A libel contained in current advertising for Audi cars in this country has set bones rattling in paleontology departments of Britain's museums.

The character defamed is the brontosaurus, that lovable dinosaur which lived between 205 million and 65 million years ago. The Audi advertisements describe it as "arguably the worst designed creature of all time" and add that it "literally ate itself out of existence."

"It is an absolutely infamous libel," says Dr. Alan Charig of the British Museum, who is a world authority on dinosaurs. "Brontosaurs survived for about 140 million years -- rather longer than we shall manage, I suspect -- and were miracles of engineering. Everything they did, they did successfully."

The advertisement draws an analogy between dinosaurs and cars -- excluding Audis, of course -- by claiming that some cars could be overtaken by evolution rather more quickly than the brontosaurus. But almost everything the advertisement says about the luckless brontosaurus is wrong. There is not scientific evidence that it "ate itself out of existence." Most theories blame its extinction on worldwide climate change.

"Since he could not venture out of his lake onto dry land without collapsing under his own weight," says the advertisement, "he finally starved in his own empty larder."

"Rubbish," says John Man, author of "The Day of the Dinosaur." "Brontosaurs may have gone into lakes on occasion, but they were designed for land. They had claws for gripping hard earth and relatively compact feet that would sink into swampy soil, lket alone lake bottoms."

Existing skeletons of brontosaurs give no indication that they might have collapsed under their own weight. On the contrary, a superb, arched spine was supported by pillar-like legs, straight to resist compression and well able to hold tons of muscle and bone.

John Man is so incensed by Audi's attack on the defenseless brontosaurus that he has lodged an official complaint with Volkswagon, the Audi distributors.

While admitting to an "unjust libel," John Ellner, director of Volkswagon's British advertising agency, says the point of the advertisement still stands. "Evolution has left man standing on his own two feet, while the brontosaurus disappeared 65 million years ago. Only the fittest or most adaptable survive, and this is true of the car market today.

"However, you can be sure we will treat the brontosaurus with more respect in the future."

The Advertising Standards Authority took a stern view of the matter. "We would not want the image of the dinosaur to be unfairly distorted by advertising," said a spokesman. "If the advertisement is wrong, we will require it to be put right."