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Dinosaurs were in decline long before asteroid finished them off, researchers say


    A replica of a 122-foot-long dinosaur is displayed at the American Museum of Natural History in New York. The dinosaur is a new species and one of the largest dinosaurs ever discovered. It has not yet been formally named by paleontologists who discovered it in Argentina in 2014. It belongs to a group known as titanosaurs.

Sixty-five million years ago, a massive asteroid slammed into Earth, causing tsunamis, earthquakes, fires, a global winter and the end of the age of the dinosaurs.

But what if the asteroid had glided safely past our planet? Would dinosaurs still be here today?

New research suggests the answer is probably not. Instead, scientists have found evidence that dinosaurs were in the midst of a long, slow decline that began millions of years before the asteroid struck.

In a study published Monday in the Proceedings of the National Academy of Sciences, researchers report that at least 40 million years before the Chicxulub asteroid landed in Mexico, dinosaur species were going extinct at a higher rate than new ones were coming into existence. With less species — and less variation in habitat requirements and ecological niches — dinosaurs would be more susceptible to environmental changes, the authors write.

“There is no doubt that the Chicxulub impact was the final nail in the dinosaurs’ coffin — with the exception of birds,” authors Manabu Sakamoto, a post-doctoral researcher at the University of Reading in England, and Chris Venditti, professor of evolutionary biology at the university, said in an email. “However, we can speculate that if the trajectory of dinosaurs continued as it was at that time, dinosaurs would eventually have become impoverished in terms of species numbers — and may have gone extinct all together.”

Dinosaurs were already in an evolutionary decline tens of millions of years before the asteroid impact that finally wiped them out, scientists from the University of Reading and University of Bristol have found.

The question of whether dinosaurs were already in decline before the asteroid put an abrupt end to their reign has been debated among paleontologists for decades. Recent attempts to address this question relied mostly on counting the number of fossils in the different geological time bins, Sakamoto said.

“The dispute has continued unresolved because of a lack of statistical rigor, and appropriate evolutionary framework,” the authors write.

In this paper, the authors turned to phylogenic trees, which show how species are related to each other, as the basis of their statistical analysis. This allowed them to study extinction and speciation rates in the three clades of dinosaurs through time.

The researchers found that speciation was in a long-term decline across all dinosaurs, and was exceeded by extinction rates between 48 million and 53 million years before the Chicxulub event.

The authors are not sure what caused the speciation rate to slow down, but they have a few ideas. They explain that the Cretaceous period (145.5 million to 65.5 million years ago) was a time of drastic geological changes. The global climate was cooling down, there was prolonged volcanic activity and the continents were breaking apart.

“Any combination of these processes could have affected dinosaur speciation,” Sakamoto and Venditti said.

Alternatively, it is possible that competition from mammals — which were just small, rodent-like creatures at the time — had something to do with it.

“Recent studies show evidence that mammals were on the rise prior to the [asteroid event], so this scenario would be consistent with our findings,” they said.


©2016 Los Angeles Times

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    • Ronin doesn’t understand that we can genetically manipulate birds during development to create dinosaur features.

      But then again he thinks Buck Angel should be forced to use the women’s bathroom.

      So what does Ronin know?

      • If you believe that an asteroid that supposedly landed in present day Mexico killed off dinosaurs all over the Earth, please explain why it did not also kill off all humans and why Mexico is still there. And yes, Buck Angel, should use female restrooms. There no doubt are some masculine looking females, but decorating their bodies with tattoos, building up muscles with steroids or weight lifting, or undergoing surgery to look like men does not make them males. The sight of Buck Angel in a male restroom is enough to scare the crap out of men, even those with severe constipation.

        • “If you believe that an asteroid that supposedly landed in present day Mexico killed off dinosaurs all over the Earth, please explain why it did not also kill off all humans and why Mexico is still there.”

          On man did you really just say that?

          That’s comedic gold. Especially since no one said anything about present day. It’s also amusing you think humans and dinosaurs coexisted. You are really uneducated.

          I’m going to bookmark this as proof you say some really crazy ****.

          And no, Buck Angel should not use the women’s bathroom. Buck should be allowed to do what Buck has done for years: use the men’s bathroom without any problems because forcing Buck to use the women’s bathroom will create way more problems than it solves.

          Anyone who’s Googled Buck Angel knows Ronin is completely full of crap.

        • Choyd, the story says the asteroid landed in Mexico. If not the present day location of Mexico, where was it? You seem to know everything, so perhaps you can enlighten me and other readers as to where Mexico was when the asteroid hit.

          And why should the whole world make an exception for Buck Angel because of what she did to herself to look like a man? You are as weird as she is.

    • Actually, geological records show that long term sustained super volcano activity was dramatically changing the climate leading to environmental pressures on all species during those times.

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