Taxonomy term

january 2016

Permian-Triassic extinctions timed differently on land and at sea

Life on land and in the sea was nearly eradicated about 252 million years ago in the largest-known mass extinction. The cataclysm, known as the Permian-Triassic (P-T) mass extinction, was likely driven by extensive flood basalt volcanism in Siberia and is thought to have affected global biodiversity simultaneously. However, based on analyses of rocks deposited around the time of the P-T boundary in the Karoo Basin of South Africa, scientists suggest in a new study that the terrestrial turnover in vertebrates occurred earlier than the marine extinction. If true, a second trigger — other than Siberian volcanism — might need to have occurred to explain both events.
 
31 Jan 2016

Rising Star cave hominid walked its own way

After dozens of human-like fossils were discovered in a cave in South Africa last summer, they were declared distinct enough to be classified as a new species: Homo naledi. Two recent studies looking in detail at the new hominid’s hands and feet are revealing how different they were from other early humans.
 
30 Jan 2016

Irrigation drives rain away in East Africa

Researchers have found that large-scale agricultural irrigation, intended to supplement precipitation, may actually drive rainfall away, potentially exacerbating conditions in some areas while improving them in nonirrigated lands. 
 
28 Jan 2016

Ancient eggshells may reveal dinosaur body temperatures

Whether dinosaurs had metabolisms more like slow, cold-blooded reptilians or fast, warm-blooded birds has long been a mystery. Fossilized bones, which don’t preserve the delicate cell membranes that facilitate heat production in warm-blooded animals, are not likely to answer the question. Fossilized eggshells, however, might be just the ticket to determining the past body temperatures of egg-laying females, which, scientists say, might help address whether the dinosaurs’ metabolisms were warm or cold.
 
27 Jan 2016

What are the odds?: Automated system calculates the likelihood that asteroids will hit Earth

By some estimates, Earth is pelted each year by tens of thousands of asteroids — from souvenir-sized nuggets 10 grams and up to the occasional meters-wide boulder. Spotting larger Earth-bound impactors that could cause serious destruction, while they’re still in space, has been a priority of the planetary science community for years. But many space objects are small enough that they can only be detected days or hours before impact — if at all. In a new study, scientists have tested and automated a new technique called systematic ranging that’s intended to rapidly calculate the probability — from only a handful of observations — that newly discovered asteroids will hit Earth.

26 Jan 2016

How deep do the Alps go?

Continental crust was long thought to be too buoyant to subduct into the mantle, unlike denser oceanic crust, which descends into the mantle in many locations around the world. But the discovery of coesite — a type of silica formed at the extreme pressures present in subduction zones — in the Alps in 1984 challenged that long-held idea. Seismic evidence backing up claims that continental crust has indeed been subducted beneath the Alps has been scant, however, until now.
26 Jan 2016

Impact or eruptions: Are both to blame in the great end-Cretaceous whodunit?

Few episodes in geologic history are as widely recognized — and debated — as the end-Cretaceous extinction. For several decades, the Chicxulub impact has been the primary suspect. But new research suggests the impact wasn’t solely responsible for the extinctions; widespread volcanism in India seemed to play a role as well.

25 Jan 2016

Land plants came prepared for terrestrial life

Plants colonized land between 450 million and 420 million years ago, and, once there, they drastically altered terrestrial landscapes and provided resources for animals leaving the oceans around the same time. One adaptation that helped plants gain a foothold on land is a symbiosis with fungi known as arbuscular mycorrhizae (AM), which help plants acquire water and key nutrients from the soil and are still associated with most land plants today. In return, plants provide the fungi with bioavailable carbon produced during photosynthesis. When this symbiosis evolved has remained unclear, but researchers recently discovered that it likely has roots in a group of freshwater algae ancestral to land plants.
 
22 Jan 2016

Three new species of extinct baleen whales found

The evolution of baleen whales from toothed whales was gradual, with intermediate fossil species found that possess both teeth and baleen. Now, the discovery of three new whale species on New Zealand’s South Island is filling in the evolutionary story of baleen whales.
 
21 Jan 2016

Subducting seamounts blocked a big quake in Chile

Chile, which lies above a massive subduction zone fault, is one of the world’s most earthquake-prone countries, experiencing nine temblors of magnitude 7 or greater since 2010. In April 2014, a magnitude-8.1 earthquake struck 95 kilometers northwest of the city of Iquique, but despite its large size, the event failed to release all the stress thought to have built up along that portion of the fault. A new study reveals that a ridge of ancient underwater volcanoes may have blocked the 2014 earthquake rupture from propagating farther, thus limiting the size of the quake.
 

 

20 Jan 2016

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