John Estaugh Hopkins didn't know there was a dinosaur buried in the backyard of his Haddonfield farm house.

Then on a summer evening in 1858 William Parker Foulke, a lawyer and amateur geologist from Philadelphia, came to dinner. Hopkins, a descendant of the town's founding family, showed Foulke mysterious bones he had discovered in his farm's marl pits.

With Hopkins' permission, the intrigued Foulke excavated the farm for three months before stumbling upon a historic find: the first nearly complete dinosaur fossil unearthed in modern times.

The Haddonfield discovery sparked scientific excitement when Joseph Leidy, a noted physician at the University of Pennsylvania who was drawn to paleontology and was Foulke's close friend, presented a paper about the discovery on Dec. 14, 1858 - 158 years ago this week.

While the Haddonfield fossil was missing its skull, there was, for the first time, material proof that allowed the world to visualize the physical appearance of a dinosaur - a term coined only 16 years before.

Then, as the years went by, the excitement subsided and, among local residents, the discovery was almost forgotten.

It took a Haddonfield boy scout and his father, in the 1980s, to rekindle the town's awareness of its dinosaur history.

"Before 1984, no one really knew where the site was," said Butch Brees, 72, a retired architectural consultant and now the self-appointed caretaker of the site where the dinosaur fossil was found.

That year, Brees helped his then-13-year-old son, Chris, look for the forgotten site as part of a research project for the Boy Scouts. They used Leidy's original maps to pinpoint the location - a ravine at the end of Maple Avenue which was used as a dumping ground.

The boy scout got funding from the Philadelphia Academy of Natural Sciences and permission from the borough to clean up the site and mark it with a plaque.

For the father, the dinosaur would become an obsession. The older Brees ever since has maintained the grounds, located at the end of a residential street of two-story homes.

The site, designated a national historical landmark in 1994, now has wooden benches, toy dinosaurs for kids, and a log book for visitors to sign. Weatherproof posters describe the historical importance of the site for visitors.

"We've had visitors from every state in the union and from all the world," said Brees, who sells dinosaur T-shirts and trinkets in town on weekends to raise funds for the site, which he says is something of "family pride."

And for a Hopkins' descendant, the dinosaur is more than a matter of pride, it's entrenched in the family's history.

"There has been a lot of interest in the dinosaur in the last 20 years, but that wasn't always the case. This all of a sudden became a big thing," said Frances Hopkins O'Neill, 73, great-great-granddaughter of John Estaugh Hopkins, who lived in Haddonfield before retiring and moving to Holgate, at the Shore.

Hopkins O'Neill said the discovery at Birdwood, the family's historic 18th century home, is the subject of countless family stories.

Birdwood, a massive, white, three-story house, is now owned by the son of former Gov. Alfred E. Driscoll, who had bought it from the Hopkins family in the 1930s. The woods around it, including the site of the discovery, are owned by Camden County.

Before Foulke's visit, the family had found countless bones, which were used as doorstops or planters in the home, she said.

"They were curiosities and they found a couple of them. They were weird looking things," said Hopkins O'Neill, who used to work as a social worker and never lived in Birdwood. She said last week that most of the bones were either given away to neighbors or kept in the home's attic before the family gave them to Leidy.

When Foulke paid the family the fateful dinner visit, she said her great-great grandfather rushed to the attic to show the geologist the bones he had found in the farm over 20 years.

After months of digging and finding the fossil, Foulke could not contain his excitement as he wrote Leidy: "I have made a digging and have taken some splendid bones from the marl," Foulke wrote in a letter now at the Academy of Natural Sciences of Drexel University.

Leidy named the 23-foot dinosaur Hadrosaurus foulkii. The first part of the name is a combination of Greek words meaning "bulky lizard". The second part honored Foulke.

Over the years, researchers have visualized it with two different skulls and it is deemed to be a duck-billed dinosaur.

"I'm very proud that the Foulkes have a dinosaur named after our surname," said Bruce Foulke, 63 of Perkasie, Pa., a descendant of the fossil hunter.

Foulke, president of the American Heritage Credit Union in Philadelphia, said the dinosaur discovery is an important part of his family's history and a common topic of conversation during reunions.

"What's amazing is when I meet a new cousin I tell them, 'Did you know you have a dinosaur named after you?' It's funny."

How Bruce Foulke's 19th century ancestor fell in love with dinosaurs is a mystery to the family, he said.

The Haddonfield dinosaur story also has fascinated two area writers.

"If you look at Haddonfield, or the broader picture of paleontology, Hadrosaurus foulkii isn't a dinosaur, it's the dinosaur," said Hoag Levins, 70, a former Inquirer reporter and resident of neighboring Haddon Township who has created a website dedicated to the historic find.

Through more than a dozen articles and short video clips, Levins has used the website to document the significance of the discovery.

Michael Dooling, 58, of Audubon borough, has made the story of the Hadrosaurus accessible to children. Dooling, an illustrator and author of children's books, published Fossil Hunter in 2015, a children's book illustrating Foulke's discovery of the fossil.

The Hadrosaurus foulkii bones are currently preserved at the Academy of Natural Sciences in Philadelphia - the same academy where the skeleton was put on display 10 years after its discovery. The 1868 exhibit was the first of its kind in the world and attracted huge crowds. The fossil is in storage, a cast is on display at the academy.

For Jason Poole, the dinosaur hall coordinator at the academy, the discovery happened at the right time in history.

"Leidy was the right guy to look at the bones," Poole said. "At the time, Leidy was an eminence in the U.S., and Philadelphia was very much a scientific capital of the U.S."

In 1991, New Jersey adopted Hadrosaurus foulkii as the state dinosaur, and in 2003, a nine-foot, bronze statue of the plant-eating creature was erected in downtown Haddonfield. They call it Haddy.

"Haddonfield may very well have some more dinosaurs in people's backyards," said Hopkins O'Neill.