Posts Tagged ‘dire wolf’

Saber-tooth Cats (Smilodon fatalis) and Dire Wolves (Canis dirus) Did Not Compete as Much as Previously Thought

August 10, 2019

Image result for Charles Knight classic painting of La Brea tar pits dire wolf

This classic painting of dire wolves contesting a carcass with a saber-tooth may give the wrong impression.  A new study suggests their diets didn’t overlap as much as previously thought.

A new study analyzing the isotopic chemistry of tooth enamel from carnivores excavated from the La Brea Tar Pits determined there was not as much overlap in the diets of saber-toothed cats and dire wolves as previously thought.  An earlier study examined the isotopic chemistry from bone collagen of La Brea carnivores, and the results of that study suggested the big 3 carnivores (saber-tooths, dire wolves, and giant lions– Panthera atrox) competed for the same prey items.  However, bone collagen can decay and become contaminated, altering the accuracy of the results.  Tooth enamel is more durable, and scientists believe it provides more accurate results.  This new study concluded both saber-tooths and giant lions were ambush predators that lived in woodlands or forests and fed upon forest-dwelling herbivores such as deer, tapir, and woodland bison.  Dire wolves and coyotes (Canis latrans) lived in more open environments and chased down horses, camels, and plains bison.  The diet of saber-tooths, giant lions, and Pleistocene cougars (Puma concolor) resulted in mathmatical values of isotopic bone chemistry identical to those of modern cougars.  The diet of coyotes changed over time.  During the Pleistocene coyotes scavenged meat from megafauna.  Following the extinction of the Pleistocene megafauna, coyotes evolved toward a reduced size and fed more on bone, smaller animals, and even fruit.  The diets of timber wolves (Canis lupus) and cougars did not change following the extinction of Pleistocene megafauna.

The results of this study did not surprise me.  Saber-tooths and giant lions were built for ambushing prey in the cover of thick vegetative growth found more in woodlands than grasslands.  So of course it makes sense they preyed upon animals in those environments.

Reference:

Desantis, L; et al

“Causes and Consequences of Pleistocene Megafauna Extinction as Revealed from Ranch La Brea Mammals”

Current Biology 29 (15) 2019

Specimen #USNM 437648

July 17, 2016

I was confused about the Harleyville Giant Cement Quarry fossil site for many years.  Some of the scientific literature reported the fossils found there were over 300,000 years old, while other papers gave them an approximate age of 20,000 years BP.  Finally, someone sent me a message, clearing up my confusion.  These are 2 different fossil sites–both in Dorchester County, South Carolina but several miles apart.  In 1989 Roy Ogilvie, an amateur fossil collector, found a nearly complete dire wolf skull at the site with the 20,000 year old bones.  This specimen is now stored at the U.S. National Museum and was given the number 437648.  It is the only dire wolf (Canis dirus) skull ever found in South Carolina, though several isolated teeth have been recovered from other sites.

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Photo of specimen #USNM 437648 from the below referenced book.  It’s nearly complete, missing just a few teeth.

The size of this skull is remarkable.  Ronald Nowak, a renowned fossil canid expert, measured 62 dire wolf skulls that were excavated from the La brea Tar Pits in California.  #USNM 437648 is larger than all of them.  It may just be coincidence, but perhaps eastern dire wolves were on average larger than their western counterparts.  In any case this was a big wolf.  However, it is not the largest dire wolf skull known.  A dire wolf skull from south Texas and another from the Maricopa tar seeps in California were slightly larger than this specimen.

The associated faunal remains, known as the Ardis local fauna, suggest #USNM 437648 lived in a mostly wooded habitat with some grassy openings and aquatic habitats.  Tapir, white-tailed deer, stout-legged llama, long-nosed peccary, woodrat, beaver, gray squirrel, flying squirrel, jaguar, Florida spectacled bear, and Jefferson’s ground sloth all are (or were) denizens of woodlands or even deep forest.  Mastodon, beaver, and river otter indicate wetland habitat.  Bison, horse, mammoth, meadow vole, hog-nosed skunk, 13-lined ground squirrel, and pampathere show that grassland environments existed here as well.  Dire wolves were a generalist species.  Specimen #437648 likely hunted in all 3 habitats.

Reference:

Sanders, Albert

Additions to the Pleistocene Mammal Faunas of South Carolina, North Carolina, and Georgia

American Philosophical Society 2002

Beringian Wolves, an Extinct Ecomorph of Canis lupus, Lived as Far South as Wyoming

May 30, 2016

Both dire wolves (Canis dirus) and gray wolves (C. lupus) lived in North America during the late Pleistocene.  The former were far more common than the latter south of the ice sheet that covered most of Canada then.  Gray wolves did occur as far south as California, but were uncommon over much of the continent, possibly because of competition with dire wolves, large Ice Age coyotes (C. latrans), and dholes (Cuon alpinus).  However, in Alaska north of the ice sheet, gray wolves were the only species of large canid.  Scientists refer to this population as Beringian wolves.  Though their size and build was similar to that of the extant gray wolf, they had stronger jaws and more robust teeth.  Paleoecologists assert this powerful bite was an evolved adaptation that allowed them to successfully prey upon large Pleistocene megafauna such as horse, bison, and musk-ox.   Fossils of Beringian wolves range in age from 7500 BP->50,000 BP.  This population of gray wolves became extinct about the same time as the Pleistocene megafauna.  (Evidence from DNA in Alaskan permafrost suggests horses occurred there until ~7500 BP).  Pleistocene Beringian wolves were not ancestral to present day Alaskan gray wolves.  Instead, wolves living in Alaska today descend from wolves that expanded their range north following the dissolution of the ice sheet. (See also: https://markgelbart.wordpress.com/2014/04/11/extinct-pleistocene-ecomorphs-of-the-cougar-puma-concolor-and-the-timber-wolf-canis-lupus/ )

 

Map showing potential migration route for Beringian wolves.

Wolves in Idaho's River of No Return Wilderness Post

I tried to find a photo of exceptionally large gray wolves on google images, but they were all marred with the despicable sadistic hunters who had murdered them.  I hate anyone who would go hunting for wolves.

Wolf fossils found in Natural Trap Cave, Wyoming puzzled scientists for many years because they had features intermediate between gray wolves and dire wolves.  A recent study, using a statistical analysis of anatomical measurements, determined these wolves were Beringian wolves, the same extinct ecomorph that lived in Alaska during the late Pleistocene.  Measurements of the jaws and lower teeth of these Wyoming wolves matched those of Beringian wolves.  The jaws and teeth were smaller on average than those of dire wolves, but larger than those of other populations of gray wolves.  Natural Trap Cave is located exactly south of the ice free corridor that existed between the Cordilleran and Laurentide ice sheets before and after the Last Glacial Maximum.  Beringian wolves followed herds of bison (Bison antiquus) and musk-oxen (Bootherium bombifrons) when they migrated back and forth through the corridor.  The authors of this study predict fossils of Beringian wolves may be found as far west as Oregon and possibly farther east than Indiana.

I hypothesize Beringian wolves were an hybrid species, resulting from crossbreeding between Canis lupus x Canis dirus.  A recent study of mammoth DNA determined that Columbian mammoths (Mammuthus columbi) interbred with woolly mammoths (M. primigenius) where the 2 species ranges overlapped, such as the Great Lakes region.  (See: https://markgelbart.wordpress.com/2016/02/18/the-southern-and-northern-range-limits-of-the-columbian-mammoth-mammuthus-colombi/ ).  This explained why fossils of mammoths from this region showed characteristics intermediate between the 2 species.  The same explanation may hold true for Beringian wolves, though convergent evolution is the alternate hypothesis for their more robust bite.  My hypothesis would be easy to test, if dire wolf DNA were available.  Surprisingly, despite this species’ abundance in the fossil record, dire wolf DNA has never been extracted.  There have been well over a thousand specimens of dire wolves excavated from the La Brea Tar Pits, but the chemical used to remove the tar from the bones also destroys DNA.  The humid environmental conditions in Florida, where dire wolf remains are also abundant, probably degrades DNA, making this another unfit potential source.

I wonder if Beringian wolves ever followed herds of megafauna when they wondered as far south as the southern Appalachians.  A study of Beringian wolf bone chemistry determined bison and musk-oxen were their favorite foods.  As I noted here ( https://markgelbart.wordpress.com/2016/05/16/the-extinct-helmeted-musk-ox-bootherium-bombifrons-and-appalachian-grassy-balds-during-the-pleistocene/  ), I believe the woodland musk-ox was the first species of megafauna to colonize grassy balds.  Maybe gray wolf/dire wolf hybrids followed them.  A wolf tooth found in north Georgia at Ladds has been alternately identified as gray wolf (by Clayton Ray) and dire wolf (by Ronald Nowak).  They could both be right.

References:

Fox-Dobbs, K.; A. Leonard and P. Koch

“Pleistocene Megafauna from Eastern Beringia: Paleoecological and Paleoenvironmental Interpretation of Stable Carbon and Nitrogen Isotope and Radicarbon Records”

Paleogeography, Paleoclimatology, and Paleoecology 2008

Gold, DA; et. al.

“Attempted DNA Extraction from Rancho La Brea Columbian Mammoth (Mammuthus columbi: prospects for Ancient DNA Extraction from Asphalt Deposits”

Ecological Evolution 2014

Leonard, Jennifer; et. al.

“Megafaunal Extinction and the Disappearance of a Specialized Wolf Ecomorph”

Current Biology 17 2007

Meachen, J.; A. Brannick and T. Fry

“Extinct Beringian Wolf Morphology Found in the Continental U.S. has Implications for Wolf Migration and Evolution”

Ecology and Evolution 2016