New discoveries of our wild, wild world

The findings described in the journal Nature Ecology & Evolution could fill in a more complex portrait of the evolution of sauropods and their relatives. Think of a sauropod, and a species like Brachiosaurus, which arose from the sauropodomorphs, whose members included "the largest animals recorded in the history of life," the authors wrote.

In order to grow into these massive eusauropoda, or "true sauropods," these animals had to undergo some major modifications, scientists say, such as straighter, tree-trunk legs to support their weight and grow quickly.

Two sauropodomorphs — Ingentia prima, a new species, and Lessemsaurus sauropoides — offer a surprising twist. They lived about 47 million years before Brachiosaurus did, and yet they grew to gigantic sizes — roughly 8 to 11 tons, about the size of a large elephant. They managed this feat with unexpected adaptations. Their legs were more bent rather than trunk-like, despite this great mass. "That's one freaky-looking animal," said Matthew Lamanna, a dinosaur paleontologist. "It shows that dinosaurs, even in their early evolutionary history, were more diverse than we give them credit for."

DNA may be key to koala's survival

The koala is an unusual creature. Native to Australia, it spends most of its time in eucalyptus trees, gorging on leaves that are toxic to nearly every animal on the planet.

The koala sleeps about 22 hours a day and spends the remainder of its time eating and resting. It might spend 10 minutes a day moving, experts said.

The unique lifestyle of the koala has helped it thrive for 350,000 years, but today the creature is facing threats from habitat loss, disease and a changing climate. Koala populations are expected to decline by 50 percent in the next 20 years, the Australian Museum said. To help protect these animals, which bring in an estimated $1.1 billion to Australia each year through koala-related tourism, an international team of researchers has published the first complete genome of the koala. Their hope is that the keys to the marsupials' long-term survival might be embedded in its genetic code.

In the ocean off Antarctica, a snail lives around scorching hydrothermal vents. Its name is Gigantopelta chessoia. From the outside, it looks like any other shelled slug. But on the inside, something strange is happening, scientists reported in Proceedings of the Royal Society B, like no metamorphosis ever observed in any other animal on the planet.

"We're calling it crypto-metamorphosis," said Chong Chen, a deep sea biologist at Japan Agency for Marine-Earth Science and Technology who discovered this transition.

Once the snail reaches a certain body length, its digestive system stops growing. Its teeth, stomach and intestine make way for an expanding esophageal gland. The organ gets so big, it takes up most of the snail's body, and basically becomes a new organ. Bacteria colonize it, and the snail, which grazed for food when it was smaller, no longer needs to eat. Instead it just sits there getting bigger, surviving on energy the bacteria produces inside the snail's cells.

To make a human comparison, imagine growing from an average size adult to one 30 to 60 feet tall, with a giant sac of bacteria living inside you.

After the change occurs, the snails gain an advantage by producing their own energy. They can grow bigger and make babies instead of searching for food.