The bones lie everywhere — fragments of 300 million-year-old ribs and vertebrae — spread across the hillsides, amid cactus, mesquite and red earth.

They sat on the surface, next to pieces of clay and caliche rock, when paleontologists and volunteers began chiseling, scratching and brushing their way, millimeter by millimeter, toward the discovery awaiting them below.

The group, from the Houston Museum of Natural Science, came to the Craddock Ranch in North Texas four years ago, hoping the Baylor County site's reputation for fossils would prove worthwhile.

Crew members worked through shards of bone 200 million years older than such creatures as Tyrannosaurus Rex and Triceratops.

Then they found it: First, pieces of skull and neck; then, early this month, a spinal cord and ribs. The near-complete skeleton was a Dimetrodon, a 287-million-year-old primitive reptile with a large, sail-like fin on its back.

As the team continued brushing and scraping through red clay last week, it uncovered clues into how some of the world's earliest land animals lived, died and then evolved, developing into dinosaurs, birds and mammals.

Working at the dig site on Sunday near the town of Seymour, the crew uncovered pieces of primitive creatures that were likely part of the diet and environment surrounding Dimetrodons.

The preserved ecosystem will be part of an exhibit that will give the 2.5 million annual visitors to the Houston Museum of Natural Science a window into a previously unknown and inconceivably distant time. The discoveries will also bring a large array of distinctly Texan fossils to a museum that has none, even though others worldwide prominently display bones from the Lone Star State. It will be featured in a new 30,000-square-foot paleontology hall set to open in 2012, part of the museum's $80 million expansion.

"Our purpose, of course, No. 1 is to get a kid-friendly display," said Robert Bakker, visiting curator of paleontology for the museum and a leading expert in the field. "We're well on our way, but there is new data. Much new data."

Unearthing 'Wet Willi'

The crew continued dissecting the dig site Sunday, meticulously sifting through rocks and bone fragments. Volunteers chipped and scraped away ancient clay using dentist tools, needles and screw drivers. They then swept aside dust with paintbrushes and makeup brushes, often revealing glimpses of large bones that had been underground for hundreds of millions of years.

Some parts of the Dimetro­don — an 11-foot specimen that sported a 4-foot-long fin and likely weighed around 300 pounds, and whose name, "Wet Willi," was influenced by its discovery in a drainage ditch — were missing, but crew members are confident they will find more fossils.

"You haven't lost anything until you stop looking," said Johnny Castillo, a volunteer from Houston who is helping with the dig. "We never stop looking."

That same enthusiasm for fossils often leads paleontologists into areas far from civilization, but the museum's current dig has found the experts in cattle country, where a search for extinct creatures doesn't excite everyone.

The crew's work has been a kind of novelty for residents of Seymour, a town in Baylor County with two traffic signals and about 2,600 people. Bakker, a scientist with long hair and a bushy white beard, has become a familiar face among the cattle herders and tractor owners here.

He is a regular at The New Maverick Cafe, a popular restaurant, where he eats breakfast with his crew each day, wearing his white cowboy hat and frequently quoting The Simpsons as he explains the team's mission to residents and draws pictures of prehistoric creatures that now hang on the cafe's walls.

"They're an unusual, different kind of group," said Joe Dickson, a retired county judge who eats breakfast with a group of friends at the cafe each morning. "Not anyone around here wants to lay on the ground and dig in the dirt with their fingers."

The digging team sets up on cots overnight in an old tractor factory owned by Nancy Markham, who converted the second floor of the 110-year-old building into her home. In an automated wheelchair, the 71-year-old shuttles between overloaded bookshelves and recycled furniture in her expansive unit to serve the team dinner each night.

Fossils and football?

Bakker and David Temple, the museum's associate curator of paleontology, have tried to pitch the Dimetrodon as the replacement mascot for the Seymour High School Panthers, suggesting they should be called the "Fighting Fin-backs." It hasn't caught on.

Some in the town haven't noticed their presence, continuing about their quail hunting or weekly church meetings unaware of the reason for the group of scientists visiting Seymour.

Others were amused "because they're a bunch of kids from Harvard with some hicks in here," said Larry McDorman, Seymour High's retired football coach, referring to the digging crew's morning breakfasts alongside locals at the cafe.

But residents visiting the dig site on Sunday were awestruck. And more digging for bones could bring about additional discoveries that could put Seymour on the map, said Bakker, who plans to place a replica of "Wet Willi" in the town.

With a wealth of Dimetrodon bone fragments littering the "bone bed," a 270-yard-long oval-shaped area that was likely a body of water, the crew will assemble at least three other composite skeletons of the creatures to add to a display at the museum.

Veritable buffet of bones

The dig has turned up an array of fossils, including primitive amphibians and sharks, as well as vomit and droppings 280 million years old.

The so-called Texas red beds are rich with fossils from the Permian Period, which began more than 300 million years ago, offering more remains than the rest of the world combined, Bakker said.

That leaves great potential for new discoveries from the dig, possibly including eggs that have so far eluded paleontologists, he said.

The museum's only current Permian display is a 50-foot-long acrylic mural.

"We're looking for the next thing — whatever the next thing is," Bakker said.

zain.shauk@chron.com