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extinction

Jaguars, cougars survived Ice Age by adjusting diets

From National Geographic: Jaguars are old cats. They first evolved in Eurasia sometime around three million years ago before spreading both west and east, eventually inhabiting a range from southern England to Nebraska and down into South America. Today’s range of southern Arizona to Argentina—over 3.4 million square miles—is only a sliver of their Ice Age expansion. And it wasn’t just the jaguar’s range that shrunk. Today the spotted cats are about fifteen percent smaller than their Pleistocene predecessors.Nevertheless, jaguars survived while the American lion, the sabercats, and other predators vanished. How? In order to investigate this question, biologist Matt Hayward and colleagues looked at the jaguar diet and how the cat’s prey preferences changed over time. … Crunching the Read More ›

Extinction is key to vertebrate terrestrial diversity?

We don’t think the World Wildlife Fund would welcome the news, put that way. Anyway, from ScienceDaily: Periods of high extinction on Earth, rather than evolutionary adaptations, may have been a key driver in the diversification of amniotes (today’s dominant land vertebrates, including reptiles, birds, and mammals), according to new research. … The new study examined the issue of adaptive radiations among early amniotes, from 315 to 200 million years ago. This time period witnessed some of the most profound climate changes on a global scale, including the dramatic shrinking of the southern polar icecap, the disappearance of equatorial rainforests, a substantial increase in temperature, and prolonged drought conditions. The time period under study also included the largest mass extinction Read More ›

Are mass extinctions driven by mineral deficiency?

There’s been a lot of ink lately around mass extinctions (maybe it’s the upcoming climate talks?) Further to the recent call for a rethink of the mass extinction 250 million years ago and the hypothesis that they happen regularly due to catastrophic extraterrestrial events, we now encounter researchers who think that most of them wree caused by mineral deficiencies. From New Scientist: A new theory suggests most of Earth’s mass extinction events could have been caused by a lack of essential trace elements in the world’s oceans, causing fatal deficiencies in marine animals, from plankton to reptiles. “It’s a complex scenario,” says John Long from Flinders University in Adelaide, Australia. He says there are probably a lot of causes conspiring Read More ›

Do mass extinctions happen every 26 million years or so?

It’s worth looking at. Recently, we looked at how new findings support a rethink of the mass extinction 250 million years ago. The rethink itself might be minor (land vs. sea timetables). The main thing to see is that each new piece added to the puzzle replaces neat theory and assumption with messy fact. Theory can no longer sustain itself by strategies such as “Darwinism is the only known theory that is in principle capable of explaining certain aspects of life. (p. 287, Blind Watchmaker, 1986)” Maybe not. Maybe after a while, no one cares how the theorists will bail themselves out of their latest mess. Meanwhile, from the Atlantic: The Chilling Regularity of Mass Extinctions Now, a pair of Read More ›

New findings support rethink of mass extinction?

Land and sea timing may have differed in the mass die-off 250 million years ago. Never mind theories of consciousness getting rocked, see this on the Permian extinction from ScienceDaily: New evidence gathered from the Karoo Basin in South Africa sheds light on a catastrophic extinction event that occurred more than 250 million years ago and wiped out more than 90 percent of life in Earth’s oceans and about 70 percent of animal species on land. The new evidence derives from a key volcanic ash deposit that the team discovered in rock layers, or strata, that were reported to chronicle the mass extinction. By dating the volcanic ash-bearing deposit, researchers concluded that two phases of this extinction — one on Read More ›

We can’t understand evolution without understanding stasis and extinction

Recently, a reader wrote to me concerning Stasis: Life goes on but evolution does not happen. Reader asked, Concerning horseshoe crabs and coelecanths, could it be possible that marine-environment organisms are under less pressure to change/evolve than terrestrial organisms? I replied, — Thank you very much for your thoughts! You could of course be correct. And then we face several conceptual tasks prior to research: 1. Specifying testable hypotheses as to why the longest-conserved marine life forms were under less pressure to change/evolve. We must not fall into the trap of assuming that they must be under less pressure because they didn’t evolve. We don’t know for sure that pressure has much to do with it. That is, we assume Read More ›

Tyrannosaur lunch: Another tyrannosaur

‘Twas ever thus: A nasty little 66-million-year-old family secret has been leaked by a recently unearthed tyrannosaur bone. The bone has peculiar teeth marks that strongly suggest it was gnawed by another tyrannosaur. The find could be some of the best evidence yet that tyrannosaurs were not shy about eating their own kind. … Serrated teeth rule out crocodiles and point directly to a theropod dinosaur like T. rex. The fact that the only large theropods found in the Lance Formation are two tyrannosaurs –Tyrannosaurus rex or Nanotyrannus lancensis — eliminates all interpretations but cannibalism, explained McLain, who will be presenting the discovery on 1 Nov. at the annual meeting of the Geological Society of America in Baltimore. … Even Read More ›

Humans are “unique super-predator”?

The BBC, having announced that chimps have “entered the Stone Age” (because they smash stuff with rocks, as do birds), has also announced that humans are unique super-predators. Actually, the point made is mostly a sensible one (for once): The analysis of global data details the ruthlessness of our hunting practices and the impacts we have on prey. It shows how humans typically take out adult fish populations at 14 times the rate that marine animals do themselves. And on land, we kill top carnivores, such as bears, wolves and lions, at nine times their own self-predation rate. But perhaps the most striking observation, say authors Chris Darimont and colleagues, is the way human beings focus so heavily on taking Read More ›

Uganda chimps number three times estimate

From ScienceDaily: Chimpanzees found to survive in degraded and human-dominated habitats (Well, given that—according to the BBC—), they have entered the Stone Age … No, but seriously, wouldn’t even reasonable people expect chimps to be at least as smart as urban raccoons? A chimpanzee population in Uganda has been found to be three times larger than previously estimated, according to research published in the open access journal BMC Ecology. The study suggests that chimpanzees may adapt to degraded habitats better than expected, but also highlights the importance of new and more focused conservation strategies. The protected Budongo and Bugoma Forest Reserves together compose approximately one quarter of the estimated total chimpanzee population in Uganda. The unprotected area between these two Read More ›

Cats face rap for killing off dogs

Like humans take rap for killing off mammoths. Yes, August. Hot weather. Stories. From ScienceDaily: Competition from cats drove extinction of many species of ancient dogs Competition played a more important role in the evolution of the dog family (wolves, foxes, and their relatives) than climate change, shows a new international study published in PNAS. An international team including scientists from the Universities of Gothenburg (Sweden), São Paulo (Brazil) and Lausanne (Switzerland) analyzed over 2000 fossils and revealed that the arrival of felids to North America from Asia had a deadly impact on the diversity of the dog family, contributing to the extinction of as many as 40 of their species. “We usually expect climate changes to play an overwhelming Read More ›

Mass extinctions can accelerate evolution?

In robots. From ScienceDaily: A computer science team at The University of Texas at Austin has found that robots evolve more quickly and efficiently after a virtual mass extinction modeled after real-life disasters such as the one that killed off the dinosaurs. Beyond its implications for artificial intelligence, the research supports the idea that mass extinctions actually speed up evolution by unleashing new creativity in adaptations. … “Focused destruction can lead to surprising outcomes,” said Miikkulainen, a professor of computer science at UT Austin. “Sometimes you have to develop something that seems objectively worse in order to develop the tools you need to get better.” In biology, mass extinctions are known for being highly destructive, erasing a lot of genetic Read More ›

Humans killed off mammoths AGAIN?

This is the time of year when pop science news recycles all the leftovers left over all over again, and this one was bound to come up—left over again: From ScienceDaily: Early humans were the dominant cause of the extinction of a variety of species of giant beasts, new research has revealed. The researchers ran thousands of scenarios which mapped the windows of time in which each species is known to have become extinct, and humans are known to have arrived on different continents or islands. This was compared against climate reconstructions for the last 90,000 years. Examining different regions of the world across these scenarios, they found coincidences of human spread and species extinction which illustrate that man was Read More ›

David M Raup 1933-2015

U Chicago News obit: University of Chicago paleontologist David Raup, SB’53, an innovative authority on evolution and mass extinctions, died of pneumonia July 9 in Sturgeon Bay, Wis. He was 82. Raup’s former students and colleagues uniformly praised his unique creativity along with his astute capabilities as an academic adviser, senior colleague and paleontological statesman. They remember him for the sweeping scope of the questions he asked, his analytical and quantitative rigor, and his skepticism and humility. “David Raup ushered in a renaissance in paleontology,” said Raup’s former student and colleague Charles Marshall, SM’86, PhD’89, director of the University of California’s Museum of Paleontology and professor of integrative biology at UC Berkeley. “Before Dave, much of the discipline was centered Read More ›

Problems with identifying extinctions

Here is an article in Cosmos that apparently wasn’t edited by Chicken Little. It addresses defects in our current knowledge: Setting aside the vague definition, calculating the extinction rate is tricky. A logical method is to divide how many species became extinct over a certain time by the total number of species on the planet. But scientists don’t know how many different animal species exist. Estimates vary wildly. One recent example was published by University of Melbourne entomologist Andrew Hamilton and colleagues in Proceedings of the National Academy of Sciences. Hamilton calculated that the number of terrestrial arthropod species – which includes insects and spiders, and is the largest single group of animals – is around 6.8 million. That’s far Read More ›

Geologist Marcus Ross on the proposed Sixth Great Extinction

  Further to: Is a sixth great extinction in progress? (It would help if a key exponent was anyone but Paul “Population Bomb” Ehrlich, a contender for the heavyweight champ of wrong-headed predictions) and Rob Sheldon on the sixth great extinction, Liberty U geologist Marcus Ross writes to say, For an abbreviated and pictorial list of species driven extinct in the past 400 years, see National Geographic You can mouse over each dot to learn about the species in question. Extinction rates in the fossil record are almost all determined at the family and genus level. In my own work on mosasaur richness during the Cretaceous (mosasaurs are large, mercifully extinct marine lizards), I focused on specimens identified to the Read More ›