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Smithsonian: The asteroid strike was only one factor in dinosaur extinction

Chicxulub Crater

Chicxulub impact crater/ NASA, JPL

Sixty-six million years ago, an asteroid hit the Yucatan Peninsula in Mexico and produced cataclysmic disruptions that, it is believed, killed off about 75% of species (the K/Pg extinction). But many researchers think there must have been other factors at work. For example,

Fish, turtles, amphibians and crocodylians all generally fared better than strictly terrestrial organisms. “People have been observing this pattern since at least the 50s, and probably before,” Holroyd says. But the resilience of waterbound species had never been quantified in detail before, and the new analysis is revealing that the solution to the extinction pattern puzzle may have been right in front of us all along.

The surprise, Holroyd found, was that the difference between the survivors and the extinct of the K/Pg event mimicked a pattern that has held true for tens of millions of years before and after the asteroid impact. Species living on land, particularly large species, tend not to persist as long as those living in freshwater environments. Terrestrial species often go extinct at a greater rate than those in aquatic environments even without a massive catastrophe to take them out of the picture. Species that lived in and around freshwater habitats appear to have persisted longer even when there wasn’t a crisis, and when the extinction at the end of the Cretaceous struck in full force, these organisms had an advantage over their purely terrestrial neighbours. Brian Switek, “We Still Don’t Know Why the Reign of the Dinosaurs Ended” at Smithsonian Magazine

Pat Holroyd hopes that as more pieces of the puzzle are filled in, we will learn more about why aquatic life forms are at less risk of extinction.

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See also: The Atlantic: “Nastiest feud in science” erupts over dinosaur extinction theory

See also: In the past, the field has been littered with speculations such as that dinosaurs were dumber than mammals and did not look after their young. But we now know that some dinosaurs did look after their young and that the capacity to do so is much older than formerly thought. Also that placental mammals are not uniformly smarter than all other life forms.

Extinction: Had the dinosaurs been dying out before the big K-T extinction?

Dino diminuendo (They were dying out before the asteroid hit.) That might help account for why all dinosaurs disappeared but only a large proportion of other vertebrates.

Smoking did not kill the dinosaurs, but dark matter might have contributed

Dinosaurs doomed by egg-laying?

Size helped largest dinos survive longer?

Do mass extinctions happen every 26 million years or so?

Study: Two years’ darkness provides clue to total dinosaur extinction


We can’t understand evolution without understanding stasis and extinction

If I am not mistaken, it was generally accepted that the dinosaurs were in decline long before the asteroid, and that the asteroid was just the tipping-point. The lack of fossils at the boundary does not bother me as conditions have to be just right for fossilization to occur. Besides, they have found fossils to within a few centimetres of the boundary. All of this is moot if birds are descended from dinosaurs. Ed George
Old news. Paleontologists have long said that if it was the Chix impactor that we would find the dinosaur fossils leading up to the KT, through the KT and just above it, with scarce to no fossils after that. Whoops, vmahuna beat me to it... ET
Wasn't there also massive volcanic activity around that time - on geologic scales - in that area of northern India known as the Deccan Traps? Seversky
This is generally misleading. First, from a geologic point of view, what we now call "the Yucatan Peninsula" was undoubtedly a VERY different chunk of ground, surrounded by VERY different seas and oceans. Second, ALL of the dinosaurs died off POOF!. This includes STRICTLY aquatic plesiosaurs, etc. While sharks, (and whales) etc., did NOT die off. And as has been pointed out by paleontologists who do field work, the K-T Boundary is NOT covered in dense piles of dino bones. That is, the dinos had ALREADY died off BEFORE the Asteroid of DOOM hit somewhere in what is now called "the Caribbean Sea". The absence of ANY dinos above the K-T Boundary is a red herring. Climate change (prior to the Big WHUMP!) doesn't work either because the frogs and amphibians made it through the transition just fine. And there is evidence that some dinos were living in areas where the average daytime temperature was around 35 degrees F. So, perhaps The Designer simply got TIRED of dinosaurs and hit the DELETE button. And then, separately, The Designer caused a big honkin' meteor to slam into Yugopatamia, because it was the end of the fiscal year and the meteor had been determined to be "excess to current needs". And of course ALWAYS consult "The Hitch Hiker's Guide" for examples of whims amongst the Design Staff. vmahuna

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