• Science & Nature

Wild Things: Life as We Know It

Killer whales, trap-jaw ants and dinosaurs

• Smithsonian magazine, November 2006

The Dinosaurs Are Coming!
When it comes to dinosaurs, scientists have only scratched the surface. There are 527 known genera, from allosaurs to tyrannosaurs. But 1,317 genera have yet to be discovered, a Swarthmore College and University of Pennsylvania study estimates. So many fossils have been found in the past two decades (an artist's reconstruction of a Rajasaurus, reported in 2003), and unexplored sites are so numerous, that the researchers upped the previous estimate of dinosaur types by 50 percent.

Timeworn Tot
The oldest known fossil of a child hominid has been found in Ethiopia. The 3-year-old female Australopithecus afarensis (the same species as the adult fossil "Lucy") lived about 3.3 million years ago. It's rare for a child's delicate bones to last long enough to be fossilized, but this skeleton, unearthed by scientists from the Max Planck Institute in Germany and elsewhere, is surprisingly complete. It shows human-like legs and feet as well as shoulders that resemble a gorilla's. Scientists know that A. afarensis could walk upright, but whether it climbed through trees is up for grabs. The fossil may shed new light on that evolutionary question.

It's a Snap
The animal kingdom has a new champ: the trap-jaw ant has the fastest known bite, besting even the great white shark. With high-speed video, researchers from the University of California at Berkeley clocked the ant's millimeter-scale jaws shutting in a tenth of a millisecond, or up to 145 miles an hour. This feat is useful for not only capturing prey but also bolting from danger: snapping its mandibles against a hard surface, the trap-jaw ant rockets two to three inches into the air.

Observed
Name: Dictyostelium purpureum, an amoeba
Known to Attend: Family reunions
What Fun: Actually, they gather only when they're starving. If food runs short on the forest floors where these one-celled organisms live, they organize themselves into a mushroom-like structure. Some die to form the "stalk"; others atop the stalk disperse spores, some of which go on to start the life cycle anew in greener pastures.
Is that Smart?: It is. D. purpureum don't band together randomly—a new study from Rice University shows that they seek out kin. Many animals recognize and make sacrifices for relatives, which presumably helps perpetuate one's genetic line. But D. purpureum is the first single-celled beast known to do so.

Listening to Luna
Luna, the killer whale separated from his pod off the coast of Vancouver Island, fascinated laypeople—and scientists. Before he was killed by a boat this past March, researchers from the UK and Canada documented that the 5-year-old orca, which had limited contact with other orcas, often mimicked the bark of California sea lions he encountered. The finding underscores the idea that orcas develop distinctive calls and that orca pods may have their own "dialects."

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