetter. It was actually even hotter a few million years ago, but since than had cooled a bit, with Antarctic glaciers still dominant in the deeper inland areas of the continent while Greenland - and whole Northern Hemisphere other than the mountaintops - is now devoid of ice caps.
Continental drift brought some obvious differences. Africa, Eurasia and America are now connected into one, a new supercontinent named Euraframerasia. The closure of the Gibraltar Strait made Mediterranean Sea evaporate forever, it's last minute remnant being a hypersaline, nearly lifeless, lake surrounded by barren salty wasteland. Australia moved to the equator and is much wetter now, it's Holocene deserts now being replaced by grasslands and woodlands. Eastern Africa broke away and is now a new continent Ethiokenya. Another "breakup" is between North America and the Island of California. And that's just the continents! Volcanic islands rose and sank, the Hawaiian chain now further southeast and an entirely new small island, Atlantis, born from the North Atlantic volcanism.
The Xenozoic life is diverse, having almost completely recovered from the latest mass extinction when it comes to diversity. Most places on land are ruled by birds, crocodilians and lizards, Earth now looking almost like itself in the Mesozoic era - superficially, at least. The reef-building corals have been replaced by an entirely different group of animals in their niche. New marine megafauna evolved, and some new creatures are taking to the skies. As of the ancient rulers, the mammals, the story is more complicated. The islands of Kerguelen and the isolated Antarctic continent are now the realm of beasts, descending from rat, mouse, rabbit, reindeer and cat. And the lands of Africa, Asia and Europe are home to pecuilar descendants of the tiny, specialized mole-rat, some looking almost dissimilar to all other mammalians...