CARLSBAD -- Paleontologists gave a group of reporters a peek Thursday at the tusks, teeth and rib bones of an elephantlike, prehistoric creature unearthed at a Carlsbad housing construction site this week.

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It's the first discovery of mastodon bones in Carlsbad, and only the third time mastodon fossils have been found in the county, said Tom Demere, curator of paleontology at the San Diego Natural History Museum.

Like the two earlier discoveries in Oceanside's San Luis Rey area and in National City, this find soon will be removed from the private property where it was discovered. Until then, officials don't want its exact whereabouts published because they don't want people disturbing the site.

The mastodon bones could go on display at the Balboa Park museum in six months, said Demere, who called the discovery a rare find.

"It's by far the most complete in terms of its dentation," he said, showing off a huge tooth that nearly filled the palm of his hand.

The parts of the mastodon's tusks that the paleontologists discovered were easily as long as a man's forearm, and the creature would have stood about 9 feet tall at the shoulders, Demere said.

Paleontologist Brad Riney, who discovered the bones Tuesday while inspecting the construction site, said it was the huge teeth that tipped him off that this was a mastodon, rather than the more commonly known woolly mammoth.

"When I found the teeth, it screamed mastodon," said Riney.

Mastodon molars are very bumpy on top -- they've got huge pointy areas and deep indentations. Woolly mammoths, who are slightly larger, have unusual, smooth teeth similar to the teeth of the giant modern rodent known as the capybara.

"A mastodon is more like a regular old tooth -- like your tooth, except it's hundreds of times bigger," Riney said.

This mastodon was youngish -- perhaps a teenager or a 20-something in human terms -- and was probably a male, given the length of its tusks, Demere said.

Based on soil data, Demere estimated that the bones were 120,000 to 220,000 years old. That would mean the animal lived long before humans, but millions and millions of years after the Tyrannosaurus Rex went extinct, he added.

When the mastodon walked through the area, oak and sycamore trees likely covered the landscape and a river ran through it, he said.

The bones were found in a clay patch of soil. When the animal died, that area probably was an "oxbow lake" -- a crescent-shaped body of water that forms when a river's main channel moves.

How the mastodon died is still a mystery, Demere said. It isn't likely another animal killed it; mastodons were so big that adult ones had little to fear from predators, he said.

Much later -- only about 10,000 years ago -- mastodons did have something to fear: Humans had arrived.

There's debate about whether hunting or climate change caused mastodons to go extinct, Demere said.

For Riney, the first close-up view of the long-buried mastodon bones came while he was walking behind a bulldozer at the construction site. He's there on a daily basis monitoring the grading work, as required by state law.

After weeks at the site, Riney knew the chances were good that he'd find fossils. Clay soil, such as this bit of old lake bottom, are frequently considered prime fossil-hunting territories because sediment layers tend to build quickly in such areas, protecting bones from damage.

While clay may be nice for fossils, it's unwanted material for builders because of soil-settling issues, said Brian Milich, a senior vice president of Corky McMillin Cos.

After the paleontologists finish their work in the next couple days, this soil will be scraped away, he added.

The construction work that uncovered the mastodon bones also damaged them, Riney said. The tusks were scraped and some other bones may have vanished under the bulldozer blades, he added.

The animal might also have been broken into pieces right after its death, Demere said.

"We haven't found the legs yet and it doesn't look like we're going to," he said.

Contact staff writer Barbara Henry at (760) 901-4072 or bhenry@nctimes.com.