The Bayan Mandahu Formation (also known as Wulansuhai Formation or Wuliangsuhai Formation ) is a geological unit of "redbeds" located near the village of Bayan Mandahu in Inner Mongolia , China, in the Gobi Desert . It dates from the late Cretaceous Period . Laid down in the Campanian , it is dated somewhat uncertainly to between 75 and 71 mya ( million years ago ).
4-465: The paleoenvironment it preserves was semi- arid and characterized by alluvial (stream-deposited) and eolian (wind-deposited) sediments. The formation is known for its vertebrate fossils, most of which are preserved in unstructured sandstone, indicating burial by wind-blown sandstorms . The fauna of the Bayan Mandahu is very similar in composition to the nearby Djadochta Formation , and
8-410: The Bayan Mandahu contains Protoceratops hellenikorhinus and Velociraptor osmolskae . An amphisbaenian species is known from the formation. An iguanian species is known from the formation. A taeniolabidoidea multituberculate is known from the formation. Arid Aridity is the condition of a region that severely lacks available water, to the extent of hindering or preventing
12-540: The growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic . Most arid climates are located in the subtropics ; these regions include parts of Africa , Asia , South America , North America , and Australia . The distribution of aridity at any time is largely the result of the general circulation of the atmosphere . The latter does change significantly over time through climate change . For example, temperature increase by 1.5–2.1 percent across
16-501: The two may have been deposited at roughly the same time. These two formations share many of the same genera , but differ in the makeup of species . For example, the most common mammal in the Djadochta is Kryptobaatar dashzevegi , while in the Bayan Mandahu, it is the closely related Kryptobaatar mandahuensis . Similarly, the dinosaur fauna of the Djadochta includes Protoceratops andrewsi and Velociraptor mongoliensis , while
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