Archive for August, 2013

Deadly Digger Wasps

August 30, 2013

Last January, plumbers installed a new drainfield for my septic tank, reducing my wealth by about $5,000.  The alternative was a monthly $200 bill to pump out a tank that had become clogged with biofilm which is just a fancy word for shit turned into mud and root masses.  They had to dig up a significant wedge of my backyard, felling a productive fig tree in the process.    They covered the new pipes with bare dirt, and I transplanted a few peach tree saplings in the empty space.  I don’t care for well manicured lawns–the boring landscape choice of most of today’s fascistic conformists. So I didn’t plant any grass.  Instead, I looked forward to seeing what plants existed in the natural seedbank, though I did plant a few rows of oats and fieldpeas and scattered a container of wild flower seeds in 1 patch.  Now, there is a nice carpet of crabgrass, nutsedge, and wild sorrel growing underneath the pokeweed (aka pigeonberry) and nightshade I choose to let stand when I swing the scythe I use to keep my yard from looking so unkempt that I get yet another city code violation.  There are still patches of hard packed sand in this miniature wilderness, and these bare spaces attract female digger wasps.

Cerceris bicornuta , the weevil wasp, digs a chamber into hard packed sand where it lays its eggs.  It then goes hunting for weevils.  It subdues the weevils with paralyzing stings and deposits them next to its eggs.  The paralyzed weevils stay alive and fresh and become food for the wasp larva when they advance past the egg stage.  I found a weevil wasp in my yard, and one evening I placed a glass jar over its chamber entrance in the hopes that I’d get a good look at it, but alas it had evidentally abandoned the nest.  Nevertheless, the below photo is a much better image than I could have gotten with my cheap camera.

Female Cerceris bicornuta on Virginia Mountain Mint

Adult weevil wasps get energy from the sugar in flower nectar, but they have an all protein diet in their larval stage.

The weevil wasp belongs to the Crabronidae family which includes 200 genera and over 9000 species.  Most of the species in this family dig chambers into the ground, though some build nests elevated above ground.  Most wasps in the Cerceris genus are specialized predators of weevils.  The Astata genus includes predators of stinkbugs, the Zyzzyx genus includes predators of flies and butterflies, the Sphecus genus are known as cicada killers, the Pison genus are murderers of spiders, the Microstigrinus genus are social wasps  preying on everything from flies to caterpillars, and the Philanthus genus slaughters bees.  Digger wasps are deadly to whatever prey they specialize in feeding to their larva, but not to humans, unless a particular individual suffers from the type of allergy that causes an extreme auto-immune response.

Today, diggers wasps benefit from human construction activities that create bare patches of hardpacked sand such as dirt road sides or cleared land where they can dig their nesting chambers.  During the Pleistocene, digger wasps likely benefited from the presence of large congregating herds of megafauna that trampled and denuded vegetation, creating the ideal bare surfaces they require to nest.  Digger wasps have existed for at least 300 million years and shared planet earth with the dinosaurs.  But most people view diggers wasps as minor annoyances with the potential to sting.  Wasps do not exist simply to sting people.  They play a central role in controlling populations of insects that may actually compete with humans for survival, as any gardener or farmer plagued with stinkbugs, flies, and aphids can understand.  They deserve our respect for they will probably still be digging nesting chambers in bare patches of earth long after Homo sapiens suffers extinction.


Pleistocene Chestnut Woodlands

August 25, 2013

The chestnut (Castanea dentata) was the most valuable tree of eastern North America’s ecosystem.  From north Georgia to central New York it composed up to 25% of the forest.  It provided a heavy annual crop of nuts eaten by every animal from mice to bison.  The chestnut tree has a tendency to become hollow, making it an important den tree as well.  The chestnut tree equaled food and shelter for wildlife.  The spring flowers attracted untold numbers of insect pollinators, and modern studies show the presence of chestnut trees increases the fertility of sandy loam soils.  Chestnut trees were found on dry rocky ridges and moist slopes.  William Bartram, heading north through Georgia  during his travels just before the American Revolution, began encountering chestnut trees in the upper piedmont where he found them growing on rocky hilltops associated with chinkapins and chinkapin oaks.  The chinkapin is a shrubby relative of the chestnut tree.  Chestnut trees grew 100 feet tall with diameters of 5 feet or more as the below photos indicate.

Stand of chestnut trees dating to sometime in the 19th century.  Incredible!  I’ve never seen a forest with trees this big.  What hath man ruined?

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Chestnut trees frequently became hollow.  Potential home for bear, giant ground sloth, peccary, bats or human.

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Chestnut leaves.  The scientific name Castanea dentata means toothy leaf.

Disaster struck in 1904 when a fungus (Cyphonectric parasitica), accidentally introduced on imported Chinese chestnut trees, spread throughout North America.  Lumbermen began clear-cutting chestnut trees, ostensibly to stop the spread of the blight for which American chestnuts had no resistance.  Unfortunately, this misguided policy eliminated many chestnuts that may have been resistant to the blight.  The once dominant American chestnut was eliminated from its range, its place in the canopy taken by oak, maple, and other less productive trees that don’t support as much wildlife.  The blight doesn’t attack the roots of chestnuts, so remaining chestnut stumps do sprout, but then die back, usually before they produce a crop of nuts.  Ecologists claim that wildlife has recovered since the chestnut tree die off, but this claim defies common sense.  The eastern forest is undoubtedly more impoverished without it.

Man is trying to undo this ecological calamity.  Horticulturalists have successfully developed resistant strains of American chestnuts by backcrossing them with Chinese chestnuts and selecting hybrids that are resistant to the blight.  Since 2006, they have planted thousands of hybrids that are 15/16 American chestnut x 1/16 Chinese chestnut in secret locations in North Carolina, Tennessee, and Virginia.  These locations are on  national forest land where they will be protected from timber operations.  American chestnuts are reportedly a more attractive tree and produce sweeter nuts than Chinese chestnuts.

Some rare individual American chestnuts have been found that are apparently resistant to the blight.  There is a 30 year old American chestnut in Warm Springs, Georgia; a live 85 foot tree in Talladega, Alabama; and a few in Ohio, Kentucky, New Hampshire, and Missouri.  The best known live grove  of American chestnuts is in West Salem, Wisconsin.  In 1885 a farmer planted 9 American chestnut trees here, and they increased to 2500 trees where they grow with white oak, red oak, northern pin oak, hickory, birch, basswood, black cherry, and big-toothed aspen in a remarkable forest.  They survived the initial blight attack because they were planted over 250 miles from the chestnut’s original range.  The distance kept them isolated until 1987 when the blight finally found them, but by this time scientists learned how to defeat the blight by using a slow acting virus that kills the fungus.  Chestnuts may eventually become an important eastern tree again.  They produce nuts in 7 years and outproduce oaks.  But this will take centuries.

Presettlement range of the American chestnut.  It grew as far south as Florida at various times during the Pleistocene.  Note the disjunct populations in southwestern Georgia, southeastern Alabama, and Missisippi.  These were relic populations from when this species grew throughout the coastal plain to Florida.  Chestnut trees were evidentally common in north Florida during the mid-Wisconsinian interstadial, but disappeared there during the Last Glacial Maximum when climatic conditions deteriorated.

Location of human transplanted chestnut trees that avoided the blight by being 250 miles outside the natural range of the species.  It’s the only place in the world where a person can currently see a nice mature forest dominated by American chestnut.

The chestnut tree has an interesting biogeographical history.  It’s a fairly primitive angiosperm, and an extinct species (Castanea ungeri) is known from as early as the Eocene 50 million years ago.  Fossils of Castanea ungeri  have been found on Greenland, showing how much warmer climate was then.  Some scientists speculate a species of chestnut may have even occurred during the time of the dinosaurs.  Pollen studies show that chestnut was a common tree in north Florida between 40,000 BP-31,000 BP (See:  This time period is part of what is known as Marine Isotope Stage 3 (which includes the time period ~60,000 BP-~30,000 BP), and it is also referred to as the mid-Wisconsinian Interstadial.  Climate fluctuated greatly during MIS-3 with broad-leafed trees increasing at the expense of pine during warm wet stages and vice versa during cold arid stages.  MIS-3 was not as cold and arid as the Ice Age, but summers were generally much cooler than those of today, perhaps explaining why chestnuts grew in the southeastern coastal plain then but didn’t at the time of European settlement.  Evidence of chestnut trees  disappears from Florida’s pollen record about 29,000 BP when climate became cooler and drier with the onset of the most severe era of the Ice Age.  The diverse forest of MIS-3 was replaced with more monotonous pine and oak woodlands and an increase in grasslands.  The chestnut woodlands of MIS-3 that grew in north Florida also consisted of 40% oak.  Open woodlands consisting of chestnut and oak likely existed from north Florida throughout the rest of the south during the mid-Wisconsinian Interstadial.  I suspect chestnuts were more common in southwestern Georgia than in the southeastern part of the state, based on the pre-settlement range map.  There were relic populations of chestnut in the southwestern part of the state but not in the southeastern region.  A pollen study from sediment off the coast of Georgia found that chestnut only made up about 2% of the pollen in coastal Georgia.  The Gulf Stream kept the southeastern part of the state a little warmer, and open pine savannahs were likely more prevalent there. Chestnut trees are fire adapted, but not as fire adapted as longleaf pine.  Longleaf pine can survive annual fires that would kill chestnut saplings, but mature chestnut trees are fire resistant.  More oceanic-induced lightning storms caused more frequent fires that may have shifted the balance in this region to favor more longleaf pine savannah over chestnut and oak woodland during the mid-Wisconsinian Interstadial.  Longleaf pine savannahs grow best with fire intervals of 3 years, while chestnut-oak woodland do better with fire intervals of about 20 years.

It would have been marvelous for a naturalist to travel through Georgia during the mid-Wisconsinian Interstadial.  There were probably a mosaic of varied habitats, and a person could have wandered from oak-chestnut woodlands to open pine savannahs in less than a day’s journey on foot.  The megafauna congregated in the chestnut-oak woodlands during the fall to eat the nuts but moved to the savannahs in spring and summer to forage upon the bounty there.  I think it would be better than a trip to modern day Africa.

Another Excerpt from Frances Harper’s Mammals of the Okefinokee Swamp–the Southern Flying Squirrel (Glaucomys volans)

August 21, 2013

I’ve been periodically posting excerpts from a rare book published in 1927 entitled Mammals of the Okefinokee Swamp by Frances Harper.  This time I’m posting Harper’s collection of accounts about the southern flying squirrel (Glaucomys volans).

Southern flying squirrel

Youtube video of a southern flying squirrel gliding from tree to tree.  They can glide for up to 30 yards.

Supposedly, the southern flying squirrel is common and widespread throughout the state of Georgia, but I am skeptical.  They prefer old oak forests with lots of  snags and woodpecker holes.  I’ve never seen one in the wild and my cat never brought me a specimen, so I really doubt there are any in the woodlot behind my house or in any of the woods in my neighborhood.  Thirty years ago, a  college buddy of mine  did find and tame a specimen he found living in a birdhouse in his backyard, but that is the only time I’ve ever seen a flying squirrel in person.  Most flying squirrels commandeer woodpecker holes (sometimes eating the eggs and nestlings of the evicted birds in the process), although they do build their own nests on occasion.  The old oak forests of the Georgia piedmont have been replaced by young 2nd growth forests with far fewer snags and woodpecker nests than in former days.  Moreover, as far as I can determine from an internet search, no study on flying squirrel abundance in Georgia has been conducted…ever.  Flying squirrels are probably still common in the north Georgia mountains where unlogged oak forests still occur (See: ).  And they are a problematic predator of red-cockaded woodpeckers in south Georgia.

Fossils of southern flying squirrels have been found in several Pleistocene-aged sites in Georgia, including Kingston Saltpeter Cave and Yarbrough Cave in Bartow County, and the Isle of Hope site in coastal Georgia. The advanced evolutionary trait of gliding is probably an ancient characteristic of this species.

Below is Frances Harper’s collection of accounts of the southern flying squirrel which he refers to as the Florida flying squirrel.

Florida Flying squirrel–Glaucomys volans querceti

“The Flying Squirrel is known to most of the residents, and by its regular name.  It has been recorded or reported from the following localities in the swamp: Floyd’s, Minne Lake, Billy’s, Honey, and Chesser’s Islands, Clayhole Island, and Mixon’s Hammocks and Billy’s Bay.  It is said to be more or less common in various localities on the eastern side of the St. Mary’s River; north of Macclenny, Florida; along the Satilla River near Hoboken; and near Milltown, Lanier County…

…In the choice of its home within the Okefinokee this species does not exhibit a narrow taste, being found in such widely varying habitats as hammocks, pine barrens, and cypress bays.  It is perhaps attracted more particularly to the hammocks by reason of the acorns which it finds there on the live oak and other oaks.  Without the swamp it is found in unwelcome abundance in pecan groves.  It is entirely nocturnal, as far as my observations go.

In early January, 1917, at our camping place in the hammock on Floyd’s Island, several Flying Squirrels were heard moving about in the great live oaks overhead, and giving their slight, sharp, sibilant, little cries.  They were known to feed on some shelled corn stored in a large wooden box, and two specimens were trapped there.  In June, 1921, Jackson Lee reported hearing this species in the same camp.

On several nights in September, 1922, I heard the squeaky tseet, tseet, tseet of Flying Squirrels in the oaks about our camp in the hammock on Chesser’s Island.  One evening acorns began dropping outside my tent, and a couple of times one of the little creatures seemed to be scampering over the tent fly.  It was very successful, however, in eluding the rays of  a flashlight which I tried more than one to turn upon it. 

Ben Chesser once found a Flying Squirrel in a nest of  Spanish Moss which it had built in a quart cup about 6 feet above the ground by a spring in the piney woods on this island.

On June 19, 1922, David Lee cut down a dead slash pine (Pinus elliottii) in the pine barrens close to the hammock on Billy’s Island.  As the tree fell, a Flying Squirrel jumped out to another tree, then made for still another, but fell short and was caught.  It was kept in captivity for about six weeks, meanwhile feeding upon pecans, watermelon seeds, and huckleberries (the last with perhaps special avidity).  It refused peanuts.

Harry Chesser spoke of seeing several in the pine barrens on Billy’s Island.  Two sailed out of a living pine which he was cutting in the spring of 1922.  W.F. Keaton reported one or two during the previous spring in an old dead pine on Honey Island.

During the summers of 1921 and 1922 several were reported in holes in girdled cypresses, and one in a ‘green’ or living cypress.

On August 6, 1921, between 8 and 9 p.m. , a Flying Squirrel jumped on the roof of our tent, which was pitched on an oak ridge along the St. Mary’s River north of Macclenny, Florida.  At about the same time we began to take note of a shrill, sibilant, almost incessant calling on the part of two or three creatures of some sort, apparently in the trees overhead.  At the time I was inclined to consider them insects rather than Flying Squirrels, although, as David Lee remarked on a later occasion, the note of the latter is so much like that of some insects that it is difficult to tell them apart.  Meanwhile, several rat traps, baited with peanuts, were set on the trunks of near-by oaks, and presently, one of them contained a fine specimen of a Flying Squirrel.  Several nights later one was heard about our camp in a pine grove about 5 miles south of Traders Hill.

Some prejudice has been aroused against this species on account of its depredations on pecans in various localities near the swamp, where the pecan-growing industry has been considerably developed in recent years.  Its nocturnal habits enable it to pilfer to an extent not possible for a diurnal animal, and in places it evidentaly becomes a rather serious nusiance.  For example, various members of James Johnson’s family, living near Thompson’s Landing on the St. Mary’s, stated that a cat of theirs had caught 37 Flying Squirrels about their place during the pecan season of 1921.  The cat would eat each squirrel behind a certain door, and leave the tail there, thus enabling the members of the household to keep a tally.  They themselves made no effort to kill the animals saying, ‘It ain’t no use.’  Further complaints were heard concerning depredations on pecans near Cornhouse Creek, Charlton County, near Hoboken, Pierce County, and near Milltown, Lanier County.

Black’s Bluff Preserve and the Coosa River Lock and Dam Park

August 17, 2013

There used to be a little girl who lived in my house, but now she’s a big girl and attends college on the other side of the state.  It is strangely quiet in our house, since she moved.  There’s no longer the sound of a constant video game every evening.  The dreaded day when we helped move her into her dorm room came and went, and I couldn’t help feeling sad because the moment reminded me that nothing last forever.  Nevertheless, I suppose I will get used to the new situation, and I think living away from home should be a good experience for her.

While we were in Rome, Georgia, I had a chance to go on a little nature excursion.  I visited Black’s Bluff Preserve and the Coosa River Lock and Dam Park.  Black’s Bluff Preserve is a 263 acre property of The Nature Conservancy located next to Floyd County State Prison.  Supposedly, it is a rock garden growing on a bluff consisting of Conasauga limestone.  I mostly saw invasive species.

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Visiting this preserve is by appointment only.  I played the part of rebel and walked past the sign .  There isn’t any path that leads to the bluff anyway, other than a narrow game trail.  At the base of the bluff ,diseased persimmon trees along with non-native kudzu and bradford pear grow.  At the top of the bluff is a an unimpressive stand of  2nd growth loblolly pine.  I didn’t see anything botanically significant at this site.

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The view of the bluff is impressive.

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Another view of the bluff.

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I found this enormous black or Shumard oak (I can’t tell the difference between those 2 species) at the Coosa River Lock and Dam Park.  I estimate it is about 24 feet in circumference.

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Here’s another view of the giant black oak.  it looks like the top half must have broken off during a storm at one time and has been removed.  The tree next to it is a large hackberry.

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Here’s a black walnut tree.  I wish I had a few in my yard.  They are expensive.

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The Coosa River is muddy, but it hosts over 70 species of fish.  The Coosa River Valley serves as a corridor for Coastal Plain flora and fauna where they can penetrate into the mountain region.

The Fishbait Tree (Catalpa bignoniodes) may be an Anachronism

August 13, 2013

The bignonia family includes 700 species of mostly tropical distributions.  The calabash tree (Cresenctia cajeta) of South and Central America is a species of bignonia that some scientists consider anachronistic, meaning it seems out of time and place.  The calabash tree produces large fruits with hard rinds that no extant native animal can crack.  Thus, this species has a limited distribution because no native animal can spread its seed in their dung.  However, introduced horses can bite through the rind and spread the seed.  During the Pleistocene horses along with ground sloths and the mastodon-like gompotheres aided in this species dispersal.  Another species of bignonia, the sausage tree (Kigela africana) of Africa produces large fruit pods that are known to be dispersed in the alimentary canals of elephants, giraffes, hippos, and baboons.

Some species in the bignonia family do occur in temperate regions.  The trumpet vine (Campsis radicans) is perhaps the best known and widespread.  The 2 species of catalpa trees, like the calabash tree, may be examples of anachronisms because they had  limited distributions before man widely transplanted them, and they produce long seed pods that no modern animal disperses.  Before European settlement the northern catalpa tree (Catalpa speciousa) was limited to the Mississippi River Valley from Arkansas north to Indiana, while the southern catalpa (Catalpa bibnonioides) ranged from southern Mississippi to western Georgia and the Florida panhandle.  The limited range of both species suggests they weren’t being dispersed as readily following the end of the last Ice Age as they may have been, if the megafauna hadn’t become extinct.

Illustration of the southern catalpa.  It has big showy flowers, big leaves, and long seed pods.  It was probably more widespread during the Pleistocene when climatic conditions were favorable.

Proposed pre-settlement range of northern catalpa (Catalpa speciosa).  It has been widely transplanted.

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Proposed pre-settlement range of southern catalpa (Catalpa bignoniodes).  No one knows for sure what its exact pre-settlement range was because it has been widely transplanted as an ornamental.

Between 60,000 BP-30,000 BP, forests and woodlands in southeastern North America hosted many diverse species, but the climate deteriorated rapidly after 30,000 BP, and the species rich woodlands were replaced with pine and oak dominated landscapes.  Catalpa trees and other less hardy species were restricted to small refuges such as ravines that were protected from the harsher climate.  When climatic conditions improved ~15,000 BP, animals such as mastodons and ground sloths were headed toward extinction and were no longer common enough to be  effective dispersal agents.  Catalpa trees prefer early successional moist woodlands and are intolerant of fire, ice storms, and shade.  The megafauna inadvertently shaped the ideal environment for catalpa trees.  The presence of megafauna reduced the intensity of fires because they consumed so much flammable material.  The megafauna also maintained open sunny woodlands by grazing, browsing, and trampling. Catalpa trees thrived in these primeval rich environments during warm interglacials and interstadials, but their ranges contracted during cold stadials when low CO2 levels, drought, cold, and ice storms proved problematic for this big leaved species.

I am unaware of any genetic studies comparing northern and southern catalpa trees.  All the species in the bignonia family found in North America are descended from tropical species that evolved to survive in temperate climates.  Northern and southern catalpa trees likely split from a common ancestor.  I’m curious whether the 2 species split early during the Pliocene ~5 million years ago when Ice Ages began to occur or if they are a recent divergence resulting from a more recent Ice Age.

The reason catalpas are called fishbait trees is because they are the sole host of the catalpa worm (Ceratomia catalpae).  It’s not actually a worm but rather the caterpillar stage of a brown sphinx moth.  According to fishermen who use them, catalpa worms are a fair bait, if used as is, but are an excellent bait when the head is pinched off and their body is pulled inside out.

Catalpa worm.  They feed on catalpa leaves and after consuming enough food burrow into the ground and pupate.  They  then emerge as adult moths to mate and lay eggs which hatch into caterpillars.

A catalpa tree is a mini-ecosystem in itself.  Heavy catalpa worm infestations attract a whole swarm of predators.  Tiny braconid wasps insert their eggs into the caterpillars, and the wasp larva eat their way through the unfortunate caterpillars.  Ants then prey on the wasp larva.  Tachnid flies also parasitize catalpa worms, and a species of snout-nosed beetle preys directly on the caterpillars .

At least 1 species of braconid wasp parasitizes catalpa worms.  Tachnid flies parasitize them too.

Wasp larva chewing up a catalpa worm.  It’s doomed.

Catalpa worms build up a chemical compound from their diet of catalpa leaves that makes them distasteful to most species of birds, but the yellow billed cuckoo is an exception.  Cuckoos enjoy a specialized diet of caterpillars, and they relish catalpa worms.

Yellow billed cuckoo (Coccyzus americanus).  These birds specialize in eating caterpillars.  They are supposedly common summer migrants in North America.  They winter in South America.  I’ve maybe seen 1 in my entire life.  I may plant a catalpa tree in my yard in the hopes of attracting this bird.

Catalpa trees are resilient and regenerate leaves within the same growing season following a heavy infestation of worms that completely defoliates them.  Most trees, especially older individuals, can survive repeated defoliations.  This is evidence they could also have withstood having their leaves heavily browsed by mastodons and ground sloths.  Catalpa seedpods were probably consumed along with their leaves in the fall and deposited in big nutritious manure piles.  Man began cultivating catalpa trees as ornamentals and for fishbait in 1726.  Man has replaced the megafauna as a disperal agent for catalpa trees.

Carcharodon Megalodon is NOT still Extant. Shame on the Discovery Channel.

August 9, 2013

The Discovery Channel began its annual Shark Week with a 2 hour program about an extinct species of shark, Carcharodon megalodon (or Carchocles megalodon–scientists dispute the classification).  The programming executives care more about ratings than scientific accuracy because they chose to run a phony sensationalist documentary rather than a show based on fact.  It was an embarrassing hoax.  Two supposed marine biologists claimed they had evidence that megalodon was still extant and had bitten a yacht in half off the coast of South Africa in April 2013.  All the evidence they disclosed had alternate and more likely explanations.  For example they showed a photograph of a beached whale that supposedly had its tail bitten off by a megalodon.  They failed to consider that a ship’s propeller could have done the exact same damage.  While I was watching this fake documentary,  I noticed the so-called scientist didn’t act like a scientist.  He proposed killing the shark to prevent another attack.  The recent supposed attack was a rare anomaly–another attack seemed unlikely.  Moreover, I doubt a scientist would propose killing an unknown, possibly rare and endangered species.  The producers of this documentary  staged a dramatic ending.  The team’s scientific vessel dragged a big mock whale behind them littered by a massive bombardment of chum in order to attract a megalodon.  A scientist in a shark cage tagged the supposed megalodon with a tracking device, they all barely survived with their lives, and they then watched the sonar image of the shark carry the tracking device to crush depth where the device was destroyed–a convenient explanation for why they can’t locate it again.

The 2 supposed marine biologists who conducted this study expedition, Collin Drake and Madelyn Joubert, are unknown.  They are not employed by any university and probably are an actor and actress and are not scientists.  I also could find no evidence of a yacht sinking off the South African coast with all hands lost in April 2013.  Shame on the Discovery Channel for misleading the public.  I’m sure there are millions of people out there now who think megalodon is still extant.  It’s not–the evidence strongly suggests it has been extinct for at least 2 million years.

Jawbone of a megalodon compared to the jawbone of a great white shark.  The dispute over the scientific name stems from a controversy over whether megalodon is closely related enough to the great white shark to be considered in the same genus–Carcharodon.  Scientists who think it is not closely related put it in the genus Carchocles.  There probably isn’t enough evidence to determine who is correct.  A DNA test is required but megalodon’s fossils are too old and no longer hold DNA.

Megalodon was one of the most awesome predators to ever live on earth.  It first evolved 18 million years ago as a shark that specialized in feeding upon whales.  Its teeth were specially adapted for biting off hard bony whale flippers, a brutal action that would have quickly disabled the leviathons.  By contrast, great white sharks attack the soft body parts of their prey.  Megalodon was large, growing to 60 feet long and likely preyed upon dugongs, sea turtles, and fish as well as whales and dolphins.

Artist’s rendition of megalodon about to attack a whale.

The heyday of megalodon was the mid to late Miocene, an era when both the oceans and the continents hosted a greater diversity of life than later eras.  During this time period a tropical ocean current revolved between North and South America.  The shallow sea located between the 2 continents was a calving ground for many more species of whales than live on earth today, and it was also a nursing ground for sharks, fish, and invertebrates.  There were 20 genera of baleen whales living in the oceans then compared to just 6 genera today.  An extinct species of sperm whale, Leviathon mellvillei , like megalodon, specialized in feeding upon baleen whales.  Unlike the extant species of sperm whale, Physeter macrocephalus, which specializes in sucking down squid, Leviathon mellvillei had upper teeth built for shearing off whale fins.

A tropical current used to flow between North and South America.  When the landbridge emerged to join the 2 continents, this tropical current and migratory pathway shut down, causing a massive number of marine extinctions, including megalodon.

Megalodon began declining during the Pliocene about 3 million years ago when a landbridge gradually emerged connecting North and South America.  This landbridge caused a massive number of marine extinctions.  The landbridge itself replaced the shallow seas that served as a nursery  for whales and fish, but more importantly it blocked tropical whale migrations and the ancient ocean currents that had existed as part of the marine ecosystem for millions of years.  All the tropical baleen whale species that migrated between North and South America became extinct.  Many fish and saltwater snail species also couldn’t survive the change in oceanic currents.  All surviving species of baleen whales follow circumpolar migration routes.  Because megalodon was a warm water species, there were no whales to feed upon when the remaining species of whales migrated to arctic or antarctic waters.  That’s probably why megalodon became extinct.  There is no evidence megalodon still lives, despite the Discovery Channel’s disgraceful fake documentary.

Second Elasmosaurus Fossil Skeleton Found in Alabama

August 6, 2013

Most schoolteachers and students don’t realize they are writing with fossils when they use chalk.  Chalk consists of plankton, especially coccoliths, that mixed with mud millions of years ago.  This lime-mud eventually fossilized, turning to stone.  Chalk that became exposed to heat and pressure when buried deep under sediment metamorphized into marble–perhaps the most beautiful of natural building materials.  The majority of chalk on earth formed during the late Cretaceous and early Paleocene between 100 million to 60 million years ago.  Chalky soils are abundant in Mississippi and Alabama where the shrink-swell properties of this type of dirt help grass outcompete trees in black belt prairies.  Parts of this black belt prairie extend into Georgia (See ).  Many Cretaceous-age vertebrate fossils are found in the black belt prairie region because it is located near the shoreline of what was the Western Interior Seaway, a body of water that existed during the Cretaceous and well into the Eocene era.  An educational program in Alabama allows high school and middle school students to help paleontologists collect fossils there.  Noah Taylor, a teenaged assistant, pointed out what he thought was a rock in a quarry paleontologists were excavating.  It was more than just a rock–it was the backbone of an elasmosaurus.

Location of Greene County, Alabama where a skeleton of an elasmosaurus was recently found.  The only fossil of a velociraptor found on the Appalachia side of the Western Interior Seaway was discovered here too.

Artist’s rendition of a couple elasmosaurii.

Paleontologist Dana Ehret holds one of several Elamosaur fossils discovered by 14-year-old Noah Taylor and paleontologist Takehito “Ike” Ikejiri. (Photo: Dusty Compton / Tuscaloosa News)

Scientist holding a bone of an elasmosaurus found by Noah Taylor.  The caption of this photo from a news account claimed this was a backbone.  I believe this is an error.  It doesn’t look like a backbone but rather a limb bone.

This is what an elasmosaurus backbone looks like.  All backbones look similar to this.

Map of North America during the Cretaceous.  North America was separated into 3 island continents by shallow seas.

The Demopolis Chalk Formation in Greene County, Alabama usually yields marine fossils including those of turtles, crocodilians, sharks, fish, and sea shells.  But occasionally a dinosaur died and was swept out to sea where its bones mixed with remains of marine organisms.  Marine reptiles such as mososaurs and pleisiosaurs were predators and thus less common in the environment, explaining why their fossils are found but rarely.  The elasmosaurus was a type of long-necked pleisiosaur.  Its very long neck acted almost like a fishing pole.  Its large body was probably camouflaged to look like the color of the sea, and its head, well away from its body, could rest patiently until an unwary fish swam close.  Or perhaps they used their large body and paddles to herd fish toward their head.  We’ll never know their exact hunting technique.

At this recent dig scientists found 15 out of the 70 vertebrae that made up the long neck of the elasmosaurus, and they also excavated paddle bones, though it’s not clear from news reports exactly how much of the long dead animal was recovered.  No scientific paper about this find has been written yet.  This is the second elasmosaurus skeleton found in Alabama; the other having been excavated in 1969.

The earth was a much different world during the Cretaceous. 85% of the planet was underwater.  Frosts rarely, if ever, occurred anywhere.  Everyday was like the hottest July day in Georgia.  I sometimes fantasize about jumping in a time machine to live during the Pleistocene, but I would not want to live during the hellish Cretaceous.

The Saltville Fossil Site in Virginia

August 1, 2013

A dense forest of white pine, spruce, fir, and oak  grew in the Saltville River Valley 17,000 years ago.  There were also some alder swamps and wet sedge meadows, but unlike in the regions to the south and west of this locality, there were no prairies or open woodlands.  The Saltville River Valley is located in southwestern Virginia and during the last Ice Age, this area was much colder than the region located immediately to the south.  The oceanic Gulf Stream that carries tropically-warmed water north as far as the Canadian coast today, instead only went as far north as the Virginia/North Carolina border during the Ice Age.  This meant dry land temperatures in what is now Virginia were as much as 10-15 degrees Fahrenheight  cooler on average than those about 50 miles  further south.  Consequently, the environment in the middle Atlantic States decisively differed from most of southeastern North America.

Location of the Saltville River Valley.

Saltville, Virginia is located in a beautiful valley.  A large lake, known as Lake Totten, covered much of the valley from ~13,500 BP-~8,500 BP.  Salt mining operations have upset the hydrology here, and today as much as 20% of the valley is underwater. 

The Ice Age began waning about 15,500 years ago.  The Laurentide Glacier slowly receded, and the melting ice increased the flow of water into the Saltville River.  Sediment carried by the increased flow formed a mud dam in the Saltville Valley gap, causing the water to backflow and create Lake Totten.  The outflow was captured by another river.  Many of the species of large mammals that lived in North America then were attracted to the abundant salt springs in the area.  The individuals that happened to die during periods of increased sediment flow were buried by mud and preserved for fossil enthusiasts and scientists to find thousands of years later.

An assortment of fossils found at Saltville.  The animals were buried by mud carried by river surges resulting from melting glacial ice to the north.  Paleontologists have to pump out groundwater from their excavation sites here.  Salt mining operations have caused much of the land to flood.

The Saltville fossil site is the most southerly known location where specimens of woolly mammoth (Mammuthus primigenius) have been excavated.  Specimens of Columbian mammoth (Mammuthus columbi) have been excavated here too, showing the 2 species co-existed in some locations.   The 2 species of mammoth have also been found together at a site in South Dakota.  Columbian mammoths ranged much farther south than woolies, having occupied territory as far south as what today is Florida.  Other megafauna species recovered at Saltville include mastodon, Jefferson’s ground sloth, woodland musk-ox, bison, stag-moose (Cervalces scotti), caribou, white tail deer, horse, and giant short-faced bear (Arctodus simus).   Scientists have yet to publish their findings on the smaller species of animals discovered in the fossil deposits.


Puncture mark on a mammoth heal bone made by a giant short-faced bear’s canine.

Gnaw marks on an ankle bone, probably made by a dire wolf.

A mammoth heel bone excavated from this site has a puncture mark that matches the canine of a giant short-faced bear.  This species of bruin is thought to have specialized in kleptoscavenging.  (See: The ankle bone of the same animal was gnawed on by a canid, probably a dire wolf.

A study of the bone chemistry of fossil herbivores from this site had an unexpected result.  All the herbivores living in this region then ate C-3 (carbon 3) vegetation–trees, shrubs, and some herbs.  Even species such as mammoths, bison, and horses that predominately subsisted on C-4 vegetation (grass) elsewhere were restricted to a diet of twigs, leaves, bark, and herbs here.  This is considered evidence that prairies were absent from this particular region during this time period.  The authors of this study admit their findings weren’t sufficient evidence to make any conclusions about megafauna extinctions.  Yet, they suggested competition between grazers and browsers for the same resources may have caused megafaunal extinctions.  I disagree with this conjecture.  Instead, I think their findings are strong evidence against climate change as a cause of megafaunal extinctions because the study shows these animals were not picky eaters and could adapt well to changing environmental conditions.

Humans apparently killed, butchered, cooked, and ate a mastodon at Saltville 17,000 years ago.  Archaeologists found cut marks on a mastodon’s bones as well as congealed grease that could only be the result of cooking.  They also found heat-cracked rocks used in the cooking process.  Pre-Clovis artifacts found associated with the mastodon bones include 2 sandstone knives, a chert blade made out of rock transported from some distance away, and flakes (debitage) from tool-making.  The site was occupied 3 times prior to the Clovis era.  The most recent pre-Clovis horizon dates to about 15,000 years ago and includes a midden containing hundreds of shells from giant floater clams.  This species of freshwater mussel grows to 10 inches long and used to be abundant in North American waters before modern day pollution and river damming.

giant floater, Pyganodon grandis

Giant floater clam (Pyganodon grandis).  I’ve never eaten a freshwater mussel, but they smell like delicious oysters.

Saltville is not a new site.  Thomas Jefferson knew about fossils found here.  Scientists have been excavating fossils off and on here for over 200 years.  A team from East Tennessee State completed the most recent excavation this year.  They visited local amateur fossil collectors to examine their specimens, and they are surveying caves in the nearby mountains in the hopes of finding more fossils to help piece together the regional late Pleistocene ecology.  We haven’t heard the last about this site.


France, Christine; et. al.

“Carbon and Nitrogen Isotopic Analysis of Pleistocene Mammals from the Saltville Quarry (Virginia USA): Implications for Trophic Relationships”

Paleogeography, Paleoclimatology, Paleoecology 249 2007

Schubert, Blaine; and Steven Wallace

“Late Pleistocene Giant Short-Faced Bears, Mammoths, and Large Carcass Scavenging in the Saltville Valley of Virginia, USA”

Boreas 38 (3) August 2009