Smithsonian National Museum of Natural History

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Carboniferous

Early Late Cretaceous dinosaurs from Central Asia

 

Another long-standing research interest of mine is the evolutionary history of non-avian dinosaurs, especially from the Cretaceous Period.


Starting in the late 1970s, Lev A. Nessov (St. Petersburg State University) and his students started exploring exposure of Cretaceous continental strata in what were at that time the southern territories of the former Soviet Union. They were following up on earlier reports of vertebrate fossils from what are now the independent nations of Uzbekistan and Kazakhstan. Nessov was primarily interested in Mesozoic mammals but collected any vertebrate fossils that he and his team encountered. One site, Dzharakuduk (Kazakh for "well on the escarpment") in the central Kyzylkum Desert of Uzbekistan, proved to be particularly productive and yielded abundant remains of a very diverse biota including mammals and dinosaurs. What was particularly unexpected about the vertebrate assemblage from Dzharakuduk was the fact that it is surprisingly similar to assemblages from western North America, and unlike the famous fossil occurrences of the Gobi Desert, in its faunal composition. After Uzbekistan gained its independence, Nessov, J. David Archibald (San Diego State University), and I started planning collaborative fieldwork at Dzharakuduk, but Nessov's untimely death temporarily put these plans on hold. Fortunately, Alexander Averianov, Nessov's senior student and himself a leading expert on Mesozoic vertebrates, was able to join the project. From 1997 to 2006, our team worked with colleagues from the Uzbek Academy of Sciences, St. Petersburg State University, and the Royal Ontario Museum (where I was employed at that time) at Dzharakuduk, collecting both large vertebrate remains as well as processing sediments for microvertebrate remains. This work succeeded beyond our wildest expectations. Abundant well-preserved bones and teeth of a great diversity of fossil vertebrates occur in fluvial strata of the Bissekty Formation, the age of which was constrained to middle to late Turonian through the stratigraphic work of Chris King and his team. In collaboration with Alexander Averianov, I am now studying the dinosaurian remains from the Bissekty Formation. This rich material documents a great diversity of dinosaurs. Most of the specimens are isolated but often exquisitely preserved bones and teeth. Sauropod dinosaurs are surprisingly common. Another noteworthy record is the first definite ceratopsid from Asia. The study of the dinosaurs and other groups of vertebrates from Dzharakuduk will significantly contribute to our understanding of faunal evolution in and paleobiogeography of the Northern Hemisphere during the Cretaceous Period.

 

Simplified map of Uzbekistan and adjoining areas. "D" denotes Dzharakuduk. (Courtesy of J. D. Archibald.)

Outcrops at Dzharakuduk, Kyzylkum Desert, Uzbekistan. Field camp in the foreground. The exposures of the fossil-bearing Bissekty Formation are located on the first main terrace.

Locality CBI-14 at Dzharakuduk in 1997. Members of the field crew crawl on the outcrop surface to collect exposed bones and teeth. This site has produced a wealth of small vertebrate remains as well as some exquisitely preserved bones of dinosaurs and pterosaurs.

Partial skull (holotype) of Levnesovia transoxiana Sues and Averianov, 2009, an early relative of duckbilled dinosaurs.

Supraorbital horn core of Turanoceratops tardabilis, the first definite ceratopsid dinosaur from Asia. Ceratopsids (which include the famous Triceratops) were once thought to be restricted to western North America.

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