Archive for July, 2011

The South Central Salient of the Helmeted Musk-ox (Ovibos cavifrons or Bootherium bombifrons)

July 27, 2011

Portrait of the woodland or helmeted musk ox from the Illinois Museum of Natural History

The way scientists assign scientific names to extant and extinct species can be confusing.  The rule is simple–the scientific name given by the scientist who first describes the first specimen ever discovered (also known as the “type specimen”) is the one that supercedes all other later names.  Complications arise when other scientists discover new fossil material of the same species and mistakenly believe they’ve discovered a new species, and they assign a completely different scientific name to the specimen.  Decades often pass before other scientists compare the fossils and determine they’re one and the same species.  The extinct helmeted musk-ox provides a case study of this confusion.  Scientists discovering fossils of this wide-ranging species from all over the continent have assigned many different scientific names to this species including Bos bombifrons, Bootherium bombifrons, Symbos cavifrons, Ovibos cavifrons, Bison appalachicolus, Liops zuniensis, Symbos australis, Bootherium nivicolum,  Symbos converifrons, Ovibos giganteus, and Bootherium brazosis.  This sounds like a joke, but it’s not.  It created a real mess for later scientists to straighten out.

Fossil hunters first found a helmeted musk-ox fossil in 1804 at the Big Bone Lick Fossil site in Kentucky.  The first scientist to look at it put it in the Bos genus which is the same one domesticated cattle belong to.  It wasn’t until 50 years later that it was recognized as a type of musk-ox.  Extreme sexual dimorphism caused the proliferation of species names for just one animal.

The horns on a male helmeted musk-ox were much larger and robust than those on the female.  Scientists mistakenly thought they were from two different species.  Note the difference between the male and the female horns (f & e) in this diagram.  Diagram from the below referenced paper written by R. Dale Guthrie.

Male helmeted musk-oxen are so much larger than females that for a long time scientists believed they were seeing different species: males were classified as Symbos cavifrons, and females were classified as Bootherium bombifrons.  Finally, in a paper written in 1989 Jerry McDonald and Clayton Ray thoroughly studied all the fossil material and determined they were one and the same species.  Because Bootherium bombifrons was the older name, that is now considered the official scientific name for the species.  I mistakenly thought Ovibos cavifrons was the official name, and it makes sense because its close living relative, the woolly musk-ox goes by the scientific name of Ovibos moschatus. It seems the woolly and helmeted musk-ox should be in the same genus, but they’re not.

I’ve noticed a curious geographical distribution of helmeted musk-ox fossils.

Distribution map for helmeted musk-ox.  This map includes just the skulls, so I added a dot for a musk-ox fossil found in Nashville, Tennessee, and drew the line to illustrate the salient.  Helmeted musk-ox must have been an adaptable animal to range this far.  Map from the below referenced paper written by McDonald and Ray.

Helmeted musk-oxen fossils come from Bayou Sara in south central Louisiana, Texas, and Mississippi north to Alaska and west to northern California and east to the continental shelf off what today is New Jersey.   Their range seem to have extended south along the Mississippi River.  A south central salient of its range is notable.  Fossil sites in the piedmont region of the southeast are so rare there is no telling where its southeasternmost range occurred.  None have been found in Florida’s abundant sites, indicating its probable absence there.  Fossil sites in Nashville, Tennessee and Saltville, Virginia yield helmeted musk-oxen specimens, but it may have been absent from the southeastern coastal plain.  Looking at the line I drew on the above map, it’s likely helmeted musk-oxen did range over northern Alabama and the ridge and valley region of northwestern Georgia. 

If they could survive the warmer climates of Mississippi, Louisiana, and Texas, it couldn’t have been climate that prevented them from colonizing the southeastern coastal plain.  Perhaps, because long-horned bision were already abundant here and occupied a similar niche, helmeted musk-oxen never could become established.  Maybe, it’s just chance they never migrated into the region.  Or maybe they were present but in such low numbers as to be invisible in the fossil record. 

The extinct helmeted musk-ox differed from the living woolly musk-ox in many characteristics.  As evident from its much wider range, the helmeted musk-ox was much more adapatable.  It had longer legs allowing it to run greater distances and with more speed.  It was taller and more slender, suggesting it had more endurance.  Scientists found fur on one specimen.  The hair was shorter and finer–evidence that it did not have a heavy woolen coat like its living cousin.  The two species did coexist in parts of Alaska and unglaciated Canada, but Dr. Guthrie sees evidence of habitat parturation.  Helmeted musk-oxen lived in arid grassy steppes in this region whereas woolly musk-oxen inhabited more mesic tundra.  Dr. Guthrie favors the common name helmeted musk-ox over woodland musk-ox because the species was just as likely to be found on grassy steppes and savannahs as open parkland woods.  I agree with him and from now on will refer to it on this blog as the helmeted musk-ox.

Evidence from fossilized feces and plant fragments in fossil teeth show that helmeted musk-oxen ate a wide variety of plant foods including sedges, grasses, blueberry bushes, and willow twigs.  In fact one sample of fossilized dung consisted of nothing but willow twigs.  Some times their feces was pelletized.  Dr. Guthrie states that this is evidence of a capability to eat a lot of dried plant foods without having to eat snow for water.  It’s an adaptation of moisture conservation, enabling the species to survive frigid arid environments. 

Helmeted musk-oxen were able to live in temperate climates where human populations eventually became high.  I believe this is the reason they became extinct while woolly musk-oxen avoided human overhunting in remote regions of the arctic.  It’s ironic that an animal that was more adapatable died out because of this adaptability.  I disagree with scientists who think natural environmental changes caused their extinction.  This highly adaptable animal enjoyed a wide range during the Pleistocene as the above map shows.  This means they inhabited a great variety of habitats from Alaskan grassy steppe to prairies to open forests interspersed with meadows.  Suitable environments  for helmeted musk-oxen, especially in the midwest and upper south, never completely disappeared.  The foods they ate–grasses, sedges, blueberry bushes, willow trees–always remained abundant throughout much of the continent.  Moreover, their fossils are known from deposits as old as 300,000 years BP, meaning they survived previous transitions from glacial to interglacial.  I see no change in the environment that would cause their extinction, other than the increase in the number of people hunting them.  Dr. Guthrie suggest bison outcompeted musk-oxen on the prairies, but this makes little sense–musk-oxen and bison coexisted for hundreds of thousands of years.

Woolly musk-oxen survived extinction because they inhabit remote regions of the arctic.  Even here, human hunting reduced their numbers.  Human hunters wiped out woolly musk-oxen  in Alaska before the introduction of firearms, though the beasts have been reintroduced here.  Still, there are large areas of suitable habitat in Alaska where woolly musk-oxen are absent due to human hunting.   During the Ice Age woolly musk-oxen were more widespread living as far south as Spain.  Undoubtedly, climate change and the resulting contraction of barren tundra has played a role in diminishing habitat for this species, but suitable habitat for helmeted musk-oxen expanded following the retreat of the glaciers, especially in the midwest.  Suitable habitat in the upper south remained the same. 

I hypothesize men exploited the musk-ox’s habit of standing in a defensive circle to face down predators.  It may prove effective against wolves or big cats as long as they don’t panic and begin running (as seen in this video http://www.youtube.com/watch?v=pb6Rke7jiTc ) but it was catastrophically fatal for helmeted musk-oxen when a gang of humans confronted them.  Humans could use projectile weapons to slaughter entire herds standing stationary in one place.

Some scientists claim the scant evidence that humans hunted helmeted musk-oxen suggests they played no role in their demise.  This argument frustrates me.  There isn’t a single skeleton of a human from the Clovis era in North America.  Why should we expect to find remains of their meals?  Nevertheless, there is some evidence of humans exploiting helmeted musk-oxen.  Clovis age arrowheads associated with musk-oxen bones and with bovine blood on them were found at the St. Mary’s reservoir in Alberta, Canada.  And a human “modified” musk-oxen bone turned up at the fossil site in Saltville, Virginia (a pre-clovis site).  Scientists who argue against the human overkill model of extinction never say how much evidence would be enough to convince them.

References:

Guthrie, R. Dale

“New Paleoecological and Paleoethological Information on the Extinct Helmeted Musk-oxen from Alaska”

Ann. Zool. Fenninci 28: 175-186 Feb. 1992

McDonald, Jerry; and Clayton Ray

“The Autochthonous North American Musk-Oxen Bootherium, Symbos, Gidleyea (Mammalia: Artiodactyl: Bovidae)”

Smithsonian Contributions to Paleobiology #66 1989

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40,000 year old Bald Cypress Logs Discovered in South Carolina

July 24, 2011

This cypress tree stood with the mastodons.  (All the photos in this blog entry are from www.ancientcypress.com)

In 2003 workers mining sand along the Little Pee Dee River and the Lynches River in South Carolina discovered ancient cypress logs 40 feet below the present day surface of the land.  They found 70 cypress logs at the Lynches River site that were carbon dated to between 39,000 and 45,000 years old.  They found 20 logs at the Little Pee Dee River site dating to 25,000 years old.  They found woody material from other species as well but information on them has yet to be published.  Some of the logs were 96 feet long and a few had 1000 growth rings, meaning they lived to be over 1000 years old.  The logs were between 1-8 feet in diameter.

Depth of the excavation where the cypress logs were found.

Just imagine all the now vanished wildlife that roamed around, landed, climbed, and even lived on these trees.  Mastodons, a semi-aquatic species that inhabited river bottomland swamps and ate cypress twigs, certainly stood with these trees when both lived.  (In an article written for The State newspaper a journalist incorrectly stated that woolly mammoths may have rested in their shade.  It’s unlikely woolly mammoths lived this far south, though Columbian mammoths did.  Mammoths probably avoided swampy habitat.) Long-horned bison grazed upon the cane grass in openings by the trees when the swamp dried out.  Perhaps, if these trees had eyes, they could’ve witnessed jaguars or saber-tooths lurking in the swamp, ready to spring upon deer and peccary.  Maybe monster-sized catfish swam by their roots during high water.  Ivory billed woodpeckers, Carolina parakeets, and Pleistocene vampire bats nested or roosted in the cypress cavities.

The find is a tremendous source of scientific knowledge.  Scientists can use dendrochronolgy (the study of tree rings) and correlate the tree ring growth with carbon dates to determine past climatic patterns.  Just like with upland trees, cypress rings grow fat during wet years and skinny during dry years.  40,000 years ago, the cypress swamp at the Lynches River site stood during an interstadial, a warm climate phase within the Ice Age when sea levels rose due to glacial meltwater.  One would expect to see larger tree rings during the interstadial.  The cypress forest near the Little Pee Dee River stood during the Last Glacial Maximum–evidence that a warm thermal enclave did occur on the lower southeastern coastal plain then because cypress swamps couldn’t exist, if the climate was too cool.  Both sites are on the lower coastal plain, relatively close to the ocean.  Scientists believe slow sedimentation from changing river patterns eventually covered the forests in both locations, but they haven’t ruled out a marine transgression.

The discovery of fossil cypress wood was not only beneficial for scientists, but businessmen took advantage of it too.  The owners of the sand quarries established Ancient Bald Cypress LLC, and they manufacture custom made products out of the wood.  Incredibly, although the wood was water saturated when excavated, it had not become fossilized, and when dried proved excellent for fine artisan furniture.  They make and sell everything from $500 duck callers and $1200 bread bowls to $25,000 queen-sized beds and $150,000 custom made canoes.  This is a real testament to the durability of cypress wood.  I can understand why cypress wood is used for roofing shingles.

The sites in South Carolina aren’t the only ones where cypress logs have been discovered.  In 1921 construction workers building a skyscraper 4 blocks from the White House discovered ancient cypress logs dating to over 100,000 years old.  They were buried by ocean sediment after rising sea levels caused the Potomac River estuary to cover the cypress swamp with mud and sand.  Washington DC is slightly north of the present day range of cypress–a clue that the climate was warmer during the Sangamonian Interglacial than it is today.  That sea level eventually rose even higher than where it is today is definite evidence that climate was once warmer, and if as scientists predict, sea level rises due to present day global warming, the nation’s capital will some day have to be moved.  Pleistocene-age cypress logs have also been excavated in Newport News, Virginia; Myrtle Beach, South Carolina; Flanner Beach, North Carolina; and in Illinois.  A >50,000 year old fossil beaver dam consisting of cypress wood was excavated in a kaolin clay mine in Deepstep, Washington County, Georgia as well.

Cypress trees lived during the time of the dinosaurs and were once more widespread, living as far north as the Arctic Circle when the hot humid worldwide climate fostered the growth of swamps all over the planet.

Today, the oldest cypress tree in the world is found in the  Black River Nature Conservancy Reserve  in North Carolina.  It’s 1700 years old.  Its great age saved it from being logged because cypress wood from trees that old is of poor quality.

Reference:

http://www.ancientcypress.com/source/PDFs/subfossil.pdf

Irrational Anti-Wolf Hysteria in the Rocky Mountains

July 21, 2011

Photo of Yellowstone gray wolves from google images.  Note the color variations within the same pack.

The timber wolf (Canis lupus) is a beautiful animal well adapted to hunting big game.  It’s an ancient species having first evolved in Eurasia about 1 million years ago.  They crossed the Bering Landbridge and became widespread in western North America at least 300,000 years ago.  Based on the number and distribution of fossil specimens, dire wolves (Canis dirus) outnumbered timber wolves during most of the Pleistocene in the southern regions and lowlands, and apparently, timber wolves never penetrated the southeast, perhaps because red wolves (Canis rufus) were already present and occupying a niche not directly in competition with dire wolves.

The extermination of wolves from Yellowstone National Park and many sparsely populated regions of the west was an ecological disaster.  Elk and deer overpopulated the range, forcing National Park officials into the awkward position of having to shoot elk inside National Parks.  Canadian wolf populations rebounded, and they began recolonizing Montana and Idaho naturally in the early 1990’s.  Scientists reintroduced wolves back into Yellowstone National Park in 1995, improving the quality of the ecosystem.  Wolves now number between 1300-1600 in the northern Rocky Mountains.  Idaho held a spring hunting season on wolves in 2010 that led to the deaths of 188, not counting the puppies that starved to death following the deaths of their parents. 

The furious anger of irrational wolf haters pressured the Idaho Fish and Game Department into planning annual hunting seasons on wolves that will begin this upcoming fall, unless a lawsuit stops it.  The Idaho Fish and Game Department itself showed a bias in favor of killing wolves with the leading questions they asked on a pre-hunt survey such as “”Should wolves be managed to protect public safety?” instead of questions I would ask such as “Should wolves be slaughtered so their puppies will starve?”

The hatred of wolves is not based on reality or facts and seems most vocal among hunters who believe humans are the only animals on earth with the God-given right to kill other animals.  Although the Idaho Fish and Game Department only wants a sustainable “harvest” of wolves, many militant anti-wolf fanatics insist that wolves should be completely exterminated.  According to them, wolves “destroy all wildlife” and are causing big game populations to collapse.  It doesn’t occur to them that wolves are wildlife.  Hunter “harvest” statistics don’t support their erroneous beliefs.  I researched this and discovered how wrong they are.

Hunter “Harvest” Record from Wyoming Fish and Game Department for Selected Years

…………………………………..Elk …………………………..Deer

1994…………………………….24,534…………………………………….44,488

1996……………………………..20,612…………………………………….NA

2001…………………………….22,772…………………………………….47,943

2009……………………………22,971……………………………………..53,267

Note the elk “harvest” has remained steady in Wyoming, despite the reintroduction of wolves.  Deer “harvests” show a noticeable rise.  People spent an estimated $35 million in Wyoming just to see wolves, so their reintroduction has been beneficial economically as well as ecologically.

Hunter “harvest” table from Montana Fish, Wildlife, and Parks from selected years

……………………………………….Elk………………………..Deer

2001……………………………….20,578………………….111,783

2004……………………………….23,313…………………..119,266

2005………………………………26,201…………………….115,238

2010……………………………….24,744……………………94,730

Again, elk populations show no signs of collapsing.  Deer show a slight decline in the most recent year but this may be due to a severe winter.

According to the Idaho Fish and Game Department, in 2010 the elk population there was above management goals in 10 districts, within management goals in 13, and below management goals in 6.  Since wolves recolonized the state, the elk population has declined from 125,000 to 100,000, but “deterioration of habitat” is considered a greater factor than wolves, especially in districts where wolves are getting blamed.  There has been no economic loss due to a decline in big game tags issued.

Clearly, there is no collapse in big game populations in areas wolves have recolonized.  In any case I’ve asked some of these wolf haters how wolves could be increasing in numbers, if the population of their prey was supposedly collapsing.  A dearth of game would cause wolves to starve and decrease in numbers.  I’ve yet to see an answer to this logical point  that makes any sense.  One man insisted that after wolves exterminate elk they’d gobble up everything else including people–an ecological impossibility.

Many ranchers hate wolves as well.  However, losses of livestock to wolves is minimal.  In 2007 in Idaho ranchers lost 53 cattle, 170 sheep, and 8 dogs to wolves.  This out of a population of 2.2 million cows, 235,000 sheep, and probably hundreds of thousands of dogs.  For cattle this can be calculated to a loss of something like .000002%.  Infinitesimal.

Wolf haters also have an irrational fear that wolves will attack people.  The chances of this happening are remote–in North America there have been about 25 reported attacks of wolves on humans in recorded history.  In Europe and Asia documented wolf attacks on people number in the thousands.  In the Old World only the nobility were allowed to hunt and wolves didn’t learn to fear peasants; but in America where more people have guns in an egalitarian society, intelligent wolves did learn to avoid people.  Contrast these 25 reported wolf attacks in all of American history with 34 people killed by domesticated dogs (Canis familiaris) in the U.S. in one year, and the estimated 4.7 million dog attacks annually.  Yet, no rational person is calling for the extermination of domesticated dogs.

I’m not opposed to hunting for food. In my irregular series on this blog about my imaginary life living in Georgia 36,000 years BP, I hunt deer, elk, peccary, and bison for most of my meat (see the March archives for my most recent post on this).  But I’m disgusted with the attitude of many hunters today, and this certainly includes wolf haters who are all hunters unable to stand seeing other animals kill their game.  Direct TV offers 2 hunting channels.  More often than not on the hunting shows I’ve watched, hunters giggle like demented sadists after they’ve killed an animal.  When it comes to politics, the overwhelming majority of hunters are twisted fascists.

July 26, 2011 anti-wolf rally Federal judge Donald Molloy could once again halt a much needed wolf control hunt. - Sportsmen Needed To Protest Latest Wolf Hearing In Montana!

The controversial judge ruled against wolf haters in 1 case.  Freedom of speech does not include terroristic threats.  Whoever fashioned this sign should be arrested. (Note: the link to this photograph originally featured a picture of anti-wolf nuts hoisting a sign threatening Judge Molloy who ruled that wolves should remain protected.  Instead the photo on the embedded link was replaced with this asshole carting 4 dead wolves.) 

The above sign illustrates the intolerant hostility wolf haters have for people who oppose their point of view.  This sign is all one needs to know about these people.  They’re not nice guys.

Incidentally, one of these wolf haters who runs a ridiculous anti-wolf propaganda site known as save the elk.com was arrested recently for…felony poaching of an elk.  How ironic.

Another irrational fear wolf haters share is their belief that the federal government is going to take their guns away from them.  The way they carry on, one would think they were afraid the federal government was going to take their penises away.

References:

Idaho Fish and Game News 22 (2) August  2010

Montana Fish, Wildlife, and Parks Hunters “Harvest” Tables

Wyoming Fish and Game Department Hunters “Harvest” Tables

The Lost Pleistocene World of the Georges Bank

July 18, 2011

I’m taking an imaginary vacation this week away from southeastern North America to visit one of the few ice free spots in the northeast during the Last Glacial Maximum.

The Georges Bank used to be one of the richest fisheries in the world.  During the LGM it was an extension of the mainland inhabited by many species of megafauna.

East of the Gulf of Maine the sea floor rises 330 feet.  Both cold and warm currents sweep over this submerged island, and light can reach the shallow bottom which ranges between 10-50 feet deep.  The light and the mixture of currents create an ideal habitat for a rich zone of phytoplankton.  The phytoplankton  is the foundation of a food chain that feeds over 100 species of fish, and the gravel bottom, eroded from glacier-pushed rocks, provides excellent spawning structure.  One of the richest fisheries in the world used to be found here before fleets of international factory ships decimated the naturally abundant stocks in the 20th century.  Long before Basque fishermen discovered this amazing fishing ground in the 11th century, the Georges Bank existed as a special and beautiful part of the North American mainland.

20,000 years ago, a massive glacier, one mile thick, depressed the entire area of what’s now New England.  The weight of all that ice literally pushed the earth’s crust down.  Glaciers from previous Ice Ages had already gouged a trough off what today is Maine’s coast, explaining why the Gulf of Maine is so deep.  The most recent glacier, the Laurentide, advanced over the dried-out trough toward the receding Atlantic Ocean.  The ocean was receding because so much of the world’s water was becoming locked up as ice.  But on the narrow strip of higher land in the vicinity of the Atlantic Ocean, the climate was warmer, perhaps keeping the glacier at bay.

The Georges Bank was an extension of the mainland, 140 miles long and 75 miles wide.  It was bounded on one side by the enormous glacier, and on the other by the ocean.  The climate consisted of cool summers, thanks to the monstrous ice cube next door, and snowy but bearable winters because moderating oceanic winds prevented temperatures from plummeting as low as occurred farther inland.

Icebergs drift off shore here within site of the sand dunes where beach grass, beach pea, and bayberry grow.  Walruses swim to and fro from small ice floes to the beach.  Behind the beach dunes, brackish lagoons host ducks and geese and loons.  Forests of pine, spruce, fir, birch, and alder cover most of the island, interrupted here and there with cranberry bogs.  Grassy windswept steppes are located on the northern part of the island and on nearby Sable Island.

Tim Wichinbach dredged up this partial mastodon tusk while fishing for scallops over the Georges Bank.  Fishermen have accidentally caught Pleistocene fossils in their nets in more than 40 sites on the Georges Bank.  The list of accidental bycatch includes fossils of mastodon, mammoth, woodland musk-ox, stag-moose, long-nosed peccary, walrus, bearded seal, and wood from ancient forests.  Reportedly, tapir and ground sloth bones have also been dredged, but I can’t find documentation in the scientific literature.  A good comprehensive catalogue of Georges Bank fossils has not been published.  Information is limited to 3 old articles from very obscure scientific journals.

An early October snowstorm covers a north facing slope, yellow grass tufts stick above the white layer.  A herd of dwarf mammoths and lean musk-oxen graze on the grass, the mammoths clearing the snow with their tusks.  The horns on the musk-oxen cover their skulls like football helmets.  Closer to a forest edge in a low lying area on the other side of the slope, steam rises from a bog.  A huge solitary stag-moose stands ankle deep, a mouthful of green slime hangs from his mouth.  I think it’s a clump of duckweed.  In the open forest mastodons use their trunks to tear branches from young spruce and red pine saplings.  I can hear them grind the cellulose between their giant molars.  One of the hairy elephants has an itchy hindquarter.  He backs up against a jack pine and rubs, but it’s a dead rotten tree, and it snaps and falls over, startling a spruce grouse which flies away in panic.

5,000 years later, the climate warms, and the Laurentide glacier melts as rapidly as 300 meters a year.  Birch forests colonize the newly available land, and the animals follow, but soon, rising sea levels inundate not only the Gulf of Maine, but areas of the coast that are currently above sea level, including the future sites of Augusta and Bangor.  As the heavy weight of the glacier recedes, the land area of Maine rebounds because there is nothing pressing the earth’s crust down here any more.  This is known as isostatic rise.  Meanwhile, the Georges Bank has become a true island, surrounded by ocean water on all sides.  Eventually, sea levels rise more, dooming the animals that didn’t migrate west.  The Grand Banks to the north also falls below sea level.  Only a small spit of sand, the highest point of Sable Island, still remains above sea level in this region.

A Sad Timeline of the Rape of the Georges Bank Fishery

The Georges Bank was an astonishingly rich fishery.  When first discovered by Basque fishermen around 1000 AD, they kept it a secret for over 500 years.  Cod were so abundant fishermen could just stick a basket in the water and 50 pound cod would fill it immediately.  Early colonists living near Cape Cod complained about having to eat lobster every night.  The cod take continued to remain strong until the 20th century when industrial ships from all over the world caught thousands of tons of fish.  Finally, in 1977 the U.S. banned foreign trawlers but it was too late.  American fishermen continued to overfish and now there’s little left–a testament to man’s shortsighted greed.  It’s another sickening example of poor natural resource management.

1830–Right whales nearly exterminated

1850–Halibut disappear

1977–Herring fishery collapses

1994–Commercial cod fishing collapses.  Law passed to outlaw commercial cod fishing proves ineffective.  It’s still not policed.

In my opinion all commercial fishing on the Georges Bank should be banned for 20 years.  Maybe then, it would recover.

Pleistocene Vultures of Southeastern North America

July 13, 2011

It seems fitting to follow last week’s blog entry about saber-tooths with one about vultures, a whole class of birds that benefited from the big carnivore’s work.  The extinction of the megafauna led to the extinction of several vulture and condor-like species.  Other species of scavenging birds became less widespread and more local in distribution.

Teratorn

Teratorn–Teratornis merriami

This huge condor-like bird stood 2.5 feet tall but had a wingspan of 12 feet–the length of 2 average-sized men spread from head to foot.  Fossils of this species have been excavated in Florida, California, and several western states, so it likely ranged throughout most of the southeast.  An even larger species, Aiolornis incredibilis, had a wing span of 17 feet, but this may have been an early Pleistocene species, not present in the late Pleistocene.  The teratorn’s bill was much larger than other vultures, suggesting it often took live prey such as rabbits and bird nestlings which it swallowed whole.

African scavenging birds occupy different niches described as rippers, grabbers, and scrappers.   Rippers rip open thick-skinned, large, carcasses and eat hide and the tougher parts of the animal.  Grabbers eat the soft meat; scrappers eat the bits of meat that get scattered around the carcass.  Scientists believe the same holds true for scavenging birds in Pleistocene North America.  Teratorns were the rippers, capable of opening dead thick-skinned mammoths or ground sloths, helping make the meat available for other scavengers.

California CondorGymnogyps californianus

Photo from google images of a California condor.  Man, are they ugly.

I say this bird should be known as the North American condor because Pleistocene age bones of this bird have been found as far east as New York (the Hiscock site) and Florida.  Obviously, it lived throughout the southeast.  Scientists know from an analysis of its fossil bone chemistry that California condors survived the extinction of the megafauna because a local population of the birds learned to scavenge whale carcasses off the California coast.  Ranchers attempting to kill coyotes with ill-conceived poison control programs, instead nearly extirminated the beneficial condors.  Now, they’re back from the brink, feeding mostly on the abundant dead livestock on western ranges.

American griffin vulture?  No common name–Neophrontops americanus

An extinct American vulture related to old world vultures.  No representatives from the old world vulture family still occur in North America.

The accipitrids are old world vultures today found in Africa and Eurasia.  They’re more closely related to hawks than to extant new world vultures which are related to storks.  The physical similarity between old and new world vultures is a case of convergent evolution when unrelated species develop similar characteristics to adapt to similar conditions.  Both old and new world vultures have featherless necks to prevent the build-up of toxic bacteria.  Both are capable of digesting well-rotted food without getting sick, and they are adapted to tearing open carcasses.

American old world vulture.  No common name–Neogyps errans

This is another old world type vulture that became extinct with the megafauna.

King Vulture–Sarcaramphus papa

William Bartram described this vulture in north Florida during the 18th century.  For over a century ornithologists doubted the veracity of Bartram’s account, thinking he either had the bird confused with a mythical creature or a caracara, because no specimens of this still living species were known to occur north of Central America.  Then in 1932, Frances Harper reviewed Bartram’s field notes and discovered that Bartram actually had obtained a specimen.  The description in the field notes matched the king vulture even better than his account in his book, Travels, which was written years later apparently from imperfect memory.  Mr. Harper theorized the king vulture occurred in Florida until the great freeze of 1835.  Bartram also reported royal palms in north Florida which were extirpated from all but the southernmost region of the state after that freeze.  King vultures probably colonized and recolonized the south during warm interglacials.

Bartram noted an interesting habit of this species in Florida.  King vultures followed the frequent fires in the longleaf pine savannahs and ate the “roasted” reptiles that failed to escape the flames.

Black Vulture–Coragyps atratus

Photo from google images of a black vulture–still common.

It’s no coincidence that drivers often spy these still extant birds soaring over highways.  They’ve adapted well to the roadkilled supermarkets of our modern highways which offer a buffet of dead deer and dogs.  Two fossil specimens of black vulture nestlings found at Kingston Saltpeter Cave, Bartow County prove this bird lived here during the Pleistocene as well.

Turkey vulture–Cathartes aura

Photo of google images of a turkey vulture.  They’re easy to distinguish from black vultures even if one can’t see the red head because they’re flying high in the sky.  Note the tail is much narrower on a turkey vulture than a black vulture.

Turkey vultures are still common but don’t congregate in large flocks like black vultures do.  Their niche differs too–they subsist on smaller carrion such as dead possums, flattened road-killed snakes and squirrels, etc.

Eagles also benefited from the deaths of Pleistocene megafauna.  Grinell’s crested eagle and hawk eagles, now extinct, probably relied on carrion for an important part of their diet.  Golden eagles and bald eagles were probably more comman then, thanks to the abundance of meat on the range.

Caracaras, ravens, and magpies were also more widespread during the Pleistocene because of the greater supply of meat.

References:

Harper, Frances

“Vultura sacra of William Bartram”

The Auk October 1932

Hertz, Fritz

“Diversity in Body Size and Feeding Morphology within Past and Present Vulture Assemblages”

Ecology 75 (4) June 1994

Two New Studies of Sabertooth (Smilodon fatalis) Anatomy

July 8, 2011

Artist’s rendition of saber-tooths from google images.  The San Diego MNH warned me that I couldn’t use theirs.  This one is better anyway.  The San Diego MNH can kiss my ass.

In 1973 a Time Magazine article sparked my fascination with Pleistocene ecology.  The article was entitled “Tiger in the Bank,” and was about the discovery of Pleistocene fossils during construction of the First National Bank in Nashville, Tennessee.  Construction workers leveled 4 small Indian mounds and dug 30 feet deep into the ground to lay the foundation for the future skyscraper.  They used dynamite and heavy moving equipment to blast and dig through limestone and dirt.  An alert  worker discovered a saber-tooth tiger fang and haulted construction.   Bob Ferguson, a local fossil hunter, and scientists from Vanderbilt University  began excavating the site and found bones from many different species of Pleistocene and contemporary animals which I list below.  The carbon date on the saber-tooth bones piqued my then grade school imagination –it was estimated to be just 9,410 years old.  To me, 9400 years didn’t seem that long ago, especially compared to dinosaurs which are all at least 65 million years old.  It amazed me that something so exotic ranged through Tennessee so recently.  Since then, scientists, armed with advances in knowledge and techniques of carbon dating, no longer trust carbon dates derived in the early 1970’s.  Moreover, it’s now known those dates when adjusted to tree ring chronology were too young.  Today, a date of 9400 years is adjusted to 10,200 calender years.  The carbon date done in 1973 simply means the saber-tooth was at least 9400 years old, and a good terminal date on Smilodon doesn’t exist.  Still, after considering the low odds of a living animal becoming a fossil specimen, I think it’s probable saber-tooth populations survived somewhere  until between 6,000-9,000 years ago, although their decline in numbers began well before them.  The late Dr.  Guilday, the scientist who examined the saber-tooth bones found at this site, did test it for organic matter, and it proved fresh, supporting the recent date.  The bone still consisted mostly of organic matter and didn’t have a lot of permineralization yet.

Smilodon jaw and muscle diagram from google images.

New discoveries of Smilodon fossils are rare.  But thanks to abundant fossil material found at the La Brea Tar Pits, scientists are able to study its anatomy in detail.  The 2 new studies yield nothing surprising or contrary to expectation. The first study (“A Dynamic Model for the Evolution of Sabercat Predatory Bite Mechanics” by Per Christiansen) examined saber-tooth bite mechanics.  Saber-tooths are known to have had weak biting power compared to other carnivores.  Instead, they used their powerful neck muscles to thrust their long canine fangs forward into the neck of their prey.  Their jaw muscles were shortened and more specialized for inflicting traumatic damage and immediate mortality.  Unlike extant cats, they didn’t suffocate their prey with time-consuming throat bites which would increase the probability that struggling prey would damage their fangs.  They efficiently severed jugular and windpipe with one quick bite.

Smilodon arm bones from google images.

The second study (“Radiographs Reveal Exceptional Forelimb Strength in the Saber-tooth Cat, Smilodon fatalis” by Julie Meacham-Samuels, et. al.) calculated the arm strength of Smilodon and compared it to that of 29 other species of cats.  They measured the size of different parts of the arms based on radiographs and used 5 different formulas derived from basic laws of physics including this one: Axial Compression = pye (external caudal diameter) (external medialateral diameter)-(diameter of medullary cavity) (medialateral diameter of medullary cavity)/4.   They determined that saber-tooth arm strength far surpassed that of any living cat or even the larger extinct giant panther aka the American lion (Panthera atrox).  Not only were they naturally stronger, but wrestling with large prey built up strength, much like humans  use weight training to increase muscle mass and strength.  Experienced saber-tooths would be much stronger than those first learning to hunt on their own.  The authors of the study found that greater forelimb strength co-evolved with lengthened canines in other species as well.  It was critical for carnivores with long fangs to quickly subdue prey to reduce the risk of damage to their canines.

References:

Christiansen, Per

“A Dynamic Model for the Evolution of Saber-cat Predatory Bite Mechanics”

Zoological Journal of the Linnean Society 162 (1) May 2011 220-242

Meacham-Samuels, Julie; Blaine Van Valkenburgh, Allen Fork

“Radiographs Reveal Exceptional Forelimb Strength in the Saber-tooth, Smilodon fatalis”

Plosone 5 (7) 2010

See also my article “Why did Fanged Cats have Long Forelimbs and Sloping Backs?” from my October 2010 archives

The First National Bank Fossil Site

Photo from wikipedia of display case in the Regions Bank Center, Nashville, Tennessee, which sits on top of a Pleistocene fossil site.  These are replicas.  Officials don’t know who has the real fossils that were found at this site.

10,000 years ago, a shaft leading to a limestone cave acted as a trap for many species of animals which either fell or crawled inside and died.  Eventually, this cave filled with mud and became covered with sediment.  The shaft periodically became exposed to the surface during the Woodland Indian era of 2000 years BP, and even during Colonial times.  The Indians built 4 small mounds here.  In 1971 executives from First National Bank chose to build a skyscraper at this location.  Construction workers used dynamite to blow up the limestone rock.  Backhoes removed the fill.  One worker saw a “saber-tooth tiger” canine and haulted construction.  As I stated above, Bob Ferguson and scientists from Vanderbilt excavated what was left of the cave.  Most of the fossils they found were actually in the spoil piles that had already been removed.  Fossils and artifacts from 3 different eras were mixed in the spoil piles, ruining the chronostratigraphy.  They found fossils of colonial era livestock, mixed in with the remains of 4 buried Indians, and Pleistocene fossils.  Regions bank merged with First National Bank, but they still keep a display case of replica fossils.  Officials don’t know who has possession of the original fossils.  Bank officials claim they sent the fossils to the Smithsonian Institution.  The Smithsonian Institution claims they never received them.  If anybody knows who has possession of them, please respond to this article and tell us.

The remains of the cave still exist and can be accessed via a hatch under the basement of the skyscraper.  Reportedly, cavers who revisited the site in 2008 were unimpressed.  The archaeologist who wrote the newspaper article about this cave expedition that  was published in The Tennessean was sadly misinformed when he stated that saber-tooths didn’t overlap in time with humans. Here’s the list of fossils found at the site:

# denotes fossils were found from remnant Pleistocene strata

# Fish scales sp.?

Toad sp.?

mud turtle

water snake

garter snake

#black racer

#northern pine snake

milk snake

#rattlesnake

coot

opossum

least shrew

short-tailed shrew

eastern mole

#cottontail rabbit

swamp rabbit

squirrel sp.?

pocket gopher

deer mouse

pine vole

canis sp.?

bobcat

#saber-tooth–119 fragmented teeth and bones of 1 individual.  A canine was intact.  Bones were relatively fresh with little permineralization

raccoon

striped skunk

#mastodon–a baby tooth

#horse–more than 1 individual.  Some may be mixed in with colonial era material

domestic hog

deer sp.?

#musk ox sp.? –probably woodland musk-ox.  Just a phalanx.

long-nosed peccary

human

Reference:

Guilday, J.E.

“Saber-tooth cat, Smilodon floridanus, and associated fauna from a Tennessee Cave (40Dv40), the First American Bank Site”

Journal of Tennessee Academy of Science 52 (3): 84-94

Available online–http://iweb.tntech.edu/sstedman/JTAS%2052-3.pdf

Fire Suppression = A Decline in Biodiversity (Part 3, Plants and Landscapes)

July 5, 2011

Fire creates aesthetically pleasing landscapes populated with countless species of attractive plants.

The above image captures two species dependent on fire–longleaf pine (Pinus palustris) and wiregrass (Aristida beyrichiana).  The fallen pine needles and dried tufts of wiregrass provide tinder for frequent light fires that eliminate potential competitors.

Canebrakes dominated river bottomlands, forming impenetrable thickets that stretched for miles.  Individual canes grew to 40 feet tall.  Now, this environment is nearly extinct and is more endangered than longleaf savannahs.  Fire suppression, flood control, and passenger pigeon extinction are factors in the decline of canebrakes as I explained in last week’s blog entry.  Indians used bamboo for arrows, blowguns, fish traps, and housing construction.

Oak savannahs are so rare in Georgia that I had to use a painting by Philip Juras instead of a photograph from google images.  Oak savannahs used to be the most common landscape on piedmont uplands in the south.  Now, they are exceedingly rare.  If I could live in a prehistoric wilderness, I would build my house in an oak, or oak and pine savannah.  It’s my favorite.  Ideally, I’d like to have an oak and pine savannah on one side, and a Pleistocene beech, hickory, and Critchfield’s spruce forest on the other side sloping toward a river.

Purple coneflowers (Echinaceae purperea) used to be common in the open environments of the south.  Now, it’s regionally rare in the wild.  The federal government actively protects existing colonies.

Rosinweed (Sylphium sp.).  They look like sunflowers but they’re not even related.  The Indians used sap from the flowering plants for chewing gum.

Andropogon virginicus (Broomsedge bluestem) #22

Broomsedge is a common early dominant in old fields.  Most of the grasses that inhabit natural meadows and savannahs, including bluestem and wiregrass, grow as clumps rather than carpet-like lawn grasses.

Goldenrod (Solidago sp.).  This is one of the last plants to bloom in the fall.  It’s not to be confused with ragweed (Ambrosia sp.) which causes hay fever.  Both bloom at the same time, and they occur in the same habitats.  Goldenrod has heavy sticky pollen with big showy flowers that attracts insects for pollination.  Ragweed has tiny insignificant flowers and has light pollen dependent on wind for pollination.  Allergy medications use images of goldenrod instead of ragweed in advertisements, even though this species doesn’t normally cause allergies.