Paleontologists have debated for years over the fate of the earliest archaic birds who were very different from today's species and whether their populations declined slowly over time or were killed off by the giant impact in the Gulf of Mexico.

Now researchers at Yale University have confirmed that the catastrophic meteor strike that coincided with the disappearance of the dinosaurs 65 million years ago may also have wiped out ancient birds.

The team of paleontologists led by Yale researcher, Nicholas Longrich, says fossil evidence suggests that many primitive bird species survived right up until the time of the meteorite impact.

The team findings, which were published in this week's Proceedings of the National Academy of Sciences, reveal that all of the specimens examined lived to within 300,000 years of the mass extinction event 65 million years ago.

This proves that these species went extinct very abruptly, in terms of geological time scales, said Longrich said in a University release.

Although scientists had suspected that many ancient bird lineages went extinct along with a host of other creatures at the end of the Cretaceous period, the fossil evidence was kind of vague, Longrich noted, MSNBC reported.

This uncertainty left open the possibility that such birds actually began dying off gradually well before the mass extinction.

To help clear up this mystery, researchers examined a large collection of about two dozen bird fossils discovered in North America representing a wide range of the species that existed during the Cretaceous period.

Researchers said bird fossils from the Cretaceous period are extremely rare as bird bones are so light and fragile that they are easily damaged or swept away in streams.

Analysing 24 specimens, the researchers identified 17 species, seven of which were archaic birds that disappeared after the K-T mass extinction, BBC reported.

These findings show for the first time a diversity of archaic birds alive, right up until the end of the Cretaceous period that means the birds went extinct abruptly 65 million years ago.

Longrich said he believes a small fraction of the archaic Cretaceous bird species survived the impact and evolved into today's birds.

The basic bird design was in place, but all of the specialized features developed after the mass extinction, when birds sort of re-evolved with all the diversity they display today. It's similar to what happened with mammals after the age of the dinosaurs, Longrich said.

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