Most people come to Ox Ranch — an 18,000-acre property outside Uvalde, Texas — for the thrill of hunting exotic animals in the Hill Country. But the ranch is also home to ancient secrets, as in lines of dinosaur tracks that cut across an empty creek bed and in a dark cave under a stony hillside that contains the remnants of Pleistocene animals and humans.

The ranch is owned by Brent C. Oxley, the wealthy founder of a web hosting company who has brought in Andre LuJan to manage the property’s fossils.

Mr. LuJan is a commercial paleontologist, bald and often dressed in dinosaur-themed shirts and socks, who collects fossils and assesses their value for private clients. Such arrangements are not unusual in the vast and wealthy state, which is in the middle of a paleontological renaissance. But many specimens collected on private lands end up sold to private collections, where the broader public may never see them again.

That won’t be the case with Ox Ranch, and Mr. LuJan has bigger ambitions. He intends to open an institution he bills as the “Smithsonian of Texas” that could display fossils like the ones he has found on Mr. Oxley’s land. Texas has its share of large museums and elaborate fossil exhibitions. But Mr. LuJan sees a paleontological void in the state, which has no public museum devoted solely to its fossil treasures. He hopes an expanded version of his own institution, Texas Through Time, will fill that gap.

Texas’ ancient outcrops record broad swaths of the last 300 million years, including Carboniferous coal swamps, dinosaur-filled floodplains and Cenozoic savannas. The state has produced a remarkable spread of extinct animals and plants, including some found nowhere else, said Thomas Adams, chief curator of the Witte Museum in San Antonio. Famous past denizens include giant crocodiles, pterosaurs the size of small airplanes, a bevy of dinosaurs known from tracks and bones and a Serengeti’s worth of ancient mammals.

Institutions like the Field Museum in Chicago and the American Museum of Natural History in New York made major collecting trips to Texas throughout the early 20th century. Many of the state’s fossils flowed to public collections in other parts of the country, like the Texas fossil tracks on display beneath the Apatosaurus that is a centerpiece of one hall at the museum in New York, and a Texas Dimetrodon on display at the Field in Chicago. In the 1930s, the Works Progress Administration also opened quarries across the state that yielded discoveries, many of which are stored in collections at the University of Texas at Austin but seldom displayed.

By the 1950s, Dr. Adams said, academic collecting in the state slowed as a generation of paleontologists retired or died. Many of their replacements chose to seek fossils abroad. While work continued on previously collected material from sites like Big Bend National Park — and spectacular new fossil halls opened at the Houston Museum of Natural Science and the Perot Museum of Nature and Science in Dallas — prospecting across Texas languished. The Texas Memorial Museum, home to the state’s public repository of fossil material, is just emerging from years of underfunding and neglect.

Texas nonetheless maintains a thriving scene of amateur fossil collectors. One of them was Mr. LuJan. When he was 4, his parents took him to Dinosaur Valley State Park, southwest of Fort Worth, where hundreds of dinosaur tracks emerge from the banks of the Paluxy River.

“It was the closest thing to time travel I’d ever experienced,” he said. “I was hooked.”

As an adult, Mr. LuJan took on paleontology, first as a hobby and then as a side business, teaching himself to collect and restore fossils, and eventually selling them online and at gem and mineral shows.

The market for commercial fossil sales is lucrative, with certain specimens — generally dinosaurs — fetching millions at auction. The high prices leave public museums and academic paleontologists worried that potentially important specimens will be cloaked from scientific research. They also fear that the inflated value of fossils pushes them out of the market.

“I don’t have the money or budget to pay people for access to land,” said Ronald S. Tykoski, curator of vertebrate paleontology at the Perot Museum.

That can make collecting tricky in Texas, where a vast majority of land is privately held. Some landowners are happy to donate their finds. Others decide to take their chances selling them, or ask for compensation in return for letting people dig on their land.

“That’s their right,” Dr. Tykoski said. “It’s their property. In that regard I’m a little hamstrung compared to some of my colleagues.”

Private landowners were, and remain, the source of most of Mr. LuJan’s fossils as well, and he occasionally purchases collecting leases on private ranchland. He estimates 90 percent of the material he has sold is not important to paleontology.

“It was stuff that most museums would not pick up,” he said. “Another hadrosaur toe, another triceratops vertebra. Other than statistical appearance in the formation, there’s zero scientific value.”

By 2016, Mr. LuJan’s side business was profitable enough that he quit his day job to devote himself to fossils full time. He started PaleoTex, a general contractor for paleontological jobs including prospecting, preparation and exhibit design. He worked out of a detached three-car garage that served as both a preparation lab and a collection space. But while he maintained a hand in the commercial trade, he said, he began feeling uneasy that the fossils he’d worked on would end up away from public view.

Mr. LuJan kept thinking about how many of Texas’ fossils had left the state, including world-class Permian Period remains collected by notable paleontologists in the east like Edward Drinker Cope, Alfred Romer and Barnum Brown. Collectors “a hundred plus years ago were trying to fill their halls with amazing specimens that are going to bring people in,” Mr. LuJan said.

“Some of the specimens they collected haven’t even really been studied,” he said. “They were gobbled up and shipped away and they sit in other museums. Museums weren’t thinking long-term about the cultural context and how important those fossils might be to local stories. There’s a lot of researchers here that would love access to those specimens.”

These musings crystallized in 2017 when Mr. LuJan and his wife visited Hillsboro, a small city about 30 minutes north of Waco, in search of a space for his family as well as PaleoTex. A historic 6,500-square-foot auto garage with high ceilings and an Art Deco exterior was on sale, and it hit Mr. LuJan “like a lightning strike” that he wanted to start his own free, nonprofit museum. He and his wife purchased the property with a borrowed $130,000 and lived behind it in a trailer for months while they fixed it up.

Texas Through Time opened in 2018. PaleoTex occupies the back collection lab as a tenant; the front contains a free museum of Texas fossils. Many of the remains were donated by private collectors or landowners; others were collected by Mr. LuJan himself.

One glass case contains bits of armor and bone from an unknown ankylosaur that Mr. LuJan discovered on his West Texas ranch in 2017, and which paleontologists from the Denver Museum of Nature & Science are studying. Another case presents a spectacularly preserved shell-crushing shark. Behind the wall, in PaleoTex’s workspace, plaster jackets line the floor and 3-D printers whir, constructing casts of bone.

The garage-size Texas Through Time drew a warm reception. Mr. LuJan then set his eye on an abandoned building that had been home to Hillsboro Junior College when it opened in 1923. The town agreed to transfer to him the 40,000-square-foot, three-story edifice of brick and poured concrete for an expanded Texas Through Time. Mr. LuJan hopes that the site will serve as an educational facility for the 18 million people living throughout the Texas Hill Country.

The restoration might take a little while. “We’re going to have to take our time and open in phases,” Mr. LuJan said. “Unless someone just gives us $20 million.”

Mr. LuJan plans to refashion the ground floor into a collections space and prep lab and use the third-floor auditorium to host lectures and paleontology meetings. The classrooms and the old library on the second floor will hold an expanded museum, dedicated specifically to Texas fossils — with as much weight placed on invertebrates and plants as dinosaurs and mammals. The plan is to keep as much of the museum’s collection as possible on display, where visitors can see these “Texas natural treasures,” rather than in collection spaces away from public view.

Establishing a museum also requires establishing a reputation, which can be tough for a nonacademic researcher.

“A lot of museums — smaller places, kind of like tourist traps — they have incredible fossils, but it’s just about generating money,” Mr. LuJan said. “They’re very good at mimicking legitimate institutions, and that’s why people are a little skeptical of something that hasn’t been around a hundred years.”

“But I believe in equality in paleontology,” he added. “I think the body of your work is what you should be judged on, not a piece of paper.”

“Texas Through Time is a really nice place, but it’s really tough to be a small museum,” Dr. Adams of the Witte Museum said. Larger museums generally have an established donor base to foot the bill for staff, infrastructure and exhibitions. Smaller museums often have to start from scratch.

While Texas Through Time isn’t yet accredited by the American Alliance of Museums — the organization is in the early stages of the process, Mr. LuJan said — it’s already taking shape as a working scientific institution. All of its fossils will be held in the public trust, formally cataloged and accessible to Texas researchers. Scientific publications based on the collection are already in the works, some by local undergraduates at Hill College. Teaching labs, with medical scanners donated by the manufacturer Philips, will provide other opportunities for local students.

Other Texas museums have been beefing up their local paleontology programs as well.

The Whiteside Museum of Natural History, opened in 2014 as a repository and research hub for Permian Period fossils found in Baylor County, is partnering with the Houston Museum of Natural Science. In 2019, the Perot Museum refocused its collecting efforts on in-state fossil deposits, including the abundant Cretaceous marine deposits around Dallas. In 2020, Dr. Adams said, the Witte Museum received a grant to recatalog and rehouse its paleontology collections, with the goal of getting a paleontology program up and running. The Memorial Museum at the University of Texas is due to reopen this year, complete with new exhibitions and structural renovations and renamed as the Texas Science and Natural History Museum.

“I see those programs focusing internally in the state, and I think it’s amazingly awesome,” Dr. Adams said. He and Dr. Tykoski have been planning collecting trips together in the Big Bend. “We’re not in competition. We’re all doing our best to promote the science of paleontology. I would hope, down the road, there’ll be opportunities to work with Andre.”

Back on Ox Ranch, Mr. LuJan surveyed the line of dinosaur tracks, stepping into one the way he had as a child. Later, he ventured into the property’s cave, clambering down a dangling fire ladder into the cool depths, his flashlight picking out survey flags where he’d marked Pleistocene remains and scraps of archaic human skulls.

Mr. Oxley, the ranch’s owner, has donated everything within the cave to Texas Through Time for research. In the near future, some of the bones might lie in cases in Hillsboro, another part of Texas’ hidden past brought into the light.