Dallas-based biotechnology company Colossal Biosciences has announced what it’s calling the “world’s first de-extinction” by successfully creating three dire wolf pups using ancient DNA and cutting-edge genetic engineering. Scientists extracted genetic material from dire wolf fossils dating back 13,000 and 72,000 years, then used CRISPR technology to modify gray wolf DNA, essentially creating hybrid animals that closely resemble their long-extinct ancestors.
The pups, named Romulus, Remus, and Khaleesi (a nod to the popular HBO series “Game of Thrones” that featured dire wolves), are being raised in an undisclosed nature preserve and monitored by a dedicated animal care team.
According to Colossal, the project represents could also benefit endangered species like the critically threatened red wolf.
Dire wolves, which went extinct approximately 13,000 years ago, were formidable Ice Age predators that weighed around 150 pounds and hunted megafauna throughout the Americas. Recent genetic studies have revealed that, contrary to previous assumptions, these animals weren’t closely related to modern gray wolves. Instead, they belonged to a separate evolutionary lineage that diverged from wolf ancestors roughly 5.7 million years ago.
In a post on X has the Romulus and Remus pups howling
SOUND ON. You’re hearing the first howl of a dire wolf in over 10,000 years. Meet Romulus and Remus—the world’s first de-extinct animals, born on October 1, 2024.
The dire wolf has been extinct for over 10,000 years. These two wolves were brought back from extinction using… pic.twitter.com/wY4rdOVFRH
— Colossal Biosciences® (@colossal) April 7, 2025
Not all scientists are convinced these animals truly represent “de-extinction.” BBC quoted Dr. Nic Rawlence, a paleogeneticist from Otago University, disputing the claims. “Ancient DNA is like if you put fresh DNA in a 500 degree oven overnight,” Dr. Rawlence told BBC News. “It comes out fragmented – like shards and dust.” Critics like Rawlence argue these animals are essentially hybrid creatures with a 99.9% gray wolf genome that has been edited to express certain dire wolf traits, rather than true dire wolves brought back from extinction.
“The “dire wolf de-extinction” news is mostly mis-reported and will be used as an excuse not to protect endangered animals,” said Kathy Hessler, assistant dean for animal law at George Washington Law School. The school is hosting a webinar titled, “Making De-Extinction Extinct: Why Current Scientific Efforts to Bring Back Extinct Species Should Be Terminated” in early May.
The animals were born on October 1, 2024.
The science behind the news
Whether the news represents a de-extinction event may be a matter of debate, the development does represent a milestone in genetic engineering, relying heavily on CRISPR-Cas9 technology. Colossal’s scientists used CRISPR to make a record 20 genomic edits across 14 different genes in the gray wolf genome — the most extensive set of edits ever performed in a healthy vertebrate animal.
Of these 20 targeted modifications, 15 introduced extinct genetic variants specific to dire wolves that hadn’t existed in canids for over 12,000 years. The remaining five edits were modern adaptations chosen specifically to support the animals’ welfare and viability. For instance, researchers identified a dire wolf gene variant for white fur that carried risks of deafness and blindness, so they substituted a safer alternative gene from modern gray wolves that produced the same visual trait without the health complications.
The process began with extracting and sequencing ancient DNA from two fossils: a 13,000-year-old tooth from Ohio and a 72,000-year-old inner ear bone from Idaho. This yielded a large amount of genetic data—over 70 times more than all previous dire wolf genome studies combined. Using bioinformatics tools, including the Form Bio platform (a spinoff from Colossal designed specifically for complex genomic analysis), scientists identified genetic markers for distinctive dire wolf traits like larger size, more muscular jaws, broader heads, and thicker fur.
After editing the gray wolf cells, researchers cloned the most promising cell lines, transferred them into donor eggs, and implanted the resulting embryos into surrogate dogs. Only three embryos successfully developed to term, resulting in the pups we see today. These animals now exhibit physical characteristics consistent with what scientists believe dire wolves looked like, though they remain genetically 99.9% gray wolf.
This same technology has already shown promise for conservation, with Colossal successfully cloning critically endangered red wolves using a new, less invasive blood cloning method developed during the dire wolf research.
The World Economic Forum named the firm as one of its Technology Pioneers in 2022.
