Archive for January, 2013

Canebrakes are Forlorn Landscapes

January 28, 2013

200 years ago, landscapes in southeastern North America looked nothing like they do now.  When William Bartram traveled through the piedmont region of the south (circa 1775), the path he followed mostly stayed on the high ground because impenetrable thickets of bamboo cane (Arundinerea gigantea) grew alongside creeks and river bottoms.  His party was always in sight of canebrakes as they traveled through the open woodlands on the high ground.  Canebrakes covered tracts that were hundreds of square miles in extent.  Today, canebrakes are nearly an extinct type of environment.

Canebreaks

I looked for this photo on google images and couldn’t find it.  I did find it within a pdf document but I couldn’t link the photo directly. So I scanned it from the book Forgotten Grasslands of the South by Reed Noss.  Click to enlarge.  It’s of a man on a horseback dwarfed by a stand of 40 foot tall cane in 1906.  This was probably one of the last stands of a primeval canebrake.

Canebreaks 001

I found this stand of bamboo cane growing behind a Burger King in Madison, Georgia.  Cane is planted as an ornamental.  It’s probably not even American bamboo, but rather Asian bamboo.

Canebrakes are an ancient environment, dating back to at least the Miocene (25 million-5 million years BP).  It’s a species of grass.  Grasses began to become abundant during the Oligocene (33 million-25 million years BP).  Scientists unearthed ~5 million year old fossil bamboo from the Gray Fossil Site in Tennessee along with the bones of an extinct species of red panda (Pristinailurus bristoli) that fed upon it.  American bamboo likely shares an ancestry with Asian bamboo back when both continents were composed of a continous mosaic of tropical environments.  ( https://markgelbart.wordpress.com/2012/12/05/the-gray-fossil-site-in-washington-county-tennessee/)  Scientists disagree over whether giant gane (Arundinerea gigantea) is the same species as switch cane  (A. tecta).  Some botanists argue a structure inside switch cane makes it a different species, but others don’t think the difference is significant enough.  In any case cane grew in dense stands on rich soils, either by itself in pure stands or with an occasional tree in a savannah-like landscape.  Cane is shade intolerant and today seems to be restricted to wooded swamp edges.

Canebrakes require a complicated combination of forcing events to exist.  Formerly, floods, flocks of passenger pigeons, windstorms, or ice storms destroyed great tracts of forest.  Passenger pigeons (Ectopistes migratorius) used to roost in flocks estimated to be in the billions.  Witnesses described their roosting areas as resembling tornado damage.  Great limbs and even whole trees broke in half under the weight of the birds, and the pigeon dung killed the trees via overfertilization.  (See also https://markgelbart.wordpress.com/2010/08/27/pleistocene-passenger-pigeon-populations/) The New Madrid earthquakes in 1811 also caused the creation of large tracts of canebrakes.  Following these natural disturbances of the forest, a great amount of flammable dead wood covered the forest floor.  Lightning or human set fires burned through the woody refuse, creating vast sunny areas that allowed shade-intolerant bamboo cane to colonize large tracts of land.  Cane growing in small sunny patches within the forest could take advantage of these disturbances by spreading clonally from root rhizomes into the newly suitable habitat.  As long as fire occurred at least once a decade, canebrakes could be maintained indefinitely.  Dr. Noss suggests canebrakes were an alternate climax stage with bottomland forests near rivers and streams.  Without disturbances these areas succeeded to bottomland forests, but disturbances were so common that canebrakes may have covered an equal amount of territory.

Modern studies show that fire and windstorm double the growth of cane which can grow as fast as 20 feet annually.  Cane formerly reached heights of 40 feet, perhaps because they were enriched with pigeon dung.  Today, the tallest cane known grows in Louisiana and reaches just 30 feet in height.  It depends mostly on clonal growth and only flowers and produces seed once every 40-50 years.  It prefers rich river bottomland soils where it can become dominant.  Surprisingly, rich soils have less species diversity than poor soils.  On poor soils no one species can become dominant due to more difficult growing conditions.

Canebrakes were undoubtedly a widespread environment during the Pleistocene before man colonized North America.  There are many endemic species of animals that depend exclusively upon canebrake habitats, and it’s unlikely they evolved that dependence within the last 15,000 years.  However, canebrakes likely enjoyed a heyday during the 18th century when Native American populations collapsed.  Indians preferred to grow their crops on rich river bottomland soils and when they abandoned their fields cane rapidly colonized the land.

Modern anthropogenic changes in land use have nearly eliminated canebrakes.  Humans built levees and dams to prevent flooding.  People suppress fires.  People exterminated passenger pigeons.  These activities ended ancient patterns of disturbances that bamboo cane requires to form vast monotypical stands.  Moreover, cane grew on rich soils that farmers coveted for field crops, and the farmers let their livestock overgraze cane growing on any land left unplanted.  Today, river bottomlands left undeveloped are dominated by trees that shade out cane.  Canebrakes are a forlorn landscape and will be difficult to re-establish.

Canebrakes were a rich habitat utilized by many species of animals.  Cane is a high quality forage that formerly provided food for grazers such as mammoths, horses, and bison.  Bears and big cats liked to den inside the thickets where they could hide their cubs.  Swamp rabbits (Sylvilagus aquaticus) are also known as canecutters because they feed upon cane by gnawing through the stem to fell the tall grass so they can get at the leaves.  If it’s not extinct, Bachman’s warbler (Vermivora bachmanii) and Swainson’s warbler (Limnothlypis swainsonii) depend upon canebrake habitat.  Eastern diamondback rattlesnakes (Crotalus adamteus), also known as canebrake rattlesnakes, hunt swamp rabbits in the thickets.  6 species of butterfly depend entirely upon bamboo cane as part of their life history.

Swamp rabbits are also called canecutters.  They’re much larger than cottontails.

Bachman’s warbler.  This bird is probably extinct.  They formerly summered in canebrakes.  They built their nests in the cane thickets and foraged for insects on the ground in the fallen cane leaves.  They wintered in Cuba.  They became extinct (probably) because canebrakes are gone.  None have been seen since 1988.

A man holding an eastern diamondback rattlesnake.  They are big serpents growing to 8 feet long and weighing 35 pounds.

Southern pearly eye (Enodia portlandia).  5 other species of butterfly depend upon canebrakes for at least part of their life cycle including Creole pearly eye (E. creota), southern swamp skipper (Poanes yehl), cobweb little skipper (Amblyscertes aesolypia), cane little skipper (A.reversa), and yellow little skipper (A. carolina).  These endemic species are evidence canebrakes predate anthropogenic influences on the environment.

Native Americans also used to rely on bamboo cane.  They used to mix mud with strips of cane to build houses, and they covered the floors inside with mats made of cane.  They made baskets and fish traps and coffins from cane.  Weapons fashioned out of bamboo cane included spears, knives, body armor, and blowguns.  Indians incorporated cane into the structures of their famous mounds.  Cane even provided food.  Bamboo shoots are a tasty vegetable, and the seeds could be ground into a flour that was reputed to be almost as good as wheat flour.

References:

Ellsworth, J.W.; and B.C. McComb

“Potential Effects of Passenger Pigeon Flocks on the Structure and Composition of Presettlement Forests of Eastern North America”

Conservation Biology 17: 1548-1558 2003

Gagnon, P.R.; and W.J Platt

“Multiple disturbances accelerate clonal growth in potentially monodominant bamboo”

Ecology 89: 612-618 2008

Platt, W.J.; and C.J. Brantley

“Canebrakes: An Ecological and Historical Perspective”

Castanea 62: 8-21 1997

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Gary Haynes Speculates Pleistocene Megafauna populations Suffered 3 Stages of Shock Before their Eventual Extinctions

January 24, 2013

Many old school anthropologists and paleontologists reject the hypothesis that man overhunted the Pleistocene megafauna to extinction.  Some of their arguments against the overkill hypothesis are so illogical they leave me astonished.  For example 1 argument against the overkill hypothesis used to be that there was no archaeological evidence that paleo-Indians ever killed giant ground sloths, camels, horses, llamas, peccaries, glyptodonts, giant beavers, etc.  Since that argument was made, evidence that paleo-Indians killed giant ground sloths, camels, and horses has been found.  Nevertheless, in my opinion it is an unreasonable expectation to find such evidence.  Large regions of the North American continent are almost completely devoid of Pleistocene fossils, let alone ones that show obvious evidence they were killed and butchered by humans.  The odds against finding such evidence are astronomical.   Most recent paleoecological studies of the late Pleistocene are consistent with the overkill hypothesis.  Climate change models of extinction for this time period are becoming less tenable when all of the latest data are considered.  One old school anthropologist who has not ignored the latest paleoecological data is Gary Haynes, a professor at the University of Nevada, Reno.  Dr. Haynes uses the new data to speculate how man managed to wipe out most of the large American mammal species over a time period of a few thousand years.  He suggests the megafauna suffered 3 stages of shock before man chased them into oblivion.

Man entered North America from Asia ~15,000 calender years BP (at the latest).  A human turd found in an Oregon cave is the oldest definitive evidence of man in North America, and it dates to a few hundred years after the probable entrance date.  Dr. Haynes refers to the initial contact between man and megafauna as the foreshock stage.  When humans first encountered the megafauna, the hunters killed them opportunistically, and this fragmented the animal populations, eliminating some species from some areas.  Humans likely followed big game trails and river valleys for the same reason the animals did–they were easier to traverse than hills and swamps.  Because they followed the same paths, humans were more likely to encounter megafauna than not.  Even low levels of hunting had a big impact on megafauna species with slow rates of reproduction.  The foreshock stage may well be represented from studies of dung fungus spore abundance in 4 New York bogs and 1 kettle lake in Indiana.  Below is an in depth explanation.

Scientists from Fordham University took cores of sediment from 4 ancient bogs in southeastern New York where fossils of mastodons and stag-moose had been found.  They analyzed the sediment for pollen and charcoal content and carbon-dated the samples.  Dung fungus spores, also known as sporormiella, live in the guts of megaherbivores.  The abundance of sporormiella is used as a proxy for the presence of megaherbivores in the environment.  When sporormiella levels fall below 2%, it means megafauna is absent in the local environment.  The scientists found that megafaunal populations collapsed between 14,800 BP-13,700 BP.  This time span is known as the Boling-Alerod warm phase.  The composition of flora remained unchanged within this time span, so this finding rules out climate change as the cause of the initial population collapse.  Moreover, the megafauna populations at each lake collapsed at different times, indicating humans wiped out all the game in 1 area, then moved on to the next location and extirpated them there later.   A second study, this time of a kettle lake in Indiana, got similar results.

Appelman Lake, Indiana.  This is a kettle lake formed when a partially buried piece of a glacier melted.  A study of dung fungus spore abundance suggests megafaunal populations around this lake collapsed between 14,800 BP-13,700 BP.

Sporormiella–a dung fungus spore. Sporormiella levels rose to Pleistocene levels when Europeans introduced livestock to America.

Pollen graph from Appelman Lake.  Sporormiella abundance is represented by the blue.  Note how charcoal amounts increased after the megafauna populations collapsed.  Forests replaced savannah environments after the megafauna were killed off.  Forest fires increased in frequency because megaherbivores were no longer eating flammable material.

Dr. Haynes believes the megafauna suffered the main shock in the few centuries before and after the Younger Dryas cold phase which struck suddenly ~12,900 BP.  Megafaunal populations had already collapsed, but they persisted in fragmented local refuges.  Clovis hunters and their successors deliberately targeted these remaining populations.  The Younger Dryas was an arid cold climate stage that caused water sources to shrink.  Megafauna concentrated around the shrinking water holes where they were easy to ambush.

Dr. Haynes thinks the Pleistocene megafauna extinctions occurred during an extended aftershock when the last of the beasts were subject to many difficulties resulting from human activities.  Humans continued hunting the now rare and declining populations; isolated populations were weakened by inbreeding; an ecology long dependent upon interdependence between different megafauna species was now completely disrupted as some species disappeared; and fire frequency changed as humans set fires at unusual times of the year.  Humans didn’t have to kill every last individual of a species to render it extinct.  Instead, anthropogenic changes, including hunting, raised the mortality rate above the reproductive capacity of each individual species.

There is no way of knowing exactly when each species became extinct.  The latest terminal date for the mastodon is from a specimen found in Rochester, Indiana.  It died ~10,032 BP.  The last mastodon likely died centuries after this but didn’t become fossilized.  SedaDNA in Alaska permafrost suggests horses didn’t become extinct there until 7600 BP.  It’s probable that by 7500 BP humans had discovered and annihilated every population of Pleistocene megafauna in America.

Growth rings on  mastodon tusks are another line of evidence consistent with overkill theories of extinction rather than climate models of extinction.  Dan Fisher analyzed the growth rings from 10 mastodon specimens that date to close to the time of extinction.  The growth rings on the mastodon tusks were similar to those from African elephants that had plenty of food but were under pressure from overhunting.

References:

Fisher, Dan

“Paleobiology and Extinction of Proboscideans in the Great Lakes Region of North America”

American Megafaunal Extinctions at the End of the Pleistocene 2009

Gill, Jacquelyn; et. al.

“Pleistocene Megafaunal Collapse, Novel Plant Communities, and Evidence of Fire Regimes in North America”

Science 326 November 2009

Haynes, Gary

“Extinctions in North America’s Late Glacial Landscape”

Quaternary International 2010

http://www.unr.edu/Documents/liberal-arts/anthropology/gary-haynes/Haynes_QI%20Extinctions2012Reprint.pdf

Robinson, Guy; Lida Burney, and David Burney

“Landscape Paleoecology and Megafaunal Extinction in Southwestern New York State”

Geological Monographs 75 (3) Jan 2005

Homo sapiens is the Only Evil Species

January 21, 2013

Humans bestowed the scientific name of Panthera atrox upon the extinct Pleistocene lion that used to live in North America.  The Latin word, atrox, means terrible, cruel, horror.  How arrogant and unfair for the only truly evil species to ever walk the earth to refer to another species as a terrible cruel horror.  Sure, other species besides man commit violent acts such as cannibalism, fratricide, and the killing of young sired by another male.  But these behaviors follow the rules of surivival of the fittest.  They are examples of animal behavior shaped by evolution.  Man, however, is the only species that murders and commits other despicable acts for reasons not based on activities necessary for survival.

The animal that comes closest to matching the evil of Homo sapiens is our closest living relative–Pan troglodytes, also known as the chimpanzee.  They fight intertribal wars, and occasionally kill members of their own tribes, including infants.  Upon further contemplation, these behaviors still fall within the rules of survival of the fittest.  Chimp wars are fought over natural resources, and murdering fellow troop members may solve disputes over hierarchy–again another Darwinian survival advantage.  Even ants, which are practically pre-programmed automatons, fight wars.  So I can’t really convince myself that chimpanzees are an evil species.

Man is the only species that commits mass genocide, even when resources are not scarce.  Throughout history, genocides have never followed the evolutionary rules of survival of the fittest, nor have they been based on any kind of rational thought.  Tyrants have never ordered the killings of thousands or millions of people because they were afraid they or their biological kin were in danger of starving to death.   The fight over natural resources explains, if not justifies, human wars, but there is no evolutionary explanation for genocide.  Genocide is simply used to terrorize a population, oftentimes so an egomaniac can maintain political control.  But egomaniacs are well aware that they could survive and reproduce as an individual without ever becoming a famous tyrant.  The people who aid the tyrant also know killing mass numbers of people is not necessary for their own well being and reproduction.

Victims of the Nazis–a mass grave of Jews.  No other species devotes so much energy to genocide.  Survival of the human species doesn’t require genocide.  It’s difficult to explain the evolutionary advantage of genocide.

The German people were heavily criticized after World War II for their role in the Holocaust which would have never been possible without their cooperation.  Germans convicted of war crimes claimed they were merely following orders.  Stanley Milgram, a Jewish psychologist, wondered if all humans had a tendency to submit to authority, even if it meant performing acts they knew were morally wrong.  So he designed a now famous experiment: A person was told to administer shocks to an unseen subject who could be heard.  The subject was actually an actor who was not really given electric shocks.  An authority figure (an alleged professor) gently urged the person to continue adminstering increasing levels of electrical shock, while the actor went from expressing mild discomfort to groans to screams to begging for the experiment to stop because of his heart condition to silence and assumed unconciousness or death.  Prior to this experiment, Milgram polled psychologists on what they thought the results would be.  Psychologists thought on average that only 3% of participants would continue shocking the subject til the silence implied he might have died.  The results were shocking–66% completed the experiment, though many showed signs of stress, as if they knew what they were doing was wrong.  This experiment has been repeated numerous times with similar results, most recently on a Discovery Channel special entitled “How Evil Are You?” that aired in 2011.  The experiment shows that an authority figure can influence most people to endanger and kill other people.  All it takes is a little gentle prodding.

A bizarre incident highlights this evil element that makes up part of what is known as humanity.  A man posing as a police officer used an untraceable disposable phone to call a McDonalds in Mt. Washington, Kentucky and convince the manager to strip search an employee in a backroom because she had allegedly stolen money from a customer’s purse.  Eventually, he convinced her to call her boyfriend to watch over the poor, naked, teenaged girl.  While the manager went back to work, the perverted creep convinced the manager’s boyfriend to severely spank the employee’s naked butt, then ordered the girl to give the man a blowjob.  Both complied.  A security camera captured the whole episode as seen in this youtube clip from an episode of 20/20.

http://www.youtube.com/watch?feature=player_embedded&v=CgCSps6KgdY

The creep on the phone was a Florida prison guard named David Stewart.  Police eventually caught him but not before he (and possibly others) made over 100 similar calls.  The manager was sentenced to 1 year probation; her boyfriend received a 5 year prison sentence.  The victim sued McDonalds and won a $6 million lawsuit, later settled out of court for a lesser amount.  McDonald’s was negligent because they were aware of similar calls and had failed to alert their employees of the perverted hoax.

No other animal is capable of such evil.  A man destroyed other people’s lives because it gave him sexual satisfaction.  And people were too weak-willed to simply hang up the telephone.

This incident was recently dramatized in the movie Compliance.  Test audiences at the initial screening of Compliance unfairly accused the producer of misogyny and exploitation.  The makers of the movie were merely showing a truth about the human condition.  Outraged audience members missed the whole point of the movie.  They should save their ire for all of humanity.

Dramatic portrayal from the movie Compliance based on a real life event that occurred when a pervert on a telephone convinced a store manager and her boyfriend to strip search, spank, and rape an employee.

Logical Flaws in Studies of Pleistocene Carnivore Tooth Wear

January 17, 2013

Van Valkenburgh co-authored a study comparing rates of broken teeth suffered by large modern carnivores with those experienced by fossil carnivores excavated from the Rancho La Brean tar pits.

http://www.cof.orst.edu/leopold/class-reading/Van%20Valkenburgh%20and%20Hertel%201993.pdf

She found that large carnivores from the La Brean tar pits suffered 3 times as many broken teeth as modern day carnivores.  The fossils she examined from the pits included saber-tooth (Smilodon fatalis), American lion (Panthera atrox), cougars (Puma concolor), bobcats (Lynx rufus), dire wolves (Canis dirus), and coyotes (Canis latrans).  The modern species that she compared them to were lions, jaguars, leopards, cheetahs, bobcats, timber wolves, hyenas, and African hunting dogs.  The specimens from the tar pits dated to between ~36,000 BP-~12,000 BP.  She concluded that competition for prey was more fierce then than it is among modern large carnivores.  She believed increased competition for food forced large carnivores to utilize more of the carcass, and this led to more broken teeth from gnawing on bone.  She dismissed the alternate explanation that the higher rates of broken teeth among large Pleistocene carnivores were the result of attempting to take down larger prey than modern carnivores usually attack.  Dr. Valkenburgh suggested the larger size of the Pleistocene carnivores compensated for the larger size of the prey.

I never paid much attention to this study because using rates of durophagy as a proxy for carnivore competition seemed like a dubious assumption.  (Durophagy is just a fancy word for bone-eating.)  I think different species either eat more bone than other species because they have different nutritional needs, or they eat more for some other unknown reason that has nothing to do with competition.

Last year, a new study was published that completely contradicts Dr. Valkenburgh’s study.

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052453

Several scientists looked at teeth from Rancho La Brean predators and extant carnivores using Dental Microwear Textural Analysis (DMTA).  DMTA requires a lot of fancy equipment and procedures including a white light confocal profilometer, a scale sensitive fractal analysis, and a scanning electron microscope.  The scientists are able to see the teeth on a computer screen in 3D.  This eliminates observer measurement error.  Carnivores that avoid bone, such as cheetahs and lions, have different types of microwear on their teeth than those that eat a lot of bone, such as African hunting dogs and hyenas.

This is the equipment used to look at tooth wear in animals.

These scientists found little difference in rates of durophagy between the extinct and extant carnivores, meaning the competition between predators in the late Pleistocene in this region was no more or less fierce than that of today’s Africa.  Of course, I don’t buy the whole proxy assumption in the first place.  Most of the broken teeth were canines rather than molars.  Canines are more likely to break when taking down prey; molars are more likely to break when chewing bones, therefore they conclude the larger size of prey was the factor that explains the higher incidence of broken teeth among large Pleistocene carnivores.

One of the conclusions of this more recent study has a logical flaw.  The scientists authoring this 2nd study used DMTA to look at the teeth of Smilodon and Panthera atrox over time.  Different tar pits hold fossils of different spans of time ranging from ~36,000 BP-~12,000 BP, so they looked at 5 specimens of each species from pits of chronologically different ages.  They found no difference in tooth wear between the older specimens and the young specimens that dated closer to the time of extinction.  Many scientists think large Pleistocene carnivores became extinct because the animals they preyed upon became extinct.   They expected evidence of increased durophagy among the most recent saber-tooths and lions as they were forced to utilize more of the carcass.  But they found no evidence of this.  I think this doesn’t disprove the likelihood that carnivores did die out because their prey disappeared.  The final sentence in the abstract seems to imply that it does though.  It states : “The difference in DMTA attributes from older to younger deposits offers little evidence that declining prey resources were a primary cause of extinction for these large cats.”  Brian Switek, who writes an online blog for National Geographic, discussed this study and even goes so far as to ask what caused the extinctions of large Pleistocene carnivores, as if this study somehow disproves declining populations of suitable prey was the cause.  In my opinion this is flawed thinking.  Besides the dubious assumption that certain species of carnivores utilize more bone if prey is scarce, it seems unreasonable to expect to find the last nutritionally-stressed members of a population to be represented in the fossil record.  The odds of an animal becoming fossilized is so rare that it’s extremely unlikely that a member of the last remnant of a species headed for extinction would become fossilized.  The sample size–just 5–is also way too insignificant to detect whether or not this was occurring.  Moreover, big cats that eat mostly meat and organs and avoid bone are more likely to die of starvation before they chew on many bones.

I contacted the main author of this study, Dr. Larisa Desantis, and pointed out the logical flaws of this conclusion but she never responded.  I tried to comment on Brian Switek’s blog but he wouldn’t even allow my comment to be published.

I believe competition with humans drove saber-tooths and American lions to extinction.  Humans directly hunted them and overhunted their prey, and it was this combination that made it impossible for these species to survive.  To expect to find evidence of this by looking at a handful of fossil teeth under a microscope is ridiculous.

Evidence Humans Butchered a Jefferson’s Ground Sloth in Ohio 13,700 years ago

January 11, 2013

Some time prior to World War I, R.C. Niver found the bones of a Jefferson’s ground sloth (Megalonyx jeffersonii) and a bison on his family’s farm located near Norwich Township, Ohio.  The bones were unearthed fom 4 feet below the surface of a bog.  It’s unknown whether he was attempting to drain the swamp by digging a ditch, ploughing, or deliberately looking for fossils.   The bones were examined by the late Oliver Hay, one of the leading paleontologists of the day.  Eventually, the ground sloth bones were placed in a box mislabled as mastodon and put in the attic of the obscure Firelands Historical Society Museum where they rested for over 80 years.  One day, Matthew Burr was cleaning the attic, and he rediscovered the ground sloth bones.  Furthermore, he noticed cut marks on the bone.  Although many paleoecologists believe humans overhunted ground sloths into extinction, before Mr. Burr’s astonishing observation, no direct evidence of human exploitation had ever been reported from the archaeological record.

Photo of the bog where researchers think the ground sloth bones were originally discovered.

The ground sloth bones rested in a box labeled as mastodon in the attic of the Firelands Historical Society Museum for many decades.

Brian Redmond, a curator of the Cleveland Museum, examined the bones.  He counted 5 chop marks and 41 slice marks on an upper leg bone. (Claws, ribs, an ankle, a knee cap, and the lower leg were the other bones found along with the femur.)  Of course, the material was studied thoroughly to discount fraud and other types of morphology such as trampling or river scouring that can produce scratches that resemble anthropogenic marks.  They looked at the marks with a scanning electron microscope and confirmed they were made while the bone was fresh, and they learned they were made with 2 different stone tools.  The placement of the marks also made sense from a butcher’s point of view.  The Indian butcher cut the muscles from the most efficient angles.

There are visible cut marks on this ground sloth femur.  It’s a one of a kind specimen.  The cracks are the result of drying after the specimen was retrieved from the wet bog.

Though the Ohio ground sloth is the best direct evidence that humans exploited ground sloths, 2 other sites yielded assumed evidence.  Scientists found dermal ossicles of a Harlan’s ground sloth at the Kimmswick site in Missouri.  Kimmswick is a confirmed mastodon kill site.  Dermal ossicles make up the armor that used to help protect ground sloths from predators.  Like their cousins, armadilloes and glyptodonts, ground sloth skin was covered in armor, but theirs was covered with thick fur.  The scientists who studied the Kimmswick site believe the dermal ossicles came from a sloth hide carried by paleo-Indians to the mastodon kill site.  The hide later rotted away but the ossicles endured.  The other site is in South America where sloth bones were found associated with human artifacts.

Artist’s rendition of a Jefferson’s ground sloth.  They weighed over a ton.  The Ohio specimen discussed here was one of the largest individuals ever discovered.

Only 3 Jefferson’s ground sloth bones have ever been found in Ohio.  It’s an amazing coincidence that 1 of them showed evidence it was probably killed by humans.  The Indians may have been scavenging it, but I doubt it.  I’m sure they directly killed it.

13,700 years ago, the Laurentide Glacier had retreated northward from Ohio and Lake Erie was young, and recently filled with glacial meltwater.  The climate was rapidly warming but still quite cold during winter.  But as I wrote  in a previous blog entry, these  beasts with neotropical origins could survive cooler climate because they dug deep underground burrows. https://markgelbart.wordpress.com/2012/10/10/some-giant-ground-sloths-dug-long-burrows/

It’s sad that these amazing beasts no longer walk the earth.  When the paleo-Indians hunted them, they probably never imagined they were in the process of completely wiping them out.  They likely had no concept of extinction because they lived in a world of bounty.  To them, a ground sloth was an easy feast in a world before grocery stores existed.  (Incidentally, in his book How to Get out of the Rat Race and Live on $10 a Month George Leonard Herter claims that tree sloth tastes like pork.)  Ground sloths were well adapted to defend themselves against big cats and wolves, but they were helpless against projectile weapons.

Reference:

Lepper, Bradley

“Pre-Clovis Butchered Ground Sloth in Ohio”

The Mammoth Trumpet 28 (1)  Jan 2013

The Mysterious Nodoroc Site in Winder, Georgia

January 9, 2013

The geological origin of a mud volcano located in Winder, Georgia is a mystery waiting to be solved.  As far as I know, geologists haven’t ever studied this unexplained watery bog that last erupted circa 1800.  It’s probably similar to mud volcanoes found in Africa and southeast Asia.  About 10 years ago, a mud volcano in Cameroon exploded and killed a whole village by carbon dioxide asphyxiation. The carbon dioxide displaced the oxygen in the atmosphere.  An atmosphere of just 10% carbon dioxide causes people to become comatose; an atmosphere of 30 % CO2 causes people to drop dead immediately.

Winder, Georgia is in Barrow County which is between Athens and Atlanta.  My grandparents used to live there.

Nodoroc is a Creek Indian word meaning gateway to hell.  It’s an odd natural boggy pond that used to release a constant bluish smoke while bubbling.  The Creek Indians built an altar of heavy stones on the edge of the volcano where they executed criminals and then threw the corpses in the bog.  It was their way of sending deserving souls to hell.  They believed the volcano was protected by the wog–a devil dog with red eyes and the head of a bear.  Despite the cultural importance of the site, the Creek Indians sold the pond and the land around it to the English for 14 pounds of beads.  Some early colonist made off with the altar and now it’s lost to archaeologists.

I couldn’t find a photo of Nodoroc on google images that I could confirm was the actual site, but the below link is an aerial photograph.  The brown muddy expanse is labeled and obvious to see.  The link below that is of video of a mud volcano in Yellowstone National Park.  Unlike Nodoroc, it is still active and it probably has a different kind of origin.  The Yellowstone mud volcano is caused by heating and cooling subterranean rock on a fault line, while the Nodoroc mud volcano resulted from decaying organic matter.

http://www.wikimapia.org/#lat=33.973821&lon=-83.6727574&z=19&l=0&m=b

http://www.youtube.com/watch?v=iJ8qfpMkDs0

The first European explorers to visit Nodoroc say that it burned and dissolved everything they threw in it.  Even rainwater evaporated when striking the bog.  They reported that the area attracted lots of animals, but I think the abundance of wildlife resulted from Indians avoiding the place which they only used for executions.

Circa 1800 John Gosset built a cabin nearby and cleared a field around Nodoroc.  One day, Gosset and his wife witnessed the last eruption of the mud volcano.  His wife noticed an unusual amount of fog over the bog that morning.  She called her husband who was busy ploughing to come see it.  A loud explosion was followed by a shower of hot mud particles.  After the eruption the volcano settled several feet and cooled.  Decaying matter likely caused a fermentation reaction, releasing carbon dioxide and methane that had been trapped under the mud.

In the days of free range livestock Nodoroc was known as a cattle mire because cows constantly were  getting stuck in the quicksand-like mud.  Farmers eventually erected a fence to prevent any more losses.  Nodoroc was formerly about 5 acres in extent but circa 1900 John Harris drained part of it and grew several successful crops of corn.  While ploughing, he often came across bones and horns.  They were mostly the bones of recent cattle, but I suspect they may have been mixed in with Pleistocene fossils–a point I will discuss later.

Gary Bolton, a layman, visited the site in 1987 out of curiousity.  He noted that tulip tree saplings had colonized part of the pond, but many fell over, as if the shaky marsh ground couldn’t support deep roots.  Most of Nodoroc was covered with “thousands” of crayfish chimneys.  He mentioned sticking a shovel in the pond and finding that the level of muck was deeper than the shovel itself.

Acidic peat bogs are rare in the piedmont region of southeastern North America.  Peat bogs often contain and preserve pollen, plant macrofossils, animal fossils, and human artifacts.  So far, Nodoroc has only attacted 2 paleobotanists.  Dr. Stephen Jackson and Dr. Donald Whitehead investigated the site in 1981 and published their findings 10 years later.  They took 2 deep piston cores of sediment that they analyzed.  They did find 2 statigraphically datable segments in the core: 1 dated from 26,000 BP-22,00 BP, and the other from 3600 BP to the present.  This study was done before radiocarbon dates were recalibrated.  These dates roughly translate to between 30,000 calender years BP-26,000 calender years BP, and from 4,000 calender years to the present.  The lack of continuous stratigraphy is explained by long periods of time when water level was low and deposition didn’t occur.  The oldest segment dates to the weak interstadial immediately prior to the cold phase that led to the Last Glacial Maximum.

The site itself was probably an open marshy environment during the interstadial.  Plant macrofossils and pollen indicate an abundance of sphagnum peat moss, arrowhead (Sagitteria sp.), sedges, and carnivorous pitcher plants growing directly on the site.  Shrubs such as alder, myrtle, and mountain laurel and/or blueberry (Ericereae genus) grew on the marsh edge.  Pines and oaks dominated the forest surrounding the site.  With the exception of white pine (Pinus strobus) scientists can’t distinguish between species of pine by looking at pollen grains. After looking at the pine pollen and pine needle fossils under a microscope Drs. Jackson and Whitehead were only able to eliminate 3 species–longleaf, slash, and table mountain, none of which would have been expected to be here anyway.  However, the size of the pollen grains suggests both northern and southern species of pines were present.  Northern species of pine tend to have smaller pollen grains, while southern species of pine tend to have larger grains.  Both large and small grains were present.  My educated guess is that jack pine (Pinus banksiana) and shortleaf pine (Pinus echinata) were the dominant pinus species, while white pine was also present.  Macrofossils of jack pine, a species that now no longer occurs farther south than Michigan, have been found in Missouri and north Georgia sites dating to the mid-Wisconsinian interstadial.  Apparently, it was a more widespread species then than it is today.  Shortleaf pine, a southern species, occurs as far north as southern Ohio, and its short needles can endure snowy and icy conditions without much damage.  There’s no way of determining which species of oaks predominated here–all oak pollen looks too similar.

Other important trees growing in this interstadial forest were Critchfield’s spruce (my species assumption), fir, and hickory.  Chestnut, beech, sugar maple, and birch were present but at low levels.  (After the Ice Age chestnut became much more abundant in the region until its unfortunate extirpation 100 years ago.)  Hazelnut was a common bush growing in the understory.  During the Wisconsinian Ice Age hazelnut ranged throughout the south but is practically absent here today.  Noticeably absent or rare then were sweetgum, tupelo, and red maple all of which are common today in this area.

Fir trees thrive in regions with snowy winters.  As I mentioned in last week’s blog entry, the piedmont region of southeastern North America during the Ice Age was an abrupt transition zone between subtropical Gulf Coast Corridor grasslands and boreal forests of the Southern Appalachians.  Humid tropical fronts often hit cold air causing lots of snowfall.  Critchfield’s spruce, firs, and short-needled pines were and are well adapted to the snowy conditions that may have once blanketed the south.  It would have been interesting to see this environment where warm climate fauna frequently wandered to mix with creatures from the cold north.

I’m surprised no Pleistocene fossils habe been discovered or noticed from Nodoroc.  If cows often perished in the mire, I’m sure some of the Pleistocene megafauna did as well.  Perhaps the Indian legend of the wog is based on skeletel material of extinct beasts they discovered.  If I owned the pond I’d have it dragged for fossils and artifacts.

Artist’s rendition of the wog, a creature of Creek Indian legend that supposedly guarded Nodoroc.  Was the legend based on Pleistocene-aged fossils Indians found in the bog?  Cows used to get stuck in the mire and perish.  Pleistocene megafauna must have also.  This site should be prospected for Pleistocene vertebrate fossils which are probably mixed with modern livestock bones.

References:

Bartow County Historical Society

The History of Nodoroc and Tales of the Wog

Jackson, Stephen; and Donald Whitehead

“Pollen and Macrofossils from Wisconsinian Interstadial Sediments in Northeastern Georgia”

Quaternary Research 39 1993

Wilson, Gustavius

The early history of Jackson County, Georgia

W.E. White 1914

The Pleistocene Floral and Faunal Invasion of Southeastern North America

January 4, 2013

The Pleistocene fossil record of southeastern North America includes many species of plants and animals that had their origins in the neotropics of South America and the western grasslands of North America.  Disjunct populations of some of these species still exist in the southeast, especially in Florida.  Dr. David Webb may have been the first scientist to propose the former existence of a broad corridor on the coastal plain along the Gulf of Mexico that connected the southeast with these other regions.  This corridor has intermittently existed since the late Miocene, and most recently during the Last Glacial Maximum when sea level fell drastically as much of earth’s water became locked in glacial ice.  Dry land along the Gulf of Mexico emerged above sea level, greatly expanding this corridor as the map below shows.

Note how far dry land extended into the present day Gulf of Mexico during the LGM (~28,000 BP-~15,000 BP).  The state of Florida was twice its modern size.  A mixture of subtropical savannah, prairie, and scrub habitat probably covered most of this land.

The coastal prairies of Louisiana and Texas are a small remnant of this once more vast environment.

The coastal regions that emerged above sea level and most of south Florida supported a kind of lost world consisting of subtropical to warm temperate savannahs.  Paradoxically, climate in this corridor was warmer during the Last Glacial Maximum than today’s climate is there, and it was probably frost free.  During interglacials (such as the present one) and interstadials of the past, the gulf stream carries warm tropical water north where it cools, sinks, and returns south.  But during stadials, icebergs and meltwater break free from glaciers, and they cool and shut the gulf stream down, and the warm tropical water stays off the coast of the south Atlantic and in the Gulf of Mexico.  This created a thermal enclave in south Florida and along the Gulf of Mexico, but the palynological fossil record is incomplete, and it’s unknown exactly how far inland this thermal enclave extended.  It probably didn’t extend far because boreal taxa such as jack pine, red pine, white pine, spruce, and paper birch occurred as far south as the ridge and valley region of north Georgia.  There must have been an abrupt transition zone in the piedmont between the warm savannahs of the coastal plain and the cooler pine and spruce forests of the Appalachian Mountains.  Only 1 Pleistocene floral fossil site is known from the Piedmont region of Georgia–Nodoroc, a mud volcano that captured pollen and some framentary plant macrofossils.  But this site dates to just before the stadial that led to the LGM.  The pollen and macrofossils from this site indicate a mixed forest of northern and southern pines and oaks interspersed with meadows.

Ironically, during interstadials the Gulf Stream became re-established and warmed most of North America, but south Florida and the Gulf Corridor became cooler, though not subfreezing in south Florida.  Sea level rose and the corridor shrunk during interstadials.

Frequent tropical storms, lightning-ignited fires, and megafauna foraging gave the landscape its open appearance.  Longleaf pine savannahs and grassy prairies likely dominated the Gulf Coast Corridor.  Small areas avoiding the trio of landscape engineers became oak scrub.  Prairie acacia (Acacia angustissima) and hairy grama grass are among the notable plants that invaded the south through the corridor.  Prairie acacia is a close relative of the acacia tree that occurs so commonly on African savannahs.  Like African acacias, it was probably abundant, thanks to megafauna foraging.  Acacia trees produce edible pods eaten by elephants and formerly, mammoths and mastodons, and they spread the seed in their dung.  But the bark is poisonous and megafauna avoid eating it.  This explains the prevalence of acacia trees on landscapes where megafauna still live.  Unlike African acacias, the prairie acacia is merely a bush.  The modern range of prairie acacia includes Texas and Mexico with a disjunct population in Florida.

A thicket of praire acacia.  It was probably common on the Gulf Coast Corridor.

Hairy grama grass is among many species of western prairie grasses that have disjunct populations in the east.  A small disjunct population of hairy grama grass occurs on an island off the west coast of Florida.

Hairy grama grass.  A western species with a disjunct population on an island off the west coast of Florida.

Neotropical species of animals that invaded the south through the Gulf Coast Corridor included opposum, giant ground sloths, armadilloes, glyptodonts, tapirs, peccaries, capybaras, gompotheres, jaguars, ocelots, margays, vampire bats, Brazilian free-tailed bats, Mexican long-nosed bats, ghost-faced bats, terror birds, crested caracaras, great-tailed grackles, giant tortoises, indigo snakes, and whip snakes.  Western species of animals that invaded the south through the Gulf Coast Corridor included bison, lions, cheetahs, 13-lined ground squirrels, jack rabbits, hog-nosed skunks, badgers, pocket gophers, burrowing owls, ravens, magpies, prairie chickens, white-tailed kites, diamondback rattlesnakes, hog-nosed snakes, harvester ants, digger bees, some iceunomid wasps, and sand roaches.

The crested caracara is a tropical bird that colonized the Gulf Coast Corridor during the LGM.  In Florida caracaras and burrowing owls almost exclusively nest in heavily grazed pasture, suggesting their former close affinity with Pleistocene megaherbivores.  They prefer shortgrass environments over ungrazed tall grass areas.

Today, a few relic habitats remain from this once continous corridor.  Coastal prairies in Lousiana and Texas are perhaps the best example.  Florida dry prairies are another.  The formerly widespread longleaf pine savannahs on the coastal plain were a close analogue to the Gulf Coast Corridor but not an exact match because frosts do occur there.

Louisiana coastal prairie.  This is probably what much of the Gulf Coast Corridor looked like.

Just to the north of the warm subtropical grasslands, an environment consisting of an extinct temperate species of spruce (Critchfield’s) grew with modern hardwood species such as oak, maple, elm, hickory, and walnut.  The farther north and west from the Gulf Coast Corridor, the colder the climate was.  The spruce and deciduous forest likely predominated in this abrupt transition zone where the climate suddenly changed from tropical to temperate.  Tropical fronts often hit cold air and probably caused snowy winters here.  Summers were cool but winters moderate in the transition zone.  Birdwatching would have been interesting in the transitional zone between the warm Gulf Coast Corridor and the boreal forests of the mountains.  Harsh winters would have chased boreal avifauna farther south, and during summer tropical stragglers would have expanded their range north.

A Serpentine Barren in Georgia (Burke’s Mountain)

January 1, 2013

I almost visited Burke’s Mountain not long ago but the road leading to it looked like a long gravel driveway and in fact a sign even said, “Private Driveway,” so I didn’t want to trespass and instead turned around and went home.  Reed Noss, author of the below referenced book, and Philip Juras, a gifted landscape painter, have had the opportunity to see the site first hand, and it’s from their writing and art, respectively, that I get most of the information for this blog entry.

Columbia County, Georgia where Burke’s Mountain is located.

Burke’s Mountain is located in northeast Columbia County, Georgia near the Lincoln County line.  It is the highest elevation in Columbia County at 455 feet which makes it more of a really big hill when compared to the real mountains farther north. Serpentinite rock outcroppings cover this mountain.  Rainwater dissolves minerals from serpentinite rock, creating ultramafic soils, and this feature is what makes this site unique.  Ultramafic soils are characterized by low calcium to magnesium ratios, low fertility, and high concentrations of iron, nickel, and chromium.  This soil chemistry is toxic to many trees, and grassland thrives here as a result.  Open savannah conditions prevail without the aid of fire as the following photos and painting portray.

A Philip Juras photo of  part of Burke’s Mountain.  It is a serpentine barren.  Elk and bison probably grazed here as recently as the 18th century.

Philip Juras’s painting of Burke’s Mountain.  Note the rocky outcroppings.  Erosion of minerals from the rock create a soil chemistry that is more favorable to grass than trees.

http://www.flickr.com/photos/alan_cressler/4677376056/in/photostream/

Alan Cressler took half a dozen photos of Burke’s Mountain and posted them in the above link.

Dr. Noss found 3 species of southern pines growing here–loblolly (Pinus taeda), shortleaf (Pinus echinata), and longleaf (Pinus palustris).  This is a northern disjunct population of longleaf pine, a species more commonly found on the coastal plain and some dry ridges in the western part of the state.  He also found pyrophitic species of oaks including blackjack oak (Quercus marilandica), post oak (Quercus stellata), sand post oak (Quercus margarettae), sand laurel oak (Quercus hemisphaerica), and Georgia oak (Quercus georgiana).

William Bartram passed by Burke’s Mountain circa 1776 but didn’t specifically describe the site, but in the following passage he probably generically described it along with similar dry ridges located in present day Lincoln County.

This day’s progress was agreeably entertaining, from the novelty and variety of objects and views; the wild country now almost depopulated, vast forests, expansive plains, and detached groves; then chains of hills whose gravelly dry barren summits present detached piles of rocks, which delude and flatter the hopes and expectations of the solitary traveller, full sure of hospitable habitation; heaps of white, gnawed bones of ancient buffaloe, elk and deer, indeterminably mixed with those of men, half-grown over with moss, altogether, exhibit scenes of uncultured nature, on reflection, perhaps, rather disagreeable to a mind of delicate feelings and sensibility, since some of these objects recognize past transations and events, perhaps, not altogether reconcilable with justice and humanity.”

According to Frances Harper, the editor of the naturalists edition of Bartram’s Travels, William Bartram was likely in Lincoln County when he saw the elk bones but there’s no way of knowing for sure.  He may have seen them on Burke’s Mountain.  Though Bartram took careful notes, he didn’t actually write Travels until years after he actually traveled, and his descriptions consist of composite memories.  Sometimes his notes and his book are in contradiction.  Frances Harper followed Bartram’s path and tried to estimate where he was when he made his descriptions, but he was proved wrong on at least one occasion.  For example he incorrectly deduced the true location of The Great Buffalo Lick, as I discussed in the following linkhttps://markgelbart.wordpress.com/2011/05/21/my-expedition-to-kettle-creek-battlefield-the-little-kettle-creek-fossil-site-and-the-great-buffalo-lick/ .  The ridge Bartram wrote about must have been visible from miles away, indicating it was surrounded by open grassland rather than thick forest.  When I rode over there, I couldn’t really see the mountain from far away.  Poor Bartram initially mistook the rocky outcroppings seen from a distance for houses.  Instead of a hot meal, a bed, and companionship, he had to camp on the ground by himself again.

The elk bones Bartram wrote about seeing on a dry ridge that may have been Burke’s Mountain is rare evidence this species lived in Georgia.

The floral environment on Burke’s Mountain is interesting because it has probably remained relatively unchanged for tens of thousands, if not millions of years.  During cold glacial stages, the shallow soils under sparse shade warmed quickly and hosted a similar plant species composition compared to the present.  These same poor quality soils prevent most local hardwood trees from colonizing and dominating this locale during warm interstadials and interglacials.

Ultramafic soils are a rarity in Georgia, but mafic soils are common here.  Mafic soils also consist of a chemistry that favors grass over trees, but they aren’t as extreme.  Forests eventually replace grasslands on mafic soils, unless fire is frequent, whereas ultramafic soils can maintain an open appearance without fire.  Before humans were present, natural processes created a mosaic of forest, savannah, and even prairie in the southeast.  Horses, bison, elk, and mammoth grazed the grass; mastodon, tapir, deer, and peccary browsed the forest.  The existence of mafic soils and fire explains why the regional fossil record includes both forest and grassland dwelling megafauna.  Later, Indians expanded existing grassland openings with fire.  Perhaps Bartram could see “gravelly ridges” from a distance because Indians had started fires on the grassy mountain, and the fires spread to the surrounding area for miles all around, creating a relatively treeless plain.  Today, most of this area consists of dense young forests and suburbs that block the view that Bartram enjoyed.

References:

http://www.philipjuras.com/publications/thesis/chapter6.htm

Noss, Reed

“Forgotten Grasslands of the South”

Island Press 2012