Archive for September, 2014

Mastodons ate Wild Squash

September 28, 2014

The scent of burning leaves and baking squash always reminds me of autumn.  I love the pulpy rich flavor of an orange-fleshed winter squash, dripping with melted butter and brown sugar.  Mastodons enjoyed squash too but ate them without the additional condiments.  The species of wild squash eaten by mastodons had a bitter rind.  Mastodons avoided eating this part of the squash by stepping  on the rind to break open the squash.  The mastodon would then pick up the nutritious seeds and pulp with its trunk and place the edible matter in its mouth.  The mastodon would later defecate the still viable seeds and spread the spawn of squash all over the landscape.  We know this because mastodon coprolites containing squash seeds (but not rinds) were recovered from the Aucilla River located in northwestern Florida.  Scientists were unable to identify the exact species of squash the mastodons ate.  The morphology of the seeds differs from all known species and may perhaps be either an extinct species or an extinct variety of an extant species.  Wild squash no longer occurs in this region of Florida, however, there are 2 species that live in south Florida.

The Okeechobee gourd (Cucurbita okeechobensis) was formerly common in an environment known as pond apple forests that grew south of Lake Okeechobee.  Pond apples (Anona glabra) are a species of pawpaw–a fruit mastodons surely also consumed.  The conversion of pond apple forests to agriculture destroyed 95% of this habitat, and the Okeechobee gourd is now listed as an endangered species.  William Bartram found this species growing along the St. John’s River in 1774, but this population wasn’t rediscovered until 1993.  The presence of this disjunct population is evidence the Okeechobee gourd was formerly more widespread.  The extinction of the mastodons as a dispersal agent probably explains the limited distributions of the Okeechobee gourd and other species of wild squash.

File:Cucurbita okeechob okeechob.jpg

The Okeechobee  gourd (Cucurbita okeechobensis) .  This species once had a greater distribution.  Seeds of an unknown species similar to this have been found in mastodon coprolites.

The Okeechobee gourd has an interesting ecological niche.  It prefers growing by lakes and rivers with fluctuating water levels. High water levels kill competing plant species.  Then during droughts, water levels recede, leaving bare soil where the Okeechobee gourd can sprout before having to compete with other pioneer species.  They also thrive on alligator nests because the great reptiles clear their composting nests of competing plants.  The vines of the Okeechobee gourd grow on pond apple, willow, cypress, buttonbush, elderberry, and common reed.  Marsh rabbits gnaw through the squash rinds and help distribute the seeds, but they are an inferior dispersal agent compared to mastodons.

The other species of wild squash found in south Florida is not native but was brought from South America by Indians thousands of years ago. Native Americans began cultivating squash at least 8000 years ago, long before they cultivated corn and beans.  The word, squash, is derived from the Naragansett Indian word askutasquash, literally meaning green-thing-eaten-raw, though I’m sure they also cooked this vegetable.  The Naragansetts lived in what today is Rhode Island and Massachusetts.  The variety of C. moschata found growing wild in south Florida is known as the “Seminole pumpkin.”  The Seminoles are descendents of Creek refugees who fled to the Everglades to escape the U.S. Army.  The Creeks brought this variety with them.  The Seminoles set up their habitations on oak hammocks, the islands of hardwood trees found in the Everglades marshes.  They cultivated squash by girdling oak trees and planting the squash seeds at the base of the dead trees.  The leafless trees allowed for sunny gardens.  The squash vines grew up the dead tree trunks, and the Indians harvested the fruit by climbing into the tree tops.  Trees on the outskirts of the garden were left ungirdled, and these provided a windbreak.  The Seminoles also grew Okeechobee gourds.  Though inedible, dried Okeechobee gourds served as ceremonial rattles.


Seminole pumpkins (Cucurbita moschata).  This is the exact same species as the butternut squash commonly sold in grocery stores.

There are 27 species of squash in the Cucurbita genus.  Although many wild species sport the common name of gourd, they aren’t true gourds.  All squashes belong to the genus Cucurbita, while true gourds found in Africa belong the the Lagenaria genus.  Both genuses are in the same subfamily, so they are related.  The Cucurbita genus evolved from a common ancestor of Sechium edule–the chayote squash which is not a true squash but rather closely related to an ancestor of true squashes.

Many of the cultivated squash species commonly consumed by humans include many different varieties that differ surprisingly in appearance.  C. pepo includes zucchini, yellow crookneck squash, delicata squash, acorn squash, and field pumpkins. C. maxima includes giant pumpkins, Hubbard squash, Kabocha squash, and banana squash.  C. argyrosperma includes cushaw squash.  C. moschata includes butternut squash and Seminole pumpkins.  To add to the confusion, C. pepo can hybridize with C. moschata and C. argyrosperma; and C. maxima can hybridize with C. moschata.  The wild stinking gourd (C. foettidisima) can hybridize with all the edible species.  Four species of wild squash are perennials with strong roots, while the rest, including all the cultivated species, are annuals.

Daphne'sdorm 013

The top squash in this photo is a butternut squash I grew from a seed I obtained from one I bought in a grocery store. The bottom squash is a delicata squash I purchased at a farmer’s market.  I tried growing delicata squash from seeds but the squash bugs destroyed them.  Both are known as winter squash but they are actually 2 different species.  Butternut squash is (C. moschata), the same species as the Seminole pumpkin.  Delicata squash is the same species as summer squash–C. pepo, though it tastes quite different.  

Cucurbita pepo collage 1.png

Field pumpkins, yellow squash, zucchini, pattypan squash, and acorn squash are all the same species–Cucurbita pepo.

Giant pumpkins, Hubbard squash, buttercup squash, Kabocha squash, and banana squash are all the same species–Cucurbita maxima.  This specimen almost weighs a ton. 

 File:Cucurbita argyrosperma 2.jpg

Most canned pumpkin is actually made from cushaw squash–Cucurbita argyrosperma.

My favorite way to cook summer squash is to quarter them, put them in a baking pan well greased with olive oil, season with salt and pepper, and roast at 400 F for 30 minutes.  Then, I toss them with balsamic vinegar or lemon juice.  This brings out the flavor better than any other method.  I also like to slice them into rounds and sautee them in a pan at high heat till brown and season with salt, pepper, and chopped nuts.  Cooking winter squash is even more simple.  I just split them in half and bake in a pan of water at 350 F till tender and serve with plenty of butter and brown sugar.  Baked butternut squash pulp makes a far better pie than the watery “pumpkin pie” filling sold in cans.

I’ve had great success growing zucchini.  One year, I harvested over 100.  The next year, I decided not to add chemical fertilizer to the soil because I was being cheap.  I harvested 0.  I’ve had a harder time growing winter squash in my garden.  I did successfully grow cushaw squash once.  One summer, I harvested half a bushel of butternut squash that I didn’t even plant on purpose–they germinated from compost I added to my garden.



Megafauna Geophagy

September 24, 2014

Sometimes animals eat dirt.  The official scientific word for dirt-eating is geophagy.  Animals eat dirt for 2 reasons: to obtain minerals otherwise lacking in their diet and to prevent toxins from being absorbed into their bloodstream.  Over 200 species of animals including deer, bison, elephants, bats, primates, and birds are known to eat dirt.  Minerals aren’t evenly distributed in the soil, and plants are often deficient in certain nutrients because of  poor soil, as gardeners well know.  Animals living in these environments actively seek out soils rich in sodium, calcium, or iron.  These locations are known as mineral licks because ungulates literally “lick” the soil.

Elephants enter caves to access salt.  They grind the salt off the walls with their tusks.

Animals eat clay for a different reason.  The negatively charged clay particles bind with positively charged toxins ingested from plants high in alkaloids, preventing absorption into the blood stream.  In 1 experiment James Gilardi fed parrots quinidin, a toxin.  He made clay available to some of the parrots but not to others.  The parrots given the opportunity to eat clay had 60% less quinidine in their blood than the other parrots.  Pregnant fruit bats also eat considerable quantities of clay because they eat twice as much fruit as they normally do, and therefore ingest greater quantities of toxins.

Chimpanzee licking dirt off his (her?) fingers.  The dirt is eaten before or after the ape consumes plants containing anti-malarial compounds.  It counteracts the toxins.  This is amazing.  It’s like the chimp is creating its own pharmaceutical.

Macaws & other Parrots Eat Clay

Macaws at a clay lick.

The Diagnostics and Statistics Manual used by psychiatrists lists geophagy in humans as a mental disorder.  Psychiatrists are wrong.  Humans eat dirt for the same reasons animals do.  Eating dirt is common among women in Africa who suffer from diets low in calcium.  Eating clay reduces toxins hazardous to the fetus, and it may alleviate morning sickness.  The clay they use is often harvested from termite mounds.  The termites bring up clay from deep underground where it is free from harmful micro-organisms and parasites.  Kaopectate and Pepto-Bismol, 2 popular over the counter medications, formerly contained kaolin clay.   Kaolin clay has been replaced with synthetic ingredients that mimic the same properties.

Pepto-Bismol formerly included kaolin clay as an ingredient but it has been replaced with a synthetic substance.

Georgia is rich in clay soils, especially along the kaolin clay belt just south of the fall line.  During the Pleistocene there were probably many clay licks that attracted mastodons, ground sloths, bison, horses, tapirs, etc.  The Great Buffalo Lick in Oglethorpe County (See:  was the last known location in Georgia where megafauna herds were known to lick the soil.  The areas around the licks were quite altered.  The animals licked these spots into gullies, and the general vicinity was composed of bare soil and a few sun-loving trees.  White clay-colored fecal matter littered the general area.  These licks are just another lost natural community once common but no longer extant in the region.


Starks, Phil; and Brittany Slabach

“Would you like some dirt with that?”

Scientific American 306 (6) 2012


Changes in Vegetation Patterns Following Megafauna Extinctions

September 19, 2014

C.N. Johnson of James Cook University in Australia shares my fascination with how extinct megafauna influenced past ecosystems.  Not long ago, he published a paper about my favorite discussion topic entitled “Ecological Consequences  of Late Quaternary Megafauna Extinctions.”  He believes the extinctions of so many large mammal species led to 3 major changes in the environment.

1. The replacement of open woodlands and diverse habitat mosaics created by megafauna foraging with uniform closed canopy forests and zonal vegetation.

2. An increase in flammable plant material and thus an increased frequency of fire intervals because the plant biomass was no longer being eaten.

3. The decline of co-evolved plants such as large-seeded fruits dependent upon distribution by dung transport, and plants that put much of their energy into growing defensive thorns to deter herbivory.

Dr. Johnson relates an interesting hypothesis as to how Pleistocene ecosystems responded to megafauna foraging.  The feeding and trampling behavior of mammoths, bison, horses, and ground sloths suppressed woody regeneration.  Scrubby thickets dominated by thorny plants grew in place of highly shaded forests.  And patches of natural pastures grazed into short grass lawns impeded the fires that could potentially burn thickets.  When the thorny vegetation grew thick enough, megaherbivores avoided these locations, allowing shade intolerant species such as herbs, oaks, and hazelnuts to sprout and grow.  The widely spaced oaks and other deciduous trees would eventually shade out the thorny thickets. The megafauna would return to suppress the regeneration of the woodland as the trees aged and died, and the cycle would begin anew.  I can guess who the players were in this scenario here in southeastern North America.  Thorny greenbrier and blackberry vines along with hawthorne grew in areas temporarily left ungrazed.  The thick growth discouraged most animals larger than a rabbit from penetrating this space.  Sun-loving oaks, hazelnuts, persimmon and plum popped up.  Perhaps not coincidentally, hazelnut has a lesser distribution in North America now than it did during the Pleistocene.  A hazelnut was extracted from a mastodon coprolite found in Florida.  Hazelnuts no longer occur in Florida’s wild.

Thorny scrub habitat in south Texas.  The sharp spines of the yucca  could theoretically deter a species of large mammal from chewing on the tree or trampling it.  When the tree grows larger and older, it will shade out the spiny plants that originally protected it.

American Hazelnut Tree

American hazelnut (Corylus americana).  This species was more widespread and common in the south during the Pleistocene because the megafauna suppressed tall forest regeneration.  Hazelnut trees prefer sunny conditions and can’t grow in shade.


Photo of the actual hazelnut extracted from a Florida mastodon coprolite dated to ~14,000 calender years BP.  Hazelnut no longer occurs in Florida.

Some pollen studies in Europe dating to the last interglacial, when megafauna was abundant and climate similar to that of today prevailed, contradict the above hypothesis.  Shady closed canopy forests dominated much of northern Europe.  However, other pollen studies from evidence collected in river bottomlands do show evidence of higher populations  of diverse sun-loving plant species, and this evidence is associated with  the abundant remains of dung beetles. This suggests patchy environments influenced by megafauna activities did occur near rivers.  This makes sense: large herds of megafauna likely occurred where water was an easily accessible resource.  If we were to go back in time and search for megafauna in Georgia, our best bet would be to travel along river corridors.  Large mammals were probably scarce or even absent in locations far from water.  The ancient environment of the southeast likely consisted of a mosaic of small and large grasslands, open woodlands, closed canopy forests away from where megafauna congregated, and thorny thickets.

The pollen record of southeastern North America does consistently show a large increase in shade tolerant beech approximately correlated with the timing of megafauna extinction.  This suggests forests became more close canopied when large mammals became extinct.

One study discussed in Dr. Johnson’s paper proposed that the extinct Irish elk (Megaloceros giganteus), the largest deer known to science, converted Ireland’s scrub habitat into grassland.  Megaloceros recolonized Ireland ~16,000 years ago when glaciers retreated and the land became habitable.  Willow scrub dominated the landscape initially, but Megaloceros favored browsing on shrubs for the phosphorus content.  Juniper and crowberry replaced the willow, then Ireland became mostly grassland because Megaloceros suppressed the growth of shrubs.  After Megaloceros became extinct here, willow scrub again became the primary type of environment in Ireland.

Scale drawing comparing the extinct Irish elk with a man.  This animal may have transformed Ireland from willow scrub to grassland about 16,000 years ago.


Johnson, C.N.

“Ecological Consequences  of Late Quaternary Megafauna Extinctions.” 

Proceedings of the Royal Society of Biological Sciences 2009

Shame on the National Audubon Society for Masquerading Alarmist Propaganda as a Scientific Study

September 14, 2014

Every single species of North American bird alive today survived the Sangamonian Interglacial Period (~132,000 BP-~118,000 BP), a climate phase when average annual temperatures were as much as 7 degrees F warmer than those of today in the northern latitudes of the northern hemisphere.  This fact alone directly debunks the National Audubon Society’s Birds and Climate Change Report.  The report claims 314 out of the 588 species of birds that live in North America are in danger of extinction by the year 2080 due to global warming.  Their report was not published in a peer reviewed scientific journal.  Instead, it was published as a special issue in the National Audubon Society’s magazine–a periodical that is sent to members who donate to their organization.  In other words it is a propaganda magazine.  Yet, all the major media outlets covering their press release regurgitated their findings without asking a single critical question.   A google search reveals the findings of this report repeated uncritically by The New York Times, USA Today, and dozens of smaller newspapers across the country.  This demonstrates the unanimous scientific illiteracy of journalists who are quick to hop on the bandwagon of anything alarmist and headline-grabbing.  The National Audubon Society’s climate report is akin to the infamous DNA study of bigfoot that was not published in a peer-reviewed scientific journal, but instead was the only article ever published in a phony made-up journal.  Without peer review, the National Audubon Society can publish any kind of nonsense and get away with it.

I study scientific journal articles as a hobby and can recognize the difference between a legitimate scientific study and propaganda. So when I heard David Yarnold, the president of the National Audubon Society, answer questions on National Public Radio about this report, I immediately recognized the report for what it is: a public relations press release.  It’s a total fantasy, not based on real science, and it could not be published in a reputable scientific journal.

Cover of The National Audubon Society’s Propaganda Magazine.  It is not a peer-reviewed scientific journal.  They could put any kind of misleading data in this. The large media outlets regurgitated it without asking a single critical question.

David Yarnold, president and CEO (yes that’s right…a CEO) of the National Audubon Society.  I thought CEO’s were only found in businesses.  The title seems to suggest this so-called charity is actually a money-making business. $1 in every $200 donated to the National Audubon Society goes to this idiotic crook’s salary.

During the NPR interview David Yarnold made some comments that were grossly untrue.  He claimed that “climate is changing at a scale or pace never before seen.”  The below chart shows David Yarnold is completely ignorant of recent climatic history.  Following Dansgaard-Oeschger events (which occurred with frequency), average annual temperatures increased by as much as 14 degrees F within a decade.  Climate did not change slowly in the past over thousands of years as Yarnold falsely claimed.  We are currently enjoying a period of relative climatic stability compared to the past. Yet, all 588 North American birds species that are with us today survived the drastic and sudden climatic upheavals of the past.

Yarnold also confused climate with weather in his NPR interview. He lamented the failure of raptors to nest in southern California this year due to drought.  This drought event is a short term weather event.  It hasn’t occurred long enough to be considered a climatic trend.


Chart showing average annual temperatures as recorded from air bubbles in the Greenland Ice Core.  Note how we are now in a period of relative climatic stability.  This chart clearly shows the current rate of climate change in not unprecedented as Yarnold falsely and stupidly claimed on NPR last week.  A finer scaled chart would show even more clearly how drastic and sudden past climate changes were.

Yarnold makes $460,489 a year as CEO and President of the Audubon Society.  His salary is paid for by the 1 in every 200 dollars donated to the society.  I thought the Audubon Society was supposed to be a charity.  If it was a true charity, this crooked shmuck should work on its behalf for free.  This report is obviously a public relations ploy to increase donations to the Audubon Society, thereby leading to increases in his salary.  He is a greedy corrupt businessman, not a scientist or environmentalist.  Maybe journalists don’t question him because he’s the head of a bird society, and they assume birdwatchers are nice people.  They don’t want to look bad by asking hard questions of a supposed bird lover.

Gary Langham, the scientist behind the alarmist propaganda published by the National Audubon Society in order to solicit more donations that will go to Yarnold’s and his salary.  I can’t find what his salary is but I’m sure he makes 6 figures…far more than the average college professor with a phd in ornithology.

This so-called study used bird surveys and Christmas day bird counts to determine “climatic suitability” for all 588 North American bird species.  Then, they looked at climatic models based on “greenhouse gas emission scenarios,” and estimated where the birds could live in the future.  There are serious problems with each end of this study.  The areas where people find birds now can in no way accurately predict the parameters of where they could potentially live.  The adaptabality of the birds is entirely underestimated.  Climate models are already known to be deeply flawed.  I like to call climate models what they are…wild guesses.  And as I noted at the very start of this essay, these birds survived global warming exceeding that being predicted by these climate models.

Dr. Langham says global warming is a greater threat to birds than habitat loss.  The past climatic history of the earth proves he is wrong.  However, I do think habitat loss resulting from an increase in human development will lead to bird extinctions.  Birds will become extinct in the future but not because of global warming.

Tabloid cover about bigfoot,

The information in the National Audubon Society’s Birds and Climate Change Report is about as reliable as that found in the Weekly World News.


Gornitz, Vivien

Encyclopedia of Paleoclimatology and Ancient Environments

Springer Science and Business 2007

The Paleoenvironment of the Georgia Bight when it was Above Sea Level (~80,000 BP-~7,000 BP)

September 12, 2014

A wonderful study led by Scott Harris of the College of Charleston was published in Geomorphology last year.   The authors of this study mapped and analyzed various underwater features on the continental shelf of an area known as the Georgia (or South Atlantic) Bight.  I realized Dr. Harris, an expert on the geology of this region, might have an answer to the mystery of the Silver Bluff Shoreline (See:  This shoreline is thought by some to date to about 38,000 BP, a time when most of Canada was under glacial ice, and therefore the shoreline should have been many miles to the east.  Yet, the Silver Bluff Shoreline is near the modern shoreline.  I asked Dr. Harris about this anomaly.  He informed me that he doesn’t like the nomenclature used to delineate this paleo-shoreline.  More importantly, he’s dated this shoreline using optically stimulated luminescense, and he consistently gets dates of 80,000 BP.  These dates are before sea level fell significantly in response to glacial expansion.  In my opinion this mystery is solved: his dates make more sense, and what is known as the Silver Bluff Shoreline is much older than previous researchers estimated.  There is no anomaly.

figure 1

Map of the Georgia Bight.  The area shaded in light gray was above sea level between ~80,000 BP-~7,000 BP.  It hosted a variety of dry land environments.

The study I mentioned above and reference below has re-ignited my curiosity about the environments on the continental shelf when it was above sea level.  It was a vast extension of the coastal plain–dry land occurred as much as 90 miles east of the modern shoreline.  Dramatic climatic fluctuations influenced the composition of the various environments that existed here.  The time period between ~80,000 BP-~60,000 BP (Marine Isotope Stage 4) was a climate phase of rapid glacial expansion, causing the sudden fall in sea level that exposed the continental shelf.  The period between ~60,000 BP-~28,000 BP (Marine Isotope Stage 3) was an interstadial–perhaps the most intersting climate phase because of an alternating feedback cycle that occurred.  Sudden warming events known as Dansgaard-Oeschger Events caused average annual temperatures to increase by as much as 14 degees F within a decade.  There was increased seasonality as summers averaged 5-9 degrees F warmer than during stadials.  And precipitation increased because the warm summer temperatures melted glacial ice.  After a few thousand years, icebergs and great quantities of glacial meltwater would flood into the North Atlantic.  This is known as a Heinrich Event.  Eventually, all this cold freshwater would shut down the Gulf Stream, causing temperatures to plummet.  Ice would again accumulate into glaciers.  MIS-3 saw at least 5 sudden warm ups followed by 5 cold downturns.  Between ~28,000 BP-~15,000 BP (Marine Isotope Stage 2), temperatures mostly remained in the cold climate phase. After ~15,000 BP sea levels rose until they reached modern levels about 6,000 years ago.  I am interested in how these climatic fluctuations influenced the flora and fauna of the continental shelf.  Below is a review of the types of environments probably found on the continental shelf and how they responded to climate change.


I believe prairies were the most common landscapes on the continental shelf during cold arid stadials.  The presence of 13-lined ground squirrels (Spermophilos tridecemlineatus) in the local fossil record supports my hypothesis.   13-lined ground squirrels prefer treeless plains and are found today in the tall grass and short grass prairie regions but are presently absent in the southeast.  The abundant fossils of mammoths, bison, and horses found near the coast and underwater all suggest the existence of extensive grasslands here.  Pine savannahs, open deciduous woods, and even closed canopy forests replaced most but not all of these prairies during warmer wetter interstadials.

image: Thirteen-Lined Ground Squirrel

13-lined ground squirrels.  The presence of this species in the local fossil record suggests the existence of extensive grasslands on the continental shelf.

Pine Savannahs

Savannahs are dependent upon lightning-ignited fires which increased in frequency during interstadials.  Scrub oak thickets with some pine replaced savannahs when fire intervals were reduced.

Open Oak Woodlands and Forests

A woodland is defined as a natural community that has 50%-80% canopy cover, while a forest has >80% canopy cover.  The arid climate of stadials relegated these environments to river bottomlands and other locally moist areas, but following Dansgaard-Oeschgher Events they expanded across the continental shelf.  Pollen records dating to interstadials show oak, hickory, pine, and grass dominated this region then.  Open woodlands, consisting of large mature trees growing far enough apart to allow for a grassy understory, predominated.  Fire and megafauna foraging shaped this landscape.  However, the pollen evidence indicates the low level presence of trees that are not fire resistent and have northern affinities–hemlock, spruce, beech, and basswood. (Though this pollen may have been blown in from northern latitudes.)  Some areas of the continental shelf may have had low incidence of fires and a cool moist climate during some phases. Deer, long-nosed peccary, tapir, and bears favored these habitats.

Oak Scrub with some Pine

Much of the continental shelf had sandy soils more suitable for desert-like vegetation.  Low incidence of fire during stadials increased the extent of this scrub habitat, and it likely replaced savannah.  It would have provided favorable habitat for flat-headed peccaries and rabbits.

Cypress Swamp

Stadials reduced cypress swamps to relic status.  Low poorly drained areas likely held these relic stands, providing the seed population that allowed cypress swamps to expand following Dansgaard-Oeschger Events.  Submerged cypress swamps have been found off the South Carolina coast.  Rising sea levels at the end of the Ice Age inundated these swamps.

Sand Dune Fields

Sand dunes originating from dry river beds rolled across the landscape during both MIS-2 and MIS-4.  Scrub vegetation covered and held them down during interstadials when they became good habitat for burrowing tortoises.

Carolina Bays and Freshwater Marshes

Wetlands occurred in some low lying areas but were scarce during stadials.  Many wetlands were ephemeral and may have frequently dried out before they could succeed to cypress swamps.  This is where mastodons and giant beavers congregated.

Braided Rivers

Paleomeanders prove that large rivers such as the Savannah and the Altamaha flowed through the continental shelf all the way to the ocean.  These paleomeander scars are still visible for about 60 miles of the continental shelf but strangely disappear on the last 30 miles of the outer shelf.  Dr. Harris believes rivers that flowed over the outer shelf were shallow and had a braided pattern.  When sea level rose, sediment filled the shallower incisions, explaining why these parts of the river scars are not visible.  It has occurred to me that these shallow intermittent parts of the rivers may have impeded some fish migrations.  They may have acted as natural fish traps that paleo-indians could have taken advantage of.

Paleomeander scar 60 feet below the ocean surface off the coast of South Carolina from a sonar image taken by College of Charleston researchers.  This is evidence of rivers flowing through the continental shelf when it was above sea level.

The Narrow Coastal Zone

Sandy beaches with some rocky outcrops, salt marshes, and tidal rivers provided varied habitat for marine life.  Some arctic sea birds along with seals and walruses inhabited this zone.  It was much narrower than the modern coastal zone.  Heinrich Events brought cold currents chilled by icebergs that may have drifted as far south as Florida. Evidence of iceberg draglines on the ocean bottom is abundant off the coast of South Carolina.

In a past blog entry about Pleistocene bears of southeastern North America, I didn’t list polar bears as a species that occurred in the region, but I may have been wrong.  Predators follow their prey anywhere.  In 1534 Jacques Cartier encountered a polar bear that swam 30 miles to feast upon the sea birds nesting upon Funk Island located off the Newfoundland coast.  Strange as it may seem, that means it’s quite possible polar bear stragglers did reach the continental shelf of what’s now Georgia during the Ice Age.  Bears have an amazing sense of smell.  Though Funk Island is named for the strong smell of the tens of thousands of birds that nest there, it’s still surprising that a bear could smell them from 30 miles away.

Colony of Murres on Funk Island off the coast of New Foundland.  It’s named for the funky smell of guano from tens of thousands of sea birds.  Colonies of sea birds like this may have existed on rocky outcrop islands near the shelf edge off the coast of the Carolinas and Georgia during the Wisconsinian Ice Age.

Greenly Island April 2011

Bulls Scarp, a rocky promontory off the coast of South Carolina, probably looked something like this when this region was above sea level.  This is Greenly Island located off the coast of Labrador, Canada.


Harris, Scott; et. al.

“Continental Shelf Landscape of the Southeastern United States since the Last Interglacial”

Geomorphology 2013

Mastodons, not Giant Tortoises, were the Probable Dispersal Agent of Torreya Seeds

September 6, 2014

Shortly after posting my blog article yesterday, I realized that mastodons rather than giant tortoises were the more likely dispersal agent of torreya seeds during the Pleistocene.  Connie Barlow came to the conclusion that giant tortoises were the most important dispersal agent of this now relic species of tree, but several flaws in her reasoning occurred to me.

1. She thinks mammal teeth would destroy the torreya seeds and accordingly, the seeds would be more likely to survive tortoise consumption because tortoises have no teeth.  However, mastodon teeth have big ridges.  A tiny conifer seed could easily escape the grinding molars of these teeth and pass through to the alimentary canal.  Mastodon coprolites have been found with intact seeds such as acorns, hazelnuts, persimmon and wild squash.  Mastodons were not thorough chewers.

Mastodon Tooth

Mastodon tooth.  Note the large spaces between ridges.  A tiny conifer seed could easily pass through the teeth into the alimentary canal without getting crushed.

Torreya seed cone.  The seed inside this cone is small enough for a mastodon to swallow without chewing.

2. Ms. Barlow claims the turpene found in torreya cones is toxic to mammals but not to reptiles–further evidence that tortoises must have been their main disperser.  Turpene is found in all conifer needles.  It may be toxic to some mammals, but it obviously was not toxic to mastodons.  Although mastodons ate a wide variety of plant foods, conifer needles were usually the most common item in their diet.  Mastodon coprolites found in the midwest almost entirely consist of spruce needles.  Cypress needles along with buttonbush twigs were the most common item in mastodon coprolites found in Florida.

3. Healthy torreya trees grew to 60 feet tall.  A giant tortoise would not be tall enough to reach most of the cones.  A mastodon could easily reach most of them and tear down the tree to reach the ones at the top.  They probably injested some cones while feeding upon the needles.

4. The closest living relative of the extinct giant tortoise is the gopher tortoise, and it feeds upon succulent plants growing in open sunny savannahs and desert scrub habitats.  This is precisely the type of habitat where torreyas can not grow.  Giant tortoises were likely a denizen of these open habitats that were unsuitable for torreyas.

5.  The last torreya trees are found along rivers in protected environments.  Isotopic studies show that mastodons migrated seasonally up and down river system corridors.  This may explain why the torreya’s last stand is located by rivers.  It’s where they would have been most abundant, if they had depended upon mastodon transportation for dispersal.

The Torreya (Torreya taxifolia) is Missing its Megafaunal Disperser

September 5, 2014

The torreya (Torreya taxifolia), also known as the stinking cedar because its crushed needles give off a strong resin odor, is a relic species thought to have been more widespread during warm climatic phases of the Pleistocene.  It likely diverged from an ancestor that was even more widespread during the Miocene when warm moist forests occurred all across North America and Asia.  T. taxifolia  is an extremely rare species confined to just the east side of the Apalachicola and Flint Rivers, while a closely related sister species (T. californica) is native to California where it is found in several disjunct populations. 

Pleistocene Ice Ages fostered the spread of arid grassland environments that were unsuitable for torreyas.  Under these conditions the torreya retreated to moist refugia on steep ravines of the Apalachicola and Flint Rivers. Connie Barlow, author of the below referenced book, thinks the torreya  formerly expanded its range as far north as the southern Appalachians, following the end of Ice Ages.  They are better adapted to live in an Appalachian cove forest rather than the environments surrounding their current range.  She hypothesizes the torreya’s current rarity is the result of its disperser’s extinction.  She suspects the giant tortoises (Hesperotestudo crassicutata and H. incisa) ate the torreya cones and defecated the seeds intact.  As the climate warmed following the end of Ice Ages, the tortoise’s range expanded and torreya trees spread in correspondence with this range expansion.  She believes the tortoises were the torreya’s main disperser. Squirrels can disperse the seeds but they are more likely to eat and destroy them, and other mammals are all potentially more likely to destroy the seeds with their teeth when they consume the cones. Tortoises don’t have teeth.  Furthermore, torreya cones contain turpene which is toxic to mammals but not to reptiles.  Now that tortoises are extinct, the torreya is stuck within a tiny range where it is probably going to succomb to fungal diseases. 

Barlow’s hypothesis will be difficult to support with concrete evidence–plant macrofossil remains from warm climatic phases of the Pleistocene are rare in this region.

Connie Barlow and her husband with a very rare Torreya tree.  She hypothesizes that its rarity today is due to the extinction of its most probable disperser–the giant tortoise.

Torreya taxifolia range map.png

Torreya taxifolia range map.

Torreya trees grow in natural communities the late naturalist, Charles Wharton, referred to as “torreya ravines.”  These are cool moist micro-environments also known as steepheads, and they only occur on the east side of the rivers.  The dominant trees in a torreya ravine are red maple, southern sugar maple, beech, magnolia, basswood, elm, torreya, and sabal palm.  Most of these species have northern affinities and are more commonly found in Appalachian cove forests.  Other plants found in torreya ravines also represent species of northern affinities such as strawberry bush, hydrangea, and redbud.  Wharton found torreya growing with beech, sourwood, and plum in the Faceville Ravine on the Flint River.

Wharton catalogued Torreya Ravines in his book The Natural Environments of Georgia written in 1978.  A more recent updated version of that book (The Natural Communities of Georgia) written by several authors and published last year does not mention torreya ravines.  I fear this means torreya trees may already be extinct in Georgia.  Wild torreya trees can still be found in Torreya State Park in Florida.

Mature torreya trees grow to 60 feet tall, but today few wild torreyas exceed 6 feet before dying back due to fungal disease.  Torreya trees have been transplanted to the Biltmore Estate in Asheville, North Carolina where they are doing much better than the wild trees.  Torreya trees growing on the Biltmore Estate survived a freeze of -30 F.  This shows they are capable of surviving in more northerly latitudes, and this supports Barlow’s hypothesis.


Barlow, Connie

The Ghosts of Evolution

Basic Books 2000

Wharton, Charles

The Natural Environments of Georgia

Georgia Department of Natural Resources 1978