The Paleogene Alai Beds have a limited distribution, and are restricted to the northern slope of
Aktash Range, formed by
Paleozoic rocks, which is one of the foothills of the
Turkestan Range. The Paleogene deposits on the Aktash Range are badly exposed, they can be observed only in three
outcrops, separated by short distances about 1 to 2 kilometres (0.62 to 1.24 mi). Despite of their close position, the Paleogene deposits in these outcrops are varied greatly in composition and thickness of layers.[2]
The lower Alai Beds contain 5 metres (16 ft) of silts and siltstones, and the upper part comprises
oyster-bearing
limestones of which 2 to 3 metres (6 ft 7 in to 9 ft 10 in) are exposed. At the base of the Upper Alai Beds there is a layer of
conglomerate which produces a number of marine vertebrates, but a few terrestrial vertebrates including mammals. The section I1 is more complete and has a greater thickness, but produces a few shark teeth only. The third Paleogene section, where the mammal bearing locality Andarak 2 is located, has a much greater thickness of sands of the lower Alai Beds (more than 25 metres (82 ft) of visible thickness) with some horizons of oyster-bearing conglomerates.[3]
Fossil content
The formation has provided the following fossils:[1]
Lopatin, A. V (2006). "Early Paleogene insectivore mammals of Asia and establishment of the major groups of Insectivora". Paleontological Journal. 40: S205–S405.
Lopatin, A. V.; Averianov, A. O. (2006). "Eocene Lagomorpha (Mammalia) of Asia: 2. Strenulagus and Gobiolagus (Strenulagidae)". Paleontological Journal. 40: 198–206.
Averianov, A. O.; Godinot, M. (2005). "Ceratomorphs (Mammalia, Perissodactyla) from the early Eocene Andarak 2 locality in Kyrgyzstan". Geodiversitas. 27: 221–237.
Averianov, A. O.; Lopatin, A. V. (2005). "Eocene Lagomorphs (Mammalia) of Asia: 1. Aktashmys (Strenulagidae fam. nov.)". Paleontological Journal. 39: 308–317.
Lopatin, A. V.; Averianov, A. O. (2004). "New Palaeoryctidae (Mammalia) from the Eocene of Kyrgyzstan and Mongolia". Paleontological Journal. 38: 556–562.
Averianov, A. O (2002). "Review of Mesozoic and Cenozoic sea turtles from the former USSR". Russian Journal of Herpetology. 9: 137–154.
Danilov, I. G.; Averianov, A. O. (1999). "A new species of Calamagras Cope 1873 (Serpentes, Boidae, Erycinae) from the early Eocene of Kirghizia". Geodiversitas. 21: 85–91.
Lavrov, A. V.; Averianov, A. O. (1998). "The Oldest Asiatic Hyaenodontidae (Mammalia, Creodonta) from the Early Eocene of the Southern Fergana Basin (Andarak-2 Locality)". Paleontological Journal. 32: 200–205.
Averianov, A. O.; Danilov, I. G. (1997). "A varanid lizard (Squamata: Varanidae) from the early Eocene of Kirghizia". Russian Journal of Herpetology. 4: 143–147.
Danilov, I. G.; Averianov, A. O. (1997). "New data on the turtles from the Early Eocene of Kirghizia". Russian Journal of Herpetology. 4: 40–45.