Cave hyena

The cave hyena (Crocuta crocuta spelaea), also known as the Ice Age spotted hyena,[1] was a paleosubspecies of spotted hyena[2] which ranged from Iberian Peninsula to Eastern Siberia.[3] It is one of the best known mammals of the Ice Age, and is well represented in many European bone caves.[4] The cave hyena was a highly specialised animal, with its progressive and regressive features being more developed than in its modern African relative.[5] It preyed on large mammals (primarily wild horses, steppe wisent and woolly rhinoceros), and was responsible for the accumulation of hundreds of large Pleistocene mammal bones in areas including horizontal caves, sinkholes, mud pits and muddy areas along rivers.[1]

The cause of the cave hyena's extinction is not fully understood, though it could have been due to a combination of factors, including climate change and competition with other predators.

Description and paleoecology
The European cave hyena was much larger than its modern African cousin, having been estimated to weigh 102 kg (225 lbs).[8] In Late Pleistocene specimens from Europe, the cave hyena's metacarpals and metatarsals are shorter and thicker, while the humerus and femur are longer,[4] thus indicating adaptations to a different habitat from that of the modern spotted hyena.[9] As with the African subspecies, female cave hyenas were larger than their male counterparts.[1] Paleolithic rock art depicting the cave hyena shows that it retained the spotted pelt of its African relative.[10]

Several den sites found in Europe indicate that the cave hyena preferentially targeted large prey, with wild horses predominating, followed by steppe bison and woolly rhinoceros.[1][11][12] The cave hyena's favouring of horses is consistent with the behaviour of the modern African spotted hyena, which mostly hunts zebras. Secondary prey species included reindeer, red deer, giant deer, European ass, chamois and ibex.[1] A small number of wolf remains have also been discovered in hyena den sites. The cave hyena likely killed wolves due to intraguild competition, though their presence in the cave site indicates that they were also fed upon, which is unusual among carnivores.[12] Similarly, cave lion and bear remains have been discovered in hyena den sites, thus indicating that hyenas may have scavenged on or killed them.

History of discovery and classification
Although the first full account of the cave hyena was given by Georges Cuvier in 1812, skeletal fragments of the cave hyena have been described in scientific literature since the 18th century, though they were frequently misidentified. The first recorded mention of the cave hyena in literature occurs in Kundmann's 1737 tome Rariora Naturæ et Artis, where the author misidentified a hyena's mandibular ramus as that of a calf. In 1774, Esper erroneously described hyena teeth discovered in Gailenreuth as those of a lion, and in 1784, Collini described a cave hyena skull as that of a seal. The past presence of hyenas in Great Britain was revealed after William Buckland's examination of the contents of Kirkdale Cave, which was discovered to have once been the location of several hyena den sites. Buckland's findings were followed by further discoveries by Clift and Whidbey in Oreston, Plymouth.[13]

In his own 1812 account, Cuvier mentioned a number of European localities where cave hyena remains were found, and considered it a different species from the spotted hyena on account of its superior size. He elaborated his view in his Ossemens Fossiles (1823), noting how the cave hyena's digital extremities were shorter and thicker than those of the spotted hyena. His views were largely accepted throughout the first half of the 19th century, finding support in de Blainville and Richard Owen among others. Further justifications in separating the two animals included differences in the tubercular portion of the lower carnassial. Boyd Dawkins, writing in 1865, was the first to definitely cast doubt over the separation of the spotted and cave hyena, stating that the aforementioned tooth characteristics were consistent with mere individual variation. Writing again in 1877, he further stated after comparing the two animals' skulls that there are no characters of specific value.[13]

Analyses of the DNA sequences of the mitochondrial cytochrome b genes in both modern African and Pleistocene spotted hyenas demonstrated that the two were the same species.