Hummingbird-Sized Ants Once Ro

貢獻者:游客187198 類別:英文 時間:2011-05-06 18:58:11 收藏數:91 評分:-0.5
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It’s not a bird or a plane, but it is an ant the size of a hummingbird.


A winged ant queen fossilized in 49.5-million-year-old Wyoming rock ranks as the first body of
a giant ant from the Western Hemisphere, says paleoentomologist Bruce Archibald of
Simon Fraser University in Burnaby, British Columbia.

The new species, Titanomyrma lubei, is related to giant ants previously found in German fossils.
These long-distance relatives bolster the notion that the climate of the time had
hot blips that allowed warmth-loving giant insects to spread from continent to
continent, Archibald and a U.S.-Canada team propose online May 4 in the Proceedings
of the Royal Society B.

An ancient ant wing from Tennessee had hinted that big ants lived in North America during this
time, says Torsten Wappler of the University of Bonn in Germany. “But complete preserved
specimens were not known until Bruce came up with this beautiful preserved fossil.”


The new fossil caught Archibald’s eye as he and co-author Kirk Johnson poked around storage
drawers at the Denver Museum of Nature & Science, where Johnson works. The spookiest

thing about the Wyoming ant may be that even at 5.1 centimeters [2 inches] long,
she is not the largest ant ever found. A German specimen is slightly longer, as
are queens of a living African driver ant, Dorylus wilverthi.

Although ants overall trend toward greater size in cooler places, Archibald notes that the
eight largest living species dwell mostly in the tropics. The team looked at climate
reconstructions for the fossil species and found hot spots where the ancient giants
lived as well.

For a tropical lineage to have sprawled between continents meant taking ancient land
bridges through Greenland or Iceland. During much of the ants’ time those northern
routes were merely temperate. But brief hot spells were possible, Archibald and his


colleagues say.

Climate scientists have already suggested there were several around 50 million years
ago. One, for example, lasted about 170,000 years.

That idea of tropical moments of opportunity fits the interpretation of other fossils



from the far north, says paleoclimatologist Appy Sluijs of Utrecht University in the
Netherlands. Findings in northern regions of preserved hippo predecessors, tropical
plankton and pollen from tropical palms support the idea. Now, he says, “The major
challenge is to explain how a region that does not receive sunlight for six months
keeps from freezing its giant ants and other creatures that don’t tolerate frost.”

Community ecologist Michael Kaspari of the University of Oklahoma in Norman has
studied the cooler-bigger connection and says that so far he’s “agnostic” about
whether supersized ant species have tropical tastes. In any case, he says, the
species ranks as “a magnificent ant.”

Image: A fossil ant queen found in Wyoming is the size of a rufous hummingbird’s
body and is the first giant ant species documented by more than a wing in North
America. (Copyright Bruce Archibald)

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