Posts Tagged ‘9 banded armadillo’

My Pleistocene Mammal Checklist of East Central Georgia 36,000 Years BP Revised

August 13, 2021

8 years ago, I wrote a blog entry listing the exact species of mammals I thought probably lived in east central Georgia 36,000 years ago. I chose this time because it was the most recent period when climate was similar to today’s climate, coinciding with the last time when man was probably absent. I wondered what mammals would live in an environment untouched by man but with a similar climate. My list was an educated guess because there is only 1 Pleistocene-aged fossil site in this region, though there are some to the immediate north, south, and east. This time period was an interstadial–a warm wet period between colder drier Ice Ages. Pollen evidence suggests oak tree populations expanded. So I assumed the ecosystem was a mix of open oak woodlands, some grasslands, wetlands, and relict arid scrub environments persisting from the previous stadial. Since I wrote this blog, new information has come to light, and my list needs to be revised. Before I started to write this, I didn’t realize I had already edited some of the changes into my original article. (See: https://markgelbart.wordpress.com/2013/12/27/if-i-could-live-during-the-pleistocene-part-xii-my-mammal-checklist/ )

The 9-banded armadillo is an addition to my list. 9-banded armadillos have recently recolonized the region, but until a few years back scientists didn’t realize this species had also lived in southeastern North America during the Pleistocene. Their fossils had been confused with those of the beautiful armadillo, a different extinct species that was about twice as big. But analysis of genetic material shows that both co-existed over the same range.

On my original list I put question marks next to species that I was unsure lived in the region during this time period. Fox squirrels are 1 that should have a question mark next to it. There is no evidence in the Florida fossil record of fox squirrels until very late during the Pleistocene ~12,000 years BP. However, fox squirrel remains have been found in a Georgia cave that date to the LGM ~21,000 years ago. They may be a late invader of southeastern North America, but on the other hand they could just have been local in distribution and perchance never left remains in fossil sites. By contrast gray squirrels are commonly found in regional fossil sites. Perhaps east central Georgia was an area where fox squirrels occurred 36,000 years ago and from where they expanded into the rest of the south, but the dearth of fossil sites explains why this is unknown.

On my original checklist I included 2 species of horses, but it seems likely there was only 1–Equus caballus. Fossils of the pseudo-asses that date to the late Pleistocene are restricted to the west. The pseudo-asses did occur in southeastern North America during the Pliocene and early Pleistocene, but by 36,000 years ago they were not living in the region.

I included elk on my original checklist, but genetic evidence suggests this species did not colonize North America until about 15,000 years ago. No radiometrically dated remains of elk on the continent prior to that date have ever been found. Unless there was an extinct lineage of elk ranging here, I don’t think they lived in the region. White-tailed deer were likely the most common species of deer in the region then, just like today. However, I do believe woodland caribou and the extinct stag-moose did occasionally range into the region. Fossil remains of both species have been found at this latitude. They were probably more common in the region during Ice Ages, but I think it seems likely a few stragglers did wander into the region during interstadials. After all, this was unchecked wilderness. Some caribou herds likely migrated haphazardly, and sometimes they wandered into the region.

I think herds of caribou wandered into east central Georgia even during interstadials.

Scientists identify the remains of a medium-sized canid as coyote from fossil sites that are known to date throughout the late Pleistocene. However, genetic evidence suggests coyotes diverged from the population of gray wolves that crossed the Bering Land Bridge into North America just 20,000 years ago. So what were these coyote-like canids? I think they are an unnamed extinct species anatomically difficult to discern from modern day coyotes. This species likely played a similar ecological role. On my list Canis latrans should be changed to unnamed extinct canid.

Dire wolves and jaguars were likely the most common large predators in the region. Giant lions and saber-tooths may have existed in low numbers here. The former were more common in the more open grasslands to the south of the region. But I think bears were by far the most common carnivores. If a person could travel back in time and take a walk in the woods of this region, it would be impossible not to run into a bear. Bears are omnivores and can breed and reproduce even when there are low populations of other large mammals. Grizzly-sized black bears, Florida spectacled bears, and giant short-faced bears all roamed the region then.

I still think most of the other famous Pleistocene megafauna occurred in the region, but some may have been transitory. I think Jefferson’s ground sloth and Harlan’s ground sloth were year round residents as were stout-legged llamas and long-nosed peccaries. Herds of long-horned bison roamed around looking for fresh pasture. Mammoths possibly passed through during annual migrations. And mastodons moved up and down the river valley bottoms.