Posts Tagged ‘Armbruster’s wolf’

African Hunting Dogs Lived in North America during the Middle Pleistocene

November 21, 2014

The African hunting dog (Lycaon pictus meaning painted wolf) stars in many nature documentaries, but few people are aware that close relatives of this species formerly lived across Eurasia and even into North America.  At least 2 different species occurred in North America during the middle Pleistocene between ~1.5 million BP-~300,000 BP.  Fossil remains of Xenacyon lycaonoides were excavated from 2 sites in Alaska and 1 in the Yukon.  The first paleontologist who looked at these specimens misidentified them as dhole (Cuon alpinus) teeth, but a more recent examination of the dentition determined they belonged to a canid more closely related to African hunting dogs.  These scientists also examined the only other dhole fossils found in North America (from San Josecitos Cave in Mexico) and did confirm that identification.  The other American species of canid closely related to the African hunting dog was Xenacyon texanus, and it’s known from just 1 fossil locality–Rock Creek in northwest Texas.  The sum total fossil remains of X. texanus are part of 1 jaw with teeth, a leg, and a shoulder fragment.  Based on this scant anatomical material, scientists believe X. texanus was slightly larger the X. lycaonoides which was about the size of a timber wolf.

Photo: An African wild dog with pups

Two extinct and little known species of canid, closely related to present day African hunting dogs, lived in North America during the middle Pleistocene.

Dholes tearing up a deer.  Fossil remains of this canid have been found from just 1 site in North America.  It originated in Asia, yet it inhabited Mexico during the late Pleistocene.  It must have been more widespread in North America than the fossil record indicates.

Wolf fossils in North America are much more common than those of X. lycaonoides, X. texanus, and Cuon alpinus.  This suggests these species of hunting dogs didn’t compete well with American wolves.  During the middle Pleistocene X. texanus would have occupied the same ecological niche as Armbruster’s wolf (Canis armbrusteri), the probable evolutionary ancestor of the dire wolf (Canis dirus).  Nevertheless, X. texanus did live in North America long enough to have evolved into a different species from X. lycanoides.  Obviously, they were more widespread and successful than the fossil record indicates.  It’s possible this species persisted into the late Pleistocene but was restricted to regions where their remains were not likely to be preserved.  The only dhole fossils found in North America were discovered in Mexico, yet this species originated in Asia, crossed the Bering landbridge, and must have occupied large areas of North America before colonizing Mexico.  Dholes co-existed with dire wolves and timber wolves (Canis lupus) in North America for some undetermined length of time.  The oldest dire wolf fossil dates to 252,000 BP (from a uranium-series dated deposit in South Dakota).  Timber wolves crossed the Bering landbridge 100,000 years ago and co-existed with dire wolves in western North America until the end of the Pleistocene.  It’s not known when dholes crossed the Bering landbridge.  Timber wolves and dholes are not known from the fossil record of southeastern North America.  I think dire wolves kept these other big game-hunting canids from occupying this more wooded region where prey was less abundant than on the grassy plains of the west.

The Rock Creek Fossil Site

File:TXMap-doton-Plainview.PNG

Rock Creek, the only known fossil site where Xenocyon texanus has been found, is located just north of Plainview, Texas, represented by the dot on this map.

The Rock Creek fossil site is located just north of Plainview, Texas.  This is the only locality where remains of X. texanus have ever been found.  E.L. Troxell excavated this rock quarry and published his findings in 1915.  Along with the rare canid, he found the remains of gopher tortoise, giant tortoise, Harlan’s ground sloth, glyptodont, Imperial mammoth, flat-headed peccary, camel, llama, Soergel’s musk-ox, and horse.  He identified the remains of another canid as dire wolf, but he was probably in error.  The geological formation where these fossils were found is thought to be no younger than 400,000 years BP.  Dire wolves probably didn’t evolve yet, so the canid remains probably should be referred to as Armbruster’s wolf.

The composition of species excavated from Rock Creek suggests the region during this climatic phase consisted of arid grassland and scrub with milder winters than those of today.  Some scientists assume it was frost free due to the presence of giant tortoise, but I believe this species could survive light frosts.  Although winters were warmer then, it’s not safe to assume there were no frosts.  The horses, camels, and peccaries likely served as dinner for X. texanus.

References:

Tedford, Richard; et. al.

“Philogenetic Systematics of North American Fossil Caninae (Caninae: canid)”

Bulletin of the American Museum of Natural History 2009

Of Lycanthropy and Dire Wolves (Canis dirus)

October 19, 2011

The fictional depiction of lycanthropic transformation is reminiscent of an oversimplified depiction of evolution. Although it seems a bizarre twist of logic, evolutionary science does support the existence of an animal that was part man and part wolf.

Man is a beast.  I think the ancient superstitious legend of the werewolf originates from a fear of ourselves or at least a fear of feral individuals within our society.  People with various mental illnesses don’t follow the rules of civilization and behave as if they were wild animals.  In modern cinema and literature the transformation of man to wolf appears as a kind of reverse evolution, depicting the man de-evolving into the most feared animal in medieval Europe–the wolf.  Of course, this doesn’t parallel the reality of evolution.  Evolution doesn’t reverse course, though occasionally retro mutations take place that begin new lines of progression.  But if evolution could reverse course in a linear regression, a man transforming back into beast would become apelike rather than as a canid/human hybrid.  On the tree of evolution primates are far removed from canids.  Despite the vast distance between the two on the evolutionary timescale, primates and canids do share a common ancestor.  Both man and wolf can trace their evolutionary lines back to a single unknown species of insectivore that diverged into two species early in the Eocene 55 million years ago, or probably earlier.  The split may have occurred as early as the Paleoecene or the Cretaceous.  When dinosaurs walked the earth what was to become man and wolf was the same animal.  According to what we know of evolution, werewolves were real and may have lived with the dinosaurs.  But they were nothing like the monsters depicted in fiction.  Instead, they were shrew-like animals, something a modern day house cat could toy with.

This is not a man wearing a werewolf mask.  He has a rare condition known as hypertrichosis.

The legend of lycanthropy may predate written language.  Both the Greeks and the Romans believed in the existence of men who could temporarily transform themselves into wolves.  The word, lycanthrope, itself is Greek: lycaos means wolf, anthrope means man.  A belief in the existence wolf men persisted in medieval Europe.  Today, we can be certain the legend was based on a number of strange factors that modern science can explain.  Then as now, serial killers occasionally terrorized society. Instead of blaming a deranged man for mutilations and murders, authorities scapegoated wolves despite conflicting evidence implicating a human.  They couldn’t comprehend that a man could be so vicious.  Diseases such as rabies and and the disorder of hypertrichosis compounded the confusion because symptoms of these conditions partly mimic the legend.  The Age of Reason ended the widespread belief in the existence of werewolves, but the legend lives on as a popular monster of horror fiction.

Here’s a skull comparison between a dire wolf and a timber wolf.  I found this photo on another wordpress blog. 

When paleo-indians encountered dire wolves they were forced to deal with a real monster.  Unlike timber wolves (Canis lupus) which originally evolved in Eurasia, dire wolves evolved in America where the large pack-hunting canids never learned to respect or fear man.  Studies of the fossil record suggest dire wolves appeared suddenly about 200,000 years BP.  They replaced Armbruster’s wolf which had been the dominant canid in America for over a million years.   It’s unclear whether dire wolves evolved from Armbruster’s wolf or another canid (C. nehringi), a little known extinct canid that inhabited South America.  Dire wolves ranged from coast to coast and from what’s now southern Canada to Peru.  They’re very common in the fossil record, suggesting they were the most abundant large predator on the continent.  In the northern parts of their range they co-existed with timber wolves.  In the southeast they co-existed with red wolves (C. rufus) and coyotes (C. latrans). 

I didn’t include an illustration of a dire wolf because at first glance, they would’ve probably looked just like a modern day timber wolf.  There were some subtle anatomical differences.  Dire wolves had a broader head, larger teeth, stronger jaws, and shorter but stouter legs.  On average they were significantly larger than timber wolves.  The average weight of an adult timber wolf is ~80 pounds.  The average weight of an adult western dire wolf was  ~120 pounds; the average of an adult eastern dire wolf was ~140 pounds.  Scientists noted a difference in size between eastern and western dire wolf fossils.  Eastern dire wolves also had longer legs than their western cousins.  Thousands of dire wolf skulls have been recovered from the La Brea tarpits in California.  Coincidentally, one of the few dire wolf skulls found in South Carolina was larger than all but one of the California skulls.  Though timber wolves average 80 pounds, some individuals do reach 160 pounds.  That suggests a really large dire wolf would’ve approached 200 pounds.  White tail deer are not large enough to sustain a pack of wolves consisting of individuals of this size.  Dire wolves required abundant bison, horses, llamas, and juvenile mammoths and mastodons.  Man and the extinction of the megafauna caused the downfall of the dire wolf.  

Interestingly, the appearance of dire wolves coincides with the evolution of the larger Smildon fatalis from the smaller Smilodon gracilis, indicating an arms race of sorts between the two.

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A comment on last week’s nudie photo

I thought the hypothesis I discussed in my last week’s blog entry would be of interest to members of the fossil forum, so I posted a thread about it.  I wanted to kick my hypothesis around and see what they thought of it.  A moderator pulled the thread because my blog, which I linked, had a photo of a naked woman.  He remarked that they like to keep the fossil forum “kid friendly.”  Of course, they have the right to control the comment on their website, just as I have the right to moderate my own.  But I don’t agree with the value system behind their reasoning.

The thread was pulled on a Saturday.  It occurred to me that violent college football was on television all day.  Football is a sport where men break each other’s bones on a regular basis, and a significant risk of inflicting permanent brain damage is high.  Society is ok with exposing kids to violence, but the image of a beautiful naked woman is somehow not “kid friendly.”  Violence is good; sex is bad.  I don’t get it.

A few years ago, people were freaking out because of Janet Jackson’s wardrobe malfunction.  For some reason parents were furious because children might have accidentally viewed a woman’s breast.  The same thing happened once when an intro for Monday Night Football included a sexy seductive woman.  Yet, they’re ok with big defensive lineman clobbering quarterbacks in a game.

I’m a big Georgia Bulldog fan.  David Pollack was one of my favorite players, but I found his religious values somewhat twisted.  He refused to participate in his selection as  a Playboy all-American because of his religious beliefs.  He wears a wristband with the quote of “What would Jesus do?”  Well, I’m pretty sure Jesus wouldn’t knock the shit out of a quarterback.

Our society considers it acceptable to expose children to violence as entertainment but rejects exposing them to images of naked women.  Our society has a twisted value system that teaches kids violence is good but sexuality is dirty and bad.  I don’t agree with the notion that viewing images of naked women is in any way harmful to children.