One critic is Dr. Kenneth Carpenter, a paleontologist at the Denver Museum of Natural History. ''To be blunt,'' he said in an interview, ''the computer simulations are another case of garbage in, garbage out.''

Dr. Carpenter questioned whether the bony segments of the dinosaur tails could have produced a supersonice boom. Even if that was possible, he said, using the tail like a whip might have been both painful and damaging to dinosaurs. The last few segments might even snap off.

In their report, Dr. Myhrvold and Dr. Currie emphasized that only the last two or three inches of the dinosaur tail would have exceeded the speed of sound. The possibility of pain or damage might be minimized or eliminated, they pointed out, if the most extreme part of the tail extended past the last vertebra as a piece of skin, tendon or keratin, the protein that can take the form of scales, claws or feathers. ''If whips made from the skins of cows and kangaroos are able to withstand supersonic motion,'' they said, ''why not dinosaur skin and tendons?''

But the two researchers agreed with the paleontologists who now reject the idea that the sauropods regularly used their tails defensively. The animals would probably have sustained as much injury to their tails as they inflicted on attackers.

As chief technology officer at Microsoft, Dr. Myhrvold presumably has more pressing research matters than dinosaur tails. But dinosaurs have fascinated him since childhood, and he has probably never met a research problem he did not try to use a computer to solve. He got in the habit of stretching the imagination when he studied cosmology under Dr. Stephen W. Hawking at Cambridge University in England.

''I don't claim it's relevant to Microsoft,'' he said of the dinosaur simulations. ''It's just an interesting problem to me.''

In particular, Dr. Myhrvold was intrigued by the analogy of the bullwhip to explain the sauropod tails, as suggested a few years ago by Dr. R. McNeill Alexander of the University of Leeds in England. The progressive rate of tapering from the base of the tail to the tip is comparable to that of a bullwhip from the grip to the tip. Each successive vertebra in a sauropod tail is about 6 percent smaller than its predecessor.