Archive for May, 2012

The Woods of Home

May 30, 2012

My home is located on the top of a fall line hill in south Richmond County.  The top of the hill resembles a plateau that stretches flat for several square miles, and it is bisected by Piney Grove Road and Hephzibah-Mcbean Road.  An ephemeral creek bounds the north end of the pleateau before the topography rises.  Mcbean Creek, a more substantial tributary of the Savannah River, borders the south end of the plateau where the elevation falls.  I hypothesize Mcbean Creek is at least 7,000 years old, originating when water tables across the south rose following the dissolution of glacial Lake Agassiz in Canada (https://markgelbart.wordpress.com/2011/01/06/temporal-correlations-between-lake-agassiz-the-okefenokee-swamp-and-ancient-flood-myths/).  Mcbean Creek may have sporadically dried up and reappeared in correlation with glacial-interglacial cycles over millions of years because this is a low lying area closer to the water table than a hill and would be likely to host a stream during wet climate phases.

This tree has the thickest trunk of any in my neighborhood.  It is a sand laurel oak (Quercus hemisphaerica) aka Darlington oak with a 4.9 foot diameter.  It’s only about 50 feet tall.  Very few trees in my neighborhood get taller than 60 feet.  The soil is poor.  Sand laurel oak  is the co-dominant tree in this part of Richmond County along with loblolly pine.  It looks almost exactly the same as laurel oak (Quercus laurifolia).  The latter has small hairs growing on the underside of the leaves.  Other than that, the only difference is habitat requirements.  Sand laurel oak requires dry sandy soils and will not grow at all in moist conditions.  Laurel oak only grows in moist soils and will not grow at all in dry sandy soils.  Fossil mastodon dung from the Aucilla River contained laurel oak twigs and acorns.

Another nice specimen of sand laurel oak almost as thick as the one in the above photo.  It is an evergreen species like the more well known live oak.

The soil in this immediate region is of poor quality and sandy.  Over 30 million years ago, south Richmond County was a sea shore, explaining the origin of all this sand.  During later dry climatic phases when streams and rivers dried up and vegetation cover was reduced, even more sand was exposed and the wind blew additional layers on top of what was already here.  Eocene age sea shells were found on the Burke County side of Mcbean Creek circa 1900, but I think that fossil locality has been obliterated by a sand mine.

The sandy soil supports nice stands of second growth forest dominated by sand laurel oak and loblolly pine.  Other common trees include southern red oak, slash pine, shortleaf pine, black cherry, sweetgum, magnolia, hickory, sassafras, American holly, and persimmon.  The undergrowth consists of Virginia creeper, greenbriar, muscadine grape,  haw, and beautyberry.  In recently cleared areas pokeweed, dog fennel, sassafras, sumac, blackberry, low bush blueberry, prickly pear cactus, and bahia grass sprout rapidly.  Several areas nearby support acres of a small blackberry of mediocre quality.  Few of the trees appear to be older than 60 years, evidence that by early in the 20th century this entire region had been completely clear cut.  The soil seems too poor to have ever been productive cropland, so I assume the land was mostly used as horse pasturage in the days when the main mode of transportation was horse and buggy.  100 years ago, the population of horses in America was much higher than it is today.

The woods behind my house.  None of the trees in this forest appear to be much more than 60 years old.  I found the trace of an old wagon road back here.  It was probably a dirt road that went through a field or horse pasture. 

I’ve often contemplated the forest compostion of my neighborhood before European colonization.  William Bartram traveled along the Savannah River when he journeyed through south Richmond County and he missed my neighborhood by at least 5 miles.  Nevertheless, I base my speculation on his descriptions of similar latitudes in Georgia.  I’ve seen no evidence that Indians ever settled directly on this plateau, but their annual fires probably spread here, and I’m sure it was part of their hunting territory. (One of the oldest pine trees on my property has burn marks on the trunk.  My house was built in 1983.  The tree is ~60-70 years old.  This suggests a fire between 30-70 years ago.) I hypothesize the 18th century forest here was an open woodland with a greater diversity of plants than is hosted here today.  South Richmond County is on the border of 2 ecotypes: oak-hickory-pine of the piedmont and longleaf pine savannah of the coastal plain.  During colonial times the plateau (a dry ridge) was likely open woods consisting of sand laurel oak, post oak, blackjack oak, and longleaf pine with lots of grass and wildflowers growing between the widely spaced trees.  Many of the trees were hundreds of years old and had large diameters.  Bamboo cane probably grew in thick impenetrable stands along the creeks that border this flat-topped hill.  While driving along Hephzibah-Mcbean Road, I’ve noticed 2 trees that may be longleaf pine, but I haven’t had a chance to measure the needles in order to make an accurate identification.  This slow growing species has been completely replaced in Richmond County by faster growing loblolly and slash pines.

Determining what the landscape looked like before the Indians settled the region is a bit more complicated.  Climate fluctuated rapidly during the Pleistocene, leading to many compositional changes.  Though sand laurel oak dominates this region now, it is near the northern periphery of its range.  During cold stadials it may have been completely absent and probably didn’t colonize the area until the Boling-Alerod interstadial, a warm spell that began 15,000 years BP.  The Last Glacial Maximum (~28,000 BP-~15,000 BP) likely saw a desertlike landscape in this area with wide open spaces consisting of clumps of grass, bare soil, scrub oak thickets, and scattered pine forests.  The abundant prickly pear still present here may be a relic from this climatic phase.  Warmer and wetter interstadials probably saw a greater influx of oaks and hickories and a temporary return to forested conditions.

I often wonder what was the exact final date that a species of extinct megafauna last crossed withing a square mile of where my home now stands.  Two studies have concluded that megafauna populations began to decline as early as ~15,000 BP (https://markgelbart.wordpress.com/2010/05/13/2-concentration-of-dung-fungus-sporessignificant-megafauna-populations/).  All terminal dates on megafauna fossils fall between ~13,500 BP-~12,000 BP in calender years.  I’m convinced some species lasted somewhat longer than this, but the overall populations were reduced enough so that the final remnant populations don’t show up in the fossil record.  Occasionally, carbon dates of megafauna come back reading younger than these widely accepted terminal dates, but these are always dismissed as being contaminated samples.  That may be the case for some of them, but I wouldn’t be surprised if megafauna populations did linger in scattered locations long past the accepted terminal dates of extinction.  In any case my curiosity burns over when the last time a mammoth or a saber-tooth or a long-nosed peccary crossed what is now my neighborhood.  Was it 15,000 years ago? 12,000 years ago?  9,387 years ago?

Today, the only wild native megafauna to inhabit my neighborhood is the white tail deer which I frequently see directly or indirectly (tracks).  I’ve seen coyotes, a bobcat, gray foxes, opposums, raccoons, armadilloes (only as road kill), cottontail rabbits, and lots and lots of gray squirrels.  The avifauna nesting on my property includes chimney swifts, mockingbirds, cardinals, eastern kingbirds, and tufted titmice.  Mourning doves, crows, blue jays, brown thrashers, bluebirds, chipping sparrows, robins, pileated woodpeckers, flickers, red-headed woodpeckers, downy woodpeckers, and quail are all either common residents or occasionals.  Turkey vultures, black vultures, red-shouldered hawks, marsh hawks, Mississippi kites, barrred owls, and screech owls are the meat-eating birds that have inhabited my neighborhood recently.  A wood stork passing through is the only rare bird I’ve ever seen here.  Cattle egrets are the most recent edition to my neighborhood bird checklist.  Two weeks ago, I saw them foraging in a field around the corner from my house.

Of snakes I’ve seen timber rattlers, corn, gray rat, eastern king, black racers, and hog-nosed.  Anole lizards, thirteen-lined skinks, and little sand skinks make up the lizard population.  Box turtles occasionally march by, and I’ve even seen quite large chicken cooters and snapping turtles far from water.  Toads, bullfrogs (found in our septic tank and toilets), and green tree frogs represent the amphibians.

Look What the Cat Dragged In

A former boss once used that expression when I showed up for work one day.  What a jerk.  He was a dumb jock redneck with a reputation for cheating on his wife.  I think I’m a more substantial man than any of the following creatures my cats have murdered.  The victims of house cat predation represent a good account of the small animals that live in my yard.

A baby possum.  The cat broke its neck but didn’t eat it.  Lucky thing…possums carry trichinosis.

Eastern mole.  A common victim of the murderous cats.

Short-tailed shrew.  The most common small animal killed by the local cats.

Remember a month or two ago when I wrote a blog entry about the cedar waxwings flocking to my yard.  One of the poor birds went after some low-hanging holly berries.  The berries just happened to be growing in a spot where the cat rested and napped.  The bird must have flown right into the cat’s paws.  Cardinals and brown thrashers also frequently fall victim to the cats.

Other victims of my cats that I haven’t been able to take a photo of include a star-nosed mole, 2 house mice, baby rabbits, baby rat snakes, anole lizards, skinks, green tree frogs, and large insects.  A semi-feral cat that formerly inhabited the woods behind my house was able to kill full grown squirrels.  Noticeably absent are native field mice (Peromyscus sp.).  I haven’t ever seen a single one nor any signs of any in my yard.  Hmm?  Augusta, Georgia is not officially within the range of the star-nosed mole, but my cats prove the range map is wrong.

Supposed range of the star-nosed mole.  Scientists need to expand it to include south Richmond County.  My cats killed 1  a few years back.  However, for that 1 star-nosed mole, they’ve killed at least 10 eastern moles which must be far more common.

Lone Ranger and Hissy Fit.  They kill a lot of small creatures.  Lone Ranger got so sick last week, I was sure she was going to die, but she’s better now. She’s a slutty runt.  She mated with her own brother.

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The Camelot Fossil Site in Harleyville, South Carolina

May 25, 2012

Despite the wealth of information provided by this fossil site, only a few scientific studies have been published about it, so I had to piece together information gathered from those sources with that from websites written by amateur fossil collectors lucky enough to have been invited to the dig.

Location of Harleyville, South Carolina.  There is an impressive fossil site here.

The fossil hunting grounds formerly owned by Lafarge cement company.  Last year, they sold it to a South American company that forbids fossil collecting.  Photo by Ron Ahle.

Ancient hurricane storm surges repeatedly flooded the South Carolina low country hundreds of thousands of years ago.  Each of these floods drowned numerous animals, especially the young and old individuals too weak to swim through the surge, and then carried the corpses until snagged by an impediment. The landscape here consists of uneven ridges formed by Eocene-age limestone deposits originating from when this was a marine environment.  During Pleistocene floods these above ground ridges acted as dams, trapping and accumulating bones which were quickly covered with sediment, thus becoming lag deposits.  About 20 years ago the Lafarge Cement Company began bulldozing the fossil rich dirt to reach the underlying limestone which is used to make cement.  They dumped the fossils and dirt into spoil piles and many amateur fossil hunters trespassed the site and combed through the fossiliferous mounds.  Paleontologists caught wind of the treasure and were granted permission to collect here.  They named the site “Camelot” for the abundance of llama fossils.  Llamas are members of the camel family.

Paleolama mirifica, the stout-legged llama.  Unlike all modern species of llamas and camels which inhabit arid or montane grasslands, the 2 species that inhabited the southeast during the Pleistocene were animals that either lived in forests or forest edge environments.

Skeletel reconstruction of Hemiauchenia macrophela, the large-headed llama.  This was another common species found at the Camelot fossil site.

Yesterday's Camel

Camelops hespernus, yesterday’s camel–another extinct Pleistocene species of camel.  This once common species formerly found in western North America did not live in the southeast as far as we know.  Nevertheless, I wanted to include an illustration of this impressive animal in my article.

The scientists who originally catalogued the fossils and published the results estimated the fossils from the site dated to 19,000 BP and referred to it as the Ardis local fauna.  Unfortunately, this study was published in an extremely obscure and now defunct journal, and I haven’t been able to find out how they came up with this age estimate.  Scientists continued excavating Camelot and by 2003 determined the site was much older than that based on the physical characteristics of the extinct species.  The fossils resemble mid-Pleistocene representatives of species rather than those from the late Pleistocene.  Now, the mammal fossils here are considered to be between 250,000-400,000 years old which might put them in the Irvingtonian Land Mammal Age, not the Rancho La Brean, though the fossils may have accumulated at different times following different flood events.

The original catalogue of species listed dire wolf, a late Pleistocene species, but later excavations found Armbruster’s wolf, a mid-Pleistocene species.  The dire wolf specimen may have been misidentified based on the inaccurate chronological assumption of the first study.  Likewise, a specimen of Bison antiquus, a late Pleistocene species, may have been misidentified and was probably an earlier form of bison. 

One of the few studies of the fossils found here examined carbon isotope ratios in the bones of white tail deer, Vero tapir, stout-legged llama, large-headed llama, horse, Jefferson’s ground sloth, saber-tooth, and Armbruster’s wolf.  By examining the carbon isotope ratio in the bones, scientists can determine what kinds of foods these long dead beasts were eating.  Plants growing in forests tend to have high amounts of carbon-3; plants growing in grasslands tend to have high amounts of carbon-4. They found that deer ate the highest amount of forest vegetation.  Jefferson’s ground sloths, Vero tapirs, and stout-legged llamas also heavily relied on forest vegetation.  Large-headed llamas were mixed feeders.  Horses depended upon grassland.  Armbruster’s wolves mostly ate forest dwelling herbivores.  Saber-tooths inhabited mixed woodland and grassland environments where they ambushed prey.  The scientists didn’t analyze bone from the mid-Pleistocene cheetah (Miracynonyx inexpectus), but they assume this was the primary predator of the grasslands.

Paleobotanists found macrofossils of cypress trees, water lillies, water milfoil, and algae as well as pollen from pine, hickory, oak, hazelnut, sweetgum, grass, and composites (daisies, sunflowers, etc.).  During the time of deposition the site must have been a cypress swamp surrounded by an upland environment consisting of oak and pine woods mixed with substantial meadows.  Hazelnut apparently was common in the deep south during cool climate phases, but it no longer naturally ranges south of the Appalachians.

Bird fossils were excavated here, but to learn which species, I’m going to have to spring for a back issue of Current Research in the Pleistocene because the info from that study is not available online.

A new species of extinct giant tortoise, still undescribed in the scientific literature, was unearthed here as well as many other freshwater turtle specimens.  The Eocene-aged limestone underneath the Pleistocene deposit holds many fossil shark teeth and other marine specimens, making this site a kind of double bonus for paleontologists.  Below is a list of mammal species that I’m aware were found here.

short-tailed shrew

southeastern shrew

star-nosed mole

eastern mole

beautiful armadillo

northerm pampathere (a giant armadillo the size of a bear)

Jefferson’s ground sloth

mink

river otter

striped skunk

spotted skunk

hog-nosed skunk

Armbruster’s wolf

gray fox

raccoon

Florida spectacled bear

jaguar

bobcat

saber-tooth (over 5 skulls)

mid-Pleistocene cheetah

13-lined ground squirrel

gray squirrel

southern flying squirrel

beaver

giant beaver (Castor ohioensis)

rice rat

cotton rat

field mouse sp.

woodrat

meadow vole

pine vole

Florida muskrat

southern bog lemming

Florida bog lemming

horse

Vero tapir

long-nosed peccary

Paleolama

large-headed llama

bison sp.?

mastodon

mammoth

References:

Beaty, Melissa

“Paleoecological and Depositional Environments of a Middle Pleistocene Vertebrate Fossil Locality in Harleyville, South Carolina”

GSA abstracts March 2007

Bentley, C.C. ; et. al.

“The Mammals of the Ardis Local Fauna (Late Pleistocene), Harleyville, S.C.

Brimleyana 21: 1-55 1992

Kohn, Matthew; et. al.

“Dining in the Pleistocene–Who’s on the Menu?”

Geology 2005

www.blackriverfossils.org

 

 

Blueberry and Bumblebee

May 21, 2012

I have 4 cultivated blueberry bushes.  They usually flower in March, produce fruit in June, and offer lovely red foilage in  fall.  This year, winter ended 2 weeks earlier than normal, and Saturday (May 19th) I harvested my first blueberries.  They were plump from a recent drought-breaking rain.  I made my first batch of blueberry pancakes the following morning.  My bushes give me all the berries I need for pancakes, muffins, and desserts for about a month.

My blueberry bushes flower in February and March.  The bees swarm to them every year.  Without these pollinators there would be no fruit.

Note the bees.  The most common species pollinating the flowers are the southeastern blueberry bees and bumblebees.  The former looks similar to the latter but is smaller.

Two bushes.  Two varieties.  One of the four bushes (not pictured) is stunted and doesn’t produce much yet.

Good plump berries by May 18th.

Blueberry flowers attract several kinds of bees well adapted to late winter/early spring weather conditions.  Because these species of bees are covered with hair, they are able to withstand colder temperatures than most other insects and are among the first arthropods to emerge in early spring.  The black coloring also helps increase their body heat.  The southeastern blueberry bees, bumblebees, and honeybees pollinate over 96% of the blueberry crop in southeastern North America.  The southeastern blueberry bee (Hapropodia laboriosa) is by far the most common type pollinating my bushes.  They look like a small bumblebee and are a solitary species.  The female digs a long burrow in sandy soil and broods her nest in it.  Their lifespan matches the length of time blueberry bushes flower–about 3 weeks.  They are completely dependent upon blueberry bushes, unlike bumblebees (Bombus sp.) which pollinate a much greater variety of plants.  Bumblebees live in colonies of from 200-2000 individuals.  They also nest in burrows where the overwintering queen becomes the sole survivor when hard weather hits.  Both of these native bees are not aggressive.  I’ve never been stung by either one.  One would have to roughly handle one of these species or invade a nest to get stung.

Horticulturalists cultivated high bush blueberries, creating hundreds of varieties, but low bush blueberries only grow in the wild.  Nevertheless, there are such extensive stands of low bush blueberries in Maine that they’re gathered wild and can be found in the frozen food section of many supermarkets.  Low bush blueberries grow wild in my neighborhood, including my front yard.  These ripen in late July/early August but are of disappointing quality compared to my cultivated high bush blueberries.  Euell Gibbons claimed wild blueberries work better in muffins than cultivated ones, but the variety that grows in my neck of the woods is hard and bittersweet.  My wife and daughter love cultivated berries but declined to eat the wild ones after trying them.  Eight species of blueberries are native to the piedmont region of the southeast: sparkleberry (Vaccinium arboreum), black high bush blueberry (V. atroccum), high bush blueberry (V. corynborum), Elliott’s blueberry (V. elliotti), southern low blueberry (V. pallidum), deerberry (V. stamineum), slender blueberry (V. tenellum), and early low blueberry (V. vaccillum).

Blueberries generally grow in colonies and prefer sandy acidic soil.  They thrive in sunny open areas with little to no tree canopy.  They can tolerate a few pine trees which don’t shade them.  They’re another fire adapted plant–underground runners help them resprout following ground fires.  When Euell Gibbons went hunting for blueberries, he’d visit the office of a National Forest ranger and ask him to point out on a map where the most recent burns had taken place.  Native Americans set fire to the woods nearly every year to foster habitat for berries, though this was done for several other reasons as well such as improving habitat for game, eliminating insect and snake refuges, and increasing visibility to avoid being ambushed by other Indians.

Undoubtedly, blueberries were a common component of southern Pleistocene landscapes.  Dynamic factors–sudden climate changes, unchecked wild fires, and megafauna foraging–created highly diverse environments including the open spaces blueberries require.  Pleistocene-aged heath pollen in measurable amounts occurred in Nodoroc, a mud volcano near Winder, Georgia (the central part of the state).  The pollen dated to ~30,000 BP, a brief interstadial immediately preceding the Last Glacial Maximum.  The pollen record here suggests an environment dominated by pine, oak, and grass; though hickory, spruce, and fir were common, while maple, beech, chestnut, and birch were present in this diverse landscape. The presence of high amounts of ragweed, an early successional species, is evidence of an environment in constant flux.  Pine pollen and macrofossils at Nodoroc suggest a mixture of southern species (shortleaf) and northern species (jack, red, and white).  In Maine wild blueberries grow in large barrens and are associated with the northern species of pine mentioned above.  One caveat–the heath family also includes common non-blueberry species such as azalea, mountain laurel, and fetterbush, so it’s likely they contributed to the heath pollen.  Scientists can’t differentiate to the species level when examining heath family pollen.

Pleistocene environments in Georgia may have included vast blueberry barrens such as those occurring in Maine today, especially with large flocks of passenger pigeons spreading the seeds that eventually found ideal habitat.  William Bartram rode his horse through miles of what he referred to as “strawberry plains” in north Georgia and North Carolina.  This environment–common just 200 years ago–is now completely extinct. Strawberries require sunny conditions, just like blueberries.  In the extensive wilderness of the Pleistocene perhaps blueberry barrens and strawberry plains covered miles of territory.

Maine blueberry barren.  This photo must have been taken during fall when the leaves turn red.  The owners of this land burn it often to faciliate the growth of wild blueberries–an uncultivated cash crop. Did Pleistocene Georgia have extensive blueberry barrens such as this?  Or did they just grow in small colonies wherever a fire burned a small section of forest?

Sturgeon and Lamprey

May 16, 2012

The destruction of the sturgeon population mirrors the devastation of southeastern primeval forests.  Both of these astonishing natural resources have been utterly obliterated.  In a previous blog entry from about a year ago, I excerpted William Bartram’s 18th century description of a magnificent forest in Georgia consisting of trees with diameters 8-12 feet thick.  I drove through the same area last summer and was hard pressed to find a single tree greater than 1 foot in diameter.  The story of Georgia’s most impressive river fish follows the same plotline.


 

 

 

 

 

Man Alive!  Look at the size of this Atlantic sturgeon.  There used to be so many of these fish in our southeastern rivers that they posed a navigational hazard.  Now, they are almost extinct.

The sturgeon run in southeastern rivers began in mid-May.  For the first month of the run most of the spawning sturgeon averaged 3-4 feet in length, but beginning in mid-June and lasting until mid-September sturgeon averaging 6-9 feet in length were common.  Captain John Smith, founder of the Jamestown colony, caught 62 sturgeon in 1 haul of a net, though that take was extraordinary, even for that time.  More often, netting would yield 7 or 8 large sturgeon in a few hours.  The schools of sturgeon “clogged” the river and made for a dangerous navigational hazard that could upturn boats.  Occasionally, the giant fish even jumped into a boat.  John Lawson, an early naturalist who traveled and settled in North and South Carolina circa 1704, wrote that he saw hundreds of sturgeon every day. (He also mentioned pulling 300 chain pickerel from 1 fish trap in a single day.)  Now, sturgeon are almost extinct.  There is a tiny breeding population in Georgia’s rivers but none of the rare sturgeon found in mid-Atlantic rivers breed there.  About 1850  men began overfishing sturgeon which formerly were considered trash fish.  This decimated the population, but dams and muddy erosion from agriculture blocked and smothered much of their former spawning grounds–perhaps the final death blow.  Sturgeon need shallow water with gravel bottoms for spawning, but instead, if the spawning fish themselves are not blocked by dams, the gravel bottoms have become covered in mud, making them unsuitable.  The sturgeon eggs need to adhere to gravel.

Three species of sturgeon, all endangered, live in Georgia.  The Atlantic sturgeon (Acipenser oxyrhincus) reaches the most spectacular size, obtaining a maximum length of 9 feet and a weight exceeding 800 pounds.  The adults live in the lower stretches of the river and near offshore ocean water, but they used to spawn as far as 300 miles up the river.  The juveniles stay in the river until they’re about 7 or 8 years old before they migrate to the ocean.  They return when they reach breeding age which isn’t until they’re between 10-30 years old, explaining why it’s so difficult to bring back sustainable population levels.  They feed on the bottom by scooping out depressions and lying in ambush nearby.  Smaller fish and invertebrates carried by the current fall into these saucer-shaped traps next to where the hungry sturgeon awaits.  The short-nosed sturgeon (Acipenser brevirostrum) is similar in habit to the Atlantic sturgeon, but it is smaller in size reaching 4-5 feet in length and just 50 lbs in weight.  A landlocked population of lake sturgeon (Acipenser fluvescens) lived in the Coosa River  until 1965.  In 2003 biologists reintroduced them to the Etowah River.  The Coosa River lake sturgeon must have been a relic population that some how made their way from the Mississippi River system, perhaps from a chain of wetlands that existed during the Pleistocene in northern Alabama.  Floods between river basins must have facilitated the spread of this species.

Flickr

Sturgeon piccatta, broccoli, and stuffed squash blossoms.  I’ve never eaten fresh sturgeon.  I think I’ve had smoked but it’s been so long I can’t remember for sure.  I’ve had caviar…tastes like fish guts.

It’s hard to believe the early settlers considered sturgeon a trash fish and fed the flesh and caviar to the hogs and dogs.  Sturgeon flesh when dressed correctly is reportedly supposed to be mild and durable and an acceptable substituted for boneless chicken breasts or veal in recipes.  Caviar, of course, is considered a delicacy but in my opinion tastes like fish guts.  Mixed with cream cheese, it’s palatable.  In my fantasy Pleistocene world, I’d definitely be harvesting and eating the sturgeon.

Sea lampreys parasitize fish, latching on and ingesting blood.  Sea lampreys no longer occur in the Savannah River, but they used to.  They must have been dependent on the large sturgeon population.

Sea lampreys (Petromyzon marinus) are no longer recorded from the Savannah River, but there is a historical record of 1 from the upper part of this river where Clark Hill Reservoir now inundates.  John Lawson mentions sea lampreys as a fish the Indians refused to eat (though the French consider them a delicacy).  This anectodal evidence suggests sea lampreys used to be fairly common in southeastern rivers.  They’ve likely disappeared from the Savannah River because they depended upon sturgeon for sustenance and now that the sturgeon are all but gone, so are the lampreys.  It’s no coincidence that sea lamprey spawn in the same habitat as sturgeon–shallow water with gravel bottoms.  The larva move downstream after hatching, then burrow into sandy or muddy bottoms and become filter feeders, living on detritus and algae until they grow into their parasitic phase.  When they reach this stage they actively attack fish as depicted in the figure above.  I suspect sturgeon were their primary prey/host in southeastern rivers.  Striped bass and swordfish have been recorded as preying on sea lampreys, but probably any large predatory fish will eat them.

At least 3 other species of lampreys inhabit Georgia’s rivers–the southern brook lamprey (Ichthyomyzon gagei), the American brook lamprey (Lampetra appendic), and the least brook lamprey (Lampetra aegypidtra).  The former occurs in the Chattahoochee River, and the latter 2 live in north Georgia rivers.  None of these have a parasitic phase and they live as filter feeders burrowed in mud for most of their lives, except when they spawn.  They all have rasping mouths, however.  This is evidence they evolved from parasitic species.

Sturgeon are an ancient family of fish.  Fossils of sturgeon dating to the Cretaceous prove they swam when dinosaurs roamed the earth.  Lampreys long ago evolved to exploit this once abundant food source.  It’s a shame both of these remarkable fish have nearly vanished in the last 150 years in the wake of man’s environmental destruction after they’d successfully survived natural ecological changes for over 100 million years.

An Addendum to The Truth about the Red Wolf’s Status as a Species

May 14, 2012

I asked Ronald Nowak if he knew where the red wolf fossil found in Fern Cave, Jackson County, Alabama was.  (Ronald Nowak is one of the world’s foremost authorities on recent canine evolution and morphology.) He did.  He said it’s located in the U.S. National Museum of Natural History in Washington D.C.  It is specimen #348063, and it is in the mammalogy collection, not the paleontology collection because it appears to be 100-200 years old.  Although Pleistocene-aged fossils were found in Fern Cave, the wolf skeleton doesn’t look as old as the others.

He agrees this specimen would help clarify the red wolf’s status as a species.  It’s a complete skeleton including the skull.  It even has a thin layer of nonskeletel material (skin?), but not fur as I originally assumed.  He wrote that for years he’s been trying to get molecular biologists interested in this specimen, but so far they have ignored it.  Hopefully, some day they’ll analyze it.  There should be plenty of mtDNA and material for carbon dating.

Unexpected Items in the Diet of the White-Tail Deer

May 11, 2012

I remember my 7th grade biology teacher arguing with a student who insisted her family’s cow ate their chickens.  Mr. Amick assured her that a cow was an herbivore and would never eat meat, but the farm girl adamently asserted what she had witnessed.  I thought of this argument 20 years later when I read an article in Natural History magazine about how red deer living on an island ate sea bird nestlings.  Scientists concluded the deer ate the birds because the plants growing on the island were deficient of calcium, and the deer obtained this nutrient from the bird bones.

White-tail deer scavenging a rabbit.

It’s not at all unusual for deer to eat meat protein. White-tail deer have been recorded eating injured birds, bird nestlings, quail eggs, carrion (especially dead fish), and insects. The following link to a youtube video shows a deer eating a young bird before it had learned how to fly.  http://www.youtube.com/watch?feature=player_detailpage&v=sQOQdBLHrLk

Alewives frequently wash up on the shores of Lake Michigan, and one scientific study found they made for a common item in the deer’s diet there.  But this isn’t an isolated localized behavior.  Deer have been observed eating fish on the sea shores and along Florida’s lakes.

Like cows, deer have 4-chambered stomachs, and they chew their cud.  Plant material is more difficult to digest than meat, but meat protein probably passes through a deer’s stomach without requiring further chewing.  Imagine how nasty cud mixed with dead fish would be.

During the Eocene, ungulates arose from a common ancestor shared with carnivores, so it shouldn’t be a surprise that they’ll enjoy a meal of meat when they can get it.  But they’ve become specialized toward a primarily herbivore niche and can no longer actively stalk and catch most prey.  Hogs are among the most primitive of ungulates and are well known for being omnivorous.  One Eocene age species of pig, the enteledont, is believed to have rammed and killed other animals.  Despite being an ungulate, it was one of the top predators of its time.

The ability to exploit many different foods improves the survival rate of white-tail deer.  In a forested environment it’s the omnivores that are the most abundant large animals. Instead of a sea of grass, there is a wider variety of foods.  In late Pleistocene Georgia the 3 most common large mammal species were white-tail deer, long-nosed peccary, and black bears.  Even during arid stadials when grassland habitat expanded, forests were still the most common ecotype in this state.  Being able to eat a wider variety of foods allowed these 3 to dominate the faunal assemblage in terms of sheer numbers.  Today, because forest is still the predominant ecosystem here, deer and hog are prevalent in large numbers and bears would be too, if humans could tolerate more of them.

Mylohyus nasatus–the long-nosed peccary.  They were almost as common as deer in Georgia during the PleistoceneIf I could live in eastern Georgia 36,000 years ago (as I occasionally fantasize about in my irregular series “If I could live in the Pleistocene”), I would expect this species along with deer and bear to be the most abundant large animals, especially since this time period was an interstadial with warmer temperatures and more precipitation than the stadials, and therefore more forests than grasslands.

Black bears (Ursus americanus) were also very common during the late Pleistocene.  The short-faced bears were more abundant in the early Pleistocene, but they were specialists with 2 species more carnivorous and 1 more herbivorous than black bears.  The generalized diet of black bears evidentally helped them become more successful toward the end of the Pleistocene than the short-faced bears and perhaps explains how they survived the megafauna extinction.

The Truth About the Red Wolf’s Status as a Species

May 9, 2012

There are a lot of hostile jerks on the internet who are quick to insult the intelligence of people they disagree with. Not long ago, I encountered one of these shmucks.  Scottie Westfall writes the Retrieverman blog which is an interesting one focusing on dog breeding, evolution, and genetics.  He’s convinced recent genetics studies support his long held belief that the red wolf (Canis rufus) is nothing more than a hybrid between the gray wolf (Canis lupus) and the coyote (Canis latrans).  I commented on his blog, suggesting how the natural history of this hybridization could have occurred beginning in the Pleistocene.  My comment was consistent with the findings of the study he cited.  I wasn’t disagreeing with his premise.

 A Shmuck on the internet.

His response to my comment revealed blind hostility.  He wrote that my “inability to understand the study and my parrotting of data it falsified was telling.”  This would be a cleverly worded retort, if I had been in conflict with his opinion.  But I wasn’t.  It was obvious he didn’t understand what I wrote because I wasn’t even disagreeing with his conclusion.  And his response implied that I was some how evil or an idiot simply because we supposedly disagreed about some obscure scientific controversy.  On this same response thread he’s carrying on a long debate (92 responses and counting) with an ardent anti-hunter in which his tactic is to call her an “idiot.”  What’s that say about his mentality and personality?

Now, I’ve had time to read the literature in depth, and I’ve discovered the genetic studies are contradictory.  Evolution is seldom black and white.  Usually, there is quite a bit of gray area, and the status of the red wolf as a species is certainly an example of the uncertainty involved in determining when speciation has occurred.  Scottie Westfall’s blog gives only one side of the issue–the genetic studies that support his opinion.  I commented on his blog with a link to a study that contradicted the genetic studies he touts as conclusively supporting his position, but he removed my comment and apparently he’s decided to block all of my comments from now on.  Because his blog tops google searches, I feel it’s necessary to offer both sides of this issue, so those researching this controversy can gain a better unbiased understanding.

Red Wolf (Canis rufus? Canis lycaon? Canis latrans x Canis lupus? Canis rufus x Canis latrans? Canis lupus rufus?)

This 80 pound canine was recently shot inside this hog trap somewhere in Georgia.  It’s black and had a white spot on its breast.  Another trailcam photo posted at the Georgia Outdoor News forum also photographed a black coyote with a white spot on its breast.  Early colonists and explorers in the southeast noted that black wolves with white spots on their breasts were the common color variation of wolves in Georgia and Florida.  I’ve also seen large reddish colored coyotes in south Richmond County Georgia.  Supposedly, wolves were extirpated from Georgia and Florida by 1917.  Did a population survive?  Is it breeding with the recent influx of western coyotes or was the southeastern wolf simply a big subspecies of coyote?  DNA tests are contradictory.

All scientists agree that the remaining population of red wolves, now confined to the Alligator Wildlife Refuge in North Carolina, have at least some coyote blood.  The final population of red wolves captured along the Lousiana/ Texas border had been reduced to such low numbers that they’d been breeding with the more abundant coyotes.  Scientists chose those individuals with the physical characteristics most consistent with those of the red wolf and successfully bred them in captivity before releasing them in the North Carolina wildlife refuge which then was far away from the expanding coyote population but now suffers a coyote invasion.  Biologists are attempting to trap and remove coyotes to prevent them from again breeding with red wolves, but I doubt they’ll be successful.

About 20 years ago, R.K. Wayne of UCLA noticed an absence of genetic markers in red wolves distinct from those of coyote or gray wolf.  He proposed that the red wolf was simply a coyote/gray wolf hybrid.  A few years later, he examined DNA from 6 skins of red wolves killed in Arkansas circa 1900, and the evidence supported his proposal.  A few other studies supported his contention, but other scientists were skeptical.  They were suspicious of Dr. Wayne’s choice of specimens.  They originated from Arkansas which bordered the historical range of the gray wolf and the red wolf.  The specimens may in fact be from gray wolves, not red wolves.

In 2000 Dr. Paul Wilson, a Canadian scientist, led a study of eastern Canadian wolf and red wolf DNA.  He found none of the eastern Canadian wolf or red wolf DNA from specimens prior to the 1960’s contained gray wolf mtDNA sequences.  Moreover, there was a high degree of genetic affinity between eastern Canadian wolf (Canis lycaon) and red wolf mtDNA.  He considered them the same species.  In both wolves he found mtDNA control sequences more closely related to coyotes that are not found in gray wolves.  However, both eastern wolves had specific unique haplotypes not found in western coyotes.  So his study did find specific genetic markers unique to red wolves that were not found in gray wolves or coyotes–something Dr. Wayne didn’t find in his study proposing that red wolves were coyote/gray wolf hybrids.  Below is his proposed evolutionary tree which is consistent with the fossil record.

Dr. Wilson found a genetic divergence between gray wolves and eastern wolves of 8% which he calculated to mean they diverged from a common ancestor 1-2 million years ago.  The genetic divergence between coyotes and eastern wolves is only 1-2% which he calculated to mean they diverged from a common ancestor 150,000-300,000 years ago.  Coyotes have recently (within the last 100 years) come into contact with eastern wolves and have hybridized.

Last year, scientists led by Bridgett Von Holdt used existing genetic data to create a genome wide analysis of worldwide canine DNA.  The findings in this study directly contradict the findings in Dr. Wilson’s study, though it should be noted this study used the same contested samples of red wolf specimens that Dr. Wayne used.  Dr. Von Holdt found no close affinity between eastern Canadian wolves and red wolves.  They determined the current population of red wolves were 75%-80% coyote with the balance being gray wolf.

So which study is correct?  Who knows?  I would like to see a study of DNA from red wolf specimens originating from 17th or 18th century Florida, Georgia, Alabama, and Tennessee.  Evidence from such a study might resolve the controversy.  I’m not sure a study such as I propose can be conducted.  There may just be a shortage of readily available museum specimens.  But I know of one.  I recall a red wolf specimen with fur was discovered in Fern Cave, Alabama in 1970 along with much older remains of the giant short-faced bear (Arctodus simus).  I don’t know who possesses this specimen but it should be genetically analyzed.

I believe red wolves evolved from coyotes following the extinction of dire wolves.  Coyotes were present in the Pleistocene southeast but eventually became absent.  I formerly thought red wolves drove coyotes out of the region, but now I think eastern coyotes grew bigger to exploit a deer-hunting niche left vacant when dire wolves became extinct.  Whether or not they’re a distinct species, a large subspecies of coyote, or a coyote/gray wolf hybrid is debatable?

References:

Wayne, R.K.

“Molecular Evolution of the Dog Family”

Trends in Genetics 1993

Wilson, Paul; et. al.

“DNA Profiles of Eastern Canadian Wolf and Red Wolf Provide Evidence for a Common Evolutionary History Independent of the Gray Wolf”

Canadian Journal of Zoology 78 2000

Von Holdt, Bridgett; et. al.

“A Genome Wide Perspective on the Evolutionary History of Engimatic Wolf-like Canids”

Genome Research 2011

Big Cats Hunting Elephants

May 6, 2012

The big fanged cats, Smilodon fatalis and Dinobastis serus, of the Pleistocene evidentally hunted mammoths and mastodons.  Even with their advantageous adaptations of long canines and powerful upper bodies, it seems incredible that they could bring down prey so much larger than they were.  Yet on rare occasions African lions successfully attack juvenile elephants.

The pride of lions in this photo successfully killed this elephant.

http://www.youtube.com/watch?v=q2ZW0EvMzSM

Here’s a youtube video of the incident as narrated by David Attenborough.

The big question, another Pleistocene mystery unlikely ever to be answered with certainty, is how did North America’s big Ice Age cats kill mammoths and mastodons?  We know for sure at least 1 species did.  The remains of mammoth and mastodon  were found in Friesenhahn Cave, Texas associated with fossil skeletons of the scimitar-toothed cat.  (https://markgelbart.wordpress.com/2010/10/08/why-did-fanged-cats-have-long-forelimbs-and-sloping-backs/ )   Gnaw marks on the long bones of the proboscideans match those from the teeth of this cat.  All of the proboscidean teeth belonged to juveniles.  They were not necessarily baby mastodons and mammoths, but rather from yearlings because the babies were too well-guarded by adults but the yearlings, as most young of a species, possessed a reckless curiousity and wandered farther away from the herd, making them vulnerable.  Full grown adults probably were just too big to bring down.  Did the scimitar-toothed cat work in groups or did they have a special skill allowing them to tackle a juvenile proboscidean themselves?  I lean toward the latter scenario because most cats are solitary species.  The above video shows that it takes a very large pride of lions to bring down an elephant.  They have difficulty penetrating the tough hide of an elephant with their relatively short canines.  But scimitar-tooths and saber-tooths had specially adapted canines capable of slicing right through tough hide.  A bite through the neck could cause a  quick death.

A family group of scimitar-tooths traveling through the snows of, who knows, let’s say Arkansas.  This beautiful illustration and the next were drawn by Mauricio Anton for the book The Big Cats and their Fossil Relatives by Alan Turner (Columbia University Press 1997).

Beringian lions among woolly mammoths in Alaska.  Lions depicted here may be an inaccurate portrayal.  They probably didn’t have manes.

Most of the mammoth and mastodon fossils found in Friesenhahn Cave were teeth.  This puzzled scientists because proboscidean skulls seem heavy and awkward for even a big cat to carry any distance, and it’s certain they obtained their prey from some water holes hundreds of yards away where they ambushed their victims.  However, C.W. Marean and  C.L. Ehrhardt determined that’s exactly what they did.  I propose the big cats used the trunk as a handle.  Perhaps, the cats long necks were an adaptation to help carry the dismembered heads of mammoths.  By clenching the trunk between their jaws, they could trot along and clear the ground as they carried their gruesome prize.

There’s no direct evidence that Smilodon also hunted juvenile mammoths and mastodons, but I’m sure they did.  The existence of long canines is indirect evidence.  One study of Smilodon bone chemistry from Rancho la Brean specimens found evidence they mostly ate horse and bison, but I think the fangs gave them the ability to exploit proboscideans when the other prey animals were temporarily unavailable.  Panthera atrox, the giant lion or panther, may have also hunted probosideans but only if they lived in prides like their African cousins.  This is uncertain.  I think we can rule jaguars out as probosidean hunters.  Perhaps large packs of dire wolves attacked juvenile mammoths but I doubt they were often successful.  Even a juvenile, if on the rampage, could trample many individuals and decimate a pack.

Being able to kill juvenile proboscideans gave fanged cats an evolutionary advantage over other predators in environments where mammoths or mastodons were present in greater biomass than smaller prey items.  The extinction of these beasts made it more difficult for the fanged cats to survive, especially when humans may have considered them number 1 on the most wanted list and probably killed them on site with spears.

Reference:

Marean, C. W. and C.L Erhardt

“Paleoanthropological and Paleoecological implications of the Taphonomy of a Saber-tooth’s den”

Journal of Human Evolution  29 1995

Three Pleistocene Lions: Were they Distinct Species or the Same Animal?

May 2, 2012

Some time ago, I wrote a blog entry detailing an excellent 2009 study by Per Christiansen that suggested Panthera atrox was a unique distinct species and not a subspecies of lion, as previously believed (https://markgelbart.wordpress.com/2010/07/28/panthera-atrox-what-kind-of-cat-was-it/).  Dr. Christiansen measured every part of the skulls from numerous specimens of all 4 extant species in the Panthera genus, plus some from the extinct Panthera atrox.  He statistically analyzed the measurements and found that the measurements from  Panthera atrox skulls clustered distinctly from those of lions, tigers, jaguars, and leopards.  He concluded this meant they were a unique species of panthera that was neither lion, jaguar, nor tiger.  Although the skulls of  Panthera atrox greatly resembled those of extant lions, they aren’t an exact match.  Moreover, their jaws are a closer match to those of jaguars.   So he assumed Panthera atrox shared an immediate common ancestor with the jaguar.  He believed they were isolated from the Eurasian parent population by an Ice Age glacier, and diverged into 2 different species–Panthera atrox and jaguars.

Panthera atrox vs. Smilodon

Cave painting of Eurasian cave lion, Panthera spelaea.  I chose this one over other illustrations on the web because it was drawn by artists who actually saw the beast.

Three months after Dr. Christiansen published his paper, another group of scientists led by Ross Barnett published their studies of panthera mtDNA.  Evidence from this study of genetics suggests Panthera atrox diverged from the Eurasian cave lion about 340,000 years ago.  Not coincidentally, this is the same time period bison, a major prey item, colonized North America.  This precludes the possibility that Panthera atrox shared a close evolutionary relationship with the jaguar because the latter occupied North America long before this date.  Moreover, there is a wide genetic variance between those species, but there is a marked similarity between Panthera atrox and lion DNA.

The results of the DNA study do support Dr. Christiansen’s findings that Panthera atrox was a distinct species.  The authors of the DNA study noticed a lack of gene flow between the 3 types of Pleistocene lions, even though there was no known geographical barriers between the African and Eurasian lions and the Eurasian lions and American lions for millenia.

Range map of Pleistocene lions from the below referenced study.  The Beringian lion (color coded red) is considered a subspecies of the Eurasian cave lion.

An African species of the panthera genus appeared first in the fossil record from a site in Tanzania that dates to ~3.5 million years BP.  One of its descendents, the African lion (Panthera leo), ranged from southern Africa to southern Eurasia, including India and Greece.  The Eurasian cave lion (Panthera spelaea) appeared in the fossil record as suddenly as the African lion.  Its oldest dated remains come from a fossil site in Italy dating to ~700,000 years BP.  The genetic evidence suggests that Panthera spelaea was derived from the African lion.  Their ranges came into contact in parts of the Near East, yet it’s apparent the 2 types of lions stopped interbreeding–almost certain evidence they evolved into 2 separate species.  Some Russian scientists have also suggested that Panthera spelaea was a distinct species from the African lion based on notable differences in morphology.  The Eurasian cave lion colonized Alaska when sea levels  lowered during Ice Ages, thus creating the Bering land bridge.  It was this population that gave rise to Panthera atrox ~340,000 years BP.  A glacier separated the 2 populations initially, and the ones south of the ice evolved into atrox.  However, the glacier completely dissipated at least twice for tens of thousands of years at a time, so for much of this ancient era, there was no geographical barrier between the 2 populations.  Yet here too, there was no gene flow–again almost certain evidence they’d evolved into separate species, despite the genetic similarity.

Panthera atrox was on average 25% larger than the African lion, and it had a significantly larger brain.  Considering the consistent size difference, the lack of gene flow, and Dr. Christiansen’s statistical analysis of skull differences, I’m convinced Panthera atrox was indeed a unique and now extinct species.  There is one caveat concerning the genetic study.  Although they used plenty of samples of Panthera leo and Panthera spelaea, they only used a small sample size of Panthera atrox specimens.  They had 2 specimens from Consolidated Pit 48 in Edmonton, Canada, and 2 from Natural Trap Cave in Wyoming.  Panthera atrox lived all across North America as far east as South Carolina (1 fossil from Edisto Beach) and Florida, and it ranged into South America at least as far south as Peru.  It would be interesting to learn the genetic variance from populations of Panthera atrox that were farther removed geographically from their ancestral population.

Incidentally, there’s evidence from a cave in Idaho that humans cooked and ate one particular Panthera atrox.  The youngest carbon date of this species is about 13,000 calender years from the Edmonton site.

The study of lion DNA found another interesting tidbit of ecological mystery.  About 50,000 BP the genetic diversity of Eurasian cave lions greatly declined from 8 haplogroups to 1.  The genetic diversity of wooly mammoths, bison, and horses also declined during this time period.  This puzzles scientists, but I think I have a viable explanation.  The decline in genetic diversity coincides with the timing of a severe stadial.  A more varied environment of forests, scrubs, and lightly wooded savannah gave way to an expansion of arid frigid grasslands known as the Mammoth Steppe.  Only the populations of those species best adapted to this type of environment survived whereas those better adapted to woodland, partially wooded savannahs, and scrub habitat died out.

Reference:

Barnett, Ross; et. al.

“Phylogeography of lions (Panthera leo ssp) Reveals Three Distinct Taxa and a Late Pleistocene Reduction in Genetic Diversity”

Molecular Ecology 2009