A fossil skull unearthed in 1996 has puzzled researchers for decades --
they referred to the animal it came from as “strange beast.”
In the desert of Shenzen, China,”strange beast” is one of a myriad of fossils has been uncovered,
painting a picture of the diverse group of animals that thrived over 14 million years ago.
Now, a study in Science reconstructs what this strange beast looked like,
and how it fit in with neighboring herbivores.
First, the started took CT scans of the specimen’s skull.
They found that the outer wall of its inner ear was very similar to
giraffoids–a family of animals with only two living species, the giraffe and okapi.
Back in the Miocene many other kinds of giraffoids prospered, sporting a variety of bony structures
affixed atop their heads. But the “strange beast’s” headgear stood out.
No antlers here, instead it’s topped/donned a thick, flat layer of bone.
Up close the bone was rough, suggesting a tough outer layer
coated this bony top, likely made of keratin. Comparing younger and older examples, showed how
the shape came to be. As the animal grew older, new layers of keratin pushed the older layers
upward and outward, until a rounded, helmet-shaped disc formed between the animal’s ears.
The researchers named this animal Discokeryx xiezhi – Discokeryx, meaning round-plated horn
and xiezhi, a reference to a single horned beast from Chinese legends.
Moving down from the skull to the neck, more unusual features appeared. Its vertebrae were
extremely thick, containing large areas where the joints touch each other between vertebrae.
To see if this sturdily built neck and durable headgear could have been useful for combat,
the researchers analyzed Xiezhi’s vertebrae to see how much stress it could withstand.
After running simulations of headbutting with and without this extra overlap,
they found that the thicker vertebrae better absorbed the blow of intense combat,
and prevented the head from rotating too far. Simulations also revealed that this disc-shaped
headgear better protected the brain than the horns of sheep and musk oxen.
Next, the researchers analyzed isotopes in xiezhi’s tooth enamel
to understand where they lived and foraged.
The plants animals eat contain different amounts of Carbon 13,
while Oxygen 18 varies depending on an animal’s source of water.
The high average value of Carbon 13 suggests that Xiezhi foraged on open land,
unlike other herbivores in the community which stuck to forests.
The large range of Oxygen 18 values could mean that Xiezhi drank water from multiple sources or
changed where they lived depending on the season. Together these isotope findings suggest Xiezhi
had a distinct range from other herbivores in the community.
Giraffoids – particularly today’s extremely long necked giraffes
have often been used as a lesson by those interested in how animals evolve traits.
Darwin proposed that their elongated necks evolved from competition with other browsers.
Others think that the long necks formed from necking among males in a struggle for dominance.
Both environment and combat could have played a role in how the “strange beast” got its hat.
Xiezhi fed from a different part of the ecosystem than other herbivores, comparable
to the unique area giraffes browse for food. Competition for resources among Xiezhi males
might have led to combat – and the evolution of strongly reinforced heads and burly necks.
Who knows what type of wacky headgear researchers may unearth in the future.