Scientists map the genome of the platypus

The researchers, whose analysis of the platypus' genome was published Thursday in the journal Nature, said it could help explain how mammals, including humans, evolved from reptiles millions of years ago.

The platypus is classed as a mammal because it has fur and feeds its young with milk. It flaps a beaver-like tail. But it also has bird and reptile features -a duck-like beak and webbed feet, and lives mostly underwater. Males have venom-filled spurs on their heels.

"At first glance, the platypus appears as if it was the result of an evolutionary accident," said Francis S. Collins, director of the U.S. National Human Genome Research Institute, which funded the study.

"But as weird as this animal looks, its genome sequence is priceless for understanding how mammalian biological processes evolved," Collins said in a statement.

The research showed the animal's multifaceted features are reflected in its DNA with a mix of genes that crosses different classifications of animals, said Jenny Graves, an Australian National University genomics expert who co-wrote the paper.

The platypus is an early example of reptiles' evolution into mammals, but unlike other evolving mammals, the platypus retained characteristics of snakes and lizards, including the pain-causing poison that males can use to ward off mating rivals, Graves said.

More than 100 scientists from the United States, Australia, Japan and other nations took part in research. Their work added to the growing list of animals whose genetic makeup has been unraveled.

By comparing platypus genes to those of humans and other mammals, scientists hope to fill in gaps in knowledge about mammals' evolution and to better identify certain species' specific traits.

Des Cooper, an evolutionary biologist at the University of New South Wales who did not take part in the research, said it represented a big step forward in the world's knowledge of mammals.