A Lost-and-Found Nomad Helps Solve the Mystery of a Swimming Dinosaur

By KENNETH CHANG

Davide Bonadonna

An artist's interpretation of how Spinosaurus aegyptiacus might have looked and how its size might have compared with that of a human.

A model of the largest known predatory dinosaur, and the only dinosaur known to spend much of its life in water, will be displayed in Washington.

The family of Darwyn Hanna has owned land in Bastrop County, Tex., for five generations.

Aquifer Is No Quick Fix for Central Texas Thirst

By NEENA SATIJA

Experts disagree how much water the Carrizo-Wilcox Aquifer holds and how long it would be able to sustain Central Texas’s growing population.

A study finds that restrictions on certain pesticides have helped, but city streams are more contaminated than ever.

Pesticide Levels in Waterways Have Dropped, Reducing the Risks to Humans

By MICHAEL WINES

Regulation has helped clean up agricultural and mixed-use waterways, but the ubiquity of some chemicals in household products has increased the threat to aquatic life in urban streams.

Hopes for a Strong El Niño Fade in California

By HENRY FOUNTAIN

In its latest monthly forecast, the federal Climate Prediction Center said that while El Niño was still expected, it would not bring the heavy rains California needs to end its drought.

Trumpeter swans are among the species that, by 2050, are not expected to be able to live in most of their current territory, according to a report.

Climate Change Will Disrupt Half of North America’s Bird Species, Study Says

By FELICITY BARRINGER

The National Audubon Society foresees danger for more than half of the 650 species of birds in North America.

Green Column

Interest in Solar Water Heating Spreads Globally

By KATE GALBRAITH

Many developing countries, which struggle with high energy prices relative to income, have embraced the technology.

Mexico: Strides for Endangered Wolves

By THE ASSOCIATED PRESS

Officials on Wednesday presented the first litter of Mexican gray wolves conceived in the country by artificial insemination, part of an effort to save one of the hemisphere’s most endangered animals.

Michael Knoblauch, a plant cell biologist, uses the lift to get a measurement in the Harvard Forest, a 3,500-acre research plot in central Massachusetts.

Exploring a Tree One Cell at a Time

By HENRY FOUNTAIN

A 20-year quest to prove a longstanding hypothesis about how nutrients are transported may come to an end thanks to tiny needles that probe leaves 40 feet up an oak tree.

Mount Tavurvur in Papua New Guinea erupted Friday, forcing evacuations and rerouting flights.

Papua New Guinea Volcano Erupts, Locals Evacuate

By THE ASSOCIATED PRESS

Several communities were evacuated and some international flights were diverted Friday after a volcanic eruption on Papua New Guinea.

Where ice once capped the Sermeq Avangnardleq glacier in Greenland, vast expanses of the Arctic Ocean are now clear.

U.N. Draft Report Lists Unchecked Emissions’ Risks

By JUSTIN GILLIS

The report says that warming has already led to food and climate crises, and that the failure to reduce emissions will lead to worse catastrophes.

Green Column

Cities’ Air Problems Only Get Worse With Climate Change

By KATE GALBRAITH

Scientists predict that higher temperatures will speed up the creation of lung-damaging ozone in the world’s metropolises.

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W.H.O. on Use of Experimental Ebola Drug

Dr. Marie-Paule Kieny, the World Health Organization’s assistant director general, announced that the agency would endorse the use of drugs untested in humans to combat the Ebola virus in West Africa.