Posts Tagged ‘caribou’

New Trout Cave, West Virginia

June 2, 2015

No scientist has written a comprehensive paleoecological review of the fossil remains excavated from New Trout Cave, West Virginia.  Bones of mammals, birds, reptiles, amphibians, and fish were found in well stratified deposits here dating from 13,000 BP-over 50,000 BP.  The composition of species represent different climatic stages, making this a valuable site for ecologists interested in how faunal composition changed over time.  This blog entry is my layman’s review based on information I gathered from the paleobiology database and individual papers written about the vampire bat and pika remains dug from the cave.  A paper written about the reptiles and amphibians found here was published in an obscure journal I can’t obtain with convenience.  The bird and fish remains are completely undescribed in the scientific literature.  My review is entirely based on the ~50 species of mammal remains from the cave.

 

 

Map of West Virginia highlighting Pendleton County

New Trout Cave is located in Pendleton County, West Virginia.

Many of the species excavated from the cave were typical of those preyed upon by owls.  These smaller species prefer specific environments, so they are a better indicator of nearby paleohabitats than larger species.  The full glacial environment of the West Virginia/Virginia border seems to have been a mix of cold arid grassland, especially at higher elevations; and boreal forests in the valleys.  I counted 9 species with a definite preference for spruce forests–snowshoe hare, least chipmunk, red squirrel, northern flying squirrel, porcupine, boreal bog lemming,  heather vole, rock vole, and pine marten.  All but the least chipmunk, boreal bog lemming, and taiga vole still live in West Virginia, a state that still hosts some spruce forests.

The highest elevations in this region must have included tundra-like habitat.  The Labrador collared lemming (Dicrostonyx hudsonicus) occurred here during the Ice Age when its present day range was covered by uninhabitable glacier.  The taiga vole (Microtus xanthognatus) is another rodent that prefers tundra habitat.  Caribou (Rangifer tarandus) were also comfortable in these tundra-like conditions but likely wandered down to lower elevations.  Pikas (Ochotona sp.), a relative of the rabbit, formerly lived at higher elevations in the Appalachians.  They are known from 9 Pleistocene-aged sites in the northeast, including New Trout Cave.  These adorable animals like to take refuge under boulders where they store the alpine vegetation they eat.  Grassy rocky balds formerly provided excellent habitat in the Appalachian Mountains, but pikas became extirpated in the east following the end of the Ice Age.  Pikas still live in the Rocky Mountains where they were able to adjust to warming climate by moving to higher elevations.

Picture

Taiga vole.  They no longer occur anywhere near West Virginia.  The presence of this species in West Virginia 29,000 years ago is evidence winters were harsher here then.

Distribution of Microtus xanthognathus

Present day taiga vole range map.

Woodland Caribou

Caribou and white-tailed deer were the 2 species of deer that lived in West Virginia 29,000 years ago.

Dicrostonyx hudsonius map.svg

Present day range map of the Labrador collared lemming.

American Pika
The American pika, known today only from high elevations in the Rocky Mountains, lived in West Virginia during the late Pleistocene.
The short-faced skunk (Bracyhprotoma obtusata) is an extinct species known from just 6 sites, including New Trout Cave.  This small skunk was probably a denizen of spruce forests.  It never expanded its range north when the glaciers receded.  Instead, it died out, and no scientist has a good explanation for its demise.
The grassy cold hilltops that provided habitat for collared lemmings and pikas also attracted western prairie fauna, including badgers, 13-lined ground squirrels, plains pocket gophers, and prairie voles.  None of these species occur in West Virginia today.  Horses (Equus sp.), flat-headed peccaries (Platygonnus compressus), and helmeted musk-ox (Bootherium bombifrons) were among the larger mammals that preferred the open spaces, though horses are a semi-generalist animal that can live in woods, if patches of grass are available.  Remains of lions (Panthera atrox), bison (Bison antiquus), and woolly mammoths (Mammuthus primegenius)  were not found in New Trout cave but I strongly suspect they were a part of the faunal mix here during the Last Glacial Maximum.
Over 27 species recovered from the cave were temperate or generalist species such as woodchuck, southern flying squirrel, gray squirrel, eastern chipmunk, jumping mice, beaver, muskrat, southern bog lemming, pine vole, meadow vole, wood rat, cottontail rabbit, white tail deer, red fox, coyote, dire wolf, raccoon, black bear, weasels, Jefferson’s ground sloth, shrews, and bats.   I can’t determine from the information available whether they co-occurred with the boreal/tundra/grassland species or represent a fauna from a different climatic phase.  It’s likely relic temperate habitat persisted in valleys, even during full glacial climate phases.  Some beech, oak, and hickory probably grew among the spruce in protected moist coves.  I’m sure beavers were able to survive the harsher winters wherever waterways existed.  Black bears live as far north as Alaska, so they remained in West Virginia during the glacial maximum.  Jefferson’s ground sloths ranged as far north as Alaska as well and undoubtedly were capable of surviving harsh winters.  White tailed deer are at home in Canada today.  They may have roamed with caribou in mixed herds here then.  Following the end of the Ice Age, most of these temperate species increased in abundance here, while the boreal/tundra species retreated north or perished.
Some of the fossil remains found in New Trout Cave represent a warmer climate phase than enjoyed by residents of the region today.  The Pleistocene vampire bat (Desmodus stocki) and the Florida muskrat (Neofiber alleni) required mild winter temperatures.  The remains of the vampire bat were found at a level dated to about 30,000 BP, a time of a weak interstadial before the Last Glacial Maximum.  But they are probably older than this.  The scientists who studied these remains noted the reddish color of the vampire bat bones.  This color matched those of bones that were from much older sediment, including the Florida muskrat remains. The younger remains from the colder climate phase were lighter in color, and apparently, the older vampire bat bones “intruded” into this younger layer.

Round-tailed Muskrat Neofiber alleni.png

The Florida muskrat lived as far north as West Virginia during the late Pleistocene.  Fossils of this species were found in a deeper older level and were associated with vampire bats and an herpetofauna that suggests warmer winters than occur presently.

Distribution of Neofiber alleni

Present day range map for the Florida muskrat. 

Florida muskrats need standing water with year round green vegetation.  Modern day vampire bats can’t survive subfreezing temperatures, and it can be assumed Pleistocene vampire bats were also not well adapted to freezing temperatures, though because of their larger size, I believe they likely could withstand light frost.  During the Sangamonian Interglacial Pleistocene vampire bats were widespread across North America, living as far north along a line from northern California to West Virginia.  Even during this warm phase, some light frosts during winter must have occurred. ( See: https://markgelbart.wordpress.com/2011/10/24/the-pleistocene-vampire-bat-desmodus-stocki/)  They also may not have been year round residents in the northern parts of their range.  I believe they may have followed migrating herds of mammoths and mastodons north when those behemoths sought summer foraging grounds.

Incredibly, the presence of the Florida muskrat and vampire bat suggests West Virginia experienced winters as mild as present day south Georgia or north Florida during this ancient warm climate phase.  The remains probably date to the Sangamonian Interglacial (~132,000 BP-~118,000 BP) when climate was warmer than modern day temperatures.  We don’t know the exact date because carbon dating can’t be used to date anything older than 50,000 BP, and other types of radiometric dating may not be possible here.  West Virginia suffered a stunning climate reversal following this warm climate phase when arctic tundra species invaded the once forested hilltops, while vampire bats retreated south.

Reference:

Grady, Fred; et. al.

“Northernmost Occurrence of Pleistocene Vampire (Chiroptera: Phillostomidae: Desmodus stocki) in Eastern North America)

Tributes to the Career of Clayton Ray: Series Publications of the Smithsonian Institution

Mead, Jim; and Fred Grady

“Ochotona Lagomorphs from Late Quaternary Cave Deposits in eastern North America”

Quaternary Research 1996

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The Paleoenvironment of the Ice Free Corridor

November 11, 2013

The Wisconsinian Ice Age was an epoch when 2 massive Ice Sheets expanded over Canada.  The Cordilleran Ice Sheet expanded over the western Canadian Rocky Mountains south of Alaska, while the Laurentide Glacier covered all of eastern Canada and even extended over New England, Ohio, and other midwestern states.  (Ironically, most of Alaska stayed ice free during this time and consisted of a barren grassy environment known as the mammoth steppe.)  About 30,000 years ago, the Cordilleran Ice Sheet and the Laurentide Ice Sheet conjoined into 1 massive glacial slab that blocked all human and animal migratory routes between Alaska and the rest of America.  Formerly, scientists thought this barrier of ice existed from ~30,000 BP-~11,000 BP, but more recent studies suggest the 2 Ice Sheets began to separate as early as ~15,000 BP, creating an Ice Free Corridor that men and animals could have migrated through.

Map of North America circa 15,000 calender years BP.

A quite interesting environment existed in the Ice Free Corridor as the 2 Ice Sheets began to recede.  Initially, the area between the Ice Sheets was covered by bare soil, rock, and glacial outwash sands.  Wind blew the sands into deep eolian  dunes, some measuring 15 feet high and a mile long.  Scientists used optically stimulated luminescense dating of these sands to determine that deglaciation occurred earlier than previously thought.  Chunks of ice left behind by retreating glaciers and buried by sand became kettle lakes.  Meltwater streams carried chunks of ice into the corridor and these also became kettle lakes.  Glaciers blocked some meltwater streams, and the backflow created massive glacial lakes.  All these bodies of water attracted large flocks of ducks, geese, swans, and cranes.

Black duck (Anas rubripes).  Waterfowl such as ducks, geese, swans, and cranes nested in the abundant kettle lakes that formed in the Ice Free Corridor following the end of the Last Glacial Maximum.  This source of food attracted Paleo-Indians and enticed them to colonize the newly inhabitable region.

Lichens grew on the bare exposed rock, and caribou were the first large mammal able to survive in the corridor because they can subsist on this fungi/algae symbiote.

Caribou likely were the first large mammal species to colonize the Ice Free Corridor.  They can survive on lichens that  grew on rocks centuries before grass returned to the region.

The melting ice and snow made the soils rich in nitrogen, and glacier-pulverized rock added pottasium and phosphorus.  Within centuries, wind blown grass seeds from north and south of the corridor colonized the area, converting it into a grassy mecca that attracted camels, horses, bison, and elk.  The wolf (Canis lupus) was probably the most common large carnivore to colonize the corridor.  Dire wolves (Canis dirus) never made it this far north.  However, this clad of gray wolves is not ancestral to today’s wolves of Canada and Alaska.  Mysteriously, this lineage died out and was replaced by another line of gray wolves.  Lions may have followed prey into the corridor as well, but the lions living to the north were a different species than the lions living to the south, and the 2 species apparently didn’t interbreed.

The extinct yesterday’s camel (Camelops hesternus). It was well adapted for living in the environment of the Ice Free Corridor.  It would have been one of the first large mammals to colonize the arid grasslands that formed on the rich newly deglaciated soils.

The timing of the closure and opening of the Ice Free Corridor is important for archaeologists speculating about when man first entered North America.  Pre-Clovis cultures were present in North America before the Ice Free Corridor became passable, even if the new dates are taken into consideration.  Therefore, many archaeologists believe paleo-Indians took a Pacific coastal route to arrive in North America via boat.  This may be true, but I’m not so quick to dismiss the possibility that man first came to America through an overland route within the corridor before it closed.  The timing of the initial closure is uncertain, and it may not have occurred until ~21,000 BP.  I suspect a population of humans made it to North America before the Ice Free Corridor closed, but they were too few in number to be visible in the archaeological record.

The deglaciation of the Ice Free Corridor attracted humans from north and south.  Archaeologists have discovered a mixture of artifacts here from cultures that originated separately on both sides of the Ice Sheet.  Populations that had been separated for thousands of years came into contact in the corridor while following herds of game and flocks of waterfowls.  It must have been a challenging environment.  Though the mix of grasslands, wetlands, and bare soil provided plenty of protein, it was a melancholy barren world.  The katabatic winds blowing between the 2 Ice Sheets made for some long cold nights.  There were no trees for firewood or boat construction.  Glacial lakes and frigid meltwater streams made the corridor once again impassable during summer, though they did freeze solid for overland travel during winter.  Nevertheless, man did survive in this unique natural conduit for thousands of years.

Reference:

Pinson, Ariane

“The Ice Free Corridor and the Peopling of the Americas”

Mammoth Trumpet 28 (4) October 2013

The Saltville Fossil Site in Virginia

August 1, 2013

A dense forest of white pine, spruce, fir, and oak  grew in the Saltville River Valley 17,000 years ago.  There were also some alder swamps and wet sedge meadows, but unlike in the regions to the south and west of this locality, there were no prairies or open woodlands.  The Saltville River Valley is located in southwestern Virginia and during the last Ice Age, this area was much colder than the region located immediately to the south.  The oceanic Gulf Stream that carries tropically-warmed water north as far as the Canadian coast today, instead only went as far north as the Virginia/North Carolina border during the Ice Age.  This meant dry land temperatures in what is now Virginia were as much as 10-15 degrees Fahrenheight  cooler on average than those about 50 miles  further south.  Consequently, the environment in the middle Atlantic States decisively differed from most of southeastern North America.

Location of the Saltville River Valley.

Saltville, Virginia is located in a beautiful valley.  A large lake, known as Lake Totten, covered much of the valley from ~13,500 BP-~8,500 BP.  Salt mining operations have upset the hydrology here, and today as much as 20% of the valley is underwater. 

The Ice Age began waning about 15,500 years ago.  The Laurentide Glacier slowly receded, and the melting ice increased the flow of water into the Saltville River.  Sediment carried by the increased flow formed a mud dam in the Saltville Valley gap, causing the water to backflow and create Lake Totten.  The outflow was captured by another river.  Many of the species of large mammals that lived in North America then were attracted to the abundant salt springs in the area.  The individuals that happened to die during periods of increased sediment flow were buried by mud and preserved for fossil enthusiasts and scientists to find thousands of years later.

An assortment of fossils found at Saltville.  The animals were buried by mud carried by river surges resulting from melting glacial ice to the north.  Paleontologists have to pump out groundwater from their excavation sites here.  Salt mining operations have caused much of the land to flood.

The Saltville fossil site is the most southerly known location where specimens of woolly mammoth (Mammuthus primigenius) have been excavated.  Specimens of Columbian mammoth (Mammuthus columbi) have been excavated here too, showing the 2 species co-existed in some locations.   The 2 species of mammoth have also been found together at a site in South Dakota.  Columbian mammoths ranged much farther south than woolies, having occupied territory as far south as what today is Florida.  Other megafauna species recovered at Saltville include mastodon, Jefferson’s ground sloth, woodland musk-ox, bison, stag-moose (Cervalces scotti), caribou, white tail deer, horse, and giant short-faced bear (Arctodus simus).   Scientists have yet to publish their findings on the smaller species of animals discovered in the fossil deposits.

i-e31f309f269263d58d9d4415fc70ea37-bear-bite-mark-thumb-469x346-21211.jpg

Puncture mark on a mammoth heal bone made by a giant short-faced bear’s canine.

Gnaw marks on an ankle bone, probably made by a dire wolf.

A mammoth heel bone excavated from this site has a puncture mark that matches the canine of a giant short-faced bear.  This species of bruin is thought to have specialized in kleptoscavenging.  (See: https://markgelbart.wordpress.com/2012/12/10/bearzilla-the-biggest-bear-in-history/) The ankle bone of the same animal was gnawed on by a canid, probably a dire wolf.

A study of the bone chemistry of fossil herbivores from this site had an unexpected result.  All the herbivores living in this region then ate C-3 (carbon 3) vegetation–trees, shrubs, and some herbs.  Even species such as mammoths, bison, and horses that predominately subsisted on C-4 vegetation (grass) elsewhere were restricted to a diet of twigs, leaves, bark, and herbs here.  This is considered evidence that prairies were absent from this particular region during this time period.  The authors of this study admit their findings weren’t sufficient evidence to make any conclusions about megafauna extinctions.  Yet, they suggested competition between grazers and browsers for the same resources may have caused megafaunal extinctions.  I disagree with this conjecture.  Instead, I think their findings are strong evidence against climate change as a cause of megafaunal extinctions because the study shows these animals were not picky eaters and could adapt well to changing environmental conditions.

Humans apparently killed, butchered, cooked, and ate a mastodon at Saltville 17,000 years ago.  Archaeologists found cut marks on a mastodon’s bones as well as congealed grease that could only be the result of cooking.  They also found heat-cracked rocks used in the cooking process.  Pre-Clovis artifacts found associated with the mastodon bones include 2 sandstone knives, a chert blade made out of rock transported from some distance away, and flakes (debitage) from tool-making.  The site was occupied 3 times prior to the Clovis era.  The most recent pre-Clovis horizon dates to about 15,000 years ago and includes a midden containing hundreds of shells from giant floater clams.  This species of freshwater mussel grows to 10 inches long and used to be abundant in North American waters before modern day pollution and river damming.

giant floater, Pyganodon grandis

Giant floater clam (Pyganodon grandis).  I’ve never eaten a freshwater mussel, but they smell like delicious oysters.

Saltville is not a new site.  Thomas Jefferson knew about fossils found here.  Scientists have been excavating fossils off and on here for over 200 years.  A team from East Tennessee State completed the most recent excavation this year.  They visited local amateur fossil collectors to examine their specimens, and they are surveying caves in the nearby mountains in the hopes of finding more fossils to help piece together the regional late Pleistocene ecology.  We haven’t heard the last about this site.

References:

France, Christine; et. al.

“Carbon and Nitrogen Isotopic Analysis of Pleistocene Mammals from the Saltville Quarry (Virginia USA): Implications for Trophic Relationships”

Paleogeography, Paleoclimatology, Paleoecology 249 2007

Schubert, Blaine; and Steven Wallace

“Late Pleistocene Giant Short-Faced Bears, Mammoths, and Large Carcass Scavenging in the Saltville Valley of Virginia, USA”

Boreas 38 (3) August 2009

The Amazing Adaptable Whitetail Deer (Odocoileus virginiana)

March 5, 2013

The whitetail deer is probably the oldest large mammal species in North America.  Some whitetail deer fossils found in Florida  date to an astonishing 3.5 million years BP.  By contrast Homo sapiens as a species is roughly 200,000 years old.  Whitetail deer evolved from a similar species known as Odocoileus brachyodontus that existed from about 3.9-3.5 million years BP.  O. brachyodontus had different teeth and antlers from O. virginiana, but otherwise was a similar animal.  The direct ancestor of O. brachyodontus is unknown, but it was probably a species closely related to the Eurasian roe deer that crossed the Bering landbridge during the late Miocene.  As far as I know, a genome wide study of the deer family has yet to be completed.  The roe deer is the Eurasian species anatomically most similar to the Odocoileus genus, and therefore most likely to share a common ancestor.

Deer ecologically replaced the slender 3-toed species of horses and the American rhinos that formerly occupied the browsing niche in forested environments during the Miocene.  Ice Ages began occurring early in the Pliocene, and deer were better adapted to the resulting environmental changes than 3-toed horses and rhinos.  South of the ice sheets, a once year round climate of warm temperatures deteriorated to cycles of summer/hot and winter/cold patterns.  Drought became more frequent.  Broad-leafed trees evolved to drop their leaves during long cold winters and during prolonged droughts.  Deer were better able to survive in these deciduous forests.

Whitetail deer buck in its summer red coat.  This is the time 0f year pioneers collected deer hides and sold them for a dollar, hence the word “buck.”

Whitetail deer in its dull winter coat that helps it blend in a deciduous woods background.  Maybe it’s this adaptation that allowed it to survive when 3-toed horses couldn’t.

Whitetail deer thrive in fragmentary forests, explaining why they’ve been successful for so long.  Forests in southeastern North America have always been fragmentary.  Factors such as fire, windstorms, megafauna foraging, insect damage, plant diseases, and seed consumption create the patchy forest edge environments of constantly changing composition favored by whitetail deer.  The teeth of whitetail deer evolved from those of O. brachyodontus to enable them to include more grass in their diet–another advantage over Miocene browsers as the amount of grassland increased when climatic conditions changed.

Contrary to what I’ve read on some websites, during the Pleistocene, whitetail deer were just as widespread as they are today.  It is more accurate to say that in some regions they were less common than some now extinct species of megafauna.  In south Florida for example long-nosed peccaries apparently were more abundant than whitetails.  Llamas and tapirs likely competed with deer for the same resources in forested environments, while bison and horse were more successful in grasslands.  But deer were present just about everywhere, and I suspect they were the most common large mammal in the mid-south, even during most of the Pleistocene.

Modern anthropogenic land usage contributes to the fragmentary habitats whitetail deer are so well adapted to.  Men converted farmland to wooded suburbs, and abandoned farmland has become second growth forest.  Overhunting by man is the only threat to the existence of whitetail deer.  Whitetails do reproduce faster than all the extinct species of megafauna that couldn’t withstand human hunting pressure.  But in the past, intense human hunting has eradicated whitetail deer populations in many areas.  Deer were reported as scarce near large Indian settlements as early as 1704.  By the early 20th century deer were almost extinct in Georgia, but deer from the Great Lakes region were re-introduced here, and with proper management practices they remain abundant.  When I go jogging in my neighborhood I see fresh tracks daily, and I see  deer sprint in front of me about once every 6 weeks.  Some hunters complain deer are becoming less common, and they’re quick to blame coyotes.  I think the DNR needs to take a second look at the annual limit which is now up to 10.  30 years ago, the limit was just 3.  I find it ironic when hunters shoot 10 deer on their property, then wonder why they don’t see any deer the next year.  “It’s the coyotes,” they say.  Couldn’t it have something to do with the overgenerous season limits?

Whitetails are outcompeting mule deer (Odocoileus hemionus) in parts of the west undergoing suburbanization.  The latter prefer unbroken wilderness rather than the fragmentary habitat favored by their close relatives.  Mule deer evolved from an isolated population of whitetail deer some time during the early Pleistocene.  Some scientists proposed that the mule deer is a recent species resulting from a hybridization of blacktail and whitetail deer, but the fossil record and genetic studies debunk this hypothesis.  There are distinct fossils of mule deer dating to the mid-Pleistocene of California.  Moreover, studies of mule deer genetics show that blacktails and mule deer are the same species, despite sporting marked differences in physical appearance.  During the Last Glacial Maximum the Cordilleran Glacier separated mule deer from West Coast blacktails for thousands of years, accounting for the different physical traits, but they are still considered the same species by most experts.

Incidentally, Bjorn Kurten mentioned Pleistocene mule deer fossils found in Arkansas.  This is about 100 miles east of the species’ current range.  Whitetails are the only deer species found throughout the south, but the fossil record shows that elk (Cervus elephus), caribou (Rangifer tarandus), and the extinct stag-moose (Cervalces scotti) ranged into the mid-south during the Pleistocene.  Elk likely inhabited grassy hilltops in the piedmont region of Georgia until about 1760.  Elk fossils have been found as far south as Charleston, South Carolina.  Caribou fossils have been recorded from north Mississippi, north Alabama, north Georgia, the continental shelf off the coast of North Carolina; New Bern, North Carolina; and Charleston, South Carolina.  Most caribou fossils found in the south date to the Last Glacial Maximum, but 1 specimen came from interglacial strata. In the primeval wilderness of the Pleistocene there were probably a considerable number of stragglers that broke from huge herds located farther to the north, and these stragglers often wandered south.  There were no manmade barriers stopping them.  Fossils of the stag-moose have been found in Charleston, South Carolina and north Mississippi.  Elk, caribou, and stag-moose never could colonize the lower south and Florida because winters were too short and mild to limit the populations of blood-sucking insects that weaken northern species of deer.

Mule deer.  During the Pleistocene they ranged as far east as Arkansas.  Unlike whitetails, they prefer unbroken wilderness.

Elk.  William Bartram found elk bones on a grassy hilltop that I believe is located in Columbia County just above Augusta.  See https://markgelbart.wordpress.com/2013/01/01/a-serpentine-barren-in-georgia-burkes-mountain/

Woodland Caribou wandered south, especially during the Last Glacial Maximum when stragglers broke off from huge herds migrating south of the ice sheets in what is now southern Ohio, Kentucky, and Pennsylvannia.

Replica skeleton of a stag-moose, aka elk-moose.  Neither common name is accurate.  It wasn’t closely related to either elk or moose.  I prefer calling it the giant stag deer.  It was slightly bigger than a modern day moose.

South American red brocket deer.   All South American deer likely evolved from whitetails.  There’s no convincing evidence that any South American deer species ever lived in North America, though a member of the fossil forum claims he may write a paper about material he found in Florida that can be attributed to a South American species.

I used to think an additional extinct species of deer populated the upper south–the stilt-legged deer (Sangamona fugitiva).  But scientists analyzed the remains attributed to this species and determined all the material came from whitetails or elk.  Sangamona fugitiva is no longer considered a valid species, and as I related last week, fossil remains of marsh deer in Florida are probably from an incorrectly identified whitetail.

All South American deer probably evolved from whitetail deer.  Andean mountain deer, marsh deer, brocket deer, and pudus became geographically isolated from whitetails.  The latter do range into northern South America, but environmental change throughout the Pleistocene isolated the original populations of whitetails further south in the continent, resulting in varied speciation.  Dry climatic phases isolated tropical forests, causing them to become separated by vast grasslands and wetlands, and isolated populations of whitetails evolved into different species.

Caribou (Rangifer tarandus) in Pleistocene Georgia

January 1, 2012

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

What was the Deer-Hunting like in Pleistocene Georgia?

September 3, 2010

Deer-hunting season begins in Georgia this month.  The only native species of deer modern hunters can hunt in state is the white tail deer (Odocoileus virginianus) which numbers close to 1.2 million, making it the second most common large mammal in the state, behind man.  This season, hunters are allowed to take an astonishing 10 antlerless and 2 antlered deer, suggesting either a shortage of hunters or an overpopulation of deer.

The fossil record provides evidence that white tail deer were a common large mammal species during the Pleistocene too.  Their bones are found in almost all Pleistocene-dated sites in state.  They’re a species that prefers forest edge habitats, and the dynamic ecosystems of the Ice Age with fire, rapid climate fluctuations, and megafauna  destruction of trees, created extensive areas of this type of habitat.

Photos I took of white tail deer at Fripp Island, South Carolina.  The deer here are numerous and have little fear of humans.  Nevertheless, they should not be approached or fed because they are unpredictable wild animals and dangerous.  They can use their hooves to stomp people.  Deer have been known to kill dogs.

I suspect elk (Cervus canadensis) may have been the second most common kind of deer in what’s now Georgia during the Ice Age, ranging as far south as the fall line between the piedmont and the coastal plain.  Elk fossils from Kingston Saltpeter Cave in north Georgia, and near Charleston, South Carolina are the southernmost record of this species.  None have been found in Florida’s abundant fossiliferous deposits.  I think this is evidence of an abrupt difference in climate between the piedmont region of southeastern North America and the coastal plain.

Scientists don’t know much about the extinct fugitive or stilt-legged deer (Sangamona fugitiva).  It was like a white tail deer but approached an elk is size, maybe being slightly smaller.  The deer lived in east central North America from Missouri to West Virginia and a definitive record comes from Hamblen, Tennessee.  It probably occurred in northern Georgia because Dr. Clayton Ray found a tooth that may or may not have been from this species–the specimen was in too dodgy a condition to identify with certainty.

That caribou (Rangifer caribou) lived in northern parts of southeastern states during the Ice Age fascinates me.  Caribou fossils discovered in Bell Cave, Yarbrough Cave in Georgia, and near Charleston, South Carolina are evidence this species lived much further south than it did in historical times.  Were they stragglers or members of large migrating herds that regularly travelled through Georgia?  I wish I knew.

The stag-moose, or elk moose (Cervalces scotti) is kind of misnamed for it wasn’t closely related to a moose or an elk.  It was named so because it slightly surpassed a moose in size and sported antlers similar to those of the elk.  However, it was a distinct species, now extinct.  Its fossils are occasionally found in places like Ohio or New York.  One tooth of this species was discovered in Magnolia Phosphate Mine near Charleston (as I noted in a previous blog entry about the site)–evidence a small population roamed the upper south.

Pleistocene venison may have had a bitter flavor.  According to pollen records, wormwood (Artemesia) flourished more abundantly in the south than it does today.  This plant still commonly occurs in western localities, such as in Yellowstone National Park.  Reportedly, game that’s been eating wormwood acquires a bitter taste.  I can attest to the fine qualities of wild Georgia white tail deer meat–it tastes like dry beef, and I think the wild venison is better than New Zealand farm-raised animals, which though also good, tastes more like lamb.