What Are Dire Wolves? Inside Colossal Biosciences’ De-Extinction of the Dire Wolf

Colossal Biosciences has brought back the now-formerly-extinct dire wolf. If you’re a Game of Thrones fan, you’ll probably recognize the name of the animal that vanished from the face of the earth thousands of years ago. Scientists from the Texas-based company found a way to bring back the species with their adolescent male pups named Romulus and Remus and one female named Khaleesi.

Learn all about the history of dire wolves, why they went extinct and how they’ve made a comeback below.

What Is a Dire Wolf?

A dire wolf is a now-de-extinct canine that lived in the Americas during the Late Pleistocene and Early Holocene epochs, which were between 125,000 to 10,000 years ago. These wolves were usually white in color, according to Colossal Biosciences’ findings.

How Big Was the Dire Wolf?

According to multiple outlets, the dire wolf was around 6 feet long, and they weighed anywhere between 130 to 150 pounds. 

Why Did Dire Wolves Go Extinct?

There are several factors that contributed to the extinction of the dire wolf. For starters, climate change and the competition with other species tend to cause an animal’s extinction. Additionally, the dire wolf was reliant on megaherbivores (large plant-eating animals), which is credited as one of the reasons why it went extinct.

What Is Colossal Biosciences?

Colossal is a biotechnology and engineering company specializing in de-extinction. The team at Colossal has also worked on the de-extinction of the woolly mammoth, the northern white rhinoceros, the Tasmanian tiger and the dodo bird.

According to an April 2025 press release, Colossal CEO Ben Lamm said, “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. Our team took DNA from a 13,000 year old tooth and a 72,000 year old skull and made healthy dire wolf puppies. It was once said, ‘any sufficiently advanced technology is indistinguishable from magic.’ Today, our team gets to unveil some of the magic they are working on and its broader impact on conservation.”

How Did Colossal Biosciences De-Extinct the Dire Wolf?

In Colossal’s press release, the company detailed how they successfully managed to de-extinct the dire wolf. In the following list, the team:

• Extracted and sequenced ancient DNA from two dire wolf fossils
• Assembled ancient genomes from both and compared those to genomes from living canids, including wolves, jackals, foxes and dholes
• Identified gene variants that were specific to dire wolves
• Determined that dire wolves had a white coat color, and long thick fur
• Performed multiplex gene editing to a donor genome from their closest living relative, the gray wolf
• Screen edited cell lines via whole genome sequencing and karyotyping
• Cloned high quality cell lines using somatic cell nuclear transfer into donor egg cells
• Performed embryo transfer and managed interspecies surrogacy
• Successfully birthed an extinct species

Who Is Dr. George Church?

Dr. George Church is a a geneticist, molecular engineer, chemist and the co-founder of Colossal Biosciences. Among the scientist’s most famous feats is being a professor at Harvard University, where he founded about 50 biotech companies in his laboratory. Not only that, but he’s also listed in 2017’s Time 100, the list of most influential people in the world.

Church weighed in on his company’s de-extinction of the dire wolf in a statement that was included in Colossal’s press release. The geneticist said, “Preserving, expanding, and testing genetic diversity should be done well before important endangered animal species like the red wolf are lost. Another source of ecosystem variety stems from our new technologies to de-extinct lost genes, including deep ancient DNA sequencing, polyphyletic trait analyses, multiplex germline editing, and cloning. The dire wolf is an early example of this, including the largest number of precise genomic edits in a healthy vertebrate so far. A capability that is growing exponentially.”