Archive for May, 2010

The Edisto Beach Fossil Site

May 25, 2010

Approximately 47,ooo years ago, the Laurentide glacier began expanding over what’s now Canada.  Much of the water that existed in the atmosphere became trapped in this growing sheet of ice.  As a result of decreasing precipitation, the Atlantic Ocean receded many miles to the east of what today is the coast of South Carolina and other ocean-bordering states.  Somewhere to the east of what would become Edisto Beach 40,000 years later, grass, shrubs, and finally trees colonized the new top soil that had formed from sea bird guano, plant detritus, pulverized shells, sand, and river deposited mud.  This soil built up on top of a fossiliferous geological formation dating to the early Miocene when the area was deep under the ocean.  The later Pliocene and early Pleistocene strata, for some reason, washed away, creating what geologists refer to as an unconformity where the late Pleistocene strata overlay the Miocene–strata from the ages in between is missing here.  For some unknown reason conditions were favorable for fossilization here, and many Pleistocene age vertrebrate fossils became preserved over thousands of years.

Now, the glacier has melted and the Atlantic Ocean has once again advanced.  Strong currents blast through both the Pleistocene strata, and the Miocene formation, eroding slabs of fossils into the sea where the waves carry them to the shore.  Edisto Island is a productive fossil site, albeit the fossils are from three different ages and are totally mixed, so that Miocene and Holocene marine fossils are found right next to Pleistocene land vertebrate specimens.  Shark’s teeth, including those of the giant great white shark, Carcharodon megalodon, are often discovered here, but perhaps the list of Pleistocene mammals recovered from this beach and close offshore is even more impressive.  Here’s the list:

Opposum–Didelphis virginiana

Beautiful Armadillo–Dasypus bellus

Giant Armadillo–Holmesina septentrionalis

Glyptodont–Glyptotherium floridanum

Jefferson’s ground sloth–Megalonyx jeffersonii

Harlan’s ground sloth–Mylodon harlani

Dire wolf–Canis dirus

Gray fox–Urocyon cinereoargenteus

Florida spectacled bear–Tremarctos floridanus

Raccoon–Procyon lotor

Saber-tooth–Smilodon fatalis

Lion/Giant panther?–Panthera leo atrox

Cougar–Puma concolor

Bobcat–Lynx rufus

Walrus–Odobenus (cf) rosmarus

Gray seal–Halichoerus grypus

Monk seal–Monachus tropicales

Giant beaver–Casteroides ohioensis

Beaver–Castor canadensis

Porcupine–Erethizon dorsatum

Extinct capybara–Neochoerus pinkneyi

rabbit–Syvilagus sp.?

False killer whale–Psuedo crassidens

Bottlenose dolphin–Tursiops (cf) truncatus

Sperm whale–Physeter sp.?

an undetermined species of baleen whale

Tapir–Tapirus (cf) veroensis

Long-nosed peccary–Mylohyus nasutus

Stout-legged llama–Paleollama mirifica

White tailed deer–Odocoileus virginianus

Elk–Cervus elephas…southernmost record

Bison–Bison (cf) antiquus

Manatee–Trichechus sp.?

Mastodon–Mammut Americanum

Mammoth–Mammuthus columbi

Edisto State Park

I chose to prospect for fossils here because it’s a publicly accessible area, requiring no special permission, and an evening in nearby Charleston would satisfy my wife who is not at all interested in fossils.

Tons and tons of sea shells cover Edisto Beach, and they’re concentrated in many areas such as depicted in the following two photos.

I collected about ten pounds of sea shells, but none that I could definitively call a fossil, though a few of them can be categorized as maybe fossils.  Here are the ones I brought home with me.

The following photos are of what’s probably part of a lag deposit–stone and possibly small bones cemented together with sea shells–a cockle and two oysters.  Perhaps it was part of the Pleistocene-aged deposit that contains all the specimens of mammals washing ashore.

The cockle shell below, next to two oyster shells, suggests relatively great age.  It has a blueish-gray color different from most of the other sea shells and has invertebrate bore holes, indicating it had been buried under sediment for some unknown period of time.

The whelk shell below also suggests considerable age–it’s pock-marked with dozens of bore holes. 

Both species–the cockle and the whelk–are still extant, so there’s no affordable way of telling how old they are.  They might be thousands of years old, but it’s difficult to say for sure because recent sea shells are mixed together with ancient ones at this site.  But they do give an aged appearance.

When I first picked this up, I thought it looked like a dugong or manatee bone that ocean waves had eroded into an oddly-shaped pebble as often happens.  The more I look at it, however, the more it looks like just a pebble.

Even though this isn’t a fossil, it’s the best specimen I found on the beach that day.  It’s a sea pen (Atrina rigida), named after its shape, similar to an old fashioned ink pen.  They’re fragile and usually are found broken, but this one is complete on both sides.  Barnacles grew on one side of this specimen.  According to Euell Gibbons, sea pens make good eating.  They have a muscle that tastes just like a scallop, only better.

Botany Bay

Not far from Edisto State Park is the Botany Bay Wildlife Management Area–a misnomer because it’s actually a hunter’s management area.  Food for game animals is grown here to improve hunting for humans.

Note the corn and wheat fields grown for deer, turkey, and dove.

Humans are allowed to hunt and remove live animals, but aren’t allowed to remove the bones of long dead ones.  I reject this on the grounds of inconsistancy.

Botany Bay is a beautiful area–a maritime forest of live oak, palm, and southern pine interspersed with salt marshes and fronted by the beach.  By far the most common birds I saw were laughing gulls, brown pelicans, and mourning doves.  The live oak acorns support a high population of gray squirrels that were hard to avoid even when going 15 mph on the long dirt road through the WMA.  Here are some photos of pelicans, live oaks, and salt marsh.

Charleston, South Carolina

I found an intersting restaurant in the old town of Charleston called the Hominy Grill.

They serve traditional low country dishes such as shrimp and grits, chicken perloo, country captain, and fried catfish with peanut geechee sauce served over fried grits.

This is fried catfish, fried grits, and peanut geechee sauce.

They also have daily specials that vary.  When I was there the specials included pit roasted lamb po’ boys and grouper cooked in a tomato crab sauce.  For dessert we had a rich home made chocolate ice cream.  It was all delicious.

Later we took a stroll around Charleston Harbor.

This is a picture of salvaged brick from Fort Sumter.  Notice the powder burns and bullet holes from that old Civil War battle.

References:

Gibbons, Euell

Stalking the Blue Eyed Scallop

David McKay Company 1964

Sanders, Albert

Additions to the Pleistocene Mammal Faunas of South Carolina

American Philosophical Society 2002

Fossiling in Florida by Mark Renz

May 20, 2010

The best chapter in Fossiling in Florida: A Guide for Diggers and Divers by Mark Renz is the one called Prehistoric Portraits–33 pages of nice black and white photographs of fossils that a fossil hunter would likely find in Florida and other southern states.  This makes the book a handy indispensible reference.  Its arrival in my mail box was timely–next week I’m going on an actual fossil-hunting expedition to the low country of South Carolina.  I found a site there readily accessible to the public where late Rancholabrean fossils (over 30 species) have turned up, mixed in with Pliocene-aged marine fossils and shark’s teeth.  In next week’s blog entry I’ll have lots of interesting photographs, hopefully of some specimens I discover myself.

Now back to the book.

Mr. Renz snorkles the backwaters of Florida’s alluvial fossiliferous deposits, feeling his way through sediment that is much richer in prehistoric treasure than that of most other states in North America.  His accounts of avoiding alligators and speeding boats, while searching for fossils, are some of the most entertaining parts of the book.  His wife’s sketches also add to the charm of this work.

One of the reasons I bought the book was because I thought it was self-published, and I wanted to see how another non-academic, self-published author tackled a similar subject to that of my book.  I didn’t know the University of Florida Press published this book.  I found his website–www.paleopress.net/paleo5.htm.  He has two other books: Megalodon: Hunting the Hunter and Giants in the Storm.  Those must be the ones he self-published.  I’ll have to check those out too.  The cover for the latter looks outstanding.

Anyway, stay tuned for next week’s blog entry.  I’m really looking forward to the upcoming rare opportunity to find some fossils.

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This week, I’ve been obsessed with a new paper I came across that was published last fall.  (I’ve only read the abstract.) Two scientists did a thorough study of Panthera leo atrox skulls.  They determined that the North American lion was more like a giant jaguar, or a completely different species altogether than a lion.  The skull does resemble that of a lion, but the lower jaw was more like that of a jaguar.  They theorize that when the glacier cut Beringia and Eurasia off from the North America that the large Panthera cat south of the glacier evolved into two species–Panthera atrox and Panthera onca.  The species of big cats from the Panthera genus in America then consisted of a giant jaguar and a large jaguar.  Panthera onca augusta (the Pleistocene subspecies jaguar)  is considered large compared to modern jaguars, but Panthera atrox was gigantic weighing on average 25% larger than modern African lions.

I think this study makes sense.  If specimens of an extinct cat are consistently that much larger than living representatives of the presumed species, than the chances are good it was a different species.  Moreover, atrox had a larger brain capacity.  This is evidence it may have  hunted in prides like African lions, but we’ll never know for sure.  Based on where most of its skeletel material has been found, it seems to have preferred open country.  The large size of the males would have made it difficult for this species to hunt singly.  At the very least, they must have hunted in pairs.

I’m going to try to get my hands on this paper, so I can give a more detailed discussion in a future blog entry.

+2% Concentration of Dung Fungus Spores=Significant Megafauna Populations

May 13, 2010

I’ve become a subscriber to the Mammoth Trumpet magazine because I think it will provide plenty of fascinating fodder for this blog.  All four articles in the first issue I received covered controversial topics fiercely debated among scientists.  It seems as if nothing in ancient archaeology is clear cut.  I suppose this is understandable, considering the information we have often consists of minute and even microscopic details.  Today, I’ll give my opinion (for what it’s worth) on two of these controversies–the ones I’m most familiar with.

Dung Fungus Spores aka Sporormiella

I covered the megafauna extinction controversy extensively in my book, devoting a whole chapter to it, and I’m not going to rehash it all here. (Don’t forget, Georgia Before People is available as a download for only $3.)  Suffice to say, I’m convinced man overhunted the megafauna into extinction, but it was a protracted overkill that took place over a 1500-2000 year time period, not the sudden blitzkrieg Paul Martin first proposed.  I believe a study of dung fungus spore concentrations undertaken by some scientists from Fordham University conclusively supports a protracted overkill model of extinction, though I admit this evidence is still circumstantial.  For those unfamiliar with these studies, a brief summary is necessary.

Dung fungus occurs in the intestinal contents of all herbivores, but especially in those of the large plant-eating mammals, such as mammoths and mastodons.  Scientists study sediment from cores they take of lake bottoms.  From these cores they find and count pollen grains, including spores from dung fungus. (Though technically, spores are not pollen, they are a reproducing element of fungus.)

See also http://tolweb.org/sporormiceae/60141 for really nice pictures of sporormiella taken by Asa Kruys.

From cores taken at various sites in New York scientists counted the number of dung fungus spores and used them as a proxy to estimate past populations of megafauna there.  Scientists discovered that megafauna populations declined well before the Younger Dryas cold snap that proponents of climate change models of extinction touted as the cause of megafauna demise.  Moreover, the declines occurred at different times at different sites, suggesting an irregular pattern–hunters wiped out the game in one area, then moved to another area.  Another study in Madagascar (where megafauna extinctions occurred between 2000 BC and 500 BC), also show a haphazard gradual decline in megafauna populations, also taking place over about a 1500 year period.  These studies support an earlier study, a computer simulation, that estimated even low levels of human hunting could have caused the extinction of most large, slow-reproducing mammals within a 1,640 year time period.

The article in the Mammoth Trumpet, “Decoding the Mammoth part III,” discusses a new study, this time of Appleman Lake in Indiana, that further supports the results of earlier studies along this line.  Here, megafauna populations declined between 14,800 BP-13,700 BP,  long before the Younger Dryas.  Instead, the decline occurred during the Boling-Alerod, a period of warming climate.  However, the composition of plant species remained the same during this population decline, and the megafauna did survive previous warm interstadials, so climate is not likely a factor in their extinctions.  Instead, man is probably the culprit because we know he was present on the continent–human coprolites dating to 14,250 BP were found in Paisley Cave, Oregon.  The megafaunal population decline also predates Clovis culture (13,400 BP-12,900 BP).  Pre-Clovis people were driving the large mammals to extinction; Clovis and post Clovis people, after developing improved tool kits, probably finished off the small relic populations of megafauna that lasted until about 12,500 BP.  Perhaps improved hunting weapons and techniques were needed to hunt down the, by then, wary animals that had belatedly learned to avoid man.

Comet Impact

The above-mentioned studies eliminate extraterrestrial impact models of Pleistocene extinction.  Frankly, I’ve always thought Dr. Firestone’s comet impact hypothesis was preposterous.  He thinks a comet slammed into the Laurentide glacier; causing the Younger Dryas cold snap, Pleistocene extinctions, massive fires, and it created Carolina Bays, those mysterious oval depressions along the south Atlantic coastal plain.  All of these events can be explained by simpler more logical causes: a natural cyclical climate fluctuation brought on the Younger Dryas, man overhunted the megafauna, anthropogenic fires ignited the excess deadwood resulting from reduced megafauna foraging, and wind and water action created the Carolina Bays.

The article in the Mammoth Trumpet, “The Clovis Comet Revisited,” reports that two scientists were unable to replicate Dr. Firestone’s findings.  Todd Surovell could not find any unusual quantities of microspherules at the strata (and at many of the same sites) that Dr. Firestone’s team did.  Microspherules are one of the evidences of an extraterrestrial impact. Dr. Firestone’s team is preparing a rebuttal to Surovell’s paper.  They’re claiming Dr. Surovell didn’t follow certain protocols–that he didn’t have the correct size samples or sample intervals.  At the very least, this proves Dr. Firestone et. al. wrote a bad paper, if they left out specific sample sizes and intervals crucial for scientist trying to replicate their work.  In my opinion scientists favoring the comet impact hypothesis of megafauna extinction are full of Sporormiella.

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I’m still waiting for the mailman to deliver Fossiling in Florida by Mark Renz.  A review of that book will probably be the subject of my next blog entry.

References.

Mammoth Trumpet 25 (2) April 2010

Alroy, John

“A multi-species Overkill Simulation of the End Pleistocene Megafaunal Extinction”

Science 292 (5523) pp. 1893-1896 2001

www.centerforthefirstamericans.com

Burney, David et. al.

“Sporormiella and the late Holocene extinctions on Madagascar”

PNAS 100 (19) September 2003 pp. 10800-10805

Firestone, R.B. et. al.

“Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling”

PNAS 104 (4) Oct. 2007

Robinson, Guy et. al.

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

Geological Monographs 75 (3) Jan. 2005

Surovell, Todd

“An Independent Evaluation of the Younger Dryas Extraterrestrial Impact Hypothesis”

doi:10.1073/pnas.0907857106

The Big Bone Lick Fossil Site in Kentucky

May 7, 2010

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I’ve decided to make Georgia Before People a weekly blog.  If you follow this blog, check most Fridays for new entries.  I read somewhere that successful blogs should have daily entries, but a reader ought to get a week’s worth of information from my lengthy blog entries.  I’m not going to worry about the blog police.

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Big Bone Lick

In my chapter on fossil sites in Georgia and other southeastern states, I left out the great state of Kentucky.  Though Kentucky is in the SEC and can be considered a southern state, being south of the Mason-Dixon line, during the Pleistocene it was mighty close to the Laurentide glacier and incorporated ecotones that probably didn’t exist in Georgia and the states it borders, so I omitted mentioning Kentucky fossil sites.  But there are no space limitations in the cyberworld.  Here are my thoughts about one of the best Pleistocene fossil sites east of the Mississippi–Big Bone Lick.

Sulphurous smelling salt springs abound at Big Bone Lick, a poorly drained area, 45 miles south of Cincinnati.  The springs served as a natural salt lick for great herds of megafauna that migrated here from hundreds of miles away.  Herbivorous animals get plenty of pottassium from the plants they eat, but they’re oftentimes desperately in need of sodium, and the long journey was beneficial for their health and even survival.  The region around the salt springs would’ve been heaven for wildlife film-makers, if any had existed yet, because almost every North American hooved animal frequented the site.

During the last Ice Age, the Laurentide glacier advanced as far south as southeastern Ohio.  I was surprised to learn that during some previous Ice Ages (probably the Illinoian) glaciers even advanced into northern Kentucky as evidenced by large errattic boulders that could only have been transported here by ice.  But during the most recent Ice Age, the glacier stopped north of the state.  Still, ice dams formed across the Ohio River, creating many glacial lakes.  Periodically, the sudden warm climate cycles of the wildly fluctuating Pleistocene caused these ice dams to melt, and the great glacial lakes flooded the low lying site of Big Bone Lick, drowning multitudinous herds of beasts, and sometimes burying them under sediment, thus preserving them for future fossil hunters and scientists.

A list of species recovered here not only included the fauna of the savannahs, open woodlands, and forests commonly found in the Pleistocene ecotones of what’s now Georgia and other southern states, but also had representatives of the steppe grass environment that stretched all the way across Beringia into Eurasia.  North of  Kentucky, this steppe grass ecotone was probably interspersed with patches of forest that grew all the way to the glacier.  This meant that ranges of many species normally inhabiting different ecosystems overlapped here.  Big Bone Lick is one of the few fossil sites with the remains of both woolly mammoths and Columbian mammoths.  Woolly musk-oxen shared the range with its now extinct temperate cousin, the woodland musk-oxen.  There were forest species–Jefferson’s ground sloth, mastodons, stag-moose, and white tail deer, alongside grassland species such as Harlan’s ground sloth, bison, horses, elk, and caribou.  After the megafauna extinction the surviving species–elk and bison–continued to journey here for the salt.  Even in Colonial times the area was so rich in game that the Indians declared most of what’s now Kentucky a neutral hunting ground, and Daniel Boone got into trouble with them when he trespassed on this land.  A generation later, John Audobon, the famous wildlife painter, remarked on how beautiful Kentucky’s prairies were, though by the time he was an old man much of the game had been shot out.

Big Bone Lick became famous for fossils early on, exciting the interest of President Thomas Jefferson who made the first scientific description of Jefferson’s ground sloth.  His support for the Lewis and Clark expedition was inspired by his wish to find living representatives of the mammoth and ground sloth bones found here.  The presence of fossil specimens from animals that no longer apparently existed upended religious wisdom of the time.  Theologians didn’t think one of God’s perfect creatures could die out.  Then as now, illogical religious beliefs conflicted with scientific facts, and even though Jefferson wasn’t particularly religious (he thought Christianity would go the way of Greek myths) he couldn’t conceive of the concept of extinction.

Another Pleistocene fossil site in Kentucky worth mentioning (there are more but I’ll save those for a future blog entry) is Welsh’s Cave.  Like Ladds Mountain, one of the best fossil sites in north Georgia, Welsh’s Cave is a mostly collapsed and eroded cave system.  Here, scientists found the remains of at least 31 flat headed peccaries, an extinct species of javelina that preferred open environments.  Fossils of grizzly bears found here are evidence of the eastern most occurrence of a species that was unknown east of the Mississippi River during Colonial times.  Other present day western species found at this site, which is located in central Kentucky, includes badgers, gophers, and ground squirrels.

Today’s blog entry was inspired by a fellow Fossil Forumite who goes by the handle, Cousin it.  His blog chronicling his search for paleozoic fossils in Kentucky is http://solissymbiosus.wordpress.com His blog’s called Swimming the Ordovician Seas.

References:

Cooper, C.L.

“The Pleistocene Fauna of Kentucky”

www.uky.edu/otherorgs/kps/poky/Files/pokych10-01-29.pdf

Kurten, Bjorn; and Elaine Anderson

Pleistocene Mammals of North America

University of Columbia Press 1980

www.big-bone-lick.com

Were There Major Salt Licks in Georgia that Attracted Large Concentrations of Game?

The answer is yes.  Around 1775 William Bartram found one west of Augusta.  Here’s a passage from his Travels.

“After 4 days moderate and pleasant travelling, we arrived in the evening at the Buffalo Lick.  This extraordinary place occupies several acres of ground, at the foot of the S.E. promontory of the Great Ridge, which, as before observed, divides the rivers Savannah and Altamaha.  A large cane swamp and meadows, forming an immense plain, lies S.E. from it; in this swamp I believe the head branches of the great Ogeeche river take their rise.  The place called the Lick contains three or four acres, is nearly level, and lies between the head of the cane swamp and the ascent of the Ridge.  The earth is a cinereous coloured tenacious fatty clay, which all kinds of cattle lick into great caves, pursuing the delicious vein.  It is the common opinion of the inhabitatants, that this clay is impregnated with saline vapours arising from fossil salts deep in the earth; but I could discover nothing saline in its taste, but I imagined an insipid sweetness.  Horned cattle, horses, and deer, are immoderately fond of it, insomuch, that their excrement, which almost totally covers the earth to some distance round this place, appears to be perfect clay; which when dried by the sun and air, is almost as hard as a brick.”

Note that Bartram reported the area as being swampy.  It’s likely the salt lick existed during Pleistocene times, so there is a possiblity the swampy conditions created circumstances favorable for deposition of bones.  But it’s also possible the swamp didn’t exist then due to the more arid climate and no sediment ever washed over and preserved the bones.  In any case the site is worth searching for.