Archive for the ‘Fossil Sites’ Category

Pleistocene Terrapins (Malaclemys terrapin)

March 20, 2017

Until recently, there was little fossil evidence of diamond-backed terrapins. This species inhabits salt marshes and mangrove swamps from the Gulf of Mexico to Cape Cod, Connecticut.  For most of the past 2 million years, sea level has been much lower than it is today due to the larger ice caps of long-lasting Ice Ages.  This means many potential fossil sites where the remains of terrapins might be found are submerged deep underwater and difficult to access.  Sea level has been the same or higher than it is today probably for less than 20% of the last million years, and this reduced the chances easily accessible fossil sites developed in salt marsh zones.  However, the remains of terrapins dating to the Pleistocene have been excavated from  3 sites in Florida, 1 in Georgia, and 1 in South Carolina.  These specimens weren’t described in the scientific literature until 2012.

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The diamond-backed terrapin is adapted to living in salt marshes.

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Diamond-backed terrapin habitat–a salt marsh.

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Diamond-backed terrapin range map.

The 3 sites in Florida where Pleistocene-age terrapin remains were discovered are Page-Ladson, Aucilla River, and Wekiva River.  Terrapin material turned up at Edisto Beach, South Carolina, and fossil hunters found terrapin bones in spoil piles dumped on Andrews Island, Georgia.  (All of Andrews Island is manmade, consisting of spoil piles dredged from the South Brunswick River, aka Fancy Bluff Creek. The Army Corps of Engineers periodically dredges the river to keep it deep enough for safe shipping. Plants have taken root there and it is an haven for wildlife.) The specimens are thought to be Pleistocene in age because they are associated with bones of other species that lived then.  The 3 sites in Florida and the 1 at Edisto Beach commonly yield bones of extinct Pleistocene mammals.  The spoil piles on Andrews Island contained the remains of snapping turtles (Chelydra serpentina), yellow-bellied cooters (Trachemys scripta), and the extinct giant tortoise (Hesperotestudo crassicutata).  These species all lived during the late Pleistocene.  The presence of these 3 species along with the terrapin indicates the local environment at the time of deposition was a brackish marsh bordering an open grassy savannah. Snapping turtles and yellow-bellied cooters are fresh water species that can tolerate brackish conditions, and giant tortoises preferred dry land environments.

Terrapins are not closely related to sea turtles.  Morphological and genetic evidence suggests they are most closely related to freshwater turtles in the Graptemys genus.  In North America this genus includes 10 species of map turtles and saw backs. Terrapins are the only turtle species uniquely adapted to live in salt marshes.  They have lachrymal salt glands that help them get rid of excess salt.  These are absent on all species of fresh water turtles.  Terrapins are also able to drink the layer of rain water that temporarily floats on top of salt water.  Terrapins feed upon shellfish–periwinkle snails are their favorite but they consume shrimp, crabs, and bivalves as well.

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The salt marsh periwinkle (Littorina irrorata) is the diamond-backed terrapin’s favorite food.

Terrapins were formerly so abundant they constituted the main source of protein for coastal slaves during the 18th and 19th century.  But a faddish craze for turtle soup circa 1900 greatly reduced their numbers.  All of the finest restaurants served turtle soup, and it was the most expensive item on the menu.  I’ve only had the opportunity to eat turtle meat once.  Turtle meat is very delicious, tasting like lobster.  Because terrapins feed on shellfish, their flesh likely reflects their diet.  Terrapins are presently a protected species but are still considered threatened.  Real estate development destroys their habitat, they drown in crab traps, cars run over them, and there are people who still eat them.  Egg-eating raccoons flourish as well, since most large predators that kept their population in check no longer exist on the east coast.  If I get the urge to eat turtle again, I’ll stick with the common snapping turtle which as their name suggests are still common.

Reference:

Ehret, Dana; and Benjamin Atkinson

“The Fossil Record of the Diamond-backed Terrapin, Malaclemys terrapin (Testudines: Emydidae)”

Journal of Herpetology 46 (3) September 2012

 

A Pleistocene-age Carolina Parakeet (Conuropsis carolinensis) Fossil Finally Discovered

December 29, 2016

The Carolina parakeet was a common species living in old growth bottomland forests until Europeans settled eastern North America.  Overhunting and deforestation doomed this only temperate species of parakeet. The colorful noisy birds were an agricultural pest that destroyed ripening fruit when they fed upon the seeds inside the pulp.  Orchardists wiped out entire flocks.  Though parakeets are supposed to be intelligent, they were not well adapted to avoiding patient men with guns.  A farmer firing his weapon into a flock (the birds routinely congregated in flocks of 200-300) caused the survivors to fly in a wide circle and return to the same place where their feathered comrades had just been killed.  A farmer could slaughter the entire flock in an afternoon without moving from the same spot.  Carolina parakeets nested in large hollow trees, but lumbering operations during the late 19th century eliminated their homes as well.  The last population of Carolina parakeets was probably rubbed out by market hunters seeking red and green and yellow feathers, then fashionable in women’s hats.  The last wild specimen was taken near Lake Okeechobee, Florida in 1904, and the last captive specimen died in the Cincinnati Zoo in 1918, coincidentally the same place and year where the last passenger pigeon died.

Until recently, the only North American fossil remains of a parakeet was a specimen found in Nebraska, dating to the mid-Miocene (about 16 million years BP).  Scientists are uncertain if this specimen represents a species ancestral to the Carolina parakeet, the same species, or a different lineage.  In any case no fossil remains of a parakeet dating to the Pleistocene age (~2 million years BP-11,000 years BP) had ever been found in North America.  Carolina parakeets lived in habitat where preservational processes don’t often occur.  Most bird remains are found in caves where they were carried by roosting owls or hawks.  There aren’t many caves in the lowland habitats favored by parakeets.  Moreover, the flesh of parakeets was toxic to many predators because they fed on poisonous cocklebur seeds.  Their colorful plumage may have worked as a deterrent to predators who learned to avoid the well-marked prey that may have sickened them previously.  Although preservational bias was the probable reason why remains of this species had never been found, it was possible Carolina parakeets were a recently evolved species that colonized North America, following the end of the most recent glacial-interglacial transition.  But finally, just a few years ago, the remains of a Pleistocene-age Carolina parakeet were unearthed at the Dickerson Coquina sand pit in St. Lucie County, Florida.  Fossils found at this site are estimated to be somewhat younger than 730,000 years BP-430,000 years BP, proving that Carolina parakeets had a very long history in North America.

Map of Florida highlighting St. Lucie County

St. Lucie County, Florida.  The Dickerson Coquina Pit fossil site, located in this county, yielded the first known Pleistocene-age remains of a Carolina parakeet.

The extinct Carolina parakeet.

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Range map of the formerly widespread Carolina parakeet.  It was doomed by overhunting and deforestation.

Sand is mined from the Dickerson Coquina sand pit to replace sand lost on Hutchinson Island to erosion.  Hutchinson Island is located in the same county as the sand pit.  Pleistocene-age fossils have been found in the sand pit and on the sand dumped on Hutchinson Island Beach.  Electron spin resonance dating determined the specimens excavated from the sand pit were above a layer dated to 730,000 years BP-430,000 years BP.  The species found are consistent with this dating and were common during the late Pleistocene including giant tortoise ( Hesperostestudo crassicutata ), box turtle, snakes, sharks, rays, fish, mammoth, paleollama, tapir, horse, pampathere, dire wolf, and jaguar.  No bison fossils were found.  Bison didn’t colonize North America until 300,000 years ago, so the absence of this species is consistent with an estimated date of 400,000 years BP for the fossils found here.

The remains of at least 24 species of birds have been excavated from these sands including a number of interesting extinct or extralimital species aside from the Carolina parakeet.  (The complete list of species found is described in the paper linked below as a reference).  Ornithologists have identified the remains of great auk ( Pinguinus impennis ), short-tailed albatross (  Phoebastrea albatrus ), northern gannet ( Morus bassanus ), an extinct stork ( Ciconia maltha ), and an unnamed extinct crane ( Grus sp. ).

Today, the short-tailed albatross nests on just 4 islands in the North Pacific between Hawaii and Japan (including Midway near where the famous WWII battle took place). But the presence of their bones in Florida means this species formerly ranged throughout the North Atlantic Ocean.  They probably nested on islands that were inundated by rising sea levels about 400,000 years ago, causing their extirpation here, but they didn’t necessarily nest in Florida.  Storms may have blown flocks inland.

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Today, the short-tailed albatross is a rare bird that nests on 4 islands in the North Pacific, but it also lived in the Atlantic Ocean during the middle Pleistocene.

The great auk was a denizen of rocky islands off the coast of Maine and Canada until 1852 when it was overhunted to extinction.  I hypothesize they nested on a rocky island off the coast of South Carolina, known as Bulls Scarp, that was above sea level during Glacial Maximums.  This possible nesting site may explain why they were close enough to have fished waters off the coast of Florida.  It’s likely storms blew this species inland as well.

A large, stuffed bird with a black back, white belly, heavy bill, and white eye patch stands, amongst display cases and an orange wall.

The great auk was overhunted to extinction by 1852.  Remains of this species were also found at this site.  I hypothesize that during Glacial Maximums this species may have nested as far south as South Carolina.

Northern gannets nest on subarctic islands in the North Atlantic but range throughout most of the Atlantic when seeking fish.  They too may have nested on Bulls Scarp.  The extinct species of stork probably ate carrion and depended upon the existence of large herds of megafauna for a major part of its food supply.  Not enough skeletal material has been found here from the large extinct species of crane to officially name it.  The fossil bone recovered from the sand pit resembles that from an extinct flightless crane that formerly lived in Cuba, but it is not an exact match.  This species was probably not flightless, like its Cuban cousin, because there were too many predators on the mainland.

Reference:

Kilmer, John; and David Steadman

“A Middle Pleistocene Bird Community from Saint Lucie County, Florida”

Bulletin of the Florida Museum of Natural History 2016

http://www.flmnh.ufl.edu/files/2514/8113/2040/Vol55No1_archival.pdf

The Pleistocene Champlain Sea

December 22, 2016

The weight of a glacier depresses the earth’s crust, a geological process known as crustal downwarping.  The Laurentide Ice Sheet covered most of eastern Canada during the Last Glacial Maximum, but a sudden warm phase of climate led to the rapid recession of its southern lobe.  About 13,000 years ago ocean water flooded into this glacial depression located in the present day region of eastern Quebec and Vermont, creating the Champlain Sea. The transgression of ocean water into land recently depressed by a glacier is termed eustatic sea level rise.  The Champlain Sea was bordered on its northern edge by melting ice cliffs formed by the retreating glacier, while a marshy tundra existed on its south side.  Over time this tundra was colonized by spruce trees.  This boreal forest was in turn replaced by a landscape of mixed conifers and northern hardwoods.  Meltwater and falling chunks of ice from the glacial cliffs reduced the salinity of the Champlain Sea, making it a brackish estuary teaming with a rich diversity of marine life.

Map of the pre-historic Champlain Sea.  It was created by crustal downwarping and fed by melting glaciers.  Ocean water flooded into this basin via the St. Lawrence River.  Isostatic rebound terminated the existence of this sea.

Lévis is located in Southern Quebec

Location of Levis, Quebec.  An excellent fossil site is found in the St. Nicholas borough of this city, containing many species that lived in the defunct Champlain Sea.

The fossil record suggests the white whale ( Delphinapterus leucas ) was the most common large mammal living in the Champlain Sea.  The white whale feeds upon fish, cephalopods, and shellfish.  The presence of a large population of white whales indicates an abundance of fish, and this is corroborated by the remains of both fresh and saltwater species found in deposits dating to this age here, including cod, tomcod, eelpout, capelin, smelt, spoonhead sculpin, lake cisco, lake char, wrymouth, long-nosed sucker, lumpfish, 3-spine stickleback, sturgeon, and salmon or trout.  Humpback, finback, and bowhead whales, and harbor porpoises also frequented the Champlain Sea.  Harp and bearded seals bred on pack ice, ringed seals bred on the shore, and harbor seals swam in the open water.  Herds of walruses rested on the ice edge.  Scientists have even excavated the remains of birds here–long-tailed ducks, thick billed murres, common eiders, and arctic terns.  The foot bone of an old arthritic grizzly bear was found at St. Nicholas, the best fossil site in the region where the remains of many species were buried under tidal current sands.  Polar bears probably roamed along the shores, but fossil evidence of their presence here has yet to be discovered.Image result for beluga whale

Fossil evidence suggests white whales were the most common whale species in the Champlain Sea.

In 1849 geologists were surprised to find whale bones and the remains of marine invertebrates such as clams, scallops, mussels, barnacles, and sea urchin in landlocked Vermont, and it took them a while to determine a vast inland sea resulting from retreating glaciers was the explanation for the presence of these fossils.  The sea existed from about 13,000 BP to ~10,000 BP.  Saline levels often fluctuated, depending upon the varying quantities of meltwater, and the sea gradually became more shallow as the earth’s crust rebounded.  The rise of the earth’s crust following the retreat of a glacier is known as isostatic rebound–the opposite of crustal downwarping.  The sea also became warmer over time.  Arctic saxicoue was an early dominant clam, but eastern soft-shelled clams, a warmer water species, replaced them.

Eventually, isostatic rebound split the Champlain Sea into 2 freshwater lakes and blocked their outlets to the St. Lawrence River and Atlantic Ocean.  Lake Lampsilis, named after a common species of freshwater mussel ( Lampsilis radiati ), lasted until ~8,000 years BP, when isostatic rebound completely eliminated the basin that held the lake.  Today, Lake Champlain is a freshwater relic of what was formerly an enormous brackish sea.

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Champlain Lake is a tiny remnant of the once vast Champlain Sea.

Reference:

Harrington, C. Richard; Marc Coornoup, Michael Chastia, Tara Fulton, and Beth Shapiro

“Brown Bear (Ursus arctos) (9880 BP) from Late Glacial Champlain Sea Deposts at St. Nicholas, Quebec, Canada, and the Dispersal History of Brown Bears”

NRC Press 2014

Heinrich Events Caused Annual Mass Whale Strandings during the Pleistocene and early Holocene

October 10, 2016

Despite the universal chorus of politicized alarmists, earth is currently experiencing a period of relative climatic stability compared to the dramatic climatic fluctuations that occurred during the Pleistocene.  The presence of vast ice sheets in the northern hemisphere contributed to this ancient climatic instability.  Glaciers blocked rivers, creating huge glacial lakes.  Warm spikes in average annual temperatures weakened the ice dams and caused breaches.  Massive outflows of frigid fresh water and icebergs periodically flooded into the North Atlantic, shutting down thermohaline circulation.  The gulf stream normally carries tropically heated water into the North Atlantic, and this keeps overall climate temperate, but after torrents of cold fresh water stopped this process, average annual temperatures dropped as much as 15 degrees F in less than a decade, precipitating severe stadial conditions that lasted for hundreds or even thousands of years. These meltwater pulses are known as Heinrich events, named after the scientist who first recognized this cycle.

During Ice Ages warm stages of climate cyclically caused glacier dams to burst, releasing massive amounts of cold fresh water plus icebergs.  This shut down the North Atlantic Gulf Stream which brings tropically heated water north, resulting in a sudden decline in average annual temperatures.

A graph showing average annual temperature fluctuations over the last 100,000 years from data gleaned inside Greenland ice cores.  Cyclical Heinrich Events caused the sudden declines in temperatures.

I assumed Heinrich Events severely disrupted marine ecosystems, causing decisive population declines in most fish and other ocean fauna, though a few species may have benefitted from reduced competition or other factors.  But I thought there would be no paleontological evidence because preservation and detection of animal remains during brief time intervals in marine environments seemed unlikely.  However, a recent paper highlights evidence that Heinrich Events were detrimental to marine life.  Scientists found this evidence in a seaside Sicilian cave named la Grotta Dell’Uzzo.  This cave had previously revealed the Pleistocene remains of mammoth, rhino, lion, red deer, and wild boar.  Humans have also periodically occupied this cave from the late Pleistocene through the Holocene, and scientists have excavated human skeletons, artifacts, and food remains.  Chemical analysis of human bones found in the cave helped scientists determine the diet of the hunter-gatherers who occupied the cave during the early Holocene.  They ate red deer, wild boar, shellfish, fish caught near shore (such as grouper), acorns, grapes, and wild beans and peas.  However, 1 human specimen and 1 red fox bone, dating to 8200 BP, revealed an interesting difference. Both the human and the fox ate unusual quantities of whale meat during their lifetimes.  Red foxes don’t normally include whale meat in their diet, and humans from other generations of cave dwellers here hardly ever exploited this resource. Moreover, whale bones with butcher marks on them were found associated with the human and fox specimens in the same strata.  The scientists who examined this evidence determined humans exploited climate-driven whale strandings at this locality.

Mass stranding of pilot whales in Australia.  Heinrich Events disrupted marine ecology and caused high annual mortality among many species of whales.

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Evidence of early Holocene mass whale strandings was discovered in this seaside cave in Sicily, known as la grotto dell’Uzzo.

The last major Heinrich Event occurred 8200 years ago, following the final dissolution of glacial Lake Agassiz in Canada.  This massive meltwater pulse disrupted fish migrations and reduced fish populations, making it harder for many species of whales to find prey.  Stressed and malnourished whales are more likely to strand on beaches.  The Gulf of Castallammare, adjacent to la Grotto Dell’Uzzo, is an acoustic dead zone difficult for whales to navigate.  This is where frequent, probably annual, whale strandings occurred for centuries, and the evidence suggests humans and foxes exploited this resource.  Based on the zooarchaeological record, the most common species of whales stranded here were pilot whales (Globicephala melus), Risso’s dolphin ( Grampus griseus ), and short-beaked common dolphin ( Delphinus dolphio ). Frequent whale strandings likely occurred worldwide following Heinrich Events.  Off the coast of North America dire wolves, bears, and other large carnivores scavenged this wealth of protein during the Pleistocene.  There were certain spots, such as the 1 in Sicily, where carnivores learned to regularly search for this bounty.  Carnivore populations may have been higher near the coast due to this additional resource.  Unfortunately, evidence of these sites were long ago inundated by rising sea level.

Reference:

http://www.nature.com/articles/srep16288

Marcello, Mannino; at. al.

“Climate-driven Environmental Changes around 8200 Years Ago Favored Incidences of Cetacean Strandings and Mediterranean Hunter-Gatherers Exploited Them” 

Scientific Reports 2015

 

Pleistocene Fossils and Nazi Soldiers Buried in Latvia

September 13, 2016

About 30 years ago I took a business class at Augusta College that revealed 1 of my most disappointing shortcomings.  The professor separated us into groups of 7, and we were assigned topics for discussion everyday.  After several weeks of discussions the professor told us to rank group members in order of most to least influential.  I ranked myself 3rd and felt it was a fair assessment.  But I ranked 6th in the overall average of everybody’s rankings.  Much to my astonishment, I was ranked well behind a guy (that I ranked last) who often showed up to class tripping on acid and had not spoken 1 word during the entire assignment.  It was then when I first realized I had no influence, and I felt so depressed I almost cried.  It explained why I had such a hard time getting women to go on dates with me.  It explained why ridiculous jerks who continuously misused and abused women could get any dates they desired, while I was lucky to get a condescending rejection, if the woman even acknowledged my attention at all.

Now that I am older, I’ve learned to accept the reality that I have little influence or charisma.  I am “low key” as 1 of my former supervisors reported in a complimentary job evaluation.  I even take solace in the knowledge that some of the most influential people in history are considered monsters.  I’ve recently been re-reading The Rise and Fall of the Third Reich by William Shirer–the best history book I’ve ever read. The details of how Hitler completely took over a country amaze me.   Adolf Hitler was clinically insane.  A psychiatrist diagnosed him with manic-depressive psychosis, now known as bipolar disorder.  (The Nazis eventually killed the doctor and made it look like a suicide.)  Yet, he was easily the most influential man of the 20th century.  He drastically changed the course of history after becoming the dictator of Germany with the legal power of life and death over every citizen there and in all the territories conquered under his rule.  He even replaced the customary salutation of “hello” and “goodbye” with “Heil Hitler.”  He is responsible for the deaths and misery of millions of people.  So if anybody ever criticizes me for having no influence or lacking charisma, I can always tell them, “well, you know who DID have a lot of influence?…Adolf Hitler.”

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I’m a nice guy, but I have no influence.  Hitler…not a nice guy…was the single most influential man to live during the 20th century.  I used to feel sad about my lack of charisma, but when I think about this, I don’t feel as bad.

My late father survived the holocaust in Buzcazc, Poland.   One day, the Nazis ordered all the adult Jewish men to the town soccer stadium.  My grandfather decided not to obey that order, although he considered it.  That night, my father’s family heard shots from the direction of the soccer field and a few minutes later, an athletic man who ran and escaped, told them the Germans lined up and shot all the Jewish men in attendance.  Shortly after this incident, my grandfather paid a Ukrainian farmer to hide his family in an hayloft.  There, 6 people lived on a very low calorie diet for 2 years before they were liberated by the Russian army.  However, all of my father’s grandparents, uncles, aunts, and cousins were killed in concentration camps or shot upon initial confrontation.  My father always liked to watch WWII movies because they depicted the killing of Nazis.  Until his death, he never tired of watching “killing Nazis”–his term for his favorite war movies.  My dad would have enjoyed a movie about the Russian military campaign in Latvia during 1944 that occurred to the north of where he was liberated, but Hollywood has yet to depict this battle.  The Russians trapped 350,000 German soldiers here.  They killed 100,000 and captured the rest.  All of the bodies were buried near where they were killed, and the blue clay soil helps preserve the Nazi skeletons and artifacts that litter the subsurface of the Latvian countryside.

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Location of Latvia.  The Russian army trapped 350,000 German soldiers here.  100,000 were killed and buried on the battlefields.  In many rural areas live humans are outnumbered by buried German corpses.

Rural Latvia is an economically depressed region and most of the people who lived there moved to the city or to other European countries.  So in many places, Nazi corpses outnumber live people.  The old poor alcoholics who remain often dig up Nazi graves and sell the artifacts for cash.  German army dog tags sell for $60.  SS dog tags sell for several hundred dollars.  An helmet can fetch $90.  The market for Nazi artifacts is strong and can be lucrative.  According to Bloomberg Businessweek,  “Herman Goering’s sweat-stained uniform” sold for $126,000.  An orthodox Jew bought Josef Mengele’s diary for $245,000.

The same properties in Latvian soil that have preserved Nazi skeletons also saved paleoecological evidence dating to the Pleistocene.  Stratigraphic cores reveal evidence of past fluctuations in climate alternating between temperate, cold, and full glacial.  Pollen analysis shows a forest of elm, basswood, and hazelnut predominated during warm interglacials.  Immediately before and after glacial maximums the environment consisted of grassy steppe with pockets of birch, alder, spruce, and pine.  Glaciers have entirely covered Latvia during the glacial maximums of the numerous Ice Ages that occurred over the past 2-3 million years.  Over 40 specimens of mammoths have been excavated in Latvia (impressive for such a small little studied area), and caribou remains are common as well.  A Latvian can dig in their backyard and find Nazi skeletons, and if they keep digging deeper, they might find the remains of a mammoth too.

References:

Rogers, Thomas

“The Bodies”

Bloomberg Businessweek   September 4, 2016

Zeles, Vital; Maris Nartiss, and Tomas Satir

“Pleistocene Glaciation in Latvia”

In   Quaternary Glaciation–Extent and Chronology: a closer look

Edited by J. Ehles, P.L. Gillard and P.D. Hughes

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The Inner Space Cavern Fossil Site near Georgetown, Texas

August 18, 2016

Construction workers building an highway bridge over a railroad line accidentally discovered Inner Space Cavern in 1963.  This site is located on the edge of the Edward’s Plateau 1 mile south of Georgetown, Texas.  The eastern side of the Edward’s Plateau is a hilly landscape sitting on Cretaceous-age limestone bedrock.  Rain dissolves limestone creating many underground caves in the region.  The workers drilled down 33 feet and when the drill bit reached the cavern it fell an additional 24 feet becoming lodged in stalagmites.  Inner Space Cavern is also known as Laubach Cave, named after the family who owns the land.  The Laubachs opened up an accessible entrance to the cave, and it is now a tourist attraction.  The cave is underneath the rail line and Highway 35.  Skeletal remains of late Pleistocene age vertebrates have been excavated from 5 sites in the cave.  However, radiocarbon dating of these specimens was executed during the late 1960s and early 1970s when this technology was still in its infancy, and the resulting dates are not considered accurate.  The specimens are at least 13,000 years old, but it’s unclear if they can even be radiometrically dated.

Location of Georgetown, Texas

Location of Georgetown, Texas.  Inner Space Caverns is just south of this town.

Inner Space.

View inside Inner Space Cavern.

An unique assemblage of grazing fauna roamed central Texas during the late Pleistocene.  Mammoth, bison, horse, camel, glyptodont, and a large extinct species of pronghorn (Tetrameryx shuleri) occupied the plains.  The fossil record suggests Tetrameryx shuleri was restricted to what is now the state of Texas during the late Pleistocene.  Because it was a regional species, it was more vulnerable to extinction when man colonized the area.  A single specimen of the scimitar-toothed cat (Dinobastis serum) was found in Laubach Cave.  Although this species ranged widely over North America, the distribution of its remains suggests the region from Texas and Oklahoma to western Tennessee may have held a core population.  Other large mammal remains found in the cave include Jefferson’s ground sloth, deer (probably white tail rather than mule), flat-headed peccary, jaguar, dire wolf, and the extinct Florida spectacled bear (Tremarctos floridanus).  This is the westernmost known occurrence of the Florida spectacled bear during the late Pleistocene.

Today, the Texas kangaroo rat (Dipodomys elator) is restricted to 10 counties in north Texas bordering Oklahoma.  Remains of this species found in Laubach Cave show it formerly ranged further south.  Black-tailed prairie dogs (Cynomys ludovicianus) and meadow voles (Microtus pennsylvannicus) also no longer occur this far south.  Short-tailed shrews (Blarina carolinensis) don’t live this far west any more.  The presence of these small mammals suggests the climate in this region was wetter with cooler summers during the Ice Age than it is today.

Texas kangaroo rat (Dipodomys elator).  Skeletal remains of this species dating to the late Pleistocene were found in Inner Space Cavern.  It no longer occurs this far southeast.

Skeletal remains of this extinct pronghorn (Tetrameryx shuleri) were found in Inner Space Cavern.  This was its easternmost known occurrence. Note the 4 prongs.

Evidence from Inner Space Caverns shows the extinct Florida spectacled bear (Tremarctos floridanus) lived as far west as central Texas.

The faunal composition of Laubach Cave indicates this region during the Ice Age was dominated by grassy plains but with some riparian woodlands and mesquite/acacia scrubland.  Grazers such as mammoth, horse, and camel clearly are evidence of prairie habitat.  The presence of Jefferson’s ground sloth, deer, cottontail rabbit, spectacled bear, and jaguar (an ambush predator)  make it seem likely that finger shaped communities of trees grew alongside rivers and creeks.  These riparian woodlands probably consisted of centuries old live oaks, cottonwoods, and sycamores.  Flat-headed peccaries, jackrabbits, and kangaroo rats prefer (or in the case of the extinct species, preferred) scrub habitat.  Texas kangaroo rats almost exclusively burrow beneath the roots of mesquite.

Vegetation of this region was similar to that of today, yet slightly different.  The moderate increase in precipitation combined with cooler summer temperatures meant deeper top soils and greater stream flow through rivers.  The alternate climate caused changes in the abundance and density of some species of plants.  Prairies were mixed with some tall grass and some shortgrass, depending upon the topography.  These prairies, like many other natural communities, were thick with wildlife until man came along.

Reference:

Sansom, Jones; and Ernest Lundelius

“Inner Space Cave: Discovery and Geological and Paleontological Investigation”

Austin Geological Society Bulletin 2005

The Page-Ladson Site in Northwest Florida

June 5, 2016

During the late Pleistocene sea level contracted because much of earth’s atmosphere was locked in glacial ice.  The land area of what today is Florida doubled in size, and shorelines extended 50-100 miles west into the Gulf of Mexico.  The water table fell and many present day small rivers did not yet exist.  Instead, the land was pockmarked with many spring-fed ponds that attracted herds of megafauna and other wildlife.  The basal chemistry of these waters preserved bones and organic matter, and later when water tables rose, the Aucilla River began flowing and it covered these ponds with sediment.  The Aucilla River flows over 4 known Pleistocene pond sites–Page-Ladson, Latvis-Simpson, Sloth Hole, and Little River Quarry.  These sites contain deep layers of mastodon dung deposits.  Bones and artifacts are often mixed with the ancient piles of turds, and tracks are also visible where mastodons stepped on their own shit.  Scientists studied the dung and identified the plants mastodons ate.  Their favorite foods in Florida were cypress and buttonbush twigs and cones, but they also fed heavily on aquatic plants, oak leaves and acorns, and fruit including persimmon, plum, crabapple, grape, pokeberry, and wild squash.  At Latvis-Simpson a female mastodon skeleton with a fetus was excavated from a dung deposit.  Other dung deposits contain stone and ivory tools made by humans.

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Location of the Aucilla River. This river didn’t exist until about ~13,000 years ago.  It cuts through the site of spring-fed ponds that attracted megafauna, and eventually humans for thousands of years.

Tusk under Water.

A mastodon tusk.  Cut marks on a mastodon tusk found at Page-Ladson suggests humans butchered it for a fatty chunk of meat.

 

 

 

 

 

 

 

Radiocarbon dating of dung deposits at the Latvis-Simpson site indicated the oldest layer goes back to 32,000 BP.  The Page-Ladson site is not as old, but deposits there show man overlapped with megafauna as early as 14,550 years ago, predating the Clovis era.  The list of species remains found at the Page-Ladson site (just some of the fauna that overlapped with man) includes 2 species of gar, 2 species of pickerel, 5 species of catfish, 2 species of suckerfish, 7 species of bream, largemouth bass, black crappie, 3 species of frog, amphiuma, siren, Fowler’s toad, snapping turtle, an extinct subspecies of box turtle, gopher tortoise, an extinct species of giant tortoise, rattlesnake, alligator, great blue heron, pied-billed grebe, cormorant, Canada goose, duck, bald eagle, an extinct species of eagle, California condor, an extinct species of stork, red-shouldered hawk, red-tailed hawk, mourning dove, opossum, beautiful armadillo, pampathere, Jefferson’s ground sloth, Harlan’s ground sloth, raccoon, black bear, river otter, margay cat, bobcat, dire wolf, domestic dog, fox squirrel, beaver, muskrat, Florida muskrat, porcupine, capybara, mastodon, mammoth, bison, large-headed llama, stout-legged llama, white-tailed deer, long-nosed peccary, flat-headed peccary, horse, and tapir.  Remains of the extinct Florida spectacled bear have been collected from other Aucilla River sites, and large carnivores such as saber-tooths and jaguars left remains throughout much of the state’s other fossil sites.  Mastodon remains outnumber mammoth remains by a ratio of 4 to 1 at Aucilla River sites.  The former preferred aquatic wooded habitats, while the latter liked grassy open plains.  Remains thought to be of domestic dog may actually be coyote bones because the 2 species are difficult to distinguish from just skeletal remains.

My Georgia Before People blog was in part inspired by information gathered by the scientists who excavated the Aucilla River fossil sites.  So of course, I must highlight a new study of the Page-Ladson site.  Radio-carbon dates of organic material associated with human artifacts have long yielded dates in excess of 14,000 calendar years.  Many archaeologists dismissed these dates…they assumed error in the dating.  This new study was exhaustive–the scientists took 71 radiocarbon dates using the most modern methods–and they determined humans began frequenting the pond 14,550 years ago.  They confirmed that a mastodon tusk found here showed clear evidence of human butchery.  There are 2 additional examples of human butchering megafauna from Aucilla River sites.  Humans likely used these water sources opportunistically to specifically hunt big mammals.

The study also looked at sporormiella volumes.  Sporormiella is a fungus that grows on dung, and it can be used as a proxy for megafauna abundance.  Sporormiella volume spiked 13,700 years ago but then declined, and apparently the local megafauna became extirpated from the region by 12,600 years ago. This is within the accepted terminal extinction dates for Pleistocene megafauna.  Sporormiella volume briefly increased again about 10,000 years ago.  Researchers attribute this to a temporary migration of bison into the region, though this is based on the assumption that other species of megafauna were extinct by then.  I don’t agree with this assumption and believe local populations of now extinct Pleistocene megafauna persisted until the early Holocene but at levels so low they are difficult to detect in the fossil record.

The sporormiella spike at 13,700 is about 800 years after the first appearance of man in the region.  The entrance of man is also associated with an increase in charcoal from man made fires, and I might add, a change in climate to more frequent lightning storms.  I propose anthropogenic fires improved habitat for megafauna leading to an initial increase in megafauna populations.  But man eventually hunted these species to extinction.  As Gary Haynes proposes, the long term drought that occurred during the Younger Dryas cold snap likely concentrated megafauna around dwindling water sources, making them more vulnerable to human overhunting.

References:

Halligan, Jessi; et. al.

“Pre-Clovis Occupation 14,450 Years Ago at the Page-Ladson Site, Florida and the Peopling of America”

Science Advances May 2016

http://advances.sciencemag.org/content/2/5/e1600375

Webb, David (editor)

The First Floridians and the Last Mastodons: the Page-Ladson Site in the Aucilla River

Springer 2006

A New Study about the Devil’s Den Site in Florida was Published

April 20, 2016

An unpublished study of radiocarbon dates of extinct Pleistocene megafauna excavated from the Devil’s Den site in Florida produced unusually recent dates.  Specimens from this site were dated to between 7,000 BP-8,000 BP; about 4,000 years after the time most believe these species became extinct. I often wondered why this data seemed to be ignored in the scientific literature and why no one had attempted a follow up study of the specimens from this site.  The specimens were described in 1974, then seemingly forgotten.  (See: https://markgelbart.wordpress.com/2012/07/08/the-devils-den-fossil-site-may-have-been-located-in-one-of-the-last-refuges-of-the-megafauna/ )Finally, several scientists began analyzing the Devil’s Den specimens again, and they just recently published their data in  brand new journal named PaleoAmerica.

Devils Den - Williston, FL

Photo of the Devil’s Den site from inside the sinkhole.

I had wrongly assumed the specimens were radiocarbon dated in 1974, but I learned from reading this study that they were dated in 1961 when radiocarbon dating was primitive and not particularly reliable.  Moreover, the authors of this new study determined radiocarbon dating of these specimens could not be accurate because they didn’t have enough bone collagen left.  They also suggest radiocarbon dating for most Pleistocene-aged specimens found in Florida is not possible because the regional environmental conditions eat away at bone collagen so rapidly.  This poses a problem for scientists who want to know if humans overlapped in time with Pleistocene megafauna in North America.  Surprisingly, there is little direct evidence of this, despite the universal assumption that they did.  Human remains of confirmed Pleistocene age in North America are extremely rare.  However, human bones associated with those of extinct Pleistocene mammals have been found in several sites in Florida including Vero Beach, Warm Mineral Springs, Melbourne, and Devil’s Den.  Though this is suggestive, it’s possible humans buried their dead in the Pleistocene-aged strata, mixing the bones from different time periods.  Scientists need something more definitive than association.  Because radiocarbon dating can’t be used at these sites, the authors of this study decided to try rare earth element analysis on the specimens from Devil’s Den.

Here is an explanation of rare earth element analysis. Rare earth elements (a bit of a misnomer because they’re not particularly rare) include elements on the periodic table numbered 57-71.  They occur in groundwater in certain fixed ratios.  Animals absorb ground water by ingestion and then for thousands of years after they die their bones continue to become saturated with it.  Eventually, the bone reaches a saturation point and won’t take in any more.  The ratio of rare earth elements in that particular fossil becomes fixed.  However, over thousands of years the ratios of rare earth elements in ground water changes.  So an animal that lived 13,000 years ago will have a different ratio of rare earth elements than an animal that lived  200 years ago.

The authors of this study compared the ratios and concentrations of rare earth elements from specimens they categorized into 4 groups.  They analyzed 26 specimens from 5 different individual human skeletons found in the Devil’s Den sinkhole and compared them with the associated bones of extinct Pleistocene fauna, extant fauna thought to be of Pleistocene age, and extant fauna from the modern local environment.  They used specimens of the Florida spectacled bear (Tremarctos floridanus), flat-headed peccary, Jefferson’s ground sloth, mastodon, and muskrat that were found in the sinkhole.  The first 4 of these species are extinct, and this species of muskrat hasn’t occurred in Florida for about 3,000 years.  The extant fauna thought to be of Pleistocene age found in the sinkhole included white-tailed deer, woodrat, striped skunk, gray fox, and gopher.  Local fauna of modern age used in the study were deer, fox squirrel, gray fox, and gopher.  Specimens from 4 of the 5 human skeletons shared similar ratios of rare earth elements with Pleistocene fauna, showing they lived during the same time period.  One of the human skeletons is probably of Holocene age, but this study demonstrates without a doubt that humans overlapped in time with Pleistocene megafauna.

The authors of this study assume 4 of the human remains are older than 13,000 years old, but they have no way of knowing for sure.  The rare earth element analysis shows these individuals lived at the same time as Pleistocene megafauna, and the bones are of great antiquity, but the date of deposition is not known.  As I’ve written previously on this blog, I hypothesize some species of Pleistocene megafauna survived in small relict populations well past their accepted terminal extinction date of ~12,500 BP.  The exact extinction dates of Pleistocene megafauna in Florida will remain a mystery, especially if radiocarbon dating can’t be used.

Reference:

Purdy, Barbara; Kathryn Rohlwing and Bruce Macfadden

“Devil’s Den, Florida Rare Earth Element Analysis Indicates Contemporaneity of Humans and Late Pleistocene Megafauna”

PaleoAmerica 1 (3) 2015

The Little Salt Spring Fossil Site in Southwestern Florida

March 14, 2016

About 50 years ago, scuba divers discovered Little Salt Springs was not the shallow brackish pond everybody thought it was.  They were surprised to find it was 200 feet deep.  From an aerial view the lake is perfectly round, but underneath the surface it is hourglass-shaped with ledges that were above the water table until ~7,000 years ago.  Below 20 feet the water here has no dissolved oxygen, making it inhospitable to fish and microorganisms that would normally decompose organic material.  The conditions are exceptionally favorable for the preservation of animal bones and human artifacts.  The real estate company that owned the sinkhole and the land around it donated this scientifically significant site to the University of Miami.  That institution employed scientists who administered and studied the sinkhole for over 30 years.   Then, a few years ago, some budget-cutting troglodyte sold the site to Sarasota County, probably so the university can spend more money hiring football coaches, like Mark Richt.

Click to View Larger Map

Little Salt Spring is located on the outskirts of North Port, Florida, not far from Sarasota.

Picture

Illustration of Little Salt Spring.  There is no dissolved oxygen below about 20 feet, and therefore no bacteria, resulting in excellent preservation of ancient fossil remains and organic artifacts.

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Deer antler with 28 notches carved into it marking the 28 days of the lunar month.  It’s a kind of archaic Indian calendar. It was found in the sinkhole along with many other artifacts.

The most famous specimen discovered in Little Salt Spring is a giant tortoise (Hesperotestudo crassicutata) shell with a wooden stake stuck through it.  Archaeologists believe it fell on to a ledge that was above the water table at the time.  A Paleo-Indian killed the tortoise with a wooden stake, turned it on its back, and cooked the unlucky chelonian in its shell.  Despite the likelihood that overhunting by humans caused the extinction of this species, this is the only direct evidence that people exploited them.  Some researchers initially rejected this interpretation because the carbon date for the wooden stake didn’t match the radiocarbon date of the tortoise shell.  But improved radiocarbon dating techniques since then have confirmed the wooden stake and the tortoise shell are the same age.

A series of wooden stakes, now submerged, were planted above the ledge where the cooked tortoise shell was found.  Archaeologists think the stakes may have supported some kind of camouflage that hid the steep ledge.  Prey animals blundered or were chased off the precipice and became trapped on the ledge.  The stakes may have also supported rope ladders, so the Indians could climb down and kill the animal trapped on the ledge.

A National Geographic News article from 2009 mentions the butchered remains of a Jefferson’s ground sloth were found on a submerged ledge at this site.  This would be just the 2nd known case of human exploitation of a ground sloth in North America.  However, I can find nothing in the scientific literature about this specimen.  Although professors from the University of Miami studied this site for decades, they published just an handful of papers about it.  The volume of research they produced surprises and disappoints me.

Most of the human artifacts found at this site are early archaic.  Some of the most interesting include 4 non-returning boomerangs made of oak wood that date to ~9,000 years ago, a carved atlatl handle, a green stone pendant, and a notched deer antler used as a lunar calendar.  There are hundreds of archaic Indian graves where human remains have rested for over 5000 years.  The water table rose shortly after people were buried by the lake’s edge, resulting in excellent preservation–some skulls still have brain matter inside.

Scientists have identified the bones of mastodon, Jefferson’s ground sloth, saber-tooth, rabbit, wood stork, giant tortoise, gopher tortoise, Florida cooter, red-bellied turtle, an extinct species of box turtle, diamondback rattlesnake, and largemouth bass from Little Salt Spring.  Less than 5% of the site has been surveyed for subfossil remains and artifacts.  I’m sure the list would grow, if there was a concerted effort made by scuba-diving paleontologists.

During the late Pleistocene, Little Salt Spring was much farther inland from sea level than it is today.  Dry land extended for many miles into the Gulf of Mexico.  The composition of species suggests that when Indians first discovered this sinkhole it was a wetland oasis surrounded by arid sand hill savannahs dotted with a sparse tree canopy.

References:

Holman, J.; and Carl Clausen

“Fossil Vertebrates Associated with Paleo-Indian Artifacts at Little Salt Spring”

Journal of Vertebrate Paleontology 4 (1) September 1984

Wisner, G.

“Diving into Paleo-Florida”

Mammoth Trumpet 23 (1) 2008

 

 

 

Pleistocene Fossils Found in Southwestern Georgia and Southeastern Alabama

August 17, 2015

Geologists refer to the upper coastal plain of Alabama and southwestern Georgia as the “southern hilly Gulf Coastal Plain.”  The terrain alternates between irregular flat plains and gently rolling hills.  Many creeks and rivers erode through sediments of differing ages, exposing fossiliferous deposits that date from the Cretaceous to the Pleistocene.  During the Pleistocene a mosaic of deep forest, open woodlands, savannah, prairie, and wetlands covered this region.  Pollen from composite species (sunflowers, daisies, etc.) and pine increased during arid stadials while warmer wetter interstadials saw an increase in broad-leafed tree abundance.  Most of the plant species that occurred here then are still extant but the extinct Critchfield’s spruce; a temperate species that grew alongside oaks, walnut, and elm; was a component of this primeval wilderness.

Fossil hunters have collected mastodon fossils from Hannahatchee Creek in Stewart County, Georgia; Bogue Chitto Creek in Dallas County, Alabama; and the Warrior River in Alabama. (See:http://www.archeologyink.com/Ice%20Age.htm) Hannahatchee Creek is better known for Cretaceous fossils.  Most of the Cretaceous fossils found here are of marine species but teeth of nodosaurs, hadrosaurs, and tyrannosaurs have been collected from the stream bed.  A mastodon tooth was recovered about 1/2 mile west of Union, Georgia along Hannahatchee Creek, and a leg fragment of a mastodon was picked up upstream near Omaha.  I looked at a satellite image of this creek.  The owners of the land here allow a narrow strip of natural creek bottomland to grow, but most of the area appears to be pine plantation.  This is unfortunate because pine tree farms support very little wildlife.  During the Pleistocene the land bisected by Hannahatchee Creek could have consisted of cypress swamp, bottomland hardwoods, beaver meadows, grassy marshes, and/or canebreaks.  All of these environments would’ve made excellent habitat for semi-aquatic mastodons.

Hannahatchee Creek erodes through strata of different ages from the Cretaceous to the Pleistocene.

Mastodon Tooth

A mastodon tooth was found in Hannahatchee Creek.

Other Pleistocene remains have been recovered from at least a dozen small creeks that flow through the upper coastal plain of Alabama and Mississippi.  They include mammoth, horse, tapir, bison, white-tailed deer, long-nosed peccary, flat-headed peccary, giant beaver (Casteroides sp.), pampathere (a 300 lb armadillo), Jefferson’s ground sloth, Harlan’s ground sloth, gray fox, coyote, Florida spectacled bear (Tremarctos floridanus), giant short-faced bear (Arctodus simus), black bear, margay cat (Leopardus wiedii), and indigo snake.  The margay cat currently ranges throughout tropical forests in Central and South America, but it formerly lived in southeastern North America.  Fossil remains of the margay have been found at 2 sites in Georgia, 12 in Florida, and 3 in Mississippi and Alabama.  The latter 3 are not listed in the Paleobiology database, and I was unaware of these specimens when I wrote a blog post about this species (See: https://markgelbart.wordpress.com/2013/05/09/the-mystery-cat-of-pleistocene-georgia/).

Margay hanging from tree.

Margay fossil remains found in Alabama and Mississippi have not been posted on the paleobiology data base or faunmap.

Horse teeth dating to the Pleistocene are particularly abundant in these small creeks.  This suggests the presence of extensive grasslands in the Black Belt Prairie region that stretches across Mississippi and Alabama.  Disjunct areas of Black Belt Prairie are also found in south central Georgia.  Herds of horses attracted large predators such as dire wolf, saber-tooth, scimitar-tooth, giant lion (Panthera atrox), and jaguar.  There is some scant evidence of dire wolf in this region, but it is undocumented.  Fossil remains of the other 4 large carnivores have been found in adjacent regions, so it’s very likely they occurred on the upper coastal plain.  The first Panthera atrox fossil was found in northern Mississippi, and giant lions are part of Florida’s and South Carolina’s fossil record.  Jaguars fossil remains have been found in Georgia, Florida, and South Carolina. Saber-tooth remains have been excavated from northern Alabama, Florida, Tennessee, and South Carolina.  Scimitar-tooth bones were discovered in Tennessee and Florida.

George Phillips wrote an excellent Masters Thesis about Pleistocene fossils from this region, focusing on the non-mammalian species.  He did mention in his thesis that he would write in the future about ocelot (Leopardus pardalis) and dire wolf (Canis dirus) remains found here.  His thesis was written in 2006, yet I can find nothing on the internet about ocelot and dire wolf remains found from Alabama.  I assume this data is still unpublished.  However, an amateur fossil collector informed me that he collected a dire wolf tooth (along with mammoth, bison, and horse bones) from the Flint River in Georgia.  Dire wolves undoubtedly were a major predator of the upper coastal plain during the late Pleistocene.  As far as I know, no scientist has ever prospected the Flint River for fossils.

George Phillips thoroughly studied fish and turtle remains eroded from streamside fossil deposits.  The fish remains belonged to the same species that swim in Alabama creeks today–gar, bowfin, suckerfish, catfish, freshwater drum, and sunfish.  But some of the turtle remains belonged to species that are extinct or no longer live in the region.  That will be the subject of my next blog entry.

References:

Kurten, Bjorn and John Kaye

“Late Quaternary Carnivora from Black Belt, Mississippi”
Boreas 1982

Phillips, Georgia

“Paleofaunistics of Non-mammalian Vertebrats from the Late Pleistocene of the Mississippi-Alabama Black Belt Prairie”

North Carolina State Masters Thesis 2006

Shwimmer, David

“First Mastodont Remains from the Chattahoochee River Valley in Western Georgia, with implications for the Age of Adjacent Stream Terraces”

Georgia Journal of Science 1991