Ahl al Oughlam

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Ahl al Oughlam is a very important paleontological site in Africa . It is located just outside the eastern outskirts of Casablanca , 2.6 kilometers from Tit Mellil in Morocco . The first finds were made in 1985 in a former quarry, and systematic excavations have been taking place since 1989. The age of the site is given as about 2.5 million years, this corresponds to the beginning of the Gelasian , the highest stage of the Pliocene . Around 80 vertebrate species have been discovered so far, mainly mammals (including primates , but not hominids ) and birds . Ahl al Oughlam is thus the richest vertebrate site in North Africa .

Geological and geomorphological framework

The area surrounding Casablanca consists of folded Paleozoic basement mountains - Central Cambrian slate, greywacke and quartzite. This basement is known as the coastal meseta and structurally belongs to the Moroccan meseta . It only appears sporadically to the surface, mostly it is covered by neogene formations.

The meseta is characterized by the relative stability that this crustal area experienced after the completion of the Variscan mountain formation - in contrast to the neighboring atlas. In the period that followed, the meseta was gradually eroded into a uniform hull surface and, from the Neogene, was then covered by several transgression cycles of the Atlantic. The first and at the same time most important of these cycles took place in the Tortonian (Miocene), the second with the onset of the Gelasium - it bears the local name "Moghrebian".

Ahl al Oughlam belongs to the third cycle, the “Messaoudium”. When the sea receded, a coast-parallel dune series with a layer of scree at the base formed. The actual body of sand had meanwhile solidified into sand-lime brick . In this solidified sediment body there were karstification phenomena and crevices; the latter became the undoing of a rich fauna.

In the Pleistocene (Quaternary) there are five more dunes towards the Atlantic. It should be noted that these transgression and regression cycles coincide quite well with the interglacial and ice ages .

Ahl al Oughlam is around 6.2 kilometers from the Atlantic and is 108 meters above sea level. The coastal meseta has therefore shown strong emergence tendencies since the Neogene with the formation of large abrasion terraces .

fauna

The most common finds among the vertebrates were clearly made in the class of mammals :

Primates (Primates)

Rodents (Rodentia)

Hare-like (Lagomorpha)

Insect eater (Eulipotyphla)

Bats (chiroptera)

Predators (Carnivora)

Unpaired ungulate (Perissodactyla)

Artiodactyla (Artiodactyla)

Whales (cetacea)

Russell animals (Proboscidea)

In addition to mammals, birds are the most common animal group with 20 species, followed by reptiles with 15 species and amphibians with 3 species. In addition, countless isolated fish remains have been found.

What is striking is the large number of predators among the mammals - they obviously had their shelter in caves and crevices of the dunes.

The fauna shows overall echoes of East African sites (e.g. Omo ), but there are also southern European influences.

The remains of a walrus and a horned cattle giraffe are curious .

literature

  • S. Bailon: Amphibians et Reptiles du Pliocène terminal de Ahl al Oughlam. (Casablanca, Maroc) . In: Géodiversitas 22, 2000, 4, ISSN  1280-9659 , pp. 539-558.
  • D. Geraads: Rongeurs et Insectivores du Pliocène final de Ahl al Oughlam, Casablanca, Maroc . In: Géobios 28, 1995, 1, ISSN  0016-6995 , pp. 99-115.
  • D. Geraads: Carnivores du Pliocène terminal de Ahl al Oughlam. (Casablanca, Maroc) . In: Géobios 30, 1997, 1, ISSN  0016-6995 , pp. 127-164.
  • André Michard: Eléments de Géologie Marocaine . Editions du Service Géologique du Maroc, Rabat 1976, ( Notes et memoires du Service Geologique 252).

Web links

Coordinates: 33 ° 34 ′ 5.6 "  N , 7 ° 30 ′ 42.7"  W.