Loss of wetlands caused disappearance of turtles from Alberta
Washington: Dramatic climate change was previously proposed to be responsible for the disappearance of turtles from Alberta's Drumheller area 71-million-years ago, because they were considered to be "climate-sensitive" animals.
A new research has, however, suggested that the disappearance of turtles came before the climate cooled and instead closely corresponds to habitat disturbances, which was the disappearance of wetlands.
The dry, barren prairie around Alberta's Drumheller area was once a lush and subtropical forest on the shores of a large inland sea, with loads of wetlands inhabited by dinosaurs, turtles, crocodiles and small mammals.
But that changed about 71-million-years ago, the new study by researchers Annie Quinney and Darla Zelenitsky in paleontology at the University of Calgar revealed.
The researchers' calculations show that drastic climate change occurred during a five-million-year period in Alberta's badlands. At this time, the wetlands dried up and the warm humid climate was interrupted by a sudden cool, drying spell.
"This was a time of change in Alberta, the wetlands disappeared as the inland sea retreated and the climate cooled," said Quinney, a former master's student in the Department of Geoscience who led the study which was part of her master's degree in the Department of Geoscience.
"The big surprise is that some animals, for example turtles, appeared to be more sensitive to habitat disturbances than to climate changes. Therefore, even if climatic conditions are 'ideal,' turtles may disappear or may not recover unless habitats are just right," said and record information about the past climate and environments.
Researchers calculated precipitation and temperature levels over a five-million year interval and during that time, temperature and precipitation dropped over a few thousand years, and that cooler interval lasted for 500,000 years.
"By studying the structure and chemistry of ancient soils, we were able to estimate the ancient temperature and rainfall that prevailed when those soils formed millions of years ago," said Quinney, who is now completing a PhD at Monash University in Australia on a full scholarship.
The study was recently published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.