Caribou (Rangifer tarandus) in Pleistocene Georgia

It always fascinates me that caribou used to roam what’s now Georgia. The presence of caribou in the Pleistocene south is confirmed from fossil finds in Yarbrough Cave, Bartow County, Georgia; Bell Cave in northern Alabama; Charleston, South Carolina; and at least 3 sites in Tennessee–Baker Bluff Cave, Beartown Cave, and Guy Wilson Cave.  Caribou fossils have not been found in the abundant fossil sites in Florida, so its southernmost range limit occurred somewhere along a line drawn through what’s now middle Georgia, South Carolina, and Alabama.  The present day range of eastern woodland caribou was completely under glacial ice during much of the last Ice Age, so of course, they must have ranged further south.

What a majestic beast.

I have some questions about caribou in Pleistocene Georgia that I suppose may never be answered.  Were they year round residents or did they migrate here seasonally?   Today, barren ground caribou are known for their long distance migrations, but eastern woodland caribou are reported to stay in the same area their entire lives.  Did caribou live in the south during cold phases of climate or were they here during interstadials as well.  The caribou fossil from Charleston, South Carolina comes from strata thought to date to a warm interglacial.  There is a scientific method that can be used to answer the first question.  So far no scientist has chosen to chemically analyze the tooth enamel of fossil bones of southern caribou.  By determining the strontium isotope ratios in the tooth enamel they can compare it to that of extant mammals and mathmatically estimate where the extirpated southern caribou spent their time.  Scientists have used this technique with mastodons and mammoths.  Scientists determined from mastodon fossils found in Florida that they had spent time in central Georgia, but mammoths in Florida did not migrate long distances.

Robert Martin, a professor at Murray State and author of Missing Links: Evolutionary Concepts and Transitions in Time, first identified two caribou molars from Yarbrough Cave.  In an email he informed me there was also unsorted material from the cave but was unclear whether this consisted of more caribou specimens.  Murray State donated all of the fossils to the Florida Museum of Natural History where they probably rest in the bottom of a basement drawer.  The original fossil discoveries were made in 1991 but they have yet to be described in detail in the scientific literature with the exception of a few teeth of southern bog lemmings.  I had to ask Dr. Martin which parts of the caribou they found in the cave. 

Caribou are the only member of the deer family that have antlered females.  Male caribou shed their antlers after the rut is over, but females retain theirs through the winter.  The females dig craters in the snow, exposing lichen and grasses–their food supply.  They defend these territories against other females and antlerless males.  The females with the biggest antlers have the best chance of maintaining their top condition for next year’s pregnancy, and it improves the survival rate for the present year’s calf.  In regions with light snows where it’s unnecessary to dig craters, female caribou have smaller or no antlers.  Therefore, southern female caribou probably had smaller antlers.

For most of the year cow caribou fear or are antagonistic toward bulls.  During the rut the bull caribou approach the cows by lowering their head and bleating like a calf approaching to nurse.  (This reminds me of human foreplay–tit sucking.)  The female will stop and urinate, and the male will smell the urine to test whether she’s in estrus.  The vomerosonal organ in the nostril is used to detect the pheremone levels.  Primates lost this organ along their evolutionary pathway, but humans still wrinkle their noses at funky odors.

Reindeer warble fly.  They lay eggs under the hides of caribou.  Eskimos enjoy eating the larva–a fatty, salty snack, according to R. Dale Guthrie.  Reindeer meat is lean, and the average human would starve on such a high protein diet with no fat.  The warble fly larva provided valuable fat for people living in the Pleistocene.  Reindeer warble flies must have expanded their range into Georgia during the Ice Age.

Reindeer warble flies (Oedenagena tarandi) torment caribou all summer.  Their larva live under the hide during the winter and emerge during the spring.  Caribou meat is a healthy source of protein but is so low in fat that most humans would starve to death if they only ate this kind of meat.  Eskimos and Pleistocene Europeans eat or ate the warble fly larva which is high in fat.  It’s a valuable dietary supplement.  Warble fly larva is even depicted in paleolithic art alongside the more famous cave paintings of mammoth, bison, and horses.  Reindeer warble flies almost certainly enjoyed an expanded range during the Pleistocene and flew in Georgia then.

Yarbrough Cave

The area around this cave is clear cut, and the owner would “just as soon fill the cave in or level it.”  Many real estate developers are ignorant Nazis whose God is money.

View from inside the cave.

Yarbrough Cave is a small one about 120 feet long with a couple of small side passages.  Some woodland Indian artifacts have been excavated here.  All of the Pleistocene fossils in this cave come from a surprisingly small area–a 5 foot square, 6 foot deep hole in a side passage known as the Peccary Room.  The fossils date from between ~15,000 BP-~ 19,000 BP (from 2 different specimens), the end stage of the Last Glacial Maximum.  Like most other Pleistocene fossil sites in Georgia, the species represent a variety of habitats that must have existed nearby–woodlands, grasslands, and wetlands.  13-lined ground squirrels require extensive treeless prairies, but the other 6 species of squirrels show that forests must have been predominant.  Beaver, muskrat, river otter, and raccoon prove wetlands occurred here as well. Many more microfossils were lost here when some nameless blundering scientist botched the removal of a large section of matrix.  He probably lost all the bird bones.  There’s probably more fossils to be found here with a little digging and as I mentioned earlier the fossils already found here have yet to be described in detail.  Anyway, here’s the list of Pleistocene fossils that were excavated from Yarbrough Cave between 1988-1991. * denotes extinct species

short tailed shrew–Blarina brevicauda

least shrew– Cryptotis parva

eastern mole–Scalopus aquaticus

eastern pipistrille-Pipistrelus subflavus

big brown bat–Eptesicus fuscus

*giant ground sloth (probably Harlan’s)–Megalonychid sp.

*beautiful armadillo–Dasypus bellus

rabbit sp.?–Sylvilagus sp.

eastern chipmunk–Tamias striatus

13-lined ground squirrel–Spermophilus tridecemlineatus

red squirrel–Tamiasciurus hudsonicus

gray squirrel–Sciurus carolinensis

fox squirrel–Sciurus niger

southern flying squirrel–Glaucomys volans

northern flying squirrel–Glaucomys sabrinus

woodchuck–Marmota monax

beaver–Castor canadensis

mouse sp.?–Peromyscus

wood rat–Neotoma floridana

pine vole–Microtus pinetoreum

*?steppe vole–Microtus sp.

meadow vole–Microtus pennsylvanicus

muskrat–Ondatra zibethicus

southern bog lemming–Synaptomys cooperi

meadow jumping mouse–Napeozapus insignis

dire or timber wolf–Canis dirus or lupus.  The preliminary report says the fossil material compares favorably to the latter but tooth size overlaps between the 2 species  and I bet it’s from the former.  Ronald Nowak, the world’s foremost authority on Pleistocene canids, doesn’t think timber wolves ever colonized the southeast.

black bear–Ursus americanus

raccoon–Procyon lotor

weasel sp.–Mustela

striped skunk–Mephitis mephitis

river otter–Lutra canadensis

cougar–Puma concolor

bobcat–Lynx rufus

*long-nosed peccary–Mylohyus nasatus

*flat-headed peccary–Platygonus compressus

white tail deer–Odocoileus virginianus

caribou–Rangifer tarandus

References

Guthrie, R. Dale

The Nature of Paleolithic Art

The University of Chicago Press 2006

Martin, Robert

“A Preliminary List of Late Pleistocene Mammals from the Peccary Room of Yarbrough Cave, Bartow County, Georgia”

Palidicola 3 (2) 33-39 May 2001

http://www.forums.caves.org/viewtopic.php?f=8&t=5308

Tags: caribou, Oedenegena tarandi, R. Dale Guthrie, rangifer tarandus, reindeer warble fly, Robert Martin, Yarbrough Cave