Five million years ago, a progressive downward slope in the global climate put an end to the Miocene Epoch and brought on the Pliocene Epoch. To get a visual idea, since we humans are a visual species, this map...
...became that map only five million years ago. (Would be nice if Google had given me an actual global map of the Pliocene...) Fast-forward two-and-a-half million years, and we get to the Pleistocene:
Biologically speaking, these changes were not catastrophic because the transition was gradual. The Miocene was "warm", the Pliocene was "cool" and the Pleistocene was "cold" or "frigid" (that definition is not the same as "cool".) The transition between epochs was so gradual that the majority of species were given time and space to adapt to the progressively cooler climate.
But in an alternate Earth, no such transition existed. Five million years ago on that world, the "warm" Miocene spiked straight down into the "frigid" Pleistocene, resulting in a mass extinction. What could cause such a dramatic transition is not the question. What IS the point involves the following list of mammals:
- Cervidae (deer)
- Giraffidae (giraffes, and that includes the more extravagant extinct species like Shansitherium, Palaeotragus, Mitilanotherium, Sivatherium and Samotherium.)
- Bovidae (bison, African buffalo, water buffalo, antelopes, wildebeest, impala, gazelles, sheep, goats, musk oxen and domestic cattle)
- Antilocapridae (pronghorns)
- Hyaenidae (hyenas, including extinct species like Pachycrocuta and North America's very own Chasmaporthetes.)
- Herpestidae (mongeese)
- Nandiniidae, Prionodontidae and Viverridae (civets and genets)
Of the mammals listed above, which of these would survive and which of these would die out in the specified extinction event?