A mysterious human skull found in the 1930s has been identified as an existing species after once being thought to be a new species all together, according to researchers.

The studies — posted in the journals Cell and Science — have identified the 146,000-year-old skull known as "dragon man" has been categorized as a Denisovan.

The researchers revealed that the Denisovans were discovered by their genomes and proteins to identify them. 

However, the reason it took so long to identify was that the attempts to extract DNA from a tooth failed.

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Researchers also tried extracting DNA from the Harbin cranium as well, which also failed.

When those methods failed, researchers turned to using dental calculus, which uses calcified dental plaque.

The calcified dental plaque could hold and protect DNA due to its dense crystalline structure that resists degradation in various environments.

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Researchers used bleach on the dental plaque in order to eliminate any possible modern-day DNA.

Once extracted, researchers began to compare the genetic material discovered to previous samples.

The researchers found that the "dragon man" was not a new species but was a Denisovan and the very first intact specimen to date.

According to the researchers, Denisovans coexisted with modern-day humans and are closely related to Neanderthals.

The "dragon man" was discovered in mysterious circumstances when a Chinese laborer working on a bridge over the Songhua River found it.

The man kept the Harbin cranium well hidden as he was instructed to hide it from the Japanese army.

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The skull was donated shortly before his death in 2018, after which his family relocated the skull and gave it to the Geoscience Museum, Hebei GEO University professor Qiang Ji.

While there are limitations to this study, the researchers said there is still so much to learn moving forward.

It was called "dragon man" because it was found in the Heilongjiang province of China, which translates to Black Dragon River.

Fox News Digital’s Julia Musto contributed to this story.

Speaking in Los Angeles Friday, Vice President JD Vance criticized California state and local politicians, especially Democratic Gov. Gavin Newsom and LA Mayor Karen Bass, for "endangering" federal law enforcement and effectively declaring "open season on federal law enforcement."  

Vance said he was "shocked" to hear that "far-left agitators" have been posting the names, addresses and even family members of federal law enforcement officials in Los Angeles to harass, antagonize and threaten their lives.

"Gavin Newsom and Karen Bass have got to stop this craziness," Vance said. "Every single law enforcement officer I talked to today, every single one of them, said they feel like the local leadership — the mayor and the governor — are encouraging these far-left agitators. What is the justification for this?"

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Vance said he has been told by law enforcement officials in the area that "when they go out, let's say you have a Border Patrol official who needs to go out and arrest somebody, maybe a violent criminal who's also an illegal alien. When that Border Patrol agent goes out to do their job, they said within 15 minutes of them trying to do their job, they have protesters, sometimes violent protesters, who are in their face obstructing them, preventing them from doing their job and endangering their lives.

"Why do they have that?" he added. "Because those people have been egged on by local officials. Gavin Newsom and Karen Bass, by treating the city as a sanctuary city, have basically said that it is open season on federal law enforcement."

Newsom has been a vocal critic of President Donald Trump’s use of the National Guard and Marines to help local police quell the anti-ICE riots in Los Angeles, calling it both illegal and immoral. 

The governor launched a lawsuit against the federal government to stop the use of the military in response to the riots. Though a district court ruled in Newsom’s favor, the 9th Circuit Court ruled Thursday to allow the Trump administration to continue using the military to assist local officials.

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"They have treated Border Patrol and border enforcement as somehow an illegitimate force instead of what they are, which is the American people's law enforcement trying to enforce the American people's laws," Vance said.

"So, when Gavin Newsom encourages violence and rioting, he encourages people to get in the face of our great Border Patrol officers, he is absolutely endangering the lives of federal enforcement."

Commenting on the 9th Circuit’s ruling, Vance said, "It's interesting that, for the past couple of weeks, Gavin Newsom has said that there's an illegitimate effort to send federal resources to secure a city that he refuses to secure, and what the 9th Circuit said yesterday is that that was a completely legitimate and proper use of federal law enforcement.

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"The president has a very simple proposal to everybody, in every city, every community, every town, whether big or small. If you enforce your own laws and if you protect federal law enforcement, we're not going to send in the National Guard because it's unnecessary," he said. 

"But if you let violent rioters burn great American cities to the ground, then, of course, we're going to send federal law enforcement in to protect the people the president was elected to protect.

"What I see here today is the great tragedy when a mayor and a governor encourage their citizens to harass and endanger the lives of our police officers and our law enforcement officers," he said. "It's heartbreaking to see, and thank God we've got great people who are willing to persevere despite it."