Researchers examining lake deposits in northern Indiana noted a decline in Sporormiella spores at this time, suggesting a similar decline in the amount of dung around the lake, a proxy for the presence of large mammals such as mastodons and ground sloths.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed.By measuring the radioactive decay it is possible to establish accurately the age of the hadrosaur, a giant plant eating dinosaur with a platypus-like bill.Currently, palaeontologists date dinosaur fossils using a technique called 'relative chronology' which means establishing the age of sedimentary rocks above and below the layer in which the fossil is found.Thus, we do not consider either of these factors to have contributed significantly to their extinction.In the absence of these, we propose that their extinction was possibly the result of long-term demographic and genetic declines associated with an isolated island population.Estimates on when stegodons arrived on individual islands and the timings of their extinctions are poorly constrained due to few reported direct geochronological analyses of their remains.
Led by Larry Heaman from the Department of Earth and Atmospheric Sciences, the team say there could be several reasons why the New Mexico hadrosaur came from a line of dinosaurs that survived the great mass extinction of the late Cretaceous period (KT extinction period). Heaman said it is possible that in some areas the vegetation wasn't wiped out and a number of hadrosaur species survived.
Stegodons (Stegodontidae: Proboscidea) were a widespread and diverse family of proboscideans dating from the late Miocene to the Late Pleistocene of Africa and Asia.
We have investigated the potential of hübnerite for U–Pb dating.
Deciduous elements spread into the Midwest for the first time since the last glacial maximum. Lowlands and riparian areas are saturated, promoting the widespread development of wetlands and semi-aquatic plant communities dominated by sedges and bulrushes.
Animals found within this landscape included mastodons and relict mammoth populations.