Scientist just can't believe it. It's a lady T.rex. Of course, nobody thought that T.rex were born out of thin air, but it's for the first time such a major discovery is made: actual proof of a T.rex female, about to give birth.

But just what is the technique of telling apart the T.rex genders? Well, it's all in a small fragment of tissue, called medullary bone, which can be also found in the case of modern day birds.

This little piece of evidence from the past, found in the broken leg bone of the fossil unearthed in Montana, helped scientists establish the fact that their "Bob", as the T.rex was initially called, after the paleontologist who discovered it, Bob Harmon, what not at all a male, but a future mother.

This was possible due to the fact that this particular type of estrogen-linked tissue is present only during the modern birds' pregnancy period. Then, it is completely resorbed, until the beginning of the next egg-laying cycle.

And this brings us to another major issue. The fact that this discovery is very important because is also offers proof towards a very old theory: that of the direct link between dinosaurs and birds.

Scientist hope that this amazing discovery will offer them more insights on the evolution of species, and maybe even help them establish the genders of other fossils unearthed so far.

In any case, we can't help but wonder, isn't it sad that the terrible image advertised up until now for the T.rex might be associated from now with that of a mere chicken?