Archive for the ‘Uncategorized’ Category

Blue Crabs (Callinectes sapidus) in Freshwater Springs

April 14, 2015

Marjorie Rawlings owned an orange grove in north central Florida from 1928-1941.  She was not a native southerner but used inheritance money to purchase the property.  Many of the characters she created in her short stories and novels were based on the people she met while she lived here.  Her most famous work is The Yearling, a novel later adapted for the big screen.  I think her most interesting book is her memoir of the 13 years she lived in a farm house next to her orange grove.  The title of this memoir is Cross Creek.  The relationships she developed with the “colored help” and the white “crackers” are entertaining reading.  Though progressive for her time, she clearly viewed black people as 2nd class citizens.  On 1 occasion she spent a week long hunting trip with her visiting brother.  When she returned to the farm she was outraged to discover the live-in “colored” help had spent the week enjoying a drunken orgy (literally…2 men and 1 woman in the same bed) and not a single chore had been completed.  Her brother joined her in chasing the help off the property at the point of a shotgun.  In my opinion Rawlings was at fault for being out hunting instead of supervising.  Moreover, today, her actions would be considered an illegal eviction, and she and her brother could be jailed for making terroristic threats.  However, if I could journey to 1930s Florida in a time machine and suggest this, all the white people there would think I was out of my mind.  How times have changed.

Marjorie Kinnan Rawlings with her dog - Cross Creek, Florida

Marjorie Rawlings, author of the famous novel–The Yearling.  This dog was accidentally poisoned.  She accused her neighbor of deliberately poisoning her dog, a charge he vehemently denied.  They feuded for a year before reconciling.

My favorite chapter in Cross Creek chronicled the local cuisine.  Bread here meant cornbread, cornpone, hoecakes, hushpuppies, or biscuits.  Meat meant salt pork, known here as “white bacon.”  Pork in 1930s America was much fattier than modern day pork.  White bacon was soaked in water, floured and fried.  The grease rendered from frying the fatty pork was used to season biscuits, cornpone, sweet potatoes, black-eyed peas, green beans, and greens.  These were the staple dishes but hunting and fishing supplemented the local diet with many exotic sources of protein such as alligator, rattlesnake, turtles and their eggs, limpkin, blackbirds, bear, and squirrel.  Rawlings accompanied men who went crabbing at night.  They caught crabs from a freshwater spring that flowed into the St. John’s River.  The men stood on boats and located crabs by shining lights into the clear water.  They used 12 foot poles with iron jaws on the end to snatch the crabs.

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Blue Crab in Crystal River Spring, Florida. It’s probably a male.  The females stay in brackish water and migrate to waters with high salinity to release their eggs.

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Blue crab life cycle.

I was surprised to learn that blue crabs inhabit freshwater.  Apparently, during spring male blue crabs migrate in enormous numbers to brackish and fresh water.  During mating season the 2 sexes meet in brackish water to mate, and the females carry their fertilized eggs back to the saltier depths.  The larval stage of the blue crab is known as a zoeal.  As the zoeal grows, they shed their shells 7 times in a process known as molting.  Their bodies absorb calcium from the sea water and swell, and this extra calcium forms a hard exoskeleton.  Blue crabs are called megalops during the next stage of their life when  they move into water with lower salinity where they eventually transform into adult crabs.

Blue crabs outcompete and drive away crayfish in the freshwater springs they inhabit.  Both species eat the same foods, scavenging and actively hunting plant and animal material.  Blue crab larva can’t survive in freshwater.  If this species ever evolved that ability, they would eventually colonize freshwater creeks and rivers, causing a decline in crayfish abundance and diversity.  Fossil remains of the Callinectes genus date to about 15 million years ago, and Pleistocene-aged blue crab shells have been found from Massachusetts to the Caribbean and Texas.  It is an incredibly successful species.

Asian Elephants (Elephas maximus) and Horses (Equus ferus caballus) Refused to Eat Pawpaws in a Controlled Experiment

April 10, 2015

Some scientists have hypothesized certain fruiting plants were dependent upon now extinct megafauna for distribution.  They believe the fruits were eaten and the still viable seeds were scattered across the landscape in beneficial piles of manure.  The extinction of large mammals that ate the fruits of pawpaw (Asimina triloba) and osage orange (Maclura pomifera) explains why these plant species today have such a patchy distribution.  They are considered anachronistic fruits.  Members of the Hendrix College Biology Department in Arkansas recently tested this hypothesis by feeding these fruits to species closely related to extinct Pleistocene megafauna.  They then planted the defecated seeds to determine viability.  Oddly enough, they also included persimmon (Diospyros virginiana) in their experiment. Persimmon is a common tree, not patchy in distribution, and the seeds are known to maintain viability after passing through a raccoon’s (Procyon lotor) alimentary tract.  I don’t consider persimmon an anachronistic fruit for those reasons.

Asian elephant.  In an experiment they readily ate persimmons and did try osage orange but absolutely refused to eat pawpaws.  This does not convince me that mastodons didn’t eat pawpaws.

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Horse eating osage orange.  The experiment suggests horses were not a distributor of osage orange seeds.  No viable seeds survived the horses digestive tract.

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Horses and elephants loved eating persimmons.  Viable seeds survived elephant digestive tracts but not the horse’s.

Pawpaw Fruit

Scientists were surprised that elephants and horses didn’t eat pawpaws, a nutritious sugary fruit.  This doesn’t mean mastodons didn’t eat pawpaws.  Mastodons were not the same species as the Asian elephant and evolved in the same region as this fruit. I believe they did eat them.

Asian elephants are closely related to extinct mammoths and distantly related to extinct mastodons (27 million years of evolution separate them from the latter proboscidean).  Modern horses are arguably the same animal as 1 of the species of North American horses of the Pleistocene.  The scientists involved in the study fed persimmons, osage orange, and pawpaws to Asian elephants and horses to gauge how effective they would be as seed dispersers.  Persimmons seeds sprouted and grew well in elephant dung but failed to survive horse digestion.  One elephant ate osage oranges but refused to retry them given a 2nd helping.  Some osage orange seeds sprouted and grew in elephant dung.  But again, none survived horse digestion, though horses really liked this fruit.  Elephants and horses surprisingly refused pawpaws.  At first the horses tasted them but spit them out and visibly grimaced (known as a Flehman response) as if they tasted bad.  Pawpaws are sweet and nutritious, so it is puzzling why neither species ate them.

The results of this study suggest mastodons and mammoths could have been effective dispersers of fruit seeds, while Pleistocene horses were not.  The study doesn’t prove mastodons didn’t eat pawpaws.  Though related, mastodons are not the same species as Asian elephants and likely had different tastes.  Mastodons evolved in North America for  millions of years alongside pawpaws, and I suspect some time during that span of time the species learned to like pawpaws. Persimmons grow in Asia but pawpaws do not.  Perhaps this explains why Asian elephants were so willing to eat persimmons but not pawpaws.  It is a fruit that occurs in the region from where they evolved.

The Hendrix College Biology Department should expand their study to include other close relatives of extinct Pleistocene megafauna such as tapirs, pigs, peccaries, llamas, and tree sloths.

Reference:

Boone, Madison; et. al.

“A Test of Potential Pleistocene Mammal Seed Dispersal in Anachronistic Fruits Using Extant Ecological and Physiological Analogs”

Southeastern Naturalist 14 (1) 2015

Cloudland Canyon State Park in Dade County, Georgia

April 8, 2015

The intersection of 2 creeks eroding through sedimentary rock formed the spectacular Cloudland Canyon located in the northwest corner of Georgia.  For tens of millions of years Bear Creek and Daniel Creek cut through layers of shale and sandstone.  Both of these types of sedimentary rock formed here during the Pennsylvanian Age (320 million BP-286 million years BP) when this region was sandy shoreline and muddy shallow sea.  Sand buried under pressure conglomerated into sandstone, while shale is simply fossilized mud.  A continental collision caused the uplifting of the Appalachian Mountains raising the elevation of this area with its layers of sedimentary rock.  Shale is a soft rock and easily eroded, but sandstone is more resistant to erosion.  The creeks have eroded through the shale causing the overlying sandstone to collapse into the valley.  This ongoing process has been continuously widening this canyon.

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View of the eastside of Cloudland Canyon from the west rim.  There are at least 4 waterfalls on that side of the canyon.

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The canyon walls consist of layers of erosion resistant sandstone on top of layers of shale.  As the shale erodes, overlying sandstone shelves collapse into the canyon, widening it.

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Lookout Valley is beyond Cloudland Canyon.  Sand Mountain can be seen in the distance.

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All the rock in this location dates to the Pennsylvanian Age when this locality was at the bottom of a shallow sea.  It was then uplifted by the collision of continental plates.  There’s reportedly fossilized wood in some of these rocks, but I didn’t see any.

I walked along the overlook part of the West Rim Trail.  By far the most common trees were rock chestnut oak (Quercus montana) and Virginia pine (Pinus virginiana).  White pine, shortleaf pine, red cedar, southern red oak, post oak, sand hickory, rhododendron, and mountain laurel are also present.  Reportedly, serviceberry grows here.  I’ve never had a chance to try this blueberry-like fruit, but it doesn’t ripen until June.  There are 3 types of natural communities in Cloudland Canyon State Park–acidic oak/pine forest, acidic cliffs, and calcareous cliffs.

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Black vultures soaring. Click to enlarge. Cliff ledges make excellent nesting sites for vultures, eagles, falcons, swallows, and other smaller birds.

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Another view of the rounded peak.

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Trees are hiding this waterfall.  The intersection of 2 creeks–Bear and Daniel–created Cloudland Canyon.

Most cliffs are pristine environments because there is little industrial use for them, and they’ve been left unmodified by man.  Cliffs are fascinating environments (See: https://markgelbart.wordpress.com/2013/05/19/piedmont-cliff-ecology/).  They provide nesting habitat for many species of birds.  During the Pleistocene teratorns, California condors, golden eagles, the extinct Grinnell’s crested eagle, and ravens probably nested on the cliffs in the above photographs.

 

 

Kennesaw Mountain National Battlefield Park

April 6, 2015

William Sherman’s advance across a broad front through Georgia was a strategy borrowed from Napoleon.  I don’t understand why Napoleon is considered a great general–he lost 3 entire armies.  He lost an army to the plague in Egypt, wasted another army while campaigning during a Russian winter, then was finally outmaneuvered at Waterloo.  Nevertheless, Napoleon’s strategy was effective against outnumbered troops, and Sherman had 100,000 troops vs. 65,000 Confederates on this front.  If the rebels made a stand, the numerically superior Union forces merely had to outflank their line, threatening to surround them.  The Confederate forces were continuously forced to retreat to avoid encirclement, a scenario that would have led to the surrender of the entire army group.  Joe Johnston, the Confederate general, had no choice but to form a defensive position on Kennesaw Mountain during June of 1864, even though he was aware of Sherman’s strategy.  He did send a force to outflank Sherman’s flanking maneuver, but it ran into a fixed Union position, and the Confederates lost 1000 men.

Sherman decided to take a chance at Kennesaw Mountain and ordered the only frontal attack of his campaign through Georgia.  He believed it was worth the risk because a) a change in tactics from flanking maneuvers to a frontal assault could surprise the Confederates, b) by pressing the Confederates he could prevent them from dispatching troops to the Virginia front where Grant was struggling to defeat Lee, and c) a breakthrough at Kennesaw Mountain would split the Confederate forces in half and lead to the immediate capture of their supply depot.  However, the 2 pronged attack by 3 divisions of U.S. federal troops failed with a loss of 2500 men.  The Confederates lost 800, mostly to artillery bombardment.  Sherman wisely rejected his subordinate officer’s plans to renew the frontal assault.  Instead, he resumed his flanking actions forcing the Confederates to retreat to the Chattahoochee River on July 2nd.  Jefferson Davis unfairly fired Joe Johnston soon after this battle.  He was replaced by the inferior reckless Hood who also could not stop the inevitable Union advance.

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View of metro Atlanta from the top of Kennesaw Mountain.

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Confederate cannon.  There was a hell of an artillery duel at Kennesaw Mountain.

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Path to the top of Kennesaw Mountain.  The park also protects an oak/hickory forest that is much like the original environment here.

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View of Little Kennesaw Mountain from the main Kennesaw Mountain.  The Confederates cut a path through the woods and hoisted artillery to the top of this mountain, using rope.

Though I’m interested in military history, I really visited Kennesaw Mountain to enjoy the natural history of the park.  Kennesaw Mountain is a rare natural area located within the sprawl of metro Atlanta.  Almost 3000 acres of protected forest, field, and wetland are surrounded by heavily wooded suburbs, providing habitat for 538 species of plants and 175 species of birds.  There are 3 types of forest land in the park–oak/hickory, rocky slopes, and rocky outcrops.  The oak/hickory forests are dominated by white oak, southern red oak, mountain chestnut oak, and post oak, along with 3 species of hickories.  Beech, sweetgum, and tulip trees are also present.  The shrub layer consists of dogwood, hackberry, beauty berry, holly, black cherry, blueberry, honeysuckle, and several other species.  Trees and shrubs found on rocky slopes include hickory, American plum, blackjack oak chestnut oak, blackberry, blueberry, and others.  Shortleaf pine, American plum, blackjack oak, chestnut oak, elm, blackberry, and blueberry grow around rocky outcrops.  Wetlands within the park host buttonbush, grass, sedge, rushes, cattails, and arrowleaf.  There are also a few swamps where red maple, buttonbush, basswood, dogwood, tupelo, willow, and ferns grow.

I was excited to see a chipmunk (Tamias striatus) in Kennesaw Park.  Chipmunks don’t live in my hometown of Augusta, just 180 miles southeast of this locality.  Kennesaw Mountain provides ideal habitat for chipmunks, and I predicted I might see 1 here.  Chipmunks like to live in crevices under boulders and rock piles.  Rocky forest lands, their favored habitat, cover most of the mountain.

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The chipmunk I saw at Kennesaw Mountain scurried away too quickly for me to photograph it, but I did see several playing around this pile of old wood in my mother-in-law’s backyard the following day.  She lives in Lafayette and has a view of Pigeon Mountain from her backyard.  Click on the picture to enlarge, and 2 sitting together can be seen.

Due to the elevation Kennesaw Mountain was likely the 1st locality to host spruce trees at this latitude during the Ice Ages.  Following the end of Ice Ages, this locality was probably the last at this latitude where spruce trees grew more abundantly than oaks and hickories.

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Note all the granite and granitic gneiss.  It is resistant to erosion.  Kennesaw Mountain is composed of this granite, explaining why it hasn’t eroded like the surrounding region.

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Lichen-covered granite boulder.

Kennesaw Mountain is a monadnock–an isolated erosional remnant standing 700 feet above the surrounding terrain.  It is 1808 feet above sea level. The granite and granitic gneiss that compose the mountain are resistant to erosion.  Granite is common in the Atlanta area, but much of it is fractured.  Kennesaw Mountain and Stone Mountain are solid and less fractured and therefore stand by themselves.  The mountain consists of a  mixture of igneous and metamorphic rocks.  Some was directly spewed by volcanic action, while others were transformed deep under the earth and uplifted.  Gray migmatite is a common mineral found here.  It has alternating light and dark bands.  The light bands are composed of quartz and feldspar, while the dark bands are made of bratite and hornblende.

References:

Gore, Pamela; and William Witherspoon

Roadside Geology of Georgia

Mountain Press Publishing 2013

Hart, Liddell

Sherman: Soldier, Realist, American

De Capo Press 1993

Zomlefer, Wendy; David Giannasi, and S. Lee Echols

“Vascular Plant Flora of Kennesaw Mountain National Battlefield Park, Cobb County, Georgia”

Southeastern Naturalist 9 (1) 2010

 

 

 

Humans may be Responsible for the Extirpation of Porcupines (Erethizon dorsatum) from the Southeast

March 31, 2015

Porcupines lived in southeastern North America during the Pleistocene.  (See: https://markgelbart.wordpress.com/2012/11/07/the-extended-pleistocene-range-of-the-porcupine-erethizon-dorsatum/) Remains of this species dating to that era have been found in Florida and South Carolina.  Presently, the porcupine is absent from this region.  The porcupine’s extirpation from this region is a relatively recent occurrence–skeletal remains of this species dating to younger than 9000 years BP have been found at numerous localities in the south.

Modern range map of the Porcupine.  During the Pleistocene it also inhabited the southeast as far south as Florida.

Map of North Carolina highlighting Watauga County

Watauga County, North Carolina.  Porcupine skeletal remains have been found in a rockshelter located here.  They date to 7500 BP.  Porcupine skeletal remains even more recent than this have been found in Colbert County, Alabama, and southeastern Tennessee.

Archaeologists from Appalachian State excavated the Charles Church Rock Shelter in Watauga County, North Carolina, and they found the remains of at least 10 porcupines along with stone and ceramic artifacts, burned plant material, burned rocks, and human skeletal material.  The porcupine remains included jaws, cheek bones, and teeth.  Some of these bones had been burned–possible evidence the Indians cooked the porcupine.  Porcupine remains dating from the early to late Holocene (from 9000 BP-1500 BP) have also been found at 6 other southeastern sites including Eastman Shelter and the Tennessee River in Tennessee, Daughtery’s Cave in Virginia, Little Bear Cave and Stanfield-Worley Cave in Colbert County, Alabama, and Russel Cave in Jackson County, Alabama (which borders the Georgia state line).  Evidently, porcupines still occupied the southern Appalachians until at least 1500 years ago.  There is no evidence of permanent human settlement in the higher elevations of the southern Appalachians until the medieval warm period between 900 AD-1300 AD.  Perhaps, not coincidentally, this seems to be when porcupines disappear from the archaeological record in this region.

In  my previous blog entry about southeastern porcupines, I suggested they were unable to survive the hot prolonged summers of the modern day south because of excessive exposure to mosquito-borne disease.  I’ve reconsidered that notion, since I’ve become aware of the porcupine’s Holocene survival in the region.  The  mid-Holocene climate from 6000 BP-4000 BP was hotter and drier than that of the present day, yet porcupines were still extant in southeastern Tennessee and northern Alabama until at least 2000 BP.  Warmer climate alone can not explain the disappearance of the porcupine, a species that ironically originated in the tropics.  Instead, I agree with those who believe human overhunting led to the porcupine’s demise in the south.

I’ve long been convinced humans were responsible for the extinction of the Pleistocene megafauna, but I didn’t think humans were behind the extirpation of porcupines.  I didn’t realize porcupines, like larger species of mammals, reproduce quite slowly.  Porcupines do not reach sexual maturity until they are 2 years old.  The females are fertile for just 8-12 hours once a year.  Pregnancy lasts for 7 months, then only 1 or 2 young are born.  By contrast, rabbits reach sexual maturity in 2 or 3 months, gestation lasts about 1 month, and they can produce 7 litters a year of up to 11 young each.  This explains how rabbits can withstand human hunting pressure while porcupines can not.  Porcupines have few natural predators because their quills protect them so well.  Only the occasional cougar or fisher learns to flip them on their back, exposing their unprotected belly.  Before man appeared on the scene, porcupines had no need for a rapid reproductive rate.

Audubon’s painting of a porcupine.  I believe this is 1 of his better portraits.  His colleague, John Bachman, claimed porcupines made good pets.  They rub up against a person’s leg, just like a cat.  The quills only stand up when they are threatened.

A major reduction in hemlock forests during the mid-Holocene is an alternative explanation for the porcupine’s disappearance from the region. A pollen study of 2 kettle lakes in Canada showed that 5800  years ago hemlocks declined from 30% of the forest canopy to 5% within a few decades.  Previous researchers believed an insect pest, the hemlock looper (Lambdina fusallaria) was responsible for this decline, but this study implicates the mid-Holocene hot dry climate phase.  Hemlock trees have shallow roots and can’t survive prolonged draughts.  Porcupines like to eat the inner bark of hemlock trees, and a single porcupine can kill as many as 100 hemlock trees in a single winter.  However, I doubt the decline of 1 species of tree is what doomed porcupines in the south.  Pleistocene porcupines lived in Florida and the South Carolina coastal plain where hemlocks were uncommon, even during the Ice Age.  And porcupines survived in the southeast well after the  mid-Holocene decline of the hemlock.  I think we can squarely put the blame on hungry Indians.

Porcupines appear to have been cooked at 2 of the 7 southeastern Holocene sites where their remains have been found, including the Charles Church Rock Shelter and the Tennessee River.  Though not a big enough data base to be statistically valid, this is suggestive.  Reportedly, porcupine flesh tastes like “flabby pork.”  A book entitled Rattlesnake Under Glass provides a recipe for porcupine based on an old Indian method of preparation.  I doubt the author actually tried the recipe, and it sounds like a terrible way to cook any small animal.  The unskinned and uncleaned porcupine was covered with a 2 inch layer of clay and placed on hot coals for 2 hours.  When the clay was baked hard, it was cracked open, and I suppose removal of the clay also removed the quills.  I would never cook any kind of meat without first removing the entrails.  Otherwise, the meat is likely to literally taste like shit.  Leave the porcupines alone, but if faced with starvation and forced to eat 1 individual, I recommend removing the guts before cooking.

References:

Eastlake, Martha

Rattlesnake Under Glass

Simon and Shuster 1965

Haas, Jean; and John McAndrews

“The Summer Draught Related Hemlock (Tsuga Canadensis) Decline in Eastern North America 5700-5100 years ago”

Proceedings: Symposium on Sustainable Management of Hemlock Ecosystems in Eastern North America

Whyte, Thomas

“Erethizon dorsatum (American porcupine) Remains from the Charles Church Rock Shelter, Watauga County, North Carolina”

Southeastern Naturalist 9 (4) 2010

The Lubbock Lake Fossil Site

March 25, 2015

 

Lubbock Lake was a natural 10 acre body of water located within the city limits of Lubbock, Texas.  Wind blown sediment formed a barrier that choked the flow of a stream, creating this lake.  Springs fed the stream and were part of the headwaters of the Brazos River system.   During the 19th century Lubbock Lake served as a favorite watering hole for cowboys and their cattle, and Indians had utilized these wetlands for at least 13,000 years.  But during the 1930s too many residents had dug wells in the vicinity causing the water table to drop and the lake to dry up.  City workers dug into the dry lake bed in a failed attempt to establish a reservoir.  However, vertebrate fossils and artifacts were found in the spoil piles of dirt dug by the engineers.  Scientists began studying this locality.  Material from this site was the first ever to be radio-carbon dated.  It’s the only site where evidence humans butchered giant short-faced bear and pampathere has ever been found. In 1987 Eileen Johnson published an extensive study of all the data compiled from this site.  That’s the source for the information I write about in this blog entry.

Location in the state of Texas

Location of the Lubbock Lake Fossil Site.  There is a museum administered by Texas Tech near the site which is also known as the Lubbock Lake Landmark.

Scientists looked for fossil pollen throughout the 300 acre area around Lubbock Lake.  They wanted to determine what the environment of the area had been like over the past 13,000 years.  They had a hard time finding enough pollen to establish a statistically valid pollen data base.  Some pine and spruce pollen was found in Pleistocene-dated samples, but scientists can’t agree on interpretations of the meager data they do have.  Some plant macrofossils were found in Pleistocene-dated sediments–bulrush, spike rush, seepweed, and netleaf hackberry.  This indicates the immediate vicinity of the stream was a brushy marsh.

Fossil remains of netleaf hackberry (Celtis reticulate) were found in Pleistocene-aged sediments at Lubbock Lake.  It is a small tree adapted to arid climates.

One scientist analyzed the composition of snail species to determine how the local environment has changed over the past 13,000 years.  Pleistocene-aged strata held 46 species, including 29 land and 17 aquatic snails.  All of the aquatic species can still be found in the region, but 3 species of land snails no longer occur here.  The silky vallonia (Vallonia cyclophorella) and the moss chrysalis snail (Pupilla muscorum) no longer range this far south.  Vertigo gouldi basidens (a snail with no common name) is currently restricted to high elevations in Colorado, Montana, and New Mexico.  The retreat of these 3 species from the Lubbock Lake site suggests a cooler moister climate existed here during the Late Pleistocene.

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The moss chrysalis snail (Pupilla muscorum).  Shells of this species were found in Pleistocene-aged strata at this site.  It no longer ranges this far south.

The composition of the vertebrate fossils found in the Pleistocene-aged strata indicates the southern high plains environment was mostly grassland and desert with some brush and wetland habitats.   There are no representative species definitively representative of woodland or forested habitats, so I doubt pine and spruce trees were present in significant numbers.  Mammoth, bison, horse, camel, pronghorn, prairie dog, ground squirrel, jack rabbit, desert cottontail, burrowing owl, and tortoise prefer arid prairie habitat.  Herds of bison and pronghorns drank from Lubbock Lake until the end of the 19th century.  Based on this faunal composition, I believe the environment has changed little at this location since 13,000 years ago, though summers have gotten much hotter than they were during the Ice Age.

Eight species of extant vertebrates that lived near Lubbock Lake during the Late Pleistocene no longer occur here.  Meadow voles, southern bog lemmings, and prairie voles can’t tolerate the present day summer temperatures that can reach 100 degrees F.   Richardson’s ground squirrels have retreated to higher elevations.   Box turtles and common garter snakes can’t endure high heat without the shade of trees.  Eileen Johnson believes late Pleistocene summer temperatures here were on average 10 degrees F cooler than those of the present day.  There was also more frequent cloud cover.  I agree with this assumption but disagree with her assumption that Ice Age winters here were frost free.

She bases this belief on the presence of giant tortoise and pampathere (a species of giant armadillo) in the fossil record.  She assumes neither species could have survived a frost.  She stated they both were too large to have dug burrows that would have helped them escape freezing temperatures.  This is a curious assumption–grizzly bears grow larger than pampatheres, and they dig dens.  Since Dr. Johnson’s study was published, evidence pampatheres dug burrows has been found in southern Brazil, demonstrating they could have survived freezing temperatures by digging burrows.  And on previous blog posts, I’ve challenged the widely held assumption that giant tortoises couldn’t survive subfreezing temperatures. (See:https://markgelbart.wordpress.com/2011/04/15/the-extinct-pleistocene-giant-tortoise-hesperotestudo-crassicutata-must-have-been-able-to-survive-light-frosts/)  The giant tortoises were closely related to gopher tortoises, a species that does dig burrows; and I’m unaware of any anatomical studies that determined whether or not the giant tortoises were capable of digging.  Moreover, giant tortoises could have utilized burrows dug by giant ground sloths or pampatheres.  I believe winter temperatures at Lubbock Lake during the Ice Age were the same or just slightly milder due to greater cloud cover than those of the present day.

The most unusual vertebrate fossil found at Lubbock Lake was a specimen of the gray-breasted crake (Laterallus exilis), a bird that is presently restricted to parts of Central and South America.  During the Ice Age large lakes were abundant in southwestern North America because glacially cooled air collided with hot desert air, resulting in increased precipitation and cool cloudy conditions.  The gray-breasted crake prefers grassy marshes adjacent to lakes.  This bird along with many other species of waterfowl occurred in great numbers along these lakeshore habitats.  Wandering flocks and individuals of these species also populated the more meager wetlands found on the southern high plains, the region adjacent to the land of great lakes.

Laterallus exilis

Remains of gray-breasted crake were found at the Lubbock Lake site.  This was the most surprising faunal find at this site.  Today, the range of this species includes parts of Central and South America.

Map of Pleistocene lakes in southwestern North America.  Cooler summer temperatures meant lower evapotranspiration rates, resulting in these abundant lakes then.  This probably explains the  occurrence of several aquatic bird species found in Pleistocene-aged strata at Lubbock Lake.

Several areas within the Lubbock Lake site have been interpreted as megafaunal meat processing stations. A station buried in Late Pleistocene sediment was used by members of the Clovis Culture.  They apparently butchered mammoths, bison, horse, half-ass, camel, giant short-faced bear, pampathere, turtles, and turkey here.  They butchered a 25 year old mammoth along with 2 juveniles.  A camel leg bone was broken and gouged for marrow.  Ribs of bison, camel, and horse showed evidence of de-fleshing.  A bear bone had knife cut marks on it, and the Indians actually made a tool from a bear bone. Eighteen shells of a large extinct subspecies of box turtle found here show evidence of human modification.  I should note that not all anthropologists agree with Dr. Johnson’s interpretation.  Some think stream action rolling bones against rocks can mimic the marks made by humans using stone blades.

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This is the only known evidence that humans exploited Arctodus simus–the giant short-faced bear. There are knife cut marks on this bear’s leg bone. From the below referenced work.

Assorted Bison antiquus bones.  This was the evolutionary predecessor to the modern bison.  The Lubbock Lake site has been interpreted as a game processing station used by  paleoindians as well as archaic, ceramic, Apache, and Comanche Indians.

These are radio-carbon dates of associated organic material where these Paleo-Indian arrowheads were found.  Add about 2000 years for actual calendar year dates.

There is also plenty of evidence that later Folsom, Plainview, Highview, Archaic, Ceramic, Apache, and Comanche Indians also used this site to process game.  The Lubbock Lake site has long been the only reliable source of water for miles.  This explains why it’s an excellent archaeological site with representative artifacts from every culture that’s lived in the region for the past 13,000 years.

Below is the list of vertebrate species found here in strata dated to between 13,000 BP- 10,000 BP.

garfish–Lepisosteus sp.

quillback–Carpoides cyprinus.  This is a type of buffalo fish.

bullhead catfish–Ictalurus amieurus

black bullhead catfish–Ictalurus melas

channel catfish–Ictalurus punctatus

white bass–Morone chrysops

green sunfish–Lepomis cyanellus

warmouth sunfish–L. gulosus

unidentified darter–Percina sp.

tiger salamander–Ambystoma tigrinum

Couch’s spadefoot toad–Scaphiophus couchi

unidentified spadefoot toad–plains or western, Scaphiophus bombifrons or S. hammondi

cricket frog–Acris crepitans

plains toad–Bufo cognatus

woodhouse’s toad–B. woodhousei

bullfrog–Rana catesbiani

pickerel frog–R. palustrus

leopard frog–R. pipiens

snapping turtle–Chelydra serpentine

pond slider–Chrysemys scripta

Wilson’s tortoise–Geochelone?  wilsonii (extinct)

extinct giant tortoise–Hesperotestudo sp.

extinct subspecies of eastern box turtle–Terrapene Carolina putnami

ornate box turtle–T. ornate

soft-shelled turtle–Trionyx sp.
Texas horned lizard–Phrynosoma cornutum

Great plains skink–Eumeces obsoleteus

black racer–Coluber constrictor

worm snake–Carphophis amonus

corn snake–Elaphe guttata

western hook-nosed snake–Gyalopion canum

western hog-nosed snake–Heterodon nasicus

king snake–Lampropeltis getulus

milk snake–L. triangulum

unidentified water snake–Nerodia sp.

red bellied water snake–N. erythrogaster

unidentified snake in the Elaphe or Pituphis genus

patch-nosed snake–Salvadora sp.

ground snake–Sonora semiannulata

checkered garter snake–Thamnophis marcianus

common garter snake–T. sirtalis

lined snake–Tropidoclonion lineatum

rough earth snake–Virginia striatula

copperhead snake–Agkistrodon contortix

western diamondback rattlesnake–Crotalus atrox

eared grebe–Podiceps nigricollis

pied-billed grebe–Podilymbus podiceps

Canada goose–Branta Canadensis

snow goose–Anser caerulescens

mallard duck–Anas platyrhincus

gadwall or pintail duck–A. streptera or A. acuta

pintail duck–A. acuta

northern shoveler–A. clypeata

green winged teal–A. crecca

blue-winged teal-A. discors

cinnamon teal–A. cyanoptera

ruddy duck–Oxyura jamaicensis

marsh hawk–Circus cyaneus

unidentified galliforme–either a prairie chicken or sharp-tailed grouse

turkey–Meleagris sp.

Virginia rail–Rallus limicola

clapper rail–R. longirostris

sora rail–Porzana Carolina

gray-breasted crake–Laterallus exilis

common gallinule–Gallinula chloropus

coot–Fulica Americana

mountain plover–Charadrius montanus

burrowing owl–Athene cunicularia

common nighthawk–Chordeiles minor

northern flicker–Colaptes auratus

horned lark–Eremophilia alpestris

common raven–Corvus corvax

mockingbird–Mimus polyglotis

red-winged blackbird–Agelaius phoenicus

brown-headed cowbird–Molothrus ater

vesper sparrow–Poocetes gramicus

unidentified shrew–Blarina sp.

desert shrew–Notiosorex crawfordi

pampathere–Holmesina septentrionalis

desert cottontail–Sylvilagus audubonii

blacktail jackrabbit–Lepus californicus

Richardson’s ground squirrel–Spermophilus richardsonii

13-lined ground squirrel–S. tridecemlineatus

Mexican ground squirrel–S. Mexicanus

blacktail prairie dog–Cynomys ladovicianus

valley pocket gopher–Thomomys bottae

plains pocket gopher–Geomys bursarius

hispid pocket mouse–Perognathus hispidus

Ord’s kangaroo rat–Dipodomys ordii

plains harvest mouse–Reithrodontomys montanus

cactus mouse–Peromyscus eremicus

unidentified field mouse–Peromyscus sp.

northern grasshopper mouse–Onychomys leucogaster

southern plains woodrat–Neotoma micropus

white-throated woodrat–N. albigula

cotton rat–Sigmodon hispidus

meadow vole–Microtus pennsylvanicus

prairie vole–M. ochrogaster

muskrat–Ondatra zibethicus

southern bog lemming–Synaptomys cooperi

coyote–Canis latrans

timber wolf–Canis lupus

kit fox–Vulpes macrotis

giant short-faced bear–Arctodus simus

badger–Taxidea taxus

bobcat–Lynx rufus

Columbian mammoth–Mammuthus colombi

horse–Equus ?

half-ass–Equus ?

flat-headed peccary–Platygonnus compressus

yesterday’s camel–Camelops hesternus

llama–Hemiauchenia sp.

extinct pronghorn–Capromeryx sp.

pronghorn–Antilocapra Americana

upland bison–Bison antiquus

whitetail or mule deer–Odocoileus sp.

Reference:

Johnson, Eileen

Lubbock Lake: Late Quaternary Studies on the Southern High Plains

Texas A&M University Press 1987

 

 

 

Escaped Slaves Lived a Primitive Life in the Great Dismal Swamp Wilderness

March 21, 2015

The geological origin of the Great Dismal Swamp is similar to that of the Okefenokee.  Formerly, the Atlantic Ocean extended over both locations.  The Okefenokee region emerged above sea level early during the Pleistocene about 2 million years ago, while the location of what was to become the Great Dismal didn’t emerge above sea level until about 100,000 years ago.  Ocean currents deposited a layer of impermeable clay over both locations, explaining why drainage is so poor.  For most of the Wisconsinian Ice Age pine and spruce forests along with wet meadows and acidic bogs covered most of what’s now the Great Dismal.  Though climate was drier during cold stadials, the cooler temperatures meant a slower evapotranspiration rate, allowing for the existence of wetlands.  There was likely an influx of northern hardwoods during warmer interstadials.  Pollen studies show pine and spruce gave way to beech/hemlock forests about 13,000 calendar years ago, and oak hickory forests dominated during the middle of the Holocene when climate became hot and dry.  But about 4000 years ago, the swamp began to develop its modern characteristics.

A combination of alternating drought, fire, and tropical storms created marshes consisting of high grass, reeds, and bamboo cane covered with tangles of greenbrier and vines.  Impenetrable stands of fire-adapted white cedar grew in some places, and cypress and tupelo forests prevailed in the wettest areas.  The peat from generations of dead grass and reeds added to the impermeability of the soil, but when drought dried the peat, lightning storms ignited it.  The burning of layers of peat actually lowered elevation in places, creating large shallow lakes. The Great Dismal originally encompassed 2000 square miles.  Few ventured into this vast wilderness where thick plant growth stymied the advance of man on foot or horseback.  This made the Great Dismal an ideal hiding place for persecuted Indians, escaped slaves known as Maroons, and white outlaws.

The Great Dismal Swamp originally covered about 2000 square miles between Chesapeake Bay and Albemarle Sound. Most of it was drained and now there are just 200 square miles left.

The  Maroons lived in wattle and daub houses.  They either learned this construction technique from the Indians or they remembered how to make it from when they lived in Africa. Humans have been making dwellings from tree branches and clay for at least 6000 years. How ingenious.

 

A Native American Morrow Mountain point

Indian projectile point believed to have been reworked by escaped slaves known as Maroons.

Dan Sayers supervises archaeological excavations of small islands within the Great Dismal.  He believes islands within the swamp were home for thousands of people between 1700-1865.  The people who lived here had few material possessions and lived such a primitive life that little physical evidence remains.  Their wattle and daub houses, made with woven sticks and muddy clay, have long rotted away, and termites have consumed just about every wood artifact.  Nevertheless, he’s found foundation post holes of their dwellings and digging around the vicinity often yields artifacts, including re-used lead shot, gun flint, glass, and iron nails.  The Maroons were so desperate for tools, they even remade Indian projectile points.  What to us would be a curious artifact was for them an essential tool for survival.

Americans began digging canals in an attempt to drain the swamp in 1823.  (George Washington was 1 of the 12 original American owners of the swamp but he sold his share early on.) Maroons worked on the canals in trade for goods they needed.  The engineers in charge of excavating the canals were not always strict about enslaving every black person they encountered.  Efforts to raid the Maroon hide-outs were futile because the Maroons knew their way around the swamp better than the “lawmen” who always got lost looking for them.

It’s too bad the Maroons were illiterate and left no written record of their experiences in the Great Dismal.  Their experiences would have been of great interest to the naturalist.  J.F.D. Smythe was an English loyalist who hid in the Great Dismal from angry revolutionaries.  He did write about the Maroons in 1790 when he finally made it back to England.  He reported that the runaway slaves lived there for 10-30 years on corn, hogs, and chickens they raised.

I’m sure the Maroons depended heavily upon trapping small mammals, turtles, and fish.  It would have been difficult for them to access firearms and ammunition, so I don’t think they often exploited the abundant bear and deer populations. Instead, animals such as marsh rabbits and snapping turtles served as more attainable sources of protein.  Marsh rabbits lived on the islands with them.  Slaves were known to set fire to fields where marsh rabbits lived.  Rabbits fleeing the fire could be clubbed by the hundreds. Brave waders could catch snapping turtles and catfish by hand.  Catching catfish by hand is called “noodling,” a technique the Maroons probably learned from the Indians.  It’s possible to catch snapping turtles without injury, if the shell is grasped from behind where their jaws can’t reach.

The primitive conditions of living in the Great Dismal were difficult, but it beat living in bondage.  The Great Dismal has been drained and reduced to just 200 square miles, but that’s still enough territory for archaeologists to get lost in.  A fugitive could still potentially hide here, but prisoners probably have a better life than a person eking out a living in this bug-infested environment.  Also, the primitive skills to survive here have been lost in our modern “tech savvy” culture, and I doubt a single inmate in North Carolina or Virginia would last long here.

References:

Levy, Gerald

“The Vegetation of the Great Dismal Swamp: A Review and Overview”

Virginia Journal of Science Winter 1991

Unnamed Author

“Digging up the Secrets of the Great Dismal Swamp”

Popular Archaeology April 2011

Big Cats vs. Crocodilians

March 17, 2015

The Mcbrides track cougars (Puma concolor) for the Florida Department of Natural Resources.  Roy Mcbride began tracking Florida panthers in 1972 when there was some doubt over whether this species still existed in state.  (The Florida panther is the same species as the cougar but I prefer using the latter common name.)  A few years ago, the Mcbrides interrupted a cougar feeding upon an alligator it had killed.  They treed the cat and examined the alligator.  Cougars were known to occasionally prey on smaller alligators, but the Mcbrides were surprised at the size of this specimen.  It measured 8 feet, 8 inches–the largest gator ever known to be killed by a cougar.  The cougar had eaten the brisket (chest area) of the gator but was so spooked by the trackers it never returned to the carcass.  The Mcbrides published their discovery in the Southeastern Naturalist.  Below is the 1st page of the 2 page article.

Cats are courageous hunters. Still, it seems unexpected that they would take on such a dangerous choice of prey.  Nevertheless, caimans make up a significant portion of the jaguar’s diet in certain parts of the Amazon jungle.

Jaguar attacks a Yacare Caiman

Jaguar killing caiman.

Leopards and tigers rarely prey on crocodiles, yet they have been recorded slaying them.

Photobucket

This leopard actually dragged the crocodile from the water onto land and killed it.

Youtube video of a tiger killing a crocodile.

A big cat’s strategy for hunting a crocodilian is cunningly effective.  They attack from behind, get a good grip on the reptile, and bite through the braincase, killing it instantly.  They don’t just ambush crocodilians sunning themselves on the riverbank.  The leopard in the above photos dove into the water and yanked the crocodile from its own element.

I wonder if saber-tooths (Smilodon fatalis) ever attacked alligators.  Saber-tooths had a weaker bite force than any species of extant big cat.  Their big canines would have been at risk of breaking, if they tried to bite through an alligator’s skull.  However, they were very powerful and would have been capable of rolling the alligator on its back and slicing through its throat with their fangs.  Jaguars were 1 of the most common large predators in southeastern North America during the Pleistocene and undoubtedly took a toll on alligators here then.

Reference

Mcbride, Roy; and Cougar Mcbride

“Predation of a Large Alligator by a Florida Panther”

Southeastern Naturalist 9 (4) 2010

Pleistocene Robins (Turdus migratorius) Depended Upon Heavily-grazed Landscapes

March 14, 2015

Robins are year round residents throughout most of North America, excepting Canada and Alaska, but populations of this species tend to shift south during winter.  There is no organized migration.  Instead, flocks of robins congregate wherever they find food.  They eat insects and earthworms, but fruit makes up 60% of their diet. During winter robins can sometimes subsist entirely on overripe crabapples stubbornly clinging to leafless trees or even seemingly unpalatable juniper berries.  Robins are attracted to areas with no snow cover where they can hunt for insects and worms, and they will fly for many miles looking for snowless landscapes.  In Augusta, Georgia I see the highest number of robins in February and March when local populations are supplemented by an influx of “Yankee” robins.

Robins prefer to forage in landscapes with short grass, so they can observe and avoid potential predators.  Yet, they also like areas with shrubs and short trees for nesting, though if push comes to shove, they will nest on open ground.  Humans have created the ideal landscapes for robins by constructing and maintaining yard lawns, golf courses, cemeteries, and plowed fields.  Nevertheless, robins did exist in North America before humans ever colonized this continent.  I hypothesize Pleistocene megafauna shaped favorable habitat for robins.  Mammoths, bison, and horses heavily grazed grasslands, keeping the grass in many areas cropped short, so that a patchwork of short and tall grass habitats occurred.  The fruit seeds defecated by mastodons and ground sloths sprouted into natural orchards, providing winter and autumn food and nesting habitat for robins.  Perhaps robins were just as abundant during the Pleistocene as they are today, but there is no way of comparing Pleistocene populations with modern numbers.

https://i1.wp.com/i.telegraph.co.uk/multimedia/archive/02141/bird-worm-1_2141751i.jpg

Robins can hear earthworms moving underground.  This species of thrush forages on landscapes with short grass where they can observe potential threats.  During the Pleistocene the only landscapes with short grass were those heavily grazed by megafauna.

American Robin Range Map

Robin range map.

Pleistocene bird fossils are less common than mammal fossils because bird bones are hollow and easily crushed.  Some species of birds that were probably common during the Pleistocene are absent or nearly absent in the fossil record.  However,  I used a google search combined with data from the paleobiology database and found 8 Pleistocene-aged fossil sites that included the remains of robins in their list of species.  Specimens of Pleistocene-aged robins have been found at Hiscock in New York, the La Brae Tar Pits in California, Bell Cave in Alabama, Cheek Bend Cave in Tennessee, Clark’s Cave in Virginia, Natural Chimneys in Virginia, Dead Man’s Cave in Arizona, and Little Box Elder Cave in Wyoming.

Genetic evidence suggests robins have had as many as 5 transcontinental divergences, though they were shallow compared to those of other species of thrushes.  These divergences correspond to changes in the distribution of favorable habitats that occurred during Ice Ages.  Different populations of robins became isolated from other populations for thousands of years, but the haphazard migratory habits of this species allowed some occasional intermingling.  This is unlike many other species of North America birds that became completely separated into eastern and western clades and in some cases resulted in speciation.

Rufous-collared Thrush

Rufus-Collared Thrush (Turdus ruftorques).  This is the closest living relative of the robin.  The robin’s evolutionary ancestor probably looked similar to this species.  They are found in the highlands of Central America.

Genetic evidence also suggests robins are a relatively young species, having existed for about 320,000 years.  Other species of thrushes are thought to be much older–Hunt’s thrush has existed for 4 million years and Swainson’s thrush has existed for 2.6 million years.  Robins evolved from an unknown now extinct species of thrush.  Their closest living relative is the rufus-collared thrush found in the highlands of Central America.

Reference:

Topp, Carrie; et. al.

“How Migratory Thrushes Conquered North America: A Comparative Phylogeographic Approach”

PeerJ 2013

Ancient Shark-bitten Whale Bones off the Coast of South Carolina

March 10, 2015

I may revisit Edisto Island soon to hunt for fossils.  Ocean currents are eroding through Pleistocene and Miocene fossil deposits offshore and occasionally a nice specimen washes ashore.  Scuba divers find the best fossils here, but that sport is a bit too dangerous for my tastes. Most of the South Carolina coast is fossiliferous.  Scientists recently discovered 2 ancient whale skeletons off the South Carolina coast along with many associated shark teeth.

The 1st whale skeleton was found in the Cooper River near Charleston.  The stratigraphic context suggests the specimen is approximately 3.5 million years old.  The remains consisted of a partial skull, cheek bones, ribs, and teeth.  (The authors of the study refer to the whales plates as teeth.  Baleen whales have plates instead of teeth.) They belong to a baleen whale also known as a mysticete.  This doesn’t narrow down exactly which species of whale it was.  There are 15 species of baleen whale including bowhead, right, blue, Bryde’s, minke, fin, sei, humpack, gray, and a few others.  Shark teeth associated with this skeleton were tiger, silky, oceanic whitetip, and sandbar.  There are shark bite marks on the whale remains as well as shark teeth embedded in bone.

The tiger shark (Galeocerdo cuvier) is an impressive predator and a definite man-eater.  They reach a length of 15 feet and a weight of 2000 pounds.  They often prey on sea turtles and can bite through the shell.  The largest bite marks on the whale skeleton are from tiger sharks, though it’s unlikely they’re responsible for the whale’s death.  According to the below referenced paper, the condition of the whale ‘s”tooth” suggests the whale died of old age and the sharks merely scavenged the carcass.

Teeth of the tiger shark

Tiger shark teeth.  Shed teeth of this species associated with whale bones are evidence sharks scavenged a dead whale 3.5 million years ago off the South Carolina coast.  This is also evidence this species is at least that old.

Youtube video of a tiger shark feeding upon a sea turtle.

stylized baleen.jpg (9640 bytes)

Baleen whales have plates instead of teeth.  The plates on 1 of the whales specimens appeared to be from an aged individual, suggesting the whale died of natural causes.  Curiously, the authors of the below referenced paper referred to the plate as a tooth.

The 2nd whale skeleton was found in Port Royal Sound, Laurel Bay, Beaufort County.  It also belongs to a baleen whale of undetermined species and includes cheek, “teeth,” flipper bones, and shoulder blade. This specimen was not found in a stratigraphic context that could give an estimated relative age.  It could be from a few hundred to hundreds of thousands of years old, though the bones and teeth appeared old to the authors.  Associated shark teeth were from tiger, dusky, and sharp-nosed.  The latter species is presently the most common inshore shark at this locality.  Teeth of cownose ray and guitarfish were also found here.  The smaller sharks along with the rays and guitarfish probably fed on the scraps torn free by the larger sharks.

Reference:

Cicimurri, David; and James Knight

“Two Shark-bitten Whale Skeletons from Coastal Plain Deposits of South Carolina”

Southeastern Naturalist 8 (1) 2009