One megayear, or 1 MYA (million years ago).
It is highly unlikely. A million years is a short time on a geologic timescale. Earth will remain habitable for a few hundred million years into the future.
Yes, their biology has remained constant through 50 million years of evolution- in saltwater.
Evolution
In short, no. The Cretaceous period ended 65.5 million years ago, and mammoths first evolved about 5 million years ago.
No. It's at least 50,000 minutes short of two years.
Supermassive stars have extremely short lifespans, ranging from some 50 million years to a mere million years.
so old that it makes 10000 million years seem short
The short answer is about 380 million years. This has recently been revised with new fragmented fossil evidence dating them 50 million years earlier than previously thought.
It is: 1,000,000-764,000 = 236,000 short of a million
Brachiosaurus died out about 151 million years ago. Triceratops died out 65.5 million years ago. The dodo bird died out during the 1600's. In short, the answer is no.
Using the "short scale" number names (new name every thousand), "one thousand million years" is a "billion years", the metric equivalent being a "gigaannum" (1 Ga). (see link)