When a thirsty pregnant horse drank from a freshwater lake 47 ... given the differences in the animals' size and anatomy. The ancient mare was small — about the size of a modern fox terrier ...

The fossil’s reproductive anatomy is so advanced that researchers ... Researchers had earlier found a 44-million-year-old fossil of a pregnant horse, but the reproductive tract was not as ...

"We were able to study the impact of chromosome errors across the entire pregnancy in the horse," de Mestre said. "We found that triploidy is only associated with losses in early pregnancy." ...