Mystery on the Mall: Case Closed

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Last week, we asked for help identifying a picture.

You were all wrong. No, it wasn't a specimen from the moon. Or Anne Coulter's pet, or a portrait of Nixon, or, um, a baby panda embryo.

Paleontologist Brian T. Huber from the National Museum of Natural History's department of paleobiology reveals the creature's true identity:

"It is a trilobite, which belong to a group of arthropods that became extinct about 251 million years ago. The species shown is Walliserops trifurcatus, and it was collected from ocean sediments in Morocco that date to the Devonian Age, some 385 to 359 million years ago.

"The compound eyes of trilobites were important in predator detection and spines probably evolved to keep the predators from attacking. The projecting rod on the right of this specimen actually connects to a long, forked 'trident,' which looks like three leaves on a stem (above).

"Since many arthropods are 'dimorphic,' that is, male specimens have a different appearance than females of the same species, it is thought that the trident was used for sexual display.

"Does anybody have a guess what other purpose this strange feature may have served?

"This specimen is one of many that will be featured in a trilobite evolution exhibit within the new Ocean Hall, which will open in the Museum of Natural History in September 2008. This and many other spectacularly preserved specimens were donated from Dr. Robert M. Hazen of the Carnegie Institution of Washington."

(Courtesy of Chip Clark)

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