This “truly exceptional” fossil of a two-headed reptile is 125 million years old

Bicephalism describes a quirk of animal development that results in a two-headed individual. We’ve seen remarkable examples of this in wild animals, like this southern black runner snake that was found to have independent brains at odds with each other.

When you think about how rare two-headedness is in the world today, combined with the fact that fossilization is incredibly rare, this fossil is truly exceptional.

Dr. Dean Lomax

As we know, fossilization is a treatment given only to a privileged few of the animals that have ever lived on Earth. You have to die the right way to become a good fossil, which means that the animals we extract from rock today represent only a snapshot of their ecosystem.

So it’s rare to end up being a beautifully preserved fossil. Even rarer still is one that captures a physiological oddity like two-headedness.

Paleontologist, author and science communicator Dr Dean Lomax was particularly fascinated by the fossil, which he explains in his new book. The secret life of dinosaurs is a prehistoric reptile called Hyphalosaurus lingyuanensis. So captivated, in fact, that he became the star of this book (catch a “Giant T. rex “Penis” (excerpted in our September issue of CURIOUS). So we asked him what it felt like to see him for the first time.

“In a word, hypnotized,” Lomax said. “I’ve seen a living two-headed snake before and I’m very familiar with other, often rare, examples of two-headed animals, but having a real fossil is next level.”

“It’s extraordinary. When you think about how rare two-headedness is in the world today, combined with the fact that fossilization is incredibly rare, this fossil is truly exceptional.”

The hyphalosaurus was recovered from a Lower Cretaceous rock in the Jehol Biota fossil beds in Liaoning Province, China, estimated to be 120 to 125 million years old (and you can see photos of it here). The region is famous for producing remarkably preserved specimens, some boasting feathers and soft tissue, but one two-headed reptile really takes the biscuit.

If you scoff at this obvious “fake”, you may be interested to know that its authenticity has already been questioned and investigated, and to date no one has found any evidence to suggest it isn’t real. The mineralized remains clearly show two heads and two necks attached to the body.

If I had to really narrow down my choice, I’d have to go with something cliché like a Tyrannosaurus or Spinosaurus, because the two giant heads would look incredible.

Dr. Dean Lomax

As for the fate of our very special hyphalosaurus? It is possible that it lived shortly before its death and subsequent fossilization, as it was approximately 7 centimeters (2.8 inches) long and was not found near an adult.

So this shows that although exquisite fossilizations are rare, they do occur and sometimes capture some truly remarkable animals. So it’s also possible that we could find more two-headed animals in the fossil record, which leads us to wonder: If you could pick any dinosaur to see with two heads, which one would it be?

“Oooooh, that’s a question!” Lomax said. “There are so many choices. If I really had to narrow it down, I’d have to go with something cliché like a Tyrannosaurus or a Spinosaurusbecause the two giant heads would be amazing (of course, if they reached adulthood!).

“However, part of me also wonders what something like Diplodocus Or Brachiosaurus might look like two heads. Would they reach the same length, I wonder. Given the giant and intimidating size of these dinosaurs in general, seeing one with two heads would be pretty terrifying.

The secret life of dinosaurs is published by Columbia University Press and is available now.