Everybody loves the T. REX. Well, now that they are gone and we don't have to worry about them chasing us down and eating us.

So, how many actually roamed North America during the this period? That's a good question.

Charles Marshall has been asking his paleontologist colleagues that question for years. It's not an easy one to answer.

Journal Science is about to publish an article stating that about 20,000 adult T. rexes probably lived at any one time. That is a ballpark number based on estimates and current data.

If those numbers are in the ballpark then some 2.5 billion T-rexes lived and died over the approximately 2 1/2 million years dinosaurs walked the earth.(Berkeley News).

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If we take a look at where they were most concentrated, then the place we now call Wyoming was not a safe place to live at the time.

During the Cretaceous period Wyoming was at the bottom of the ocean. But the climate is always changing, noting stays the same. The bottom of the ocean became an inland sea, then swampy and tropical. Wyoming went from that to being covered by ice for a very long time. That is a lot different than the Wyoming we see today.

T-Rex fossils and tracks in Wyoming reveal a lot about the number and even the speed of the beast. A lot has been learned. The tracks consist of three distinct prints found in sandstone just north of the town of Glenrock in eastern Wyoming, on the fossil-rich grounds of the Paleon Glenrock Museum.

Paleontology and a UC Berkeley professor of integrative biology and of earth and planetary science, was also surprised that such a calculation was possible.

“The project just started off as a lark, in a way,” he said. “When I hold a fossil in my hand, I can’t help wondering at the improbability that this very beast was alive millions of years ago, and here I am holding part of its skeleton — it seems so improbable. The question just kept popping into my head, ‘Just how improbable is it? Is it one in a thousand, one in a million, one in a billion?’ And then I began to realize that maybe we can actually estimate how many were alive, and thus, that I could answer that question.”  (Berkley News).

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