Why did horses in North America go extinct?

[aplomado]

It seems to me that our feral horses should be considered "Native Wildlife" like any other.

 

Why did horses in North America go extinct?

 

 

[SailingAlongToo]

Horses native to North America went extinct during the last ice age. My guess would be related to loss of food (grazing grasses).

 

Europeans re-introduced horses to the continent in the 16th century.

[SailingAlongToo]

This is a good synopsis on the subject too.

 

https://www.livescience.com/9589-surprising-history-america-wild-horses.html

[gieserguy]

Check out this YouTube video! Very informative on this subject (and a great channel overall!)

 

 

[siteseer]

On 3/28/2019 at 11:03 AM, SailingAlongToo said:

Horses native to North America went extinct during the last ice age. My guess would be related to loss of food (grazing grasses).

 

Europeans re-introduced horses to the continent in the 16th century.

 

Horses were very diverse during the Miocene.  In fact there were still genera not too different from Mesohippus of the Oligocene (except larger) right up the Middle Miocene along with numerous grazing horses of different sizes during the last five million years of the Miocene.  Most of those groups died out by the end of that epoch, a time of drastic cooling climate and drop in sea level.  There were 3-4 horse genera in the Pliocene with Equus among them, the others being three-toed horses, but only Equus survived into the Pleistocene of North America.  The last of the three-toed horses still lived in Africa in the Early Pleistocene.

 

What happened to horses also happened to tapirs and rhinos in North America.  Tapirs also died out in North America at the end of the Pleistocene with rhinos gone early in the Pliocene.  We could say that these animals, all being perissodactyls (odd-toed hoofed mammals), were just better-suited to warmer climates while artiodactyls (even-toed hoofed mammals like deer, camels, and antelope) were just as well-suited for cooler climates but then we'd have to wonder why horses, tapirs, and rhinos didn't survive in Mexico or Central America.  Perissodactyls had been losing ground to artiodactyls since the Late Eocene.  Titanotheres, once quite diverse as well and including some of the largest perissodactyls, died out at the end of the Eocene along with various tapir-like forms.

 

Someone once told me that artiodactyls process grasses and other low-nutrient plants like grasses much more efficiently than horses can.  Artiodactyls seem to breed faster as well.  Over millions of years one group overlapping the same niches with a couple of slight advantages might pressure another group toward extinction.  Once horses were pared down to one extant genus, they became vulnerable to any fast-spreading deadly disease and any level of hunting by humans would have been an additional pressure especially at the greatest extent of the last glacial advance.

 

I've also heard that small populations of horses might have survived into modern times in the Americas but I don't think anyone has ever presented solid evidence of that.

[britishcanuk]

On 2019-03-28 at 2:38 PM, gieserguy said:

Check out this YouTube video! Very informative on this subject (and a great channel overall!)

 

 

That’s a great video, thanks for the link!

[Auspex]

The disparity in the megafauna collapse between N. Am. and Eurasia is a matter of geography.
A much larger percent of the N. Am. continental area is arctic, and the major mountain chains run North to South.
Eurasia has a larger percentage of temperate lands, and the mountains run East to West.
The global climate change was much harder on the N. Am. plains and their inhabitants.
It wasn't just the cooling, but the rate of cooling that made the difference. This is what happens when the rate of environmental change exceeds the capacity of the biome to adapt.

[DPS Ammonite]

3 hours ago, Auspex said:

The disparity in the megafauna collapse between N. Am. and Eurasia is a matter of geography.
A much larger percent of the N. Am. continental area is arctic, and the major mountain chains run North to South.
Eurasia has a larger percentage of temperate lands, and the mountains run East to West.
The global climate change was much harder on the N. Am. plains and their inhabitants.
It wasn't just the cooling, but the rate of cooling that made the difference. This is what happens when the rate of environmental change exceeds the capacity of the biome to adapt.

Please explain why the orientation of mountain ranges or the percent of artic lands affected climate change and/or the extinction rate of the megafauna. 

 

Thanks.

[Auspex]

12 hours ago, DPS Ammonite said:

Please explain why the orientation of mountain ranges or the percent of artic lands affected climate change and/or the extinction rate of the megafauna. 

 

Thanks.

Less impedance of a proportionally larger air mass fosters wilder swings and faster change.

The best explanation I read was in a book 10 or 12 years ago. Unfortunately, I can recall neither the title nor the author (and my copy is a 7 hour drive each way). It is about the relict ice age plants that no longer have the megafauna to distribute their seeds. If it comes to me, I'll add it to the thread!
@Carl may recall it, as i remember discussing it with him at the time.

[Carl]

5 hours ago, Auspex said:

Less impedance of a proportionally larger air mass fosters wilder swings and faster change.

The best explanation I read was in a book 10 or 12 years ago. Unfortunately, I can recall neither the title nor the author (and my copy is a 7 hour drive each way). It is about the relict ice age plants that no longer have the megafauna to distribute their seeds. If it comes to me, I'll add it to the thread!
@Carl may recall it, as i remember discussing it with him at the time.

Ghosts of Evolution by Connie Barlow. Great book!

[Auspex]

2 hours ago, Carl said:

Ghosts of Evolution by Connie Barlow. Great book!

Thanks, Carl! I am stalked by the darkening shadow of dementia, and sometimes the remember-bone draws a blank.

Now I hope that it is indeed the book that explained the geographic effects on N. Am. vs Eurasia of the Ice Age(s)...

[DPS Ammonite]

Here is a song with pictures by Connie Barlow. I guess that horses like Osage Oranges and helped them to spread.

 

An article about ghost fruits and seeds: 

[Carl]

14 hours ago, Auspex said:

Thanks, Carl! I am stalked by the darkening shadow of dementia, and sometimes the remember-bone draws a blank.

Now I hope that it is indeed the book that explained the geographic effects on N. Am. vs Eurasia of the Ice Age(s)...

Dementia? Nonsense. It's a brain filled to near capacity with fascinating thoughts trying to access them from a sea of amazing. At least that's how I explain my fracturing memory.