2
$\begingroup$

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...

enter image description here

...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:

enter image description here

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?

$\endgroup$

closed as primarily opinion-based by StephenG, Cyn, elemtilas, Measure of despare., Ash Apr 28 at 17:33

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 1
    $\begingroup$ First map seems like North America and Russia are doing a fusion dance. $\endgroup$ – Renan Apr 27 at 22:45
  • 1
    $\begingroup$ Eco systems are extremely complex and I feel the effect of such a drastic event would be beyond what could be determined reasonably and is hence opinion based. If we were to ask a similar question about modern species, which we know in great detail, I doubt any two experts would agree. $\endgroup$ – StephenG Apr 27 at 22:49
  • $\begingroup$ Please note that climate is not the only difference between the Miocene and the Pleistocene. During the missing Pliocene, the African plate was busy colliding with the Eurasian plate, raising the Alps, the Carpatians and the Caucasus mountains, severing the communication between the Mediterranean and Red Sea, land-locking the Caspian and generally massively altering the geography of Europe and northern Africa. On the other side of the Atlantic the Panama isthmus was generating the Great American Interchange. $\endgroup$ – AlexP Apr 27 at 23:13
  • 2
    $\begingroup$ the plural of mongoose is mongooses or mungoose by the way, because english always has to do things the unintuitive way. . $\endgroup$ – John Apr 28 at 3:12
  • 2
    $\begingroup$ @JohnWDailey not its not, mongoose is not related to the word goose, completely different languages of origin. If you don't believe me you can check in any dictionary. $\endgroup$ – John Apr 28 at 12:40
8
$\begingroup$

Time to answer your question with more maps. Fun!

So, here's a map, or rather two maps, of the proposed vegetation zones in the Tortonian stage of the Miocene. It's not exactly the end of the Miocene, but I doubt a lot would change in the couple million years until the epoch ended.

enter image description here

The two maps represent two different models for the amount of CO2 in the atmosphere at the time, but they're basically the same. Similar enough for the purposes of the question, at least. By the way, the legend is a bit hard to understand; from what I can discern, purple and pink are jungle, orange is C4 grassland, yellow is C3 grassland (including tundra), the greens are temperate forest and the blue is boreal forest.

But we're not done with maps my friend, make no mistake. Time to pay a visit to the Paleobiology Database. Entering Cervidae and Miocene into the database turns up this, showing the location of all known deer fossils from this period.

enter image description here

According to the biome map, they're all from temperate forest and temperate grassland localities. Keep that in mind when I address the shift to Pleistocene biomes. Here are the results for your other families during the Miocene:

Giraffidae, mainly grasslands of both types but also temperate forests.

enter image description here

Bovidae, similar to giraffids but with more density in the forests.

enter image description here

Antilocapridae, restricted to North American prairies.

enter image description here

Hyaenidae, a good mix of tropical and temperate grassland and forest.

enter image description here

Herpestidae, not many occurrences, but mainly grassland.

enter image description here

I searched for all those last civety families, but... no results turned up. The Database must be inaccurate, since I know of at least one viverrid from the Miocene (Viverra leakeyi), but I'd assume a similar distribution to the other Old World families on this list.

Now, for our final map, here's one of the biomes in the Pleistocene epoch.

enter image description here

There are some major changes, most notably the appearance of the Sahara, and the expansion of ice sheets of course. However, Africa still has much savannah and tropical grassland, which would serve as a stronghold for most of the families you specified. Pronghorns and deer might be diminished, but ultimately there are still similar habitats which hold out in their distribution ranges too.

TL;DR: All the families will probably survive.

$\endgroup$
  • 1
    $\begingroup$ I have read that fossils are harder to come by in the wet tropics, for a variety of reasons. $\endgroup$ – Willk Apr 28 at 20:18
  • 1
    $\begingroup$ @Willk Indeed they are, or at least in tropical rainforests. You're right, that's probably a source of bias on the maps. $\endgroup$ – SealBoi Apr 28 at 21:10
  • $\begingroup$ The name you will want to use for civets is ,Viverridae, they have quite a wide range. $\endgroup$ – John Apr 29 at 16:37
  • 1
    $\begingroup$ Fossils have a large biome bias, forests in general and quite a lot of arid localities leave few fossils, it is even worse in near modern time periods like the miocene as many places that were depositional in the miocene are still depositional now so unlikely to expose fossils. It is not coincidence many miocene localities are caves or industrial excavations. $\endgroup$ – John Apr 29 at 16:40
  • 1
    $\begingroup$ I think the specialists, like giraffes and others, may be more impacted by the sudden change but with what this answer says, they could potentially survive in reduced numbers and then make an adapted comeback or remain "unadapted" in a smaller habitat range than before the change. $\endgroup$ – EveryBitHelps Apr 29 at 19:50
3
$\begingroup$

Only the pronghorns go.

Pronghorns are the smallest group and as I understand it were a small group even in the time period considered. Their distribution is / was limited to temperate North America and abrupt climate change there would probably be the end of them.

All other groups are well represented in the tropics. Cooling is not going to freeze the equator and the ecosystems there will be less impacted than in temperate regions. Those groups will have surviving members.

$\endgroup$
3
$\begingroup$

All of these groups have pretty wide ranges with fairly larger latitude ranges. So in all likelihood all of them will survive. Rapid cooling can do some weird things it can actually create a more stable climate, so things that do not live near the poles have a decent shot.

However the pronghorn and giraffe would be the most vulnerable to extinction, the pronghorn have the smallest range out of all of them, on the other hand they eat damn near anything. While most of the giraffe have very specialized diets/feeding habits, making them vulnerable to ecosystem changes, they also have a fairly small range. Both also have really limited species counts which makes them more vulnerable.

$\endgroup$
2
$\begingroup$

Even if we assume that some of the animals had very little fur due to the heat, or had fur more suitable for removing than keeping heat, they are all very likely to survive when only looking at their stats. The more northern ones can move quickly to more southernly places, to find similar climate, and only need to adapt to slightly different food.

The environment is going to be the deciding factor - how much plants are affected, which animals thrive under the conditions, and such.

Herds and individuals are going to be closer together if some of them migrate south (some will also migrate in the wrong direction), which also makes hunting them easier. They will have less food suitable for them, and that will quickly be eaten and gone. Trying to adapt might make them eat plants poisonous to them.

Meat eaters will have a good time - first with the easy food from dead animals, then with the animals all moving closer together, and then with weakened animals from too little food and wrong kinds of plants. Finally, with the population of above animals going down, the meat eaters, who multiplied rapidly, will also feel the crunch. Which will make them hunt down even animals in their prime.

A few of all the smaller animals in the list will find a place here and there to hide and enough food to make it somehow. It's the larger ones which will have no way to hide from an overabundance of predators. And among those, mostly the ones who had to migrate to new territory to survive.

Giraffes have a unique food source (leafs high up in the trees) which is likely to stay. And they are tough enough to keep most predators at bay. I assume they will survive, despite their size disadvantage. Pronghorns are fast, so some of those should survive, too. All the other animals are not in any real danger. It's mostly going to be a few of the bovidae which will die out - some of them the precursors of some of our domesticated cattle.

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.