Dinosaur footprints from the Upper Cretaceous of Mongolia

We report new data on 18 dinosaur footprint localities discovered in the Upper Cretaceous of the Gobi Desert of Mongolia, where we have recognized more than 20 000 footprints of dinosaurs. There are at least four types of dinosaur footprints, attributed to theropod, ornithopod, ankylosaurid and sauropod trackmakers. We have also recognized abun dant footprints of un identified trackmakers from each locality. Co existence of footprints and many skeletal remains in the same and/or nearby beds is a remarkable feature of these Mongolian sites. Analyses of dinosaur footprints and associated body fossil remains for each locality reveal that even in the same beds, the ichnofauna differ from the fauna reconstructed on the basis of body fossils of dinosaurs. The results demonstrate that dinosaur faunal assem blages reconstructed from body fossil or footprint evidence solely should be considered very carefully

A nest of Protoceratops andrewsi (Dinosauria, Ornithischia)

A remarkable specimen of the small neoceratopsian dinosaur Protoceratops andrewsi (Late Cretaceous, Mongolia) reveals the first nest of this genus, complete with fifteen juveniles. The relatively large size of the individuals and their advanced state of development suggests the possibility that Protoceratops juveniles remained and grew in their nests during at least the early stages of postnatal development. The nest further implies that parental care and sociality are phylogenetically basal behaviors in Ceratopsia. Finally, it reaffirms the conclusion that Protoceratops lived (and died) in the sandy aeolian dune fields of the central Asian craton. © 2011 The Paleontological Society

Sedimentological and taphonomic observations on the "Dragon's Tomb" Saurolophus (Hadrosauridae) bonebed, Nemegt Formation (Upper Cretaceous), Mongolia

The famous "Dragon's Tomb" Saurolophus bonebed at Altan Uul II preserves multiple complete skeletons with skin impressions, and is exceptional among Nemegt Formation dinosaur localities as the only mass accumulation of articulated individuals. Here, we present results from an on-going paleontological project focused on the Baruungoyot-Nemegt succession in order to document this unique locality. Sedimentological data allow us to confirm that the fossils and host sediments were deposited in the thalweg of a meandering paleochannel that experienced a variety of high and lower energy flow conditions. A variety of taphonomic data were collected from exposed fossils, including those displaced by poaching. Three-dimensional maps of the host sediments and fossils were generated, and 13 m2 of exposed, in-situ bones were mapped. Previously undocumented portions of at least 13 additional Saurolophus individuals and a partial subadult Tarbosaurus skeleton were identified. The Dragon's Tomb is a monodominant bonebed with at least three size classes (juvenile, subadult, and large adult) of Saurolophus preserved. The bonebed has a minimum size of ~ 2000 m2, suggesting that over 100 Saurolophus carcasses may have contributed to the thanatocoenose. Although the data provide evidence for a catastrophic mass death of a social group of Saurolophus and provide the first evidence of gregariousness in this taxon, the cause of death cannot be determined

Sedimentological and taphonomic observations on the “Dragon's Tomb” Saurolophus (Hadrosauridae) bonebed, Nemegt Formation (Upper Cretaceous), Mongolia

The famous "Dragon's Tomb" Saurolophus bonebed at Altan Uul II preserves multiple complete skeletons with skin impressions, and is exceptional among Nemegt Formation dinosaur localities as the only mass accumulation of articulated individuals. Here, we present results from an on-going paleontological project focused on the Baruungoyot-Nemegt succession in order to document this unique locality. Sedimentological data allow us to confirm that the fossils and host sediments were deposited in the thalweg of a meandering paleochannel that experienced a variety of high and lower energy flow conditions. A variety of taphonomic data were collected from exposed fossils, including those displaced by poaching. Three-dimensional maps of the host sediments and fossils were generated, and 13m2of exposed, in-situ bones were mapped. Previously undocumented portions of at least 13 additional Saurolophus individuals and a partial subadult Tarbosaurus skeleton were identified. The Dragon's Tomb is a monodominant bonebed with at least three size classes (juvenile, subadult, and large adult) of Saurolophus preserved. The bonebed has a minimum size of â1⁄42000m2, suggesting that over 100 Saurolophus carcasses may have contributed to the thanatocoenose. Although the data provide evidence for a catastrophic mass death of a social group of Saurolophus and provide the first evidence of gregariousness in this taxon, the cause of death cannot be determined