The Texas-based Colossal Biosciences also plans to de-extinct the woolly mammoth, the dodo bird and the Tasmanian tiger.

The project aims to restore species that have been eradicated at least in part due to human activities such as overhunting, habitat destruction and pollution. 

To de-extinct a species, Colossal scientists extract the extinct species' DNA from fossils or museum specimens, reassemble its full genetic code (or genome), then compare it to the genome of their closest living relative to pick out the differences. 

Once they identify gene variants that are specific to the extinct species, they modify the living relative's genome to match the extinct species as closely as possible. In the case of the dire wolves, they made 20 changes to gray wolf DNA.

Then, they use this modified genome to make an egg cell that can be implanted into a surrogate — a female from the living relative species — who later gives birth to the previously extinct animal. 

Colossal has already sequenced the woolly mammoth's genome, and in March, its scientists managed to create 'woolly mice' in a major step toward bringing this ancient giant back. 

Ultimately, the company hopes to use Asian elephants as surrogates for their woolly mammoths, which they aim to birth by 2028.   

Scientists are also making strides toward resurrecting the dodo and the Tasmanian tiger by using museum specimens to reconstruct their genomes. 

But some wildlife conservation experts warn that reintroducing long-extinct species to today's ecosystems could have significant consequences. 

On Monday, Colossal Biosciences announced it had successfully birthed three dire wolves, naming them Romulus, Remus and Khaleesi. Made famous by the popular HBO series Game of Thrones, these ancient wolves went extinct 12,500 years ago. 

The reason for their disappearance is unclear, but scientists think it may have been triggered by the loss of their megafaunal prey — perhaps due to overhunting.

'I could not be more proud of the team. This massive milestone is the first of many coming examples demonstrating that our end-to-end de-extinction technology stack works,' said CEO of Colossal Ben Lamm.

His company claims it is humanity's responsibility to bring these species back. 'We're committed to rectifying the past and rehabilitating nature on a global scale,' the website states.

Its experts say reintroducing these animals to nature will be beneficial to the environment in many ways, even when it comes to climate change. 

De-extincting the woolly mammoth, for example, could combat global warming by restoring Arctic grassland ecosystems, they say.