On a frigid January day in 1898, city workers were digging a trench to lay a sewer pipe just blocks from the Capitol when they found something unexpected: a dinosaur.

And not the aging-Member-of-Congress type, either.

The workers hit a layer of clay containing hard lumps of ironstone near First and F streets Southeast. After they removed the ironstone, they discovered the tailbone of a large dinosaur.

The dino needed to be identified. But befitting the city in which it was found, more than a century after its discovery the true identity of the specimen remains mired in dinosaur politics.

The hefty tailbone and some bone fragments spotted near it were given to the Smithsonian Institution. About a decade later, a Yale University professor determined the bone belonged to a powerful, flesh-eating dinosaur and gave it the name Creosaurus potens. Another decade later, a Smithsonian scientist concluded the tailbone was actually from a Dryptosaurus, a meat-eating dinosaur that is an ancestor of Tyrannosaurus rex.

After that, the bone was mostly ignored, until a scientist who came to Washington to study clam fossils became the region’s resident dino expert ‘ and decided the dinosaur wasn’t Dryptosaurus after all.

Sporting a bushy, graying beard, a round brown hat and a T-shirt and shorts, Peter Kranz looks like a guy Steven Spielberg might cast as a paleontologist in a ‘Jurassic Park’ film. Kranz, who holds a doctorate in geology from the University of Chicago, came to D.C. in the 1980s to study clams and to teach.

But he found his students frequently asking him about dinosaurs, so he decided to study dinosaurs instead. After making a few discoveries of his own, he was hooked.

Kranz’s research eventually led him to the tailbone. He studied it extensively and decided the scientists before him got it wrong. ‘I’ve looked at the Dryptosaurus bones, and it’s not the same,’ he says.

Kranz thinks the tailbone belonged to a big meat-eating relative of T. rex, but he couldn’t find another dino species that matched it perfectly.

So in a 1990 Washingtonian magazine article, Kranz put forth the idea that the bone belonged to a previously undiscovered dinosaur and gave it a new name: Capitalsaurus. Kranz followed up in 1998 with a formal, scientific paper officially proposing the name.

But it turns out that political infighting isn’t limited to those other dinosaurs on Capitol Hill.

The scientific community didn’t accept Kranz’s argument, saying the tailbone is insufficient evidence to prove the existence of an entirely new species of dinosaur. In the Smithsonian’s official records, the dino remains referred to by its first name, Creosaurus potens, and the organization has specifically gone out of its way to deny the Capitalsaurus moniker.

‘Unfortunately this specimen was used to try and name a new genus, ‘Capitalsaurus,’ in honor of the nations’s capital,’ the bone’s entry in the National Museum of Natural History’s online catalog reads. ‘This is not scientifically justified and the name ‘Capitalsaurus’ has no validity.’

Although his fellow paleontologists didn’t accept Capitalsaurus, Kranz didn’t give up on his proposition. Instead, he took the argument to the D.C. Council.

Working with local schoolchildren and their parents, Kranz lobbied the council to name Capitalsaurus the official dinosaur of Washington. A bill doing just that passed the council in 1998.

And even though Capitalsaurus isn’t accepted in the scientific community, Kranz is happy with its recognition as a symbol for the community.

‘Its purpose is specifically to provide, as all symbols do, something that identifies something that a particular jurisdiction can take pride in,’ Kranz says.

The D.C. Council also passed legislation giving the name Capitalsaurus Court to the intersection at First and F streets Southeast. And on Jan. 28 each year, the city celebrates Capitalsaurus Day, marking the day the tailbone was given to the Smithsonian.

‘It’s become a cult item at this point,’ Kranz says. ‘Regardless of whether it actually gets a scientific name or not, it exists in reality.’

Kranz continues to serve as D.C.’s unofficial dinosaur guru. He runs the Dinosaur Fund, a nonprofit group that raises money for dinosaur research in the D.C. region. Through the fund, Kranz runs educational programs designed to provide real-life, hands-on dino research experience, including field trips and camps that let kids dig for fossils.

And Kranz continues to promote D.C.’s dinosaurs. He is pushing for an official dinosaur park in city limits, believing there’s a lot left to be discovered.

‘We will, sooner or later,’ he says.