(AP) -- The federal government is gaining control over an even larger expanse of rainbow-colored petrified wood, fossils from the dawning age of dinosaurs and petroglyphs left by American Indian tribes who once lived in eastern Arizona.

The National Park Service secured the first major private ranch within the Petrified Forest National Park boundaries on Thursday, capping off negotiations that began years ago with the help of a conservation group. Scientists say they're eager to explore the more than 26,000 acres that have remained largely untouched and discover even more treasures.

"The opportunity to actually go out into an area that hasn't been worked before by other researchers, the opportunity to find things that are truly new to science - there's a very good chance of that, so it's pretty exciting," said Bill Parker, a paleontologist at the park. "I think we're definitely going to be able to find some things that are new out there that are really going to enhance the story of the park."

Congress expanded the boundaries of the park in 2004 from 93,500 acres to about 218,500 acres but did not immediately appropriate any money to buy the private inholdings. The funding for land purchases came years later through a federal land protection program. The Park Service now has acquired about a third of the 120,000 acres it wants, with the most significant acreage coming from a transfer of U.S. Bureau of Land Management land and Thursday's $8 million purchase of the Paulsell Ranch within the park boundaries.

Mike Ford, the Southwest director for the Conservation Fund, said he began a quest to acquire the land for the Park Service in 1999 at the request of former Interior Secretary Bruce Babbitt. Ford recalled driving around in a pickup with the landowner, Marvin Hatch, surveying the land and trying to strike a deal that the two never quite agreed on. Hatch's family contacted Ford after Hatch died to continue the talks.

Petrified wood is scattered throughout the undeveloped ranch land south of Interstate 40 where cattle haven't grazed for years, but Ford notes "you're not going to see dinosaur bones protruding from the ground."

"I tell people about this part of the world - it's so rough and crude, it has its own beauty," Ford said. "For people who love the Southwest and love those kinds of landscapes, it's isolated, it's remote, it's out there. That crudeness has a beauty that you have to be a desert rat to appreciate."

The Park Service expects to spend a few years doing inventory on the land before it decides how the public can best enjoy it, Parker said. Some 630,000 people visit the park each year.

The ranch is a mix of grasslands that would be ideal for archaeological and wildlife finds, and badlands with fossils from the Triassic period that scientists say dates back 220 million years.

Parker said almost 90 new plant and animal species have been found in the park that was designated a national monument in 1906 and a national park in 1962. One of the most significant discoveries was Revueltosaurus, which is related to the crocodile but first was believed to be a plant-eating dinosaur because of its teeth found in New Mexico. A full skeleton was later uncovered at the petrified forest.

Institutions such as the American Museum of Natural History and the University of Texas at Austin have succeeded in finding plant and animal fossils on the ranch land, said Parker, pointing to its potential. Park archaeologist Bill Reitze said surveys of the new property also have shown promise for archaeological sites like early basket-maker villages and petroglyph sites.

"Acquisition of this land may significantly enhance our knowledge of early peoples of the area," Reitze said.

Ford, who is certain that Hatch would be thrilled to know the land is in Park Service hands, said the Conservation Fund now will work to acquire other sites within the petrified forest. Major parcels of private land are held by less than a handful of owners. The Hatch family didn't immediately respond to a request for comment.

"Certainly we don't see this as the end, but we're in a really different time right now politically, economically and otherwise," Ford said. "We trust and hope Congress continues to support important acquisitions like this."

©2011 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.