Читать книгу Hadrosaurs - David A. Eberth - Страница 115

Fastovsky et al. (1997) demonstrated the widespread existence of eolian depositional environments in the Djadokhta Formation at Tögrögiin Shiree, more specifically an erg (= sand sea) with interconnected eolian dunes. Fluvial environments occurred in patches between the dunes (at Alag Teeg and Bayn Dzak). Based on the rich discoveries of vertebrate fossils including dinosaurs (and their eggs, nests, and infant individuals) in Djadokhta eolian beds, it suggests the possibility that the eolian (arid) environments of the Djadokhta age were inhabited by dinosaurs and other vertebrates. Ornithopod specimens found at Alag Teeg are the only records of this taxonomic group in the Djadokhta Formation, making Plesiohadros djadokhtaensis an apparently minor component of the dinosaur fauna in this overall arid setting. However, the eolian depositional environments and lithology seem to preferentially preserve the remains of small vertebrates such as small-sized theropods, lizards, and mammals. But the occurrence of aquatic vertebrates, such as turtles and crocodiles, is rare. The dominance of eolian deposits at these vertebrate fossil bearing localities suggests that the faunal composition is preservationally biased in favor of small body sizes.