Archive for August, 2017

Pleistocene Saiga Antelopes

August 31, 2017

The saiga antelope (Saiga tatarica) ranged from western Europe to Alaska and the Yukon during some climate phases of the late Pleistocene.  This range closely corresponds with an environment known as the mammoth steppe.  This paleoenvironment was similar to the present day central Asian steppe but was more productive, hosting a greater variety of plants and microhabitats that included scrub, woodland, and wetland embedded in a sea of grass.  Summers were cool, winters were long, wind was constant, and precipitation was infrequent.  The bulbous nose of the saiga antelope is an adaptation for living in this kind of environment.  It helps warm frigid air and filter the dust in a dry windy climate.  The range of the saiga antelope has been greatly reduced since the late Pleistocene due to changes in the environment and overhunting by man.  Nevertheless, saiga antelope occurred in eastern Europe as late as the 17th century, indicating they are not a relict species confined to steppe grasslands.  A recent scientific study examining the bone chemistry of subfossil and extant saiga antelope specimens concluded this species can survive on a greater variety of plant foods than present day populations consume.

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Saiga antelopes are critically endangered today but lived from the British Isles to the Yukon, Canada during the late Pleistocene.

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Present day saiga antelope range.  During the Pleistocene they occurred from western Europe to Alaska.

This study found the diet of the saiga antelope overlapped with that of the caribou (Rangifer sp.) in southwestern Europe between 20,000 years BP-15,000 years BP.  It seems likely both species were subsisting upon lichen during winters when other plant foods were scarce.  Pleistocene saiga antelope apparently had a greater flexibility in their diet than present day populations.  The authors of this study suggest saiga antelope could potentially be introduced outside their present day range.  Poaching and disease outbreaks are endangering the surviving remnants of saiga antelope populations, so it could prove beneficial to establish new populations outside their present day range.  However, it’s possible some Pleistocene populations of saiga antelope may have been a distinct now extinct species with different dietary tolerances.  Some Russian paleontologist noted some morphological differences in saiga antelope specimens found outside their present day range, and they proposed a new species–Saiga borealis. Other paleontologists don’t accept this designation.  So far, no genetic studies have solved this difference of opinion.

The saiga antelope is considered a distant sister clade to the springbok-gerenuk clade.  They are the sole survivors of antelopes that roamed Europe before Ice Ages began to occur.  None of their closest relatives were able to evolve fast enough to survive deteriorating climatic conditions.

Reference:

Jurgensen, J.; at. al.

“Diet and Habitat of the Saiga Antelope during the Late Quaternary Using Stable Carbon and Nitrogene Isotope Ratios”

Quaternary Science Review March 2017

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The Korean Demilitarized Zone is an Amazing Wilderness

August 26, 2017

North Korea is not going to attack the U.S., no matter what Donald Trump says or doesn’t say.  The little fat turd who controls North Korea knows it would mean the end for him because even China wouldn’t back him, if he was the aggressor.  And the U.S. isn’t going to attack North Korea.  Trump will listen to his generals when they tell him an attack on North Korea would draw China into the war, and China has hundreds of nuclear weapons and enough surface-to-surface missiles to sink our entire Pacific fleet.

I feel sorry for the North Korean people because they are forced to live under the little fat turd’s rule.  But the U.S. voluntarily elected a giant fat turd as president.  Actually, referring to Donald Trump as a turd is an insult to turds.  A turd in a punchbowl would make a better president than Trump.

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A turd in a punch bowl would make a better president than Donald Trump.

Trump opened up his presidential campaign by calling Mexicans “drug dealers and rapists”–words that sounded like they came straight out of Archie Bunker’s mouth.  Ironically, Trump must think rape is only bad if a Mexican is the rapist because Trump brags about how he can rape women and get away with it. Trump is so dumb he equates peaceful protestors with neo-Nazis, and he thinks Jefferson Davis and other Confederate figures are comparable to George Washington and Thomas Jefferson.  They are not the same–they are the opposite.  George Washington helped found this country, while the Confederacy tried to tear it apart.  The Confederacy was an enemy of the U.S..  Enemies of the U.S. should not be venerated.  Trump has no credibility because he rarely tells the truth about anything.  He makes up absurd conspiracies and tweets them out in the middle of the night.  This is the symptom of a man who doesn’t have all his marbles.  Trump is also highly unethical, but I’m not going  to delve into this here because just the details of his crooked business interests could fill volumes.

Trump disgusts me, but I am even more disgusted with the stupid uneducated fools who voted for him.  They all look like a bunch of angry, shriveled-up losers.  They are so dumb they actually think this billionaire prick gives a shit about them.  Trump’s economic policies, if he ever is able to enact them, would greatly aid ultra rich plutocrats, like himself, while steamrolling the working class chumps who voted for him.  Trump proved this when he said he would actively work to make Obamacare fail.  This means he cares more about a legislative victory than the well being of the American people.  The election of Trump is an insult to the intelligence and integrity of the American people.  I think many people voted for him because of name recognition.  They were familiar with this dumb bigoted celebrity from his brainless TV show.  Other people are attracted to his xenophobic racism.  It is disturbing to realize there are millions of pro-rape racists living in this country.  I hate Trump voters.

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Trump supporters are shriveled up old losers.  His rallies are a sea of white faces, though occasionally there will be a token black guy carrying an awkward sign saying “Blacks for Trump.”  The Trump campaign undoubtedly paid for the token black guy to stand there.  Trump was elected by pissed off racists.  It is alarming to realize there are tens of millions of brain dead racists in this country.

The Korean Demilitarized Zone divides North and South Korea.  People haven’t lived in this zone for 64 years, and the land has reverted to wilderness.  The KDZ is 400 square miles of mountains, forests, prairies, wetlands, and tidal marshes.  At least 52 species of mammals live in the KDZ including 5 kinds of deer, wild boar, Asiatic black bears, leopards, leopard cats, and raccoon dogs.  Many of the species that live here are rare or extinct in the rest of Asia.  Critically endangered long-tailed gorals (a kind of goat), musk deer, red-crowned cranes, white-naped cranes, and black-faced spoonbills make the KDZ their home.  There are even rumors of Siberian tigers roaming the KDZ.  It seems impossible that so much wildlife can exist here.  Reportedly, there are 2500 landmines per square mile, and animals occasionally do trigger them.  Animals can thrive in minefields but can’t tolerate the presence of man–another example of how detrimental people are for wildlife.  Maybe some day, if Korea is ever unified, the KDZ will become a park.  In the rest of China and Korea wildlife has been obliterated, and pollution is a disaster.  Asia badly needs a park like this.

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The critically endangered red-crowned crane finds refuge in the KDZ.

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Ruddy kingfisher.

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Korean water deer.

Naemorhedus caudatus

Long-tailed goral.

 

Rapid Anole (Anolis carolinensis) Evolution

August 21, 2017

Misinformed creationists some times ask, if evolution is true, why isn’t it happening now?  There is a simple answer to that question.  Evolution is an ongoing process, and it IS happening now.  Evidence of continuing evolution isn’t readily apparent to the non-observant eye because usually it is a slow process–evolution often requires generations of natural selection to influence the phenotypical changes that demonstrate it.  However,  scientists discovered an example of evolution that occurred within 1 generation of an anole population in south Texas.  A team of scientists had recently studied the differences in cold tolerance between the population of anoles that live in south Texas with those that live near the northern limits of their range.  The south Texas anoles lose muscular coordination when temperatures drop to about 51 degrees F, while anoles near the northern limits of their range lose coordination when temperatures reach 43 degrees F.  An unusual cold snap struck south Texas shortly after scientists gathered this data, and they took another look at this anole population.  They discovered that exposure to cold temperatures changed the DNA of south Texas anoles.  4 genomic regions, especially those related to nervous system function, changed.  The lizards had rapidly evolved the ability to retain muscle coordination at lower temperatures, and they will pass these genetic changes on to the next generation.  This is a perfect example of evolution, defined as the change over time in the genetic characteristics of a population.  Most creationists can’t even define evolution.  They reject the fundamental basis of all biological science because it interferes with their belief in the supernatural.  Let’s see them try to deny this case study.

Anole characteristic threat display.

Anoles are a successful and rapidly evolving species. Some populations have adapted to city living, having evolved stickier toe pads that enable them to climb window glass.  In Florida the brown Cuban anole was accidentally introduced.  They occupy the same niche as the American anole.  In areas colonized by this alien anole, native anoles evolved larger toes that allow them to climb thinner branches.  This occurred in less than 15 years (20 generations for anoles living in Florida).  So now, areas with both species of anoles have a niche partition–Cuban anoles occupy lower branches, while native anoles live in the tree tops.

Worldwide, there are 391 species of anoles, but 9 are closely related to the species (A. carolinensis) that is widespread in the southeastern U.S.  Genetic studies suggests all 9 of these species descend from a founder population originating on Cuba.  A. carolinensis diverged from western Cuban anoles about 6 million years ago.  This occurred as a rafting event when a tropical storm washed debris from Cuba to the Gulf Coast of North America.  At least 1 male and 1 female were clinging to the debris when it made landfall.  All Caribbean islands were populated by anoles originating on Cuba from similar rafting events.

Fossil evidence of anoles has been excavated from 1 site in Georgia (Ladds), 1 site in Alabama (Bell Cave), and 10 sites in Florida.  None date to older than the mid-Pleistocene, but genetic evidence indicates they’ve occurred in southeastern North America since the late Miocene.

References:

Campbell-Staten, Shane; et. al.

“Winter Storms Drive Rapid Phenotype, Regulation, and Genome Shift in the Green Anole Lizard”

Science August 4, 2017

Glor, Richard; J. Losos, A. Larso

“Out of Cuba: Overwater Dispersal and Speciation Among Lizards in the Anolis subgroup”

Molecular Ecology 14 2005

Extant South American Canids are Ancient Relics

August 16, 2017

Several species of medium-sized canids native to South America descend from species that formerly occupied North America.  The extant bush dog (Speothos vunaticus), maned wolf (Chrisocyon brachyuras), and the recently extinct Falkland Islands wolf (Dusicyon australis) are (or were) similar to primitive dogs that occurred across North America during the late Miocene and Pliocene.  The emergence of the Canis genus (wolves and coyotes) early during the Pleistocene competitively excluded these primitive dogs from North America, but their ancestors pushed through the jungles of Central America, and they colonized South America where they still thrive today when not persecuted by man. The tropical rain forests of Central America served as a geographical barrier that prevented Canis species from following their primitive relatives.  Though Canis species may be more adaptable overall, their primitive relatives were better able to withstand tropical conditions, a factor that saved them from extinction.

The South American bush dog is a widespread but uncommon pack-hunter that preys on large rodents, peccaries, and rheas.  One genetic study suggests they are most closely related to maned wolves, but another more recent genetic study determined they are most closely related to African hunting dogs.  A species similar to the African hunting dog lived in North America as late as the mid-Pleistocene, so the bush dog may very well be an offshoot of this canid line.  The maned wolf is a solitary species, not a pack-hunter–additional evidence supporting a closer evolutionary link between bush dogs and pack-hunting African dogs, rather than the maned wolf.  The bush dog was known from fossil evidence found in a Brazilian cave before it was recognized as an extant species.

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South American bush dogs.  They are descended from primitive dogs that roamed North America before the Canis genus dominated that continent.

The Falkland Islands wolf was the only mammal species native to the Falkland Islands.  It was a completely naïve species, unafraid of man, and was hunted to extinction by the late 19th century.  Settlers coveted its furry coat and were afraid it would kill their sheep.  Actually, the diet of this species is unknown, but it probably subsisted on penguins, geese, and sea shore scavenging.  How this species colonized the Falkland Islands, located 285 miles from the mainland of South America, was a mystery until recently.  Geologists discovered underwater ridges connected to the mainland that were above sea level during Ice Ages.  A narrow 20 mile straight between the ridges and the Falkland Islands froze into solid ice during winters of the Last Glacial Maximum (~16,000 years ago), allowing the canids to cross.  They may have been hunting penguins on the ice, leading them to the islands.  No other mammal found motivation to cross the ice bridge.

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Extinct Falkland Islands Wolf.  Unfortunately, they had no fear of people.

Genetic evidence suggests the Falkland Island and maned wolves are most closely related to false foxes (Lycalopex sp.), 6 species of which are found in South America today.  However, the Tibetan fox is the maned wolf’s closest living relative.  The Tibetan fox is likely related to the ancestors of all false foxes.  An extinct species of maned wolf (C. nearctus) lived in North America during the Pliocene.  Fossil evidence of this species has been found at sites in Arizona, California, and northern Mexico.  The maned wolf has long legs that help it look over tall grass for rodents–its main prey item.  Genetic evidence shows maned wolf populations increased during Ice Ages when grasslands expanded and contracted during interglacials.  Pliocene environments were often dry and included an expansion of prairie habitat, so it’s likely the North American maned wolf also had long legs.  The fossil evidence of C. nearctus is limited to lower jaws and teeth, so it’s not known how long its legs were.  Maned wolves are omnivorous, and they are important dispersers of seeds.  They often defecate on leafcutter ant nests, and the ants move the viable seeds, helping them germinate.

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Maned wolf.  Maned wolves lived in North America during the Pliocene.

The maned wolf grows to about 50 pounds, but a larger genus of primitive dogs lived in North America until the early Pleistocene.  Theriodictis hunted megafauna in Florida.  Species from the Canis genus outcompeted them in North America, but they continued to thrive in South America until the late Pleistocene extinctions of the megafauna.

Reference:

Nyakatura, K.; et. al.

“Updating the Evolutionary History of Carnivora (Mammalia): A New Species Level Super Tree Complete with Divergence Time Estimates”

BMC Biology 10 (12) 2017

Tedford, Richard; X. Wang, B. Taylor

“Phylogenetic Systematics of the North America Fossil Caninae”

Bulletin of the American Museum of Natural History 2009

 

Hurricane Ivan Uncovered a 60,000 year old Cypress Forest in the Gulf of Mexico

August 9, 2017

In 2004 Hurricane Ivan spawned 140 mph winds, 90 foot waves, and the fastest sea floor current ever recorded.  That incredible sea floor current removed a sediment layer covering a 60,000 year old cypress forest in the Gulf of Mexico.  The exposed trees formed a natural reef, attracting a concentration of fish and other sea life 60 feet below the ocean surface and 15 miles offshore.  Fishermen noticed the unusual concentration of fish and asked scuba divers to investigate.  The scuba divers discovered the uncovered ancient forest, and scientists are now studying this rare site.

The scientists who visited the flooded forest were impressed with the marine life they encountered–flounder, cardinal fish, red snapper, blennies, sea bass, moray eels, sandbar sharks, hawksbill turtles, octopus, boring worms, anemones, and sponges.  But they were even more impressed with the ancient cypress wood they brought with them to the surface.  They sawed through it in the laboratory and smelled fresh sap.  Nevertheless, they couldn’t use radiocarbon dating because they discovered the wood was over 50,000 years old–too old for that method.  Instead, they found the nearest organic material that could be dated and estimated a 60,000 year old date based on stratigraphic location and assumed rates of deposition.

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Map of weather stations in south Alabama.  During Ice Ages dry land extended for miles into the Gulf of Mexico.  Mobile Bay was a valley of forests and grasslands.  Dauphin Island and Fort Morgan were high hills “hundreds of feet above the surrounding landscape.”

When it was alive, this flooded forest stood during a time period classified as Marine Isotope Stage 3.  I am fascinated with MIS3 because the dramatically fluctuating climate cycles had a major impact on natural communities.  MIS3 occurred just before the Last Glacial Maximum (the coldest stage of the last Ice Age), but unlike the LGM, MIS3 experienced warm interstadials alternating with cold phases.  Many geographical regions hosted an admixture of northern flora and fauna with warm climate species of plants and animals because of this climatic instability.  Tree rings on the fossil cypress wood excavated from this locality demonstrate this instability.  The tree rings provide a 489 year record of climate from MIS3.  The cypress tree rings show climate varied with warm wet years and dry cold spells but for the most part they are narrower than tree rings found in modern day cypress trees.  This reflects a cooler drier climate with lower levels of carbon dioxide in the atmosphere.  The trees were especially stressed during the last 50 years of their existence, and they all died at the same time, though the trees were of different ages.  Saltwater intrusion killed the trees.

Sea level rose rapidly here, probably during a warm phase of climate when glaciers were melting.  Cypress wood is resistant to decay, an adaptation for living in aquatic environments, but when exposed to air will eventually rot away.  The dead stand of cypress wood likely stood for decades, perhaps a century, before becoming covered in sand and mud.  Thus sealed off from air, it was preserved for tens of thousands of years.  Now that it is exposed to oxygen again, it will decay into nothing in a few centuries.

Scientists cored into the mud around the trees and took samples of pollen to analyze the type of natural environment that existed here 60,000 years ago.  Cypress, oak, and alder pollen dominated.  The palynologist who analyzed the pollen composition (the data as far as I know is still unpublished) concluded the forest was a rare type that no longer occurs in the region.  The closest modern analogue is classified as an Atlantic Coastal Plain Blackwater Bar/Levee Forest.  This type of forest occurs in small areas near the coasts of North and South Carolina.  Bar/Levee forests grow on soil formed on the inside bend of a river.  Sediment accumulates here through deposition, and the area is seasonally flooded.  (Indeed, this particular forest occurred alongside a river, and the paleomeander scar is still visible at the bottom of the ocean adjacent to the flooded forest.)  Dominant trees in a Bar/Levee forest are cypress, river birch, laurel oak, overcup oak, willow oak, sweetgum, red maple, elm, and loblolly pine.  The understory consists of holly and hop hornbeam along with red maple and ash saplings.  The shrub layer is made up of blueberry, titi, sweetspire, grape, poison ivy, climbing hydrangea, Alabama supplejack, greenbrier, sweet pepperbush, violet, and sedge.  Spanish moss covers the trees.  Bar/levee forests are similar to bottomland hardwood forests but are distinguished by the abundant presence of river birch or water elm (Planara aquatica which is not a true elm).

Macrofossils of Atlantic white cedar and palm have also been found among the dead cypress.  There are small disjunct colonies of Atlantic white cedar scattered throughout the southeast, indicating it was more widespread in the region during the Ice Age.  (See: https://markgelbart.wordpress.com/2012/03/11/the-discontinuous-range-of-the-atlantic-white-cedar-chamaecyparis-thyoides/ ) The presence of palm shows that climate, though cooler than that of today, was still warm enough for that species.  I suspect this was a unique forest that doesn’t exactly match any classified natural community of the present day.

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60,000 years ago, a cypress and oak forest grew at a location 15 miles off the coast of Alabama.  It was rapidly inundated during a sudden rise in sea level, becoming covered in sediment before the cypress trees rotted away.

The pollen evidence suggests alder was a pioneer species here that probably became established when the point bar of the river began depositing sediment.  Cypress and oak became dominant for about 500 years.  Then, after salt water intrusion killed the cypress, grass pollen predominates, suggesting a salt marsh replaced the cypress forest.  Extinct megafauna such as mastodon, tapir, and capybara undoubtedly passed through this environment, but vertebrate fossils have yet to be found.

Below is a documentary about the flooded forest–the source of information for much of this blog entry.

Reference:

Schafale, M; and A. Weakley

“Classifications of the Natural Communities of North Carolina, third approximation”

North Carolina Natural Heritage Program 1990

The Enigmatic Small Wolf Species of the Early-Mid Pleistocene of North America

August 6, 2017

There were at least 5 species of wolf-sized canids living in North America from about ~1.8 million years BP-~300,000 years BP.  Edward’s wolf (Canis edwardii) was a medium-sized canid, averaging about 75 pounds, that apparently occurred from coast to coast.  It’s the same species formerly known as Canis priscolatrans, and it was an evolutionary dead end–its extinction occurred about 300,000 years ago.  Armbruster’s wolf (Canis armbrusteri) co-occurred with Edward’s wolf but was a larger species, weighing on average 125 pounds.  Armbruster’s wolf is thought to be the evolutionary ancestor of the famous dire wolf (Canis dirus) which became extinct about 11,000 years ago.  Troxell’s dog (Protocyon texanus) was related to African hunting dogs.  Fossil evidence of this species has been found in Texas, the Yukon, and Alaska; and it probably had a wider range than the fossil record indicates.  Perhaps it lived in low numbers in geographic regions where processes of preservation were rare. The timber wolf (Canis lupus) was apparently confined to Alaska and Eurasia during the mid-Pleistocene and didn’t colonize North America until the late Pleistocene.  Finally, a mystery species nearly identical to the present day coyote (Canis latrans) left fossil evidence at sites in Nebraska, Colorado, California, Arkansas, Pennsylvania, Maryland, and West Virginia.  Some of the fossils at these sites are estimated to be 1 million years old.  Paleontologists identified these specimens as Canis latrans, though they cautiously also referred to them as coyote-like.  However, a recent study of wolf, coyote, and dog genetics determined the coyote is a recently evolved species no older than 50,000 years when it first diverged from timber wolves.  This result suggests the mid-Pleistocene species identified as Canis latrans may be an extinct mystery species.

In addition to the fossil record scientists can use a molecular clock to determine when 2 or more species diverged from a common ancestor.  A species has a fixed mutation rate, and scientists add up generations of mutational changes to determine the time of divergence from its closest related species.  (This is a vastly oversimplified explanation but will suffice for the purpose of this blog article.)  There are problems with using molecular clocks.  Different species have different rates of mutation, and the mutation rate can change over time.  Scientists try to calibrate the molecular clock with the fossil record by using various statistical methods.  An early study of wolf and coyote genetics determined the 2 species diverged about 1 million years ago, and this result is consistent with the fossil record, but the results of the newer study mentioned above totally contradict the fossil evidence.  There are 2 explanations for this discrepancy.  a) The new study is wrong.  Maybe the scientists used too many assumptions and dodgy statistics and just came up with the wrong number.  or b) The new study is right, and the mid-Pleistocene species identified as Canis latrans was an evolutionary dead end that went extinct.  The similarity between this mystery species and Canis latrans is just a remarkable example of convergent evolution. c) The new study is right and is not inconsistent with the fossil record.  Perhaps the common ancestor of the coyote and timber wolf was coyote-like.  Ice Age glaciers caused the divergence.  Populations north of the Cordilleran ice sheet evolved into timber wolves but populations south of it remained coyote-like.

Below are images of mid-Pleistocene  skull and jaw specimens identified as Canis latrans along with the skull and jaw of a present day coyote.  I can’t tell the difference, so I favor explanation a.  Even in a case of convergent evolution, there would have to be some notable anatomical differences between 2 different species.

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Genetic evidence from 1 study suggests coyotes diverged from gray wolves about 50,000 years ago.  However, this skull, assigned to Canis latrans (coyote) from Maryland dates to >300,000 years ago.  Is the genetic evidence incorrect or was there a species then so similar to modern coyotes it deceived paleontologists? Image from the below referenced paper by Tedford et. al.

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Present day skulls of Canis latrans.

Some zoologists think coyotes and dogs should now be classified as subspecies of timber wolf based on the data from the newer genetics study.  I don’t agree.  The behavioral characteristics of wolves, dogs, and coyotes are too dissimilar; and they don’t normally interbreed in natural conditions.  Humans can easily eradicate wolves from a region, but they can not eliminate coyotes because the latter are so much better adapted for living close to people.  Wolves and coyotes can survive in the wilderness, but they make terrible pets.  Most dogs make excellent companions for people but can’t survive in the wild.  In my opinion wolves, coyotes, and dogs are closely related but definitely different species.

References:

Tedford, Richard; X. Wang, and B. Taylor

“Phylogenetic Systematics of the North American Fossil Caninae”

Bulletin of the American Museum of Natural History  2009

Von Holdt, Bridgett; et. al.

“Whole Genome Sequence Analysis Shows that Two Endemic Species of North American Wolf are Admixtures of Coyote and Gray Wolf”

Science Advances (27) July 2016

Wilson, Paul; et. al.

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

Canadian Journal of Zoology 2000