fauna

amnhnyc:

In the not-too-distant future, scientists expect that technological breakthroughs—and availability of genetic data from specimens of extinct species—will provide ways to revive vanished species.

Museum Curator Ross MacPhee discusses the science and ethical considerations of “de-extinction” in this video: http://bit.ly/13449Tt

The Silent Forests of Guam: How Bird Losses are warming a forest

by Emma Bryce

The Mariana Fruit-dove—a vibrant creature decorated with what looks like multicolored puffs of spray paint across it chest and crest—is just one bird of many on the forested island of Guam that will never again be spied through a birder’s lens. The pigeon disappeared famously along with many other native birds in the wake of an invasion by brown tree snakes after World War II. Only now are scientists starting to piece together the effects—among them a thinning forest canopy increasingly riddled with holes, like Swiss cheese, the researchers say.

Over the next four years, ecologists from Rice University and the University of Guam will be investigating how this thinner canopy might be linked to the disappearance of the island’s birds. The US territory, which lies at the southernmost tip of the Mariana island Archipelago, once held 12 avian species, but ten were decimated by waves of voracious brown tree snakes, brought in unintentionally on ships during island reconstruction after the war…

(read more: AudubonMagazine.org)

(Photo by Dick Daniels, carolinabirds.org via Wikimedia Commons)

flocks of passenger pigeons

once spread as far as one could see when they passed. they were quite possibly the most numerous vertebrate land animal on the planet. now, there are none, because of us.

once the flocks of millions had reached a critically low point, the females stopped brooding their eggs. you see, they needed enormous colonies to reproduce and feel safe from predators. once they had reached the low number, they stopped breeding in the wild, and that was the end. we had simply killed too many of them, and they

gave up.

Lizard Named After Obama Died in Dinosaur Apocalypse

by Naomi Lubick

President Barack Obama survived a tough reelection battle this year—but scientists say an ancient lizard named for him met a far crueler fate. When a 10-kilometer-wide asteroid struck Earth 65 million years ago, killing off the dinosaurs, scientists thought that lizards, snakes, and other so-called squamates mostly survived the impact.

But a new study shows that more than 80% of squamates also died in the mass extinction, including one that researchers christened Obamadon gracilis (center). The tiny animal with tall teeth, whose second name means slender, was discovered in ancient rocks in Montana about a year ago. Mammals’ evolutionary explosion, which began within 1.5 million years after the impact, is well documented, but it turns out that the squamates had their own postimpact evolutionary bounce.

By comparing hundreds of species of lizards and their kin before and after the impact, the team uncovered both the squamates’ mass extinction and the rise of new species of squamates about 10 million to 15 million years later. That group gave rise to the ancestors of modern snakes and lizards, the researchers report online this week in the Proceedings of the National Academy of Sciences. But poor Obamadon remains a relic of ancient history.

(via: Science NOW)                         (Illustration by Carl Buell )

One Scientist Argues That Volcanoes, Not Meteorite, Killed Dinosaurs

by Tia Ghose

Volcanic activity in modern-day India, not an asteroid, may have killed the dinosaurs, according to a new study.

Tens of thousands of years of lava flow from the Deccan Traps, a volcanic region near Mumbai in present-day India, may have spewed poisonous levels of sulfur and carbon dioxide into the atmosphere and caused the mass extinction through the resulting global warming and ocean acidification, the research suggests.

The findings, presented Wednesday (Dec. 5) here at the annual meeting of the American Geophysical Union, are the latest volley in an ongoing debate over whether an asteroid or volcanism killed off the dinosaurs about 65 million years ago in the mass die-off known as the K-T extinction.

“Our new information calls for a reassessment of what really caused the K-T mass extinction,” said Gerta Keller, a geologist at Princeton University who conducted the study. For several years, Keller has argued that volcanic activity killed the dinosaurs…

(read more: Live Science)                  (image: Gerta Keller, NSF)

Galapagos Tortoise ‘Lonesome George’ May Have Company

by Megan Gannon

The death of Galápagos tortoise Lonesome George this summer was thought to mark the extinction of a subspecies, but a new study hints that the reptile may not have been the last of his kind after all.

Researchers from Yale University recently trekked to the northern tip of Isabella Island, the largest of the Galápagos, and collected DNA from more than 1,600 giant tortoises. The genetic samples showed that 17 of these tortoises were hybrids that had a parent like Lonesome Georgefrom the subspecies Chelonoidis abingdoni.

What’s more, five of those hybrids were juveniles, suggesting purebred C. abingdoni tortoises may still be roaming a remote part of the island…

(read more: Live Science)                    (photo: Natursports)

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Early humans linked to large-carnivore extinctions

Hominins could have triggered broad changes to the numbers and diversity of meat-eaters in Africa, researcher says.

by Jeff Tollefson  (26 April 2012)

Animal lovers around the world know modern otters as cute, playful and unthreatening. But the mustelid’s giant cousins in ancient Africa may have engaged in a life-and-death competition with humanity’s ancestors — and come out on the losing end.

The demise of the gigantic ‘bear otter’ (Enhydriodon dikikae) was part of a broader decline in large-carnivore diversity in Africa, which accelerated around 2 million years ago — roughly the time that the first representatives of the genus Homo appeared on the scene. Lars Werdelin, a curator at the Swedish Museum of Natural History in Stockholm has been building a case that our forebears had something to do with the change. Although direct evidence of any causal connection is sorely lacking, Werdelin says, the transition in the carnivore fossil record coincides nicely with advances in tool-making and dietary shifts among early hominins.

“The way I see it, this is one of the first ways in which we manipulated our environment on a large scale,” says Werdelin, who presented his latest findings at a symposium on human evolution and climate change at Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York. Werdelin argues that hominins may have competed indirectly with some of these carnivores by occupying prime habitat, thus forcing the animals to change their behavior without ever coming into direct contact with them. In some cases, the hominins may have out-competed carnivores directly by forcing them to surrender fresh kills. Regardless, the emergence of early humans could have cascaded through the food chain — ultimately wiping out many of Africa’s larger meat-eaters…

(read more: Nature)              

(images via NovaTaxa: TR - Victor Leshyk; B - Cal. Academy of Sci.)

Better Collision Insurance: 

Asteroids smaller than those now being actively catalogued constitute a largely neglected natural hazard 

by Russell Schweickart, Clark Chapman

In October 2001, we and 22 like-minded engineers and astronomers, including a few former and current astronauts, got together at the Johnson Space Center in Houston to discuss what we saw as a missing element in the space program: attention to the possibility of our planet being struck by a near-Earth asteroid. We knew of the accelerating rate at which such objects were being discovered. But no one, certainly no federal or international agency, was taking seriously the question of what exactly to do when an asteroid is found with our address on it.

During that initial meeting, less than six weeks after the 9/11 terrorist strike, we decided that this threat from outer space needed to be dealt with seriously and that our group might just be able to move the process along. To facilitate our work, we formed the B612 Foundation, a non-profit corporation named after the home asteroid of the title character in Antoine de Saint-Exupéry’s The Little Prince.

NASA has been spending about $4 million a year to meet a 1998 Congressional mandate to chart (by 2008) at least 90 percent of the near-Earth asteroids that are more than 1 kilometer in diameter. NASA’s Jet Propulsion Laboratory has been overseeing the effort, called the Spaceguard Survey, which has to date discovered more than 790 of an estimated 1,100 or so of these huge, rocky objects. The impact of a 1-kilometer asteroid would release the same amount of energy as 70,000 megatons of TNT or, equivalently, as 1,400 of the largest thermonuclear weapons ever detonated. The subsequent Sun-dimming pall of debris lofted high into the atmosphere would envelop our planet for months, threatening all of human civilization…

(read more: American Scientist)     (image: Russell House)

It took some 10 million years for Earth to recover from the greatest mass extinction of all time

by PhysOrg Staff

Life was nearly wiped out 250 million years ago, with only 10 per cent of plants and animals surviving. It is currently much debated how life recovered from this cataclysm, whether quickly or slowly.

Recent evidence for a rapid bounce-back is evaluated in a new review article by Dr Zhong-Qiang Chen, from the China University of Geosciences in Wuhan, and Professor Michael Benton from the University of Bristol. They find that recovery from the crisis lasted some 10 million years, as explained today in Nature Geoscience.

There were apparently two reasons for the delay, the sheer intensity of the crisis, and continuing grim conditions on Earth after the first wave of extinction. The end-Permian crisis, by far the most dramatic biological crisis to affect life on Earth, was triggered by a number of physical environmental shocks - global warming, acid rain, ocean acidification and ocean anoxia. These were enough to kill off 90 per cent of living things on land and in the sea.

Current research shows that the grim conditions continued in bursts for some five to six million years after the initial crisis, with repeated carbon and oxygen crises, warming and other ill effects. Some groups of animals on the sea and land did recover quickly and began to rebuild their ecosystems, but they suffered further setbacks. Life had not really recovered in these early phases because permanent ecosystems were not established…

(read more: PhysOrg)        (image: John Sibbick)

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More information: ’The timing and pattern of biotic recovery following the end-Permian mass extinction’ Nature Geoscience, May 27, 2012.DOI:10.1038/NGEO1475

Journal reference: Nature Geoscience

Provided by University of Bristol