11 research outputs found
Sauropod embryo-bearing rocks
11 p. : ill. (some col.), map ; 26 cm.Includes bibliographical references (p. 10-11).The stratigraphy and age of a sauropod nesting ground containing the first definitive embryonic remains of sauropods preserved inside their eggs is analyzed. The fossil locality, called Auca Mahuevo, occurs in the Anacleto Member of the RÃo Colorado Formation in Neuquén Province, Argentina. The 5 m thick interval of overbank mudstones containing the fossilized eggs and embryos occurs near the middle of a 35 m sequence of thin, fluvial, concretionary sandstones and thicker units of silty sandstone. Flooding of shallow stream channels deposited overbank silt and mud on the eggs, killing the embryos and initiating the process of fossilization. Egg fragments containing patches of fossilized integument were found as float weathering out of the mudstone on local flats. Complete eggs containing embryonic bones and teeth were quarried from a steep ridge where the mudstone was exposed. Twelve paleomagnetic samples collected throughout the lower 30 m of the section establish the presence of a Reverse geomagnetic polarity interval. This constitutes the first magnetostratigraphic characterization for this part of the RÃo Colorado Formation and for the late Cretaceous sequence of formations that comprise the Neuquén Group. Biochronologic age estimates for the RÃo Colorado fauna combined with the Reverse polarity determinations for the fossiliferous sediments in the Anacleto Member argue for an age younger than the long Cretaceous C34 Normal, which ends at the upper boundary of the Sartonian and older than the late Campanian. The Reverse interval containing the fossils at Auca Mahuevo is therefore considered to be early or middle Campanian in age, most likely correlative with C33R between 83.5 and 79.5 Ma
Stratigraphy and magnetostratigraphic/faunal constraints for the age of sauropod embryo-bearing rocks in the Neuqu\ue9n Group (Late Cretaceous, Neuqu\ue9n Province, Argentina). American Museum novitates ; no. 3290
The geology of Ukhaa Tolgod (Djadokhta Formation, Upper Cretaceous, Nemegt Basin, Mongolia) /
no. 361
The geology of Ukhaa Tolgod (Djadokhta Formation, Upper Cretaceous, Nemegt Basin, Mongolia) ; American Museum novitates, no. 3616
The geology of Ukhaa Tolgod (Djadokhta Formation, Upper Cretaceous, Nemegt Basin, Mongolia) ; American Museum novitates, no. 3616
Stratigraphy and magnetostratigraphic/faunal constraints for the age of sauropod embryo-bearing rocks in the Neuqu\ue9n Group (Late Cretaceous, Neuqu\ue9n Province, Argentina). American Museum novitates ; no. 3290
Paleogene mammals from the Andes of central Chile : a preliminary taxonomic, biostratigraphic, and geochronologic assessment. American Museum novitates ; no. 3098
31 p. : ill. (some col.) ; 26 cm.Includes bibliographical references (p. 27-31