New ‘hell chicken’ species upends understanding of dinosaur extinction

Scientists now find that small dinosaur specimen thought to be of a juvenile from known species is infact adult from whole new species

A young scientist has described his astonishment at discovering a whole new species of dinosaur dubbed a “chicken from hell”.

The discovery was made from fossils earlier thought to be of a juvenile from an already known species. Scientists say the discovery has big implications for our understanding of a period when dinosaurs were thought to have been in a state of decline.

Kyle Atkins-Weltman, a doctoral student at Oklahoma State University, told Live Science he purchased four fossils for $5,000 in 2020 when he couldn’t find the bones needed to complete one of his first research projects.

“I felt my heart skip a beat,” he said. “I was like, is this really happening to me this early in my career?” he said. The hind limb fossils were supposed to be from a cassowary-like dinosaur Anzu wyliei, nicknamed “chicken from hell”, Live Science reported. However, Mr Atkins-Weltman found they were from an unidentified species when he had the fossils scanned.

The new “chicken from hell” raptor species from the US Hell Creek Formation suggested that dinosaur populations were not in a state of decline before the fateful asteroid hit about 65 million years ago.

Until now, scientists have debated whether dinosaurs were already in a state of decline or thriving before the extinction event that wiped them out.

While some research suggested dinosaur diversity increased between 83.6 million to 71.2 million years ago, many others said the asteroid was only a final blow to an already dwindling population.

Scientists have now found that a small dinosaur specimen thought to be of a juvenile from an already known species is infact an adult from a whole new species.

This finding, published recently in the journal PLOS One, suggests there may be more species from the time of dinosaur extinction that are yet to be discovered, with the diversity of the large reptiles likely not declining before the asteroid hit.

Artist’s depiction of dinosaurs Eoneophron infernalis (top left), MOR 752 (bottom left), and Anzu wyliei (right) in the Hell Creek Formation (Atkins-Weltman et al)

Researchers assessed four hindlimb bones unearthed in South Dakota in rocks of the Hell Creek Formation, dating to the final two million years of the Cretaceous era.

Initially, it was thought to belong to a juvenile from a group of birdlike family of “chicken from hell” dinosaurs with toothless beaks, long legs and short tails known as the caenagnathids.

But juvenile specimens of this group are rare, and no definite cases of finding young ones of the species have been published in the scientific literature, researchers found.

They assessed the bone specimen for rings of growth indicating the dinosaur’s age – similar to how tree rings are used to determine the age of plants.

Scientists say that their discovery, upon examining the bones for growth rings, “completely uprooted” their initial assumptions.

The growth lines indicated the animal had slowed down growing and it was nearly at its adult size.

The new species has been named Eoneophron infernalis meaning “Pharaoh’s dawn chicken from Hell,” scientists write in The Conversation.

Researchers have also found some unique features of the small dinosaur species, including ankle bones fused to the tibia, and a well-developed ridge on its foot.

Scientists suspect there may have also been a third “chicken from Hell” species about the size of a German shepherd.

The latest findings, according to researchers, suggest populations of caenagnathids and likely of other dinosaur groups may have remained stable throughout the last part of the Cretaceous before the fateful asteroid impact.

Researchers suspect there could still be more new dinosaur species from this time period to be discovered, hinting that at least in some populations, decling diversity may be due to sampling and preservation biases.