Megafaunal wolf

Polychrome cave painting of a wolf-like canid, Font-de-Gaume, France.

The megafaunal wolf was a Late Pleistocene – early Holocene hypercarnivore similar in size to a large extant Gray wolf (Canis lupus). It had a shorter, broader palate with large carnassial teeth relative to its overall skull size. This adaptation allowed it to predate and scavenge on Pleistocene megafauna. They are now extinct.

Name

In 2007, the words "megafaunal" and "wolf" appeared separated in the title of a study.^[1] In 2013, one of the study co-authors first used the term "megafaunal wolf" in a media release.^[2]

Taxonomy

Based on limited mDNA analysis, the megafaunal wolf is regarded as an ecomorph of the Gray wolf.^[1][3] However, there was greater wolf diversity during the Late Pleistocene than exists today^[4] and this classification is now not so clear.

Morphology

Megafaunal wolves were similar in physical size to other Pleistocene-era wolves and large extant gray wolves, but with stronger jaws and teeth. They tended to have short, broad palates with large carnassials relative to their overall skull size. These features suggest a wolf adapted for producing relatively large bite forces. The short, broad rostrum increased the mechanical advantage of a bite made with the canine teeth and strengthened the skull against torsional stresses caused by struggling prey. Relatively deep jaws are characteristic of habitual bone crackers, such as spotted hyenas, as well as canids that take prey as large as or larger than themselves. Overall these features indicate that megafaunal wolves were more specialized than modern gray wolves in killing and consuming relatively large prey and scavenging.^[1]:1147

In comparison to other gray wolves, megafaunal wolf samples include many more individuals with moderately to heavily worn teeth and a significantly greater numbers of broken teeth. The distribution of fractures across the tooth row differs as well, with these wolves having a much higher fracture frequencies of incisors, carnassials, and molars. A similar pattern was observed in spotted hyenas, suggesting that increased incisor and carnassial fracture reflects habitual bone consumption, because bones are gnawed with incisors and subsequently cracked with the cheek teeth.^[1]:1148

Diet

Isotopic bone collagen analysis of the specimens indicated that they ate horse, bison, woodland muskox and mammoth i.e. Pleistocene megafauna. This supports the conclusion that they were capable of killing and dismembering large prey. Compared with Pleistocene and extant gray wolves, the megafaunal wolf was hypercarnivorous, with a craniodental morphology more capable of capturing, dismembering, and consuming the bones of very large mega-herbivores. When their prey disappeared, this wolf did as well, resulting in a significant loss of phenotypic and genetic diversity within the species.^[1]:1148

Habitat

Based on the morphological and limited genetic evidence below, the Megafaunal wolf's distribution was Holarctic. However, there is no conclusive evidence that the specimens found in each region are related because more data needs to be gathered and compared.

Beringia

Shrinking of the Bering land bridge

Beringia is a loosely defined region surrounding the Bering Strait, the Chukchi Sea, and the Bering Sea. It includes parts of Chukotka and Kamchatka in Russia as well as Alaska in the United States. In historical contexts it also includes the Bering land bridge, an ancient land bridge roughly 1,000 miles (1,600 km) wide (north to south) at its greatest extent, which connected Asia with North America at various times — all lying atop the existing North American plate, and east of the Siberian Chersky Range — during the Pleistocene ice ages. During ice ages more water was stored as ice, the sea levels fell, and a land bridge was exposed.

East Beringia

In 2007, a study was undertaken on the skeletal material from 56 Pleistocene-period East Beringian wolves from permafrost deposits in Alaska. Uncalibrated radio carbon dating showed a continuous population from 45,500 years BP to 12,500 years BP, and one single wolf dated at 7,600 BP. This indicates that their population was in decline after 12,500 BP.^[1] Megafauna was still available in this region until 10,500 BP, with the age of the more recent wolf specimen supported by the discovery of a remaining pocket of residual megafauna that still inhabited interior Alaska between 7,500–10,500 BP.^[5]

The East Beringian wolf was identified as an ecomorph of the Gray wolf (Canis lupis) with a skull morphology that was adapted for hunting and scavenging megafauna. None of the 16 mtDNA haplotypes recovered from a sample of 20 of the wolves was shared with any modern gray wolf, but similar haplotypes were found in Late Pleistocene Eurasian gray wolves. Six eastern-Beringian wolves had the same sequence found in two wolves from Ukraine dated 30,000 years BP and 28,000 years BP, and from Altai dated 33,000 years BP. Two eastern-Beringian wolves matched another haplotype with a wolf from the Czech Republic dated at 44,000 years BP. Its phylogeny indicates that, aside from the modern Canis lupus pallipes, the Beringian wolf's unique haplotypes are basal to other gray wolves. Its genetic diversity was higher than that of its modern counterparts, implying that the wolf population of the Late Pleistocene was larger than present. Modern North American wolves are not their descendents, and this supports the existence of a separate origin for ancient and extant North American wolves.^[1]

A more detailed analysis of the genetic material from three specimens were dated at 28,000 years BP, 21,000 years BP, and 20,800 years BP respectively (with the samples deposited in GenBank with accession numbers KF661088, KF661089 and KF661090) and identified as Canis lupus.^[3]

Pleistocene wolf skulls and jaws from Hutton and Banwell Cave (Somerset) and Oreston Cave (Plymouth)

West Beringia

In 2009, a study was made on the skull fragment and right mandible of a wolf (Canis lupus) found near Lake Taimyr in the Taimyr Peninsula, Arctic Siberia, Russian Federation (the Lake Taimyr wolf). It is one of the most northern-most records of Pleistocene carnivora in Eurasia. The skull was aged by radio carbon dating to 16,220 BP.^[6]

The adult skull was small and assumed to be a female as it did not differ in size to an extant female wolf skull from northern Siberia.^[6] Another study of the Lake Taimyr wolf found that its comparatively small size and characters of the cheekteeth and skull raised the possibility that it might have been a domesticated or semi-domesticated animal.^[7]

The increased skull width in comparison to extant wolves indicated pronounced development of the temporalis muscles. The specimens were compared to a wolf (Canis lupus spelaeus) fossil found near Burnberg, Germany and near the Paleolithic site of Kostenki 1 on the Don River near Voronezh, Russia. Both of the European fossil skulls demonstrated the same dentition as the fossil wolf from Taimyr. The skull and teeth arrangement suggest a considerable portion of carrion and bones in the diet. In the severe environmental conditions of the Late Pleistocene arctic zone of Eurasia, carrion had been one of the principal food sources for these animals. "Notably, the Pleistocene C. lupus from eastern Beringia, by the skull shape, tooth wear and isotopic data, is also reconstructed as a specialized hunter and scavenger of extinct North American megafauna."^[6]

Europe

The Cave Wolf (Canis lupus spelaeus) possibly belongs to a specialized Late Pleistocene wolf ecomorph. Its bone proportions are close to the Canadian arctic-boral mountain-adapted timber wolf and a little larger than the modern European wolf. It appears that in the early to middle Late Pleistocene this large wolf existed all over Europe, but was then replaced during the Last Glacial Maximum by a smaller wolf-type which then disappeared along with the reindeer fauna, finally replaced by the Holocene warm-period European wolf Canis lupus lupus. These wolves have been not well-studied and have not been well-defined by DNA.^[9]

Cave wolf populations are known from Sophie’s Cave and other caves in the same area – the Zoolithen and Große Teufels Caves. Their dens have also been identified, especially in the Zoolithen Cave which had a large population and has yielded more than 380 bones as well as several skulls (including a holotype). Some postcranial bones have been compared, having similarly large proportions to those from the Sophie’s and Große Teufels Caves where the bone sizes are closer to those of Scandinavian Arctic and Canadian Columbian wolf subspecies than to those of the smaller European wolves.^[9]

Sophie’s Cave has demonstrated the first “Early Late Pleistocene wolf den”, with intensive faecal places and the first European record of half-digested cave bear bones found within the faecal areas in the cave. It demonstrates that wolves seem to have used this cave not as a cub raising den, but they were cave dwellers that fed on cave bear carcasses, similar but less so than cave hyenas but more so than cave lions. The abundant faeces seem to play a role in the “orientation” for trail tracking similar to modern wolves, and less as den marking. The high abundance in a limited area of the Bear’s Passage of the cave might be the result of periodical short-term den use of smaller cave areas. Wolves were scavenging on the bears that hibernated and died there, and therefore a simultaneous use as both a wolf and a cave bear den cannot be expected. Remains of a skeleton of at least one high adult wolf also might have been the result of a battle within the cave with the bears, the same as in the lion taphonomic record.^[9]

The ecology of the early to middle Late Pleistocene wolves on the mammoth steppe and the boreal forests is not known, nor if they used caves as dens.^[9]

In 2009, a study of the fossil remains of Paleolithic dogs and Pleistocene wolves found that 5 wolf specimens from Trou Baileux, Belgium (reference: ULg Depaepe 1988), Trou des Nutons, Belgium, (RBINS 2559-1), Mezin, Ukraine (PM NASU 5469 and 5488) and Yakutia, Siberia (ZIN RAS 29699) had a greater snout width than recent wolves. A similar trend was discovered in North American fossil wolves from East Beringia.^[10]

Relationship with the domestic dog

A leading evolutionary biologist has stated that:

We know also that there were distinct wolf populations existing ten of thousands of years ago. One such wolf, which we call the megafaunal wolf, preyed on large game such as horses, bison and perhaps very young mammoths. Isotope data show that they ate these species, and the dog may have been derived from a wolf similar to these ancient wolves in the late Pleistocene of Europe.^[2]

References