# These Mammals Had a Good Run, So What Happened?



## Jdailey1991 (Jul 28, 2016)

The unfortunate fact about the subject of alternate history is that the question "what if" has been limited to human history.  But human history is currently 200,000 years old, hardly a speck in comparison to full history, which is currently four and a half *billion* years old.  At that length, there are so many points in the timeline where evolution and geology would have taken a different path.  But in order to create a believable point of divergence, we must first understand what happened in OTL.  The question below is one of many...




There are certain groups of mammals who had a very long run until very recent in geological history.

Paleomerycidae (55.8-4.9 MA)

Hyaenodonta

Creodonta (63.3-11.1 MA)

Entelodontidae (37.2-16.3 MA)

Merycoidodontoidea (35-5 MA)

Hyracodontidae (55.8-20 MA)

Leptictidia (70-33 MA)

Amphicyonidae (46.2-1.8 MA)

If these numbers are any indication, it proves that these prehistoric mammals had a resounding success. So what happened? What drove them into extinction?


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## CupofJoe (Jul 28, 2016)

Events... Change in Climate... The break up of continents... The arrival of [new and better] competition... There were probably a 1001 reasons


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## RedMetalHunter (Jul 28, 2016)

Would it not be, evolution...or lack thereof?


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## Ban (Jul 28, 2016)

The answer is likely simpler than you would prefer, but ultimately the survival of species depends on their ability to adapt to changing circumstances. Take the Creodonta for example. From a quick Wikipedia search I discover that the Creodonta were short-legged, long-bodied animals, likely suited for hunting in dense forests and crude terrains. A modern day comparison to this species would be a wolverine. The Oligocene and Miocene saw the decline and extinction of the Creodonta. These periods are (according to wikipedia) known for the rapid expansion of grasslands, during this time. The short-legged Creodonta would need to evolve larger legs and more slender bodies, akin to humans or wolves to be a top predator on these grasslands. They failed to do so. Evolution is not a guided process. It is an immensely large succession of random mutations, which might or might not be beneficial. Even if they are beneficial they might not be spread through the species, because of sheer bad luck. All in all, species rise and fall through adaptation, which is largely based on sheer luck.


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## skip.knox (Jul 28, 2016)

I'm not sure how this is related to fantasy, as it sounds more like straight science. Anyway, the above posts have it right. The question is so broad, the answers are going to be rather general.


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## psychotick (Jul 29, 2016)

Hi,

Alas, Mea Culpa. I was hungry and they were rather tasty! Have you ever tasted an Entelodant chop? Delicious with apple sauce like all hell pigs!!!

Cheers, Greg.


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## Jdailey1991 (Jul 29, 2016)

skip.knox said:


> I'm not sure how this is related to fantasy, as it sounds more like straight science. Anyway, the above posts have it right. The question is so broad, the answers are going to be rather general.



Speculative scenarios and alternate histories could be considered fantasy, but before I create a buyable fantasy, we need to first understand what happened on OTL and why they happened.


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## Russ (Jul 29, 2016)

To really understand what happened to those mammals you would have to do some solid science reading.  I don't think you will get too much useful information on apparent evolutionary mammalian dead ends here (if the is what they are).  The first question you need to answer is did they go extinct or were they just intermediate forms and the evolutionary line continued in another form.

In the broadest scene there are only two factors that play into a extinction scenario are reproductive success ability (absolute and relative) and contingency.


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