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Dino-Era Seabird Fossils Found in New Zealand

Dave Hansford in Wellington, New Zealand
for National Geographic News
February 22, 2008
 
The oldest known bird fossils from New Zealand were recently unearthed along a remote stretch of beach on the Chatham Islands, researchers announced.

The fossils represent possibly four new species of seabirds dating back to the late Cretaceous period, around 65 million years ago.

Other remains from the same blocks of fossil-laden sandstone suggest that the birds co-existed with marine and terrestrial dinosaurs.

"This is New Zealand's oldest fossil aviary, and it has implications for the origin of modern seabirds," said excavation leader Jeffrey Stilwell of Monash University in Australia.

Stilwell found the fossil trove along a 1.2-mile (2-kilometer) stretch of rugged shoreline on the main Chatham Island, which sits more than 500 miles (800 kilometers) east of Christchurch (see map).

Storms had washed sand away from a rocky platform on Maunganui Beach, revealing a wealth of bones from the Cretaceous, when New Zealand first separated from the ancient supercontinent of Gondwana.

"It's quite spectacular to have that many birds in one deposit," Stilwell said. "I don't know of any other site in New Zealand like it."

Tall and Slender

Stilwell, whose work was funded by the National Geographic Society Committee for Research and Exploration, would not comment on the birds' identities until they are formally described in the scientific literature.

(National Geographic News is part of the National Geographic Society.)

However, he said, he has sent samples to Sylvia Hope, a bird-fossil expert with the California Academy of Sciences in San Francisco.

"She's working on the relationships between the [newfound] birds, and it's pretty profound stuff—there are at least two new genera [and] new species."

For now Stilwell will only say that the fossils seem to resemble modern seabirds known as cormorants.

"They look very tall and slender," he said. "We have one little guy who was probably no more than 30 centimeters [12 inches] high."

But "we've got one that is over a meter [three feet] tall, and we've got other bones bigger even than that."

In fact, the excavation uncovered bones that are too large to belong to birds, including what could be the big toe from a two-legged carnivorous dinosaur known as a theropod.

(Related news: "Dino Fossils Found on Remote South Pacific Island" [April 3, 2006].)

Paleontologist Joan Wiffen, who was not involved in the new work, discovered the first evidence of terrestrial dinosaurs in New Zealand in the 1970s near Hawke's Bay on North Island.

Wiffen said that any information on New Zealand's Cretaceous birds would be new, because the fragility of bird bones means that they are very poorly represented in the fossil record.

"It's also great to have a second dinosaur site in New Zealand, so we can get a better understanding of what conditions were like," she said.

"At least half the dinosaurs had to be herbivores to keep the food chain going, so analysis of leaves and seeds and wood will help to tell us more about the environment at that time."

Making Connections

In particular, excavation leader Stilwell is hoping that the new fossils can provide more evidence for land bridges between the Chatham Islands and mainland New Zealand.

The rock layers containing the seabird fossils were probably once part of a shallow marine environment, he said.

But "the dinosaurs and birds needed land, so they were probably living and breeding and dying fairly close by," he said.

"Maybe at some point there were emergent islands there, but if we had really big dinosaurs … there had to be sufficient land to keep these species going."

About 80 to 85 million years ago a densely forested land bridge is believed to have spanned the Chatham Islands and present-day Banks Peninsula on South Island.

"There probably also had to be a connection between [the Chathams and] somewhere like Hawke's Bay, because of the dinosaurs that were found there," Stilwell said.

"I'm hoping that if we find enough bones, that we can make that connection more concrete."

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