African Hunting Dogs Lived in North America during the Middle Pleistocene

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

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2 Responses to “African Hunting Dogs Lived in North America during the Middle Pleistocene”

  1. Paleotool Says:

    Reblogged this on BLACKWATER LOCALITY #1.

  2. markgelbart Says:

    Thanks.

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