Dino Disagreements

When the Canada geese honk their way northward, we can say: “The dinosaurs are migrating, it must be spring!” ¹

Discovery Raises New Doubts About Dinosaur-bird Links

ScienceDaily (June 9, 2009) — Researchers at Oregon State University have made a fundamental new discovery about how birds breathe and have a lung capacity that allows for flight – and the finding means it's unlikely that birds descended from any known theropod dinosaurs.

The conclusions add to other evolving evidence that may finally force many paleontologists to reconsider their long-held belief that modern birds are the direct descendants of ancient, meat-eating dinosaurs, OSU researchers say. ²

The implication, the researchers said, is that birds almost certainly did not descend from theropod dinosaurs, such as tyrannosaurus or allosaurus. The findings add to a growing body of evidence in the past two decades that challenge some of the most widely-held beliefs about animal evolution.

"For one thing, birds are found earlier in the fossil record than the dinosaurs they are supposed to have descended from," Ruben said. "That's a pretty serious problem, and there are other inconsistencies with the bird-from-dinosaur theories.

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"It's really kind of amazing that after centuries of studying birds and flight we still didn't understand a basic aspect of bird biology," said John Ruben, an OSU professor of zoology. ³

OSU research on avian biology and physiology was among the first in the nation to begin calling into question the dinosaur-bird link since the 1990s. Other findings have been made since then, at OSU and other institutions, which also raise doubts. But old theories die hard, Ruben said, especially when it comes to some of the most distinctive and romanticized animal species in world history.

"Frankly, there's a lot of museum politics involved in this, a lot of careers committed to a particular point of view even if new scientific evidence raises questions," Ruben said. ⁴

Feathered dinosaur fossils find has Chinese scientists all aflutter ⁵

"These exceptional fossils provide us with evidence that has been missing until now," Xu said. "Now it all fits neatly into place and we have tied up some of the loose ends."

The finds date back to between 151m and 164m years ago, which suggest they are older than archaeopteryx, previously thought to be the oldest undisputed bird. ⁶

Xu, who is based in Beijing, said: "The fossils provide confirmation that the bird-dinosaur hypothesis is correct, and supports the idea that birds descended from theropod dinosaurs (the group of predatory dinosaurs that includes allosaurus and velociraptor)." ⁷

The team believes that the new fossil completely overturns accepted opinion on the evolution of tyrannosaurs.

Until now it had been thought that their strange body shape evolved as a consequence of their large size.

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The fossil record tells us that tyrannosaurs only grew to huge sizes during the final 20 million years of the Cretaceous.

Dr Brusatte said: "So that means that for most of their evolutionary history, about 80% of the time that they were on Earth, tyrannosaurs were small animals that lived in the shadow of other types of very large dinosaur predators.

"In short, much of what we thought we know about tyrannosaur evolution turns out to be either simplistic or out-and-out wrong." ⁸