A fast-growing, warm-blooded prehistoric ancestor to birds. Lifestyles typified by elaborate courtship rituals and lavish care for their young.

If that doesn't sound like the traditional definition of dinosaurs you learned in school, you're not alone.In fact, the above definition would be labeled heresy by most orthodox paleontologists. Orthodox thought describes dinosaurs as lumbering, cold-blooded, Godzilla-like lizards.

But the orthodoxy is flat out wrong, says the prince of dinosaur heresies, Robert Bakker.

Bakker, a colorful paleontologist with the University of Colorado and author of the popular book "Dinosaur Heresies," was in Utah as part of the Museum of Natural History's Dinosauria Lecture Series.

Bakker is a leading proponent of concepts that dinosaurs were warm-blooded ancestors of birds. Many of his views challenge fundamental thinking about dinosaurs, which ruled the Earth for 160 million years.

Paleontology, or the study of fossils, has its own interesting evolution, Bakker said. Scientists in the 1800s identified dinosaurs as warm-blooded ancestors of birds.

But by the 1950s, the orthodox view had labeled dinosaurs as cold-blooded reptiles. "There was not a shred of evidence to support that position," Bakker maintained.

"There were a lot of voices in the wilderness, but they were ignored by the establishment," said Bakker, whose theories have in large part been rejected by the establishment. "Now, the position of the orthodoxy is shifting rapidly . . . and orthodoxy is now admitting there are facts on the other side."

As a result, modern scientific thinking is shifting more toward what were once heresies. Bakker said it is common now to find school textbooks that talk about dinosaurs as warm-blooded creatures.

Even though his views are more accepted now than 20 years ago, Bakker is continuing his assault on established paleontology. His latest theories (or heresies) involved the courtship and mating practices of dinosaurs.

"We're putting sex and violence back into dinosaurs' lives," he said. That in itself is a heresy. "Sex anddinosaurs was unheard of 20 years ago," he said.

But buffalo and antelope butt heads, horses shrill and a host of other mammals fight, strut and fan their tails to attract and win mates. And Bakker said a careful analysis of dinosaur bones reveals dinosaurs also had heads for butting, tails for fanning and highly complex nasal passages for whistling.

"These were not Godzillas," Bakker said. "These were precise animals that produced very precise (and variable) sounds. Some of them had complicated echo chambers built into their snouts."

As more research is done, the newer heresies will become accepted as fact, he said.

"That you would have bull dinosaurs strutting around singing songs was a heresy a half hour ago," he said. "But researchers are working on that now."

"That dinosaur mums lavished care on their young in feeding and protecting them is a heresy. But it's being researched now."

Bakker is currently working on a book titled "A Dinosaur Owner's Manual," a guide on "where to find the spark plugs, distributor cap and ankles." It is part of Bakker's ongoing efforts to make the study of dinosaurs more understandable - and exciting - to the public.