Monday 20 November 2017

Panthera leo: A gigantic Lion from the Middle Pleistocene Natodomeri deposits of the Ilemi Triangle, East Africa.

Lions, Panthera leo, first appeared in the Late Pliocene of Africa and spread across Eurasia and North America during the Pleistocene, an expansion matched only bu one other African Mammal, Homo sapiens. During this expansion some very large Lions appeared in the northern part of this range, which are sometimes considered to be separate species, Panthera spelaea, the European Cave Lion, and Panthera atrox, the American Cave Lion. However, since modern Lions are, on average, smallest at the equator and largest at the northernmost and southernmost extent of their ranges, it is possible that these large European and American Lions are simply more extreme examples of this trend from a time when the species occupied a far larger range. This is made more complicated by the fact that very few fossil Lions are known from the Pleistocene of Africa, making comparisons difficult.

In a paper published in the Journal of Paleontology on 9 November 2017, Fredrick Manthi of the Department of Earth Sciences at the National Museums of Kenya, the late Francis Brown of the Department of Geology and Geophysics at the University of Utah, Michael Plavcan of the Department of Anthropology at the University of Arkansas, and Lars Werdelin of the Department of Palaeobiology at the Swedish Museum of Natural History, describe a new and exceptionally large Lion skull from the Middle Pleistocene Natodomeri Deposits of the Ilemi Triangle.

The Ilemi Triangle is a disputed territory located between Ethiopia, South Sudan and Kenya. It is claimed by both South Sudan and Kenya, but is currently controlled and administered by Kenya. The territory has no permanent residents, but is used seasonally by a variety of pastorialist groups (nomadic Cattle herders), whose ranges also include parts of Ethiopia, South Sudan and Kenya. The Natodomeri Deposits have been worked by archaeologists and palaeontologists since the 1960s. They comprise a former northward extension of Lake Natodomeri, producing material dating from about  205 000 to about 35 000 years ago.

The new specimen is a poorly preserved partial skull, but clearly that of a Lion. In the absence of any evidence to the contrary it is assigned to the modern Lion species, Panthera leo. It is estimated to have come from a fully grown young adult, based upon analysis of dental wear. Due to its worn and damaged state it is not possible to accurately state the size of the full skull, but the teeth, generally a good proxy for this size in Leonids, are comparable in size to those of the largest Cave Lions, suggesting that this Animal, which lived close to the equator, was as large as those northern Lions.

Partial skull of Panthera leo from Natodomeri in (top) right lateral and (bottom) occlusal views. Manthi et al. (2017).

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