Archive for the ‘Fossil Sites’ Category

Hurricane Ivan Uncovered a 60,000 year old Cypress Forest in the Gulf of Mexico

August 9, 2017

In 2004 Hurricane Ivan spawned 140 mph winds, 90 foot waves, and the fastest sea floor current ever recorded.  That incredible sea floor current removed a sediment layer covering a 60,000 year old cypress forest in the Gulf of Mexico.  The exposed trees formed a natural reef, attracting a concentration of fish and other sea life 60 feet below the ocean surface and 15 miles offshore.  Fishermen noticed the unusual concentration of fish and asked scuba divers to investigate.  The scuba divers discovered the uncovered ancient forest, and scientists are now studying this rare site.

The scientists who visited the flooded forest were impressed with the marine life they encountered–flounder, cardinal fish, red snapper, blennies, sea bass, moray eels, sandbar sharks, hawksbill turtles, octopus, boring worms, anemones, and sponges.  But they were even more impressed with the ancient cypress wood they brought with them to the surface.  They sawed through it in the laboratory and smelled fresh sap.  Nevertheless, they couldn’t use radiocarbon dating because they discovered the wood was over 50,000 years old–too old for that method.  Instead, they found the nearest organic material that could be dated and estimated a 60,000 year old date based on stratigraphic location and assumed rates of deposition.

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Map of weather stations in south Alabama.  During Ice Ages dry land extended for miles into the Gulf of Mexico.  Mobile Bay was a valley of forests and grasslands.  Dauphin Island and Fort Morgan were high hills “hundreds of feet above the surrounding landscape.”

When it was alive, this flooded forest stood during a time period classified as Marine Isotope Stage 3.  I am fascinated with MIS3 because the dramatically fluctuating climate cycles had a major impact on natural communities.  MIS3 occurred just before the Last Glacial Maximum (the coldest stage of the last Ice Age), but unlike the LGM, MIS3 experienced warm interstadials alternating with cold phases.  Many geographical regions hosted an admixture of northern flora and fauna with warm climate species of plants and animals because of this climatic instability.  Tree rings on the fossil cypress wood excavated from this locality demonstrate this instability.  The tree rings provide a 489 year record of climate from MIS3.  The cypress tree rings show climate varied with warm wet years and dry cold spells but for the most part they are narrower than tree rings found in modern day cypress trees.  This reflects a cooler drier climate with lower levels of carbon dioxide in the atmosphere.  The trees were especially stressed during the last 50 years of their existence, and they all died at the same time, though the trees were of different ages.  Saltwater intrusion killed the trees.

Sea level rose rapidly here, probably during a warm phase of climate when glaciers were melting.  Cypress wood is resistant to decay, an adaptation for living in aquatic environments, but when exposed to air will eventually rot away.  The dead stand of cypress wood likely stood for decades, perhaps a century, before becoming covered in sand and mud.  Thus sealed off from air, it was preserved for tens of thousands of years.  Now that it is exposed to oxygen again, it will decay into nothing in a few centuries.

Scientists cored into the mud around the trees and took samples of pollen to analyze the type of natural environment that existed here 60,000 years ago.  Cypress, oak, and alder pollen dominated.  The palynologist who analyzed the pollen composition (the data as far as I know is still unpublished) concluded the forest was a rare type that no longer occurs in the region.  The closest modern analogue is classified as an Atlantic Coastal Plain Blackwater Bar/Levee Forest.  This type of forest occurs in small areas near the coasts of North and South Carolina.  Bar/Levee forests grow on soil formed on the inside bend of a river.  Sediment accumulates here through deposition, and the area is seasonally flooded.  (Indeed, this particular forest occurred alongside a river, and the paleomeander scar is still visible at the bottom of the ocean adjacent to the flooded forest.)  Dominant trees in a Bar/Levee forest are cypress, river birch, laurel oak, overcup oak, willow oak, sweetgum, red maple, elm, and loblolly pine.  The understory consists of holly and hop hornbeam along with red maple and ash saplings.  The shrub layer is made up of blueberry, titi, sweetspire, grape, poison ivy, climbing hydrangea, Alabama supplejack, greenbrier, sweet pepperbush, violet, and sedge.  Spanish moss covers the trees.  Bar/levee forests are similar to bottomland hardwood forests but are distinguished by the abundant presence of river birch or water elm (Planara aquatica which is not a true elm).

Macrofossils of Atlantic white cedar and palm have also been found among the dead cypress.  There are small disjunct colonies of Atlantic white cedar scattered throughout the southeast, indicating it was more widespread in the region during the Ice Age.  (See: https://markgelbart.wordpress.com/2012/03/11/the-discontinuous-range-of-the-atlantic-white-cedar-chamaecyparis-thyoides/ ) The presence of palm shows that climate, though cooler than that of today, was still warm enough for that species.  I suspect this was a unique forest that doesn’t exactly match any classified natural community of the present day.

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60,000 years ago, a cypress and oak forest grew at a location 15 miles off the coast of Alabama.  It was rapidly inundated during a sudden rise in sea level, becoming covered in sediment before the cypress trees rotted away.

The pollen evidence suggests alder was a pioneer species here that probably became established when the point bar of the river began depositing sediment.  Cypress and oak became dominant for about 500 years.  Then, after salt water intrusion killed the cypress, grass pollen predominates, suggesting a salt marsh replaced the cypress forest.  Extinct megafauna such as mastodon, tapir, and capybara undoubtedly passed through this environment, but vertebrate fossils have yet to be found.

Below is a documentary about the flooded forest–the source of information for much of this blog entry.

Reference:

Schafale, M; and A. Weakley

“Classifications of the Natural Communities of North Carolina, third approximation”

North Carolina Natural Heritage Program 1990

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Ice Age Western Lakes and Altered Bird Migrations

April 9, 2017

I photographed a lesser yellowlegs (Tringa flavipes) at Woodbridge Lake, Evans, Georgia last weekend.  I was thrilled to see this transient species in such an unexpected locality.  Lesser yellowlegs and many other species of sandpipers spend the winter in South America, Florida, and the coasts of Georgia and South Carolina, but they migrate to their summer breeding grounds in western Canada during spring.  The present day breeding grounds of 22 American species of sandpipers, plovers, curlews, and dowitchers were mostly or completely under glacial ice during Ice Ages.  One might ask where these species bred during Ice Age summers.  Weather patterns were much different then.  Today, much of the west is arid desert, but during Ice Ages the region enjoyed a cooler and much wetter climate.  Many large lakes existed in western North America, and they provided beach, reedy marsh, and open water habitats for aquatic birds.  A large prehistoric body of water, known as Pleistocene Lake Manix, covered what today is the Mojave Desert, and Pleistocene Fossil Lake inundated the modern day site of a desert in central Oregon.  Both of these sites yield abundant remains of the aquatic bird species that formerly spent all or part of their lives there.

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Map of western North America during the Ice Age.  More precipitation and cooler weather patterns resulted in large lakes in place of present day arid landscapes.

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Lesser yellowlegs in Evans, Georgia.  This species is a transient here.  It spends winters in South America, Florida, and the southeastern Atlantic Coast, but breeds during summer in western Canada.

Lesser Yellowlegs Range Map

Range map for a lesser yellowlegs.  Many species of sandpipers have similar ranges.  Almost their entire breeding range was under glacial ice during Ice Ages.  They shifted their breeding ranges to the lakes in western North America that no longer exist and are deserts today.

The entire breeding range of the white fronted goose, the blue goose, and 10 species of ducks was also under glacial ice during the late Pleistocene.  The geese and some species of ducks shifted their breeding ranges to these western lakes.  However, harlequin, eider, king eider, and the extinct Labrador duck have/had more easterly distributions and likely bred near the Atlantic coast south of the ice sheet.  Other migratory species of birds that bred on western lakes during Ice Ages include whooping cranes, northern skuas, and arctic loons.

Many species of aquatic birds that breed in western Canada during summer still breed in western states as well wherever wetlands still exist.  Instead of shifting their breeding ground migration north, these species expanded their summer breeding grounds but still also nest within their Pleistocene range.  This list of species includes 2 loons, 2 grebes, white pelicans, 2 swans, 10 ducks, sandhill cranes, Virginia rails, Hudsonian godwits, American avocets, 3 phalaropes, and 3 jaegers.

The abundant large lakes of Pleistocene western North America attracted some species of non-migratory birds that no longer occur in the region.  Anhingas are fish-eating birds confined to southeastern North America today, but fossil evidence shows they lived in Oregon during the Ice Age.  The beautiful scarlet ibis no longer occurs north of Central America but ranged to Oregon then also.

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The scarlet ibis no longer occurs north of Central America but did live as far north as Oregon during Ice Ages.

Western lakes evaporated and turned into desert following the end of the Ice Age.  A number of species failed to adapt by shifting their ranges to newly available Canadian habitat, and they became extinct.  The extinct species include a flamingo, 2 gulls, a jaeger, a cormorant, a grebe, a swan, a goose, and a shelduck.

Breeding colonies of aquatic birds attract predatory species such as bald eagles and great horned owls.  Fossil evidence of both these species is found at most of the sites of these former Pleistocene lakes.

The extinct western lakes would have been a birder’s paradise. Paleo-indians saw the wealth of avifauna as a food source.  Paleo-indians had no television, radio, and little in the way of entertainment, so perhaps bird-watching was a leisure activity for them after they filled their bellies with spit-roasted duck.

Reference:

Jefferson, George

“Remains of the Late Pleistocene Avifauna from Lake Manix, Central Mojave Desert, California”

Bulletin of the Natural History Museum of Los Angeles County June 1985

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.”

Image result for Adolf Hitler giving a speech

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.

Image result for Latvia map

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