New York - Fossils of two dinosaurs locked in a death match failed to sell at auction on Tuesday despite predictions they would fetch a record US$9 million (S$11.2 million).

The top bid for the dinosaur fossils was US$5.5 million and did not meet the reserve price, Bonhams auction house said. Pre-sale estimates had been US$7 million to US$9 million.

The dueling dinosaurs, which were discovered in Montana in 2006, were two of the most well-preserved dinosaur remains ever unearthed and included pieces of skin, Bonhams said.

One of the skeletons belongs to a ceratopsian, which is similar to a triceratops, but there is debate about its opponent. Scientists are unsure if the second animal is a juvenile Tyrannosaurus Rex or a new species. The remains could help settle the question.

The most expensive dinosaur fossil ever sold at auction is a Tyrannosaurus Rex skeleton named Sue, which fetched US$8.3 million in 1997.

Thomas Lindgren, co-consulting director of natural history for Bonhams, said he is confident that the dueling dinos will sell in the future.

"I've had museums mention that they had difficulty coming up with the funds this quickly. But should the lot not sell, which of course occurred, they want us to be in negotiations immediately," Lindgren said.