This video is called Life in Cenozoic Times.
WASHINGTON – Details on the largest climate change since the age of dinosaurs come straight from the horse’s mouth, as equine teeth provide clues to how long, how cold and when the big chill was, scientists reported Wednesday.
Earth’s temperature dropped by 15 degrees F over a period of 400,000 years some 33.5 million years ago, the researchers said in the current edition of the journal Nature. …
However, they lacked the analytic tools to determine how much temperature change there was over how long a period, and exactly when it occurred.
After the transition, they were gone.
Scientists believe changes in ocean currents were to blame for the shift.
To figure out the details of what French researchers dubbed Grande Coupure — “big cut” — MacFadden and his co-authors examined the preserved teeth and bones of fossil horses and another cloven-hoofed mammal called an oreodont.
See also here.
In a study, (see video) researchers from eight institutions, led by scientists from the University of Florida and University of Nebraska, followed the evolution of the earliest horses about 56 million years ago and found a correlation between temperature and body size in mammals. They saw that as temperatures increased, the animals’ sizes decreased.
Ice during the Oligocene: here.
Pleistocene Horses in the New World: here.
Clalicotherium etc. fossils, here.