Striped Skunk (Mephitis mephitis) Dispersal During the Pleistocene

Most people don’t even think about where and when the various species of wildlife inhabiting their neighborhood originated. No matter how common a particular species may seem, it has not always been there.  The striped skunk is a generalist species that occurs all across the United States, and it is quite common in many regions, especially rural farm country. It is found in forests, fields, wilderness and suburbs.  They are an adaptable species, thanks to their omnivorous diet and unique defense strategy.  Yet, striped skunks have not always existed over their present day range.

The ancestors of all American skunk species came to this continent by crossing the Bering Land Bridge over 5 million years ago.  Paleontologists assign fossils of this ancestral species to the extinct  Martinogale genus.  About 2 million years ago striped skunks in the Mephitis genus diverged from spotted skunks in the Spilogale genus.  There is fossil evidence of early species of Mephitis skunks from the early and mid-Pleistocene in Nebraska, Colorado, and Florida.  However, this early species must have gone extinct over much of its range.  By 300,000 years ago, Mephitis skunks were restricted to what today is northern Mexico and southern Texas.  All present day striped skunks descend from this ancestral population, according to a study of striped skunk genetics.  Scientists studied genetic information from 314 specimens chosen from 20 states and determined striped skunks spread east and west from this population.  Early striped skunks, like their closest living relative–the hooded skunk (M. macroura), were probably well adapted to desert environments but evolved characteristics that helped them survive in woodlands and grasslands.  Over 250,000 years ago, striped skunks crossed the Mississippi River and colonized the entire southeast.  This probably occurred during a glacial stage when the river ran low and numerous sandbars facilitated the crossing.  The lower Mississippi River has served as a barrier, isolating populations of striped skunks ever since.

Dispersal of striped skunk population during the Pleistocene based on genetic evidence from 314 specimens taken from 20 states. Map from the below referenced study.

The hooded skunk (Mephitis macroura) is the closest living relative of the striped skunk.  Its range is Mexico and the extreme southwestern U.S.  Genetic evidence suggests this is also the geographic range where striped skunks originated.

Nice photo showing coat variation within the striped skunk population.  Striped skunks colonized southeastern North America about 300,000 years ago.  A primitive closely related species occupied this region before that.  It’s unclear when this predecessor became extinct.

~200,000 years ago striped skunks advanced up the Rocky Mountains from their southwestern refugium.  This population split into 2 clades on either side of the Great Basin 130,000 years ago.  This western population expanded east and colonized the Midwest.  Following the end of the last Ice Age, southeastern skunks colonized New England and expanded west, coming into contact with western populations in the Midwest.  This has resulted in an admixture of once genetically distinct populations.  The history of this dispersal explains why skunk physical characteristics vary so much. The upper Mississippi River is smaller than the lower part and is not an insurmountable barrier.  Admixtures occur along the upper part of the river.  Genetic studies of raccoons, deer mice, northern short-tailed shrews, 5-lined skinks, and leopard frogs show similar dispersal histories with the Mississippi River acting as a barrier isolating populations from each other.

Reference:

Barton, Heather; and Samantha Wisely

“Phylogeography of Striped Skunk (Mephitis mephitis) in North America: Pleistocene Dispersal and Contemporary Population Structure”

Journal of Mammalogy 93 (1) 2012

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Sand Dunes Rolling Across the South

Ice Age environmental conditions influenced the present day landscapes of many geographical localities, including the Carolina Sandhills.  A recent study determined Ice Age winds shaped the topography of this region.  The sand originated from loose sediment and eroded sandstone within a Cretaceous-age formation located near the surface.  Arid climatic conditions caused by glacial expansion exposed part of this formation.  Frequent droughts reduced vegetative cover, so there were bare patches of soil without tree and grass roots holding the sand in place.  I think overgrazing by megafauna during droughts played a role in denuding the landscape as well.  Cold winds blew the exposed sand into massive eolian dunes that rolled across the land.

The Sand Hill Region is encircled in red on this map.  At least parts of it originated during Ice Ages when cold winds blew exposed sand across the landscape here.

Vegetation stabilizes sand dunes in the region today.  Local sand dunes have been inactive for at least 6,000 years.  They were most active during the coldest driest phases of Ice Ages.

The authors of the below referenced study took core samples of sand hill sediment in Chesterfield County, South Carolina.  They found an unconsolidated layer of sand measuring from ~1 foot to about 30 feet deep.  Optically stimulated luminescence dates (See: http://www.usu.edu/geo/luminlab/whatis.html ) suggest dunes were active from 75,000 years BP-37,000 years BP when glaciers were expanding and from 28,000 years BP-18,000 years BP during the Last Glacial Maximum and again from 12,000 years BP-6,000 years BP.  The beginning of the final period of dune activity corresponds with the Younger Dryas cold reversal when average global temperatures suddenly plummeted following a warm climate cycle.  Scientists found no evidence of dune activity between 37,000 years BP-28,000 years BP and 18,000 years BP-12,000 years BP.  These dates correspond with warmer wetter interstadials when plant growth stabilized sand sheets and dunes, holding them in place.  There has been no dune activity in the Carolina Sandhills for at least 6,000 years because higher precipitation levels foster thicker vegetative growth.

The Great Kobuk sand dune in Alaska.  During the Ice Age landscapes in the sand hill region may have resembled this, though short leaf pines, grass, and scrub oak as well as spruce were the characteristic vegetation between the dunes instead of just spruce.

Sand dunes probably advanced the most on cold windy Ice Age nights.  Experiments show air temperature is a factor in sand particle transport.  Decreasing temperatures increase air density and lower water vapor thus reducing drag on the sand particles.  Larger particles can get picked up and transported by wind more easily when temperatures drop.  The region may have experienced brutally low temperatures compared to present day averages.

Sand dune origin in the Carolina Sandhill region differed a little from sand dune formation in Georgia.  The source of sand in the Carolina Sandhills is a geological formation near the surface, but many dunes in Georgia originated from dry river beds where sand was exposed because water tables dropped.  (See: https://markgelbart.wordpress.com/2012/04/09/the-ohoopee-sand-dunes/ ).

Pollen evidence indicates the dominant flora growing between the sand dunes during the Ice Age consisted of pine, spruce, scrub oak, grass, and asters (sunflowers, daisies, etc.).  It was probably an open woodland type of environment, though scrub oaks may have formed denser thickets.  I believe shortleaf pine (Pinus echinata) and possibly Virginia pine (P. virginiana) were the dominant species of pine here then.  It was too cold and windy for longleaf pine (P. palustris), commonly found here today.  I’m no longer convinced jack pine (P. banksiana) occurred this far south.  Some pollen studies list jack pine as a species present in this region during the Ice Age.  However:

1)The present day range of jack pine is too far away from the Carolina Sandhills. It seems unlikely its range would have retracted so drastically without leaving a relic population anywhere in the south.

2)  There are no definitive macrofossils of jack pine in the south.

3) Evidence jack pine was present in the south is based on identification of pine pollen, but 1 researcher makes the compelling case that jack pine pollen is indistinguishable from shortleaf pine pollen.  (See: https://www.osti.gov/scitech/biblio/564104 ).  Jack pine pollen is distinguished from other species of pine pollen based on the size of its grains but they overlap in size with shorleaf pine pollen grains.  Because shortleaf pine occurs in the region today, it seems more likely pollen evidence represents this species, not jack pine.

The species of spruce tree present in the Carolina Sandhills during Ice Ages was probably the extinct Critchfield’s spruce.  Macrofossils of this species have been found associated with temperate species of hardwoods.  The average annual temperatures of the Carolina Sandhills during Ice Ages was probably similar to present day southern Ohio or Kentucky, not like southern Canada as some researchers estimate based on their mistaken assumptions of tree species composition.  The Carolina Sandhills are located in what was a sharp transition zone of climate during the Ice Age.  A thermal refuge existed to the southeast where warm waters off the Atlantic coast pooled because thermohaline circulation (the tropically heated water that presently flows off the coast of New England) shut down.  But temperatures sharply dropped to the north and west of this thermal refuge, not unlike conditions experienced by mountain climbers rapidly ascending a mountain.

The Carolina Sandhills likely supported significant populations of megafauna, despite the vast expanses of bare sand.  Open grassy land fed mammoths, caribou, horses, bison, llamas, and Harlan’s ground sloth.  Scrub oak thickets attracted herds of flat-headed peccaries.  Giant lions and dire wolves roamed the interdunes, seeking out megaherbivores.

Reference:

Swezey, Christopher; et. al.

“The Carolina Sandhills: Quaternary Eolian Sand Sheets and Dunes along the Updip Margin of the Atlantic Coastal Plain Province, Southeastern United States”

Quaternary Research 86 (2016)

Horse Toe Bones and 14,000 Year Old Human Shit

The oldest known evidence of human presence in North America is some pieces of shit excavated from Paisley Cave, Oregon.  Carbon-dating of this feces indicates humans crapped in the cave about 14,350 calendar years ago.  The contents of these turds consists of bison, dog, bird, fish, grass, and sunflower seeds.  One study found the amount of cholesterol and phosphate in the crap points to an animal with a vegetarian rather than an omnivorous diet, and the authors of this paper don’t believe it is human manure.  They suggest the human DNA extracted from the specimens are a result of contamination from people mishandling it.  However, the contents were mostly animal matter, so I don’t understand how the naysayers who authored this paper can come to this conclusion.  Other scientists note the presence of wolf or fox DNA in the crap.  The scientists who are convinced the turds are human believe a wolf or fox pissed on the human shit after people left the latrine.  The turds contain human hair–perhaps the best evidence people were the shitters here.  Dried crap stuck to their ass crack hairs and the hair came off when they wiped with leaves.

Horse toe bones were found in Paisley Cave along with 14,000 year old human feces.

A 14,000 year old human turd found in Paisley Cave, Oregon.

Many vertebrate bones and human artifacts have been discovered in the cave.  (See: https://markgelbart.wordpress.com/2010/10/29/the-paisley-cave-pre-clovis-site/ ).  Paleontologists studied the horse toe bones excavated near the human feces because they wanted to determine which species of horse co-existed with humans in this region then.  They believe with a >99% probability the toe bones belonged to an extinct species known as the Mexican horse (Equus conversidens). Most fossil material of this species has been found in Mexico, hence the name, but it likely occurred all across North America.  The Mexican horse was stocky and stilt-legged.

Paleontologists disagree over the number of horse species that lived in North America during the late Pleistocene.  Some believe there were 2 species, while others think there were more than 14 species.  Genetic evidence supports the proposed smaller number of species.

I have no doubt humans were responsible for the extinction of North American horses through overhunting and disruption of ecosystems.  When Europeans re-introduced horses to North America during the 16th century, horses went wild and thrived everywhere on the continent.  It seems unlikely an environmental change capable of causing horse extinctions occurred for such a short interval some time between 10,000 BP and 1500 AD.  Horses eat grass and coarse vegetation–plant material that never became scarce during any climate phase or change.  Climate change models of extinction don’t work at all for such an adaptable and widespread animal as the horse.

I remember when I first started studying the debate over megafauna extinction.  Opposition to human overkill as a cause of extinction centered around the flimsy argument that there was a lack of archaeological evidence of humans hunting horses in North America.  Since then, irrefutable proof humans hunted horses here has been unearthed at several sites.  Wally’s Beach in Alberta, Canada was the first site where archaeologists agreed evidence humans hunted horses was unmistakable. Bluefish Cave in the Yukon is located north of the former Cordilleran Ice Sheet.  Evidence humans hunted and ate Ice Age horses has also been discovered in this cave, and it dates to as early as 24,000 years ago.  Humans carried horse, caribou, elk, dall sheep, bison, and bird into the cave.  36,000 mammal bones have been excavated from this site.  Wolves, lions, and foxes, in addition to people are responsible for the bone accumulation.  And now, South American archaeologists believe a cave in Argentina holds evidence of human exploitation of horse.  Stone tools are found in association with human-modified bones of horse, hippidion (an exclusively South American species of horse), llama, toxodon, giant armadillo (Eutatus) and ground sloth (Megatherium and Glossotherium).

The evidence humans did hunt megafauna is mounting but will probably never convince old school archaeologists who (I believe) stubbornly refuse to admit they were wrong for so many years.

References:

Bourgeon, L.; A. Burta, T. Higgins

“Earliest Human Presence in North America Dated to the Last Glacial Maximum: New Radio-carbon dates from Bluefish Cave, Yukon”

Plos One January 2017

McHorse, Brianna; Edward Davis, Eric Scott, Dennis Jenkins

“What Species of Horse was Coeval with North America’s Earliest Humans in the Paisley Caves?”

Journal of Vertebrate Paleontology September 2016

Politis, Gustavo; M. Gutierrez, D. Rafus

“The Arrival of Homo Sapiens into the Southern Cone at 14,000 Years Ago”

Plos One September 2016

Sistiaga, A.; F. Berna, R. Laursen, P. Goldberg

“Steroidal Biomarker Analysis of a 14,000 Year Old Putative Human Coprolite from Paisley Cave”

Journal of Archaeological Science 2014

 

First Bone-eating Dog (Borophagus sp.) Tooth Found in South Carolina

The Borophagine dogs were an incredibly successful lineage of carnivores that lived from ~34 million years BP to ~2 million years BP and perhaps beyond.  They ranged throughout North America from coast to coast and from Canada to Honduras.  16 species of Borophagine dogs are known from 12 different fossil sites in Florida alone, and in the rest of the southeast specimens have also been found in North Carolina and Maryland.  Recently, an amateur fossil collector found 1 pre-molar of a Borophagus in a spoil pile at the Martin-Marietta Orangeburg Quarry located in Orangeburg County, South Carolina.  This animal was probably common in South Carolina for millions of years, but this is the only known evidence it ever existed in the state.  Paleontologists examined the tooth and determined it compared favorably to a pre-molar of Borophagus hilli, a species that reached a weight of 130 pounds.  The age of this fossil is estimated to be between 3.9 million years BP-3.1 million years BP based on associated microfossils.  B. hilli co-occurred with another species of Borophagine dog–B. diversidens.  They must have occupied different ecological niches, maybe like modern day wolves and coyotes.

Jaw bone of Borophagus hilli–the Pliocene bone-eating dog.

Artist’s depiction of the extinct bone-eating dog.  They had bulging foreheads.  Their teeth and jaws were similar to those of the extant spotted hyena–an example of convergent evolution.

Early species of Borophagine dogs were omnivorous.  Epicyon haydenii was the largest known species of canid in history, reaching weights of over 500 pounds.  This species lived between 12 million years BP-6 million years BP, and it probably occupied a bear-like ecological niche.  Borophagine dogs later evolved into more carnivorous forms, resembling modern day spotted hyenas (Crocuta crocuta) in build and dentition, hence the reason they’re often called bone-eating dogs.

Epicyon haydenii was the largest known canid in history, growing as large as a grizzly bear.  They were more omnivorous than their later descendants.  They lived during the Miocene.

Scan of the lower 4th pre-molar of a Borophagus.  This is the only fossil evidence found in South Carolina of a species that was formerly common in the region for millions of years.

Despite their long reign as an important carnivore in the American ecosystem, Borophagine dogs became extinct during the late Pliocene or early Pleistocene.  The last species of Borophagine dogs co-existed with dogs belonging to the Canidae family for millions of years.  The Canidae were newcomers from Eurasia that crossed the Bering land bridge to reach North America.  Species from the Canidae family were better able to adapt to changes in the environment during the early Pleistocene and likely outcompeted Borophagine dogs, contributing to their extinction and completely replacing them ecologically.

Reference:

Tseng, Z. Jack; and Jonathan Geisler

“The First Fossil Record of Borophagine Dogs (Mammalia: Carnivora) from South Carolina USA”

Journal of Vertebrate Paleontology 36 (2) March 2016

Pygmy Sperm Whales of the Pliocene

The transition between the Pliocene and the Pleistocene about 2 million years ago was  marked by a major marine extinction event.  By contrast there was far less faunal turnover on land.  Many species of whales that no longer exist swam in Pliocene oceans.  Paleontologists recently analyzed fossil whale ear bones excavated from sites in Florida and North Carolina and determined at least 2 morphotypes of pygmy sperm whales occurred in the Atlantic Ocean during the Pliocene.  These specimens may represent different species or size variations within a single species.  Scientists can’t make a certain determination based on just the ear bones.  Extant bottle-nosed dolphins ( Tursiops truncatus ) occur as 2 different morphotypes in the Atlantic Ocean. Deep sea dolphins are larger and more powerful than near coastal dolphins, and dolphins living in estuaries and tidal rivers don’t even interbreed with dolphins living off the coast.  Yet, these 3 separate populations are considered the same species.  The extinct species of pygmy sperm whales may have also occupied different habitats.

The pygmy sperm whale fossils came from phosphate mines in Florida and spoil piles originating from Lee Creek Mine in North Carolina.  The Florida site is thought to yield fossils that are 5-4.7 million years old, and fossils from Lee Creek Mine are estimated to be between 4.8-3.1 million years old.  Ear bones of the larger morphotype were found at both sites, but the smaller morphotype was found exclusively in Florida.

Pygmy sperm whales are barely bigger than bottle-nosed dolphins.

Dwarf sperm whale ear bone.  The dwarf sperm whale is not the same species as the pygmy sperm whale.

The extant pygmy sperm whale ( Kogia breviceps ) grows to 11 feet long and feeds upon squid, octopus, and shrimp.  They release a kind of ink from their intestines when they are attacked by large sharks or killer whales.  I think this defense strategy is unknown among any other species of mammal.  Pygmy sperm whales are related to dwarf sperm whales ( K. sima ), and the more famous hero of the novel, Moby Dick ( Physeter macrocephalus ).  Like their larger cousin, pygmy sperm whales locate their prey using echolocation.

The sperm whale family had more relatives during the Pliocene, but those extinct species are so little known and so little evidence of them remains that we will probably never know what made each unique.

Reference:

Velez-Jaurbey, Jorge; A Ward, and C. Pimento

“Pygmy Sperm Whale (Odostecenti, Kogiidae) from the Pliocene of Florida and North Carolina”

Journal of Vertebrate Paleontology 2016

 

Dumpster Dingoes

Bacteria. Cockroaches. Flies. And even higher organisms. Mice. Rats. Sea gulls. Crows. Bald Eagles. Cats. Dogs. Wolves. Bears.  These are just some of the organisms that benefit from the food waste produced by humans.  We waste up to 40% of the food we produce.  The proliferation of Homo sapiens since the late Pleistocene has been detrimental to many species, but others have adapted to our presence.  Scientists estimate anthropogenic sources, including livestock and garbage, make up 32% of the worldwide gray wolf diet.  The last surviving population of Asiatic lions almost entirely subsists on livestock.  Studies show Australian dingoes and red foxes that live near landfills have smaller home ranges and higher survival rates than other individuals of the same species.  Dingoes living near garbage dumps grow fat and mate with domestic dogs, producing hybrids that could be called dumpster dingoes.  This same study found black bears foraging around dumpsters have shorter lifespans because they come into conflict with people and get shot.

Landfills are excellent sites for bird watching.  They attract gulls, crows, and vultures.  I have even seen a bald eagle soaring over one.

Dogs evolved from wolves that hung around human refuse heaps.

Dingo chasing a kangaroo.  Dingoes that hang around landfills get fat and lazy and mate with domestic dogs.

The existence of human refuse heaps likely spurred the evolution of wolf into dog.  The physical characteristics that differentiate dogs from wolves share the same genetic pathway with tameness.  The 2nd and 3rd generations of canids with the least flight response develop the floppy ears and multi-colored coats common in domestic dogs.  Some scientists think it possible some modern day wolves scavenging dumpsters could again evolve into a type of dog.

Genetic studies suggest dogs developed the ability to digest more starch about 4000-7000 years ago–another step in the ongoing evolution of wolf to dog.  This coincides with the development of agriculture when humans began cultivating cereal grains.  Dogs with digestive systems capable of producing more amylase, the enzyme that helps convert starch to sugar, were better able to survive on bread when humans started consuming more cereal grains instead of (or as a supplement to)  meat.

Dingoes descend from dogs brought to Australia about 4000 years ago by people from the subcontinent of India who later assimilated with Australian aborigines.  Dingoes are primitive dogs similar enough to their wolf ancestors that they can revert to the wild and thrive.  Dingoes rapidly became the top non-human predator in Australia.  Most people are unaware dingoes live in America as well. ( See: https://markgelbart.wordpress.com/2013/02/11/the-american-dingo/ ) Native Americans brought primitive dogs with them from Asia, and some of them went wild here just like they did in Australia.  North American dingoes are known as Carolina dogs and were not recognized as a distinct wild canid until a scientist found them running wild during the 1970s on the Savannah River Site in South Carolina.

The observed differences between wolf, dingo, and dog are a good example of recent evolution.  They also show the line between species can be blurry.  All 3 can interbreed and produce fertile offspring.  So some scientists think dogs and dingoes should be classified as subspecies of wolf.  On the other hand the physical and behavioral characteristics of each are quite different, and some scientists still classify them as distinct species.  Domestic dogs are entirely dependent upon humans, dingoes (a transitional form between dog and wolf) can take us or leave us, and wolves avoid us and probably wish humans would become extinct.  I prefer classifying them as separate species based on behavioral differences.

References:

Marshall-Pescini, Sarah; Ingo Besserdick, C. Kratz, F. Rang

“Exploring Differences in Dogs and Wolves’ Preference for Risk in Foraging Trash”

Frontiers in Psychology August 2016

Newsome, Thomas; Gary Ballard, Matthew Crouther, and Chris Dickman

“Dietary Niche Overlap of Free-Roaming Dingoes and Domestic Dogs: The Role of Human-Provided Food”

Journal of Mammalogy April 2014

Oro, Daniel; et. al.

“Ecological and Evolutionary Implications of Food Subsidies from Humans”

Ecology Letters October 2013

 

 

Revisiting Lewis and Clark

I haven’t written about the Lewis and Clark expedition before because I try to keep my blog focused on southeastern North America and most of their famous route went through the northwest.  However, the diary of their journey is probably as close as we could ever get to a written account of a theoretical trip by western scientists through a Pleistocene wilderness.  So it is worth covering here.  Lewis and Clark saw western North America when it was thinly populated by Indians and a few white traders.  Humans had not yet completely ruined the environment then.

Route of Lewis and Clark expedition.

I recently reread the journal of this expedition, and I was struck by how barbaric some of their practices were.  Though this was considered the Age of Reason, they still retained some medieval methods of problem-solving.  Soldiers who broke the rules were whipped.  One man was sentenced to 25 bareback lashes for poor behavior during a social event the night before they began their journey.  Lewis learned enough “doctoring” to be in charge of treating injuries and sick men.  One of his treatments was blood-letting.  At the time physicians wrongly thought bleeding patients could cure certain ailments.  When George Washington was dying of pneumonia his doctors bled him.  Of course, it didn’t work and he died anyway.

Lewis and Clark engaged in barbaric practices such as blood-letting as a medical treatment and whipping to ensure obedience from their men.

The expedition traveled by sail up the Missouri River, then crossed the Rocky Mountains and sailed down the Columbia River to the Pacific Ocean.  When the wind was unfavorable, they attached ropes to the boat, and the men and their horses pulled the boat upstream.  The company depended upon fish and game for a large part of their diet.  It’s interesting to note how the fish composition changed as the expedition traveled up river.  In the lower part of the Missouri River catfish, buffalo fish, and sucker fish were common.  In 1 beaver pond they netted 318 fish including pickerel, bass, perch, and sucker fish, in addition to crayfish which they called “shrimp.”  In another pond by the river they caught 800 fish over half of which were catfish.  As they advanced up the river they began catching trout, sauger, and goldeye.  Salmon were found in the Columbia River.

 

 

The Lewis and Clark expedition relied heavily on fish and game while they traveled on the Missouri and Columbia Rivers.  1 single catfish they caught was so big it yielded a quart of oil.

The wildlife was spectacular on the tallgrass and short grass prairies.  In the former they saw deer, elk, and feral horses.  Beavers were abundant all along the river.  The short grass prairie supported large mixed herds of bison, pronghorn, elk, mule deer, and white tail deer.  Lewis reported seeing an herd of 10,000 bison.  Big flocks of white pelicans and geese lived on oxbow lakes.  Grizzly bears were a dangerous problem.  They were difficult to kill with the primitive muskets of the day, and the men had numerous near fatal encounters with them. Cougars were present but rarely seen.  By contrast the expedition found little game when they crossed the Rocky Mountains.

Bison and pronghorn.  The expedition often saw large herds of bison, pronghorns, elk, and mule deer together.

Scene depicting grizzly chasing a member of the Lewis and Clark expedition into water.  Happened more than once.

The expedition brought flour, salt pork, canned soup, and dried corn with them, but they relied more on fish and game.  During winter and spring the animals they killed were often so poorly nourished the only edible part was the marrow bones.  Italians call this “osso bucco.”  In my opinion osso bucco is a fancy name for a dog bone.  Nevertheless, the men relished the fatty marrow. Game was in better condition during summer and fall.  One bison  or 1 elk and 1 deer or 4 deer could feed the expedition for 1 day. Game was scarce in the Rocky Mountains, and they were forced to eat their horses.  They were literally so hungry they could eat a horse.  The food they ate when they traveled down the Columbia River consisted mostly of dog, salmon, roots, and berries.  Most of the men learned to like dog meat, preferring it over venison.  On the coast they purchased whale blubber Indians had scavenged.  They ate wild fruit in summer and fall–grapes, plums, blackberries, blueberries, salmon berries, service berries, and pawpaws.

The Lewis and Clark expedition is credited with discovering 178 species of plants and 122 species of animals new to western science.  The number of animal species they supposedly discovered is wildly exaggerated.  I’ve seen the list, and it includes subspecies of already known species.  They were the first white people to report prairie dogs.  I counted 69 actual species the Lewis and Clark expedition may have introduced to western science.

I wrote a blog article a few years ago about a ring hunt that took place in Pennsylvania during 1760. (See: https://markgelbart.wordpress.com/2014/07/27/the-pennsylvania-mammal-holocaust-of-1760-a-rare-record-of-an-old-fashioned-varmint-drive/ ) Settlers exterminated wildlife in these organized hunts to protect their crops and livestock and starve out the Indians.   One of the animals killed was described as a white bear.  I assumed this was probably an albino black bear or maybe a polar bear that had wandered south.  But I learned members of the Lewis and Clark expedition referred to grizzlies as white bears because some have silver-tipped hairs.  This suggests the white bear killed in Pennsylvania was a grizzly bear that wandered east.  Perhaps, grizzlies occasionally occurred as far east as Pennsylvania during the pre-Colonial era.  Fossil evidence of grizzly bears has been found in Kentucky, but this dates to the Pleistocene.