World's oldest modern hummingbirds described in Science

04/30/04



Cinnamon hummingibrd (Amazilla rutila) feeding on Ipomoea neei (Convolvulaceae) in Mexico. The Cinnamon hummingbird measures about 11 cm (tip of beak to tip of tail) and is only slightly larger than the fossil.
[Image J. Ferdinand]

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The world's oldest known modern hummingbird fossils have been discovered in Germany. The tiny skeletons are also the first modern-type hummingbird fossils ever found in the Old World. These creatures, with strikingly similar resemblances to today's hummingbirds, lived in present-day Germany more than 30 million year ago. Although hummingbirds are currently restricted to the Americas, their long-extinct Old World "look-alikes" may have helped determine the shape of some Asian and African flowers alive today. These findings appear in the 07 May, 2004 issue of the journal Science, published by AAAS, the non-profit science society.

"This is the oldest convincing record of modern-type hummingbirds," said Gerald Mayr, a zoologist from Forschungsinstitut Senckenberg, a natural history museum in Frankfurt, Germany.

The extinct European hummingbirds were endowed with long, nectar-sucking beaks and wings designed for feeding while hovering, Mayr explained.

Mayr named the new hummingbird species Eurotrochilus inexpectatus, which means an "unexpected European version of Trochilus." Trochilus is the name of a modern hummingbird genus.

The discovery of modern hummingbirds in Europe begs the question, "What kinds of flowers did they feed on?"

In an attempt to answer this question, Mayr suggests that you can see the Old World hummingbirds' evolutionary wake in certain plants growing in Africa and Asia today, including a species of Impatiens. Hummingbirds and some Old World plants may have evolved together, to suit each other's needs.



Specimen coated with ammonium chloride.
[Image Science]

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This process of coevolution could explain the beak-friendly flowers that grow without perches, a design perfect for hummingbirds, on continents without these hovering birds. When hummingbirds disappeared from the Old World, insects like long-tongued bees could have taken over their pollination duties, Mayr speculates.

The next-oldest, modern hummingbird fossils are from South America and are only about one million years old, Mayr explained. With this new discovery, the fossil record for modern hummingbirds leaps back approximately 29 million years and zips halfway around the world.

The pair of four-centimeter-long skeletons, unearthed near the village of Frauenweiler in southern Germany, provides a glimpse into the lives of birds that died near a sea that dried up long ago. Scientists have recovered other land birds as well as marine birds, turtles, large sharks, bats and many plants from the same general area and time period.

"It's fun to study species from this time period in Earth's history, the early Oligocene, because some of the species begin resemble modern species," Mayr explained.

Three of the key features that give the skeletons modern hummingbird characteristics are their tiny size, the design of the shoulder and upper arm bone, and their long beaks, which are 2.5 times larger than their craniums even though the tips of the beaks are lost.

Details from their shoulder joints and upper arm bones suggest that the birds rotated their wings like today's hummingbirds.

"The tip of the wing makes a figure 8," Mayr explained.

This wing motion allows hummingbirds to hover in front of the flower and eliminates the need for a perch.

"The remainder of the skeleton is also very hummingbird-like," Mayr said.

Mayr noted, however, that today's hummingbirds have even more specialized hovering design.

These ancient hummingbirds grew to about the size of the Rufous-breasted Hermit Glaucis, a hummingbird from South America. While scientists have not recovered equally ancient, modern-type hummingbird fossils from South America, Mayr suspects that primitive hummingbirds lived in both Old and New World.

The question of when and why hummingbirds disappeared from Europe and other parts of the Old World, but not in the Americas, has no clear answer. Mayr, however, suspects ecological competition with other birds or with insects.

Source: Eurekalert & others

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