April 20, 2021
During 2.4 million years of existence, a total of 2.5 billion
Tyrannosaurus rex lived on Earth, and 20,000 individual animals would have been alive at any moment, according to new calculations.
Tyrannosaurus rex spanned all of ancient North America, and about 20,000 lived at once. Image via 1Ado123/ Wikimedia Commons.
During 2.4 million years of existence on Earth, a total of 2.5 billion
Tyrannosaurus rex ever lived, and 20,000 individual animals would have been alive at any moment, according to a new calculation method we described in a paper published on April 15, 2021 in the journal
Science.
To estimate population, our team of paleontologists and scientists had to combine the extraordinarily comprehensive existing research on
The big idea
During 2.4 million years of existence on Earth, a total of 2.5 billion
To estimate population, our team of paleontologists and scientists had to combine the extraordinarily comprehensive existing research on
From microscopic growth patterns in bones, researchers inferred that
T. rexfirst mated at around 15 years old. With growth records, scientists can also generate survivorship curves – an estimate of a
T. rex generations took 19 years. Finally,
T. rex existed as a species for 1.2 to 3.6 million years. With all of this information, we calculate that
T. rex existed for 66,000 to 188,000 generations.
From the fossil record alone, we had generated a
administration is ordering all its air traffic controllers back to work. the f.a.a. says control towers will be fully staffed again by tomorrow night. this follows a rough week on runways across the country. more than 5,000 delays and hundreds of cancellations. 15,000 air traffic controllers had been furloughed after mandatory federal budget cuts known as the sequester, and there simply weren t enough of them to handle the volume. as carter evans reports, congress solution to this problem may create plenty of others. reporter: it seems members of congress couldn t eave washington fast enough for their week-long recess, even after a rare show of unity. both sides agreed to quickly end the air traffic controller furloughs, whic which caused thousands of flight delays. is what we saw congress at its best or congress at its worst? i don t think it s congress at its best. democratic congresswoman karen bass arrived home friday night on time but with plenty of unfinished bus