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Ancient wolves had bone-crushing teeth, scientists find

June 21, 2007
Courtesy Cell Press
and World Science staff

A specialized breed of an­cient gray wolves once roamed Alas­ka’s icy ex­panses, with bone-crushing jaws for tak­ing on huge prey, scientists say.

The ex­tinct Alas­kan wolves had ro­bust bod­ies, strong jaws, and mas­sive ca­nine teeth for kill­ing prey larg­er than them­selves and reg­u­larly con­sum­ing large bones, ac­cord­ing to the re­search­ers. But the wolves ap­par­ently died out along with oth­er big an­i­mals at the end of the last Ice Age.

“The un­ique at­tributes of Alas­kan Pleis­to­cene [Ice-Age] wolves had not been pre­vi­ously rec­og­nized,” said Blaire Van Valken­burgh of the Un­ivers­ity of Cal­i­for­nia, Los An­ge­les, one of the re­search­ers. “The liv­ing gray wolf dif­fers dra­mat­ic­ally from that which roamed Alas­ka just 12,000 years ago.” The find­ings ap­pear in the June 21 on­line is­sue of the re­search jour­nal Cur­rent Bi­ol­o­gy. 

The gray wolf is one of the few large preda­tors that sur­vived the mass ex­tinction of the late Ice Age. Nev­er­the­less, wolves disap­peared from north­ern North Amer­i­ca at that time, she said; but they lived on in the Old World, which may ex­plain their pre­sence in North Ame­rica to­day.

To study Alas­ka’s an­cient wolves, Van Valken­burgh and col­leagues col­lect­ed bones of the an­i­mals from per­ma­frost de­posits and ex­am­ined their chem­i­cal com­po­si­tion and DNA. The late-Pleis­to­cene wolves were ge­net­ic­ally and phys­ically dis­tinct from ex­ist­ing wolves, the sci­en­tists re­ported: the skull shape, tooth we­ar and bone chem­istry sug­gest they were hunters and scav­engers of ex­tinct mega­fauna.

The archaic wolves had “more mas­sive teeth and broader skulls with shorter snouts, en­hanc­ing their abil­ity to pro­duce strong bites,” Van Valken­burgh said. “The stud­ies of their tooth wear and frac­ture rate showed high lev­els of both, con­sist­ent with reg­u­lar and fre­quent bone-cracking and -crunching.”

Those char­ac­ter­is­tics probably came in handy in an­cient Alas­ka, where the wolves faced stiff com­pe­ti­tion for food from some for­mi­da­ble com­peti­tors, she added, in­clud­ing li­ons, short-faced bears, and saber-tooth cats. Dur­ing pe­ri­ods of in­tense com­pe­ti­tion among preda­tors, mod­ern wolves al­so con­sume car­casses more ful­ly, she noted. They in­gest more bone and eat faster, in­creas­ing the risk of tooth frac­ture.

The long-ago de­mise of this spe­cial­ized wolf form may por­tend things to come for spe­cial­ized groups of ex­ist­ing preda­tors, Van Valken­burgh said. For ex­am­ple, a un­ique type of no­mad­ic North Amer­i­can gray wolf was re­cently dis­cov­ered. Packs of them mi­grate across the tun­dra along with car­i­bou and keep their num­bers in check. In con­trast, oth­er wolves are ter­ri­to­rial and non-migratory. “Global warm­ing threat­ens to elim­i­nate the tun­dra and it is likely that this will mean the ex­tinction of this im­por­tant preda­tor,” she said.

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Ancient gray wolves that once roamed Alaska’s icy expanses were a specialized form that apparently died out along with other big animals at the end of the last Ice Age, researchers have found. The extinct Alaskan wolves had robust bodies, strong jaws, and massive canine teeth for killing prey larger than themselves and regularly consuming large bones, according to the researchers. “Our results are surprising as the unique attributes of Alaskan Pleistocene wolves had not been previously recognized and show that wolves suffered an extinction at the end of the Pleistocene,” said Blaire Van Valkenburgh of the University of California, Los Angeles, one of the researchers. “If not for their persistence in the Old World, we might not have wolves in North America today. Regardless, the living gray wolf differs dramatically from that which roamed Alaska just 12,000 years ago.” The findings appear in the June 21 online issue of the research journal Current Biology. The gray wolf is one of the few large predators that survived the mass extinction of the late Pleistocene, or Ice Age. Nevertheless, wolves disappeared from northern North America at that time. To explore the identity of Alaska’s ancient wolves in the new study, Van Valkenburgh and colleagues collected bones of the animals from permafrost deposits and examined their chemical composition and genetic makeup. The late-Pleistocene wolves were distinct from existing wolves, both genetically and in terms of their physical characteristics, the scientists reported. None of the ancient wolves were a genetic match for any modern wolves, they report. Moreover, the animals’ skull shape and tooth wear, as well as a chemical analysis of their bones, suggest they were specialized hunters and scavengers of extinct megafauna. “The ancient wolves had relatively more massive teeth and broader skulls with shorter snouts, enhancing their ability to produce strong bites,” Van Valkenburgh said. “In addition, the studies of their tooth wear and fracture rate showed high levels of both, consistent with regular and frequent bone-cracking and -crunching behavior.” Those characteristics probably came in handy in ancient Alaska, where the wolves faced stiff competition for food from some formidable competitors, she added, including lions, short-faced bears, and saber-tooth cats. During periods of intense competition among predators, modern-day wolves will also consume carcasses more fully, ingesting more bone and eating faster, which increases the risk of tooth fracture. The long-ago demise of this specialized wolf form may portend things to come for specialized groups of existing predators, Van Valkenburgh said. For example, a unique type of nomadic North American gray wolf was recently discovered. Their packs migrate across the North American tundra along with caribou and keep their numbers in check. In contrast, all other wolves are territorial and non-migratory. “Global warming threatens to eliminate the tundra and it is likely that this will mean the extinction of this important predator,” she said.