[quote=@JFK]
Could be interesting. I like to be as accurate and realistic as I can feasibly be. Can we get a specific time and place that our characters will end up in?
[/quote]
 
I'd like it to be [I]just[/I] as Humans from Asia were moving into Central North America. This gives our Survivors a few years to establish themselves before they meet their first Paleo-Indians.

I need to do some more investigation about Montana in particular, which is where I would like our story to take place. But what I know now is that our story would likely take place around 14,000-12,000 BC. 

This might change a bit. I'm still researching the Pleistocene and Montana to get specifics for accuracy.

Our time period would mean that certain large now-extinct animals would have still been alive in North America. 

They would have included but would not have been limited to the following:

Woolly Mammoth (Mammuthus primigenius)

American Mastodon (Mammut americanum)

Columbian Mammoth (Mammuthus columbi)

Giant Short-Faced Bear (Arctodus simus) – The largest bear species ever, capable of running at high speeds.

American Lion (Panthera atrox) – larger than the modern African lion.

Dire Wolf (Canis dirus) – A large, powerful wolf species.

Saber-toothed Cat (Smilodon fatalis).

Giant Bison (Bison latifrons) – Much larger than modern bison, weighing several times more.

Ground Sloths (Megalonyx jeffersonii, Paramylodon harlani, Nothrotheriops shastensis) – Large, slow-moving herbivores.

Glyptodonts (Glyptotherium cylindricum) – Armadillo-like armored mammals.

Gomphotheres (Cuvieronius hyodon) – Elephant relatives with spiral tusks.

Ice Age Coyote (Canis latrans orcutti) – A larger, more robust relative of the modern coyote.

American Cheetah (Miracinonyx trumani) – A cheetah-like predator.

Giant Beaver – Beavers up to 2.5 meters long.

These animals thrived in a landscape shaped by retreating glaciers, with vast grasslands, forests, and wetlands. Their extinction began around 10,000 years ago, likely due to a combination of climate change (such as the Younger Dryas cooling event) and human hunting pressure.

Note: I didn't write all of this. I copied it from Wikipedia and edited it down. 

I'll investigate each animal more, as well as look up the many other now-extinct animals that might play a part in our story.