Aquilops

Origin of the Name and Basic Data

The scientific name Aquilops is derived from a combination of Latin and Ancient Greek.

Meaning of the Name

Latin for “Eagle” (aquila) + Ancient Greek for “Face” (ops) = “Eagle Face”

Type Species

Aquilops americanus

This specific name was chosen to commemorate the fact that it was the first “very basal neoceratopsian” discovered in the United States.

History from Discovery to Naming: Recognized as a New Species After 17 Years

The first fossil of Aquilops was discovered in 1997.
An expedition supported by National Geographic excavated a single partial skull from the Cloverly Formation (Albian stage) in Carbon County, southern Montana.
The discoverer was paleontologist Scott Madsen.

Was it Mistaken for Another Dinosaur at First?

It was not introduced to the world as “Aquilops” immediately upon discovery.
Initially, while the specimen was undergoing preparation, it was described as a different dinosaur, Zephyrosaurus.
Later, Madsen himself realized it was a new species, but it took a long time for it to be formally recognized.

Finally, in 2014—17 years after its discovery—it was named and described by Andrew Farke and colleagues, etching the name Aquilops into history.

Only 60cm Long! Physical Characteristics of the “Eagle Face”

Aquilops was a very small dinosaur.
According to estimates by paleontologist Mathew Wedel, its dimensions were as follows:

• Total Length: Approx. 60 cm
• Weight: Approx. 1.5 kg
• Skull Length: 84.2 mm (Holotype specimen OMNH 34557)

Unique Features Proposed by the Describers

As its name implies, Aquilops possessed unique facial features.

An Eagle-like Beak

This is the most defining feature of Aquilops.
The bone core of the beak curves downward, and the front possesses an arched keel with a bump.

Distinctive Dentition

The tooth row in the back of the upper jaw, when viewed from the front, is longer than the entire length of the depression seen from the side.

Pointed Antorbital Fenestra

The antorbital fenestra (the opening in front of the eye socket) is twice as long as it is tall, pointing backward and extending beneath the eye socket.

Classification and Evolution: Between Psittacosaurus and Protoceratops

Taxonomically, it is considered to have occupied a position more advanced than the famous ceratopsian Psittacosaurus, but more primitive than Protoceratops.
As a very basal neoceratopsian, it is a crucial piece of the puzzle in understanding the evolutionary process of horned dinosaurs.

Remaining Mysteries: No Frill or Body Found?

Many mysteries still surround the detailed ecology of Aquilops.

Only “Part of the Head” Has Been Found

To date, only a partial skull including the upper and lower jaws has been discovered.
Most of the back of the head and the palate are missing. Not only are the body bones—necessary to know the dinosaur’s full appearance—missing, but even the “frill,” a symbol of ceratopsians, has not been found.

The Specimen Was Likely a “Child”

Furthermore, the discovered holotype specimen itself is likely not a fully mature individual, but a “sub-adult.”
Studies comparing it with related species suggest this specimen was about 60% of the size of an adult.

In other words, the Aquilops we know is still in the growth phase, and no one yet knows what a fully grown adult looked like.

Hopes for Further Discoveries

Due to the extremely low number of specimens—and the fact that only partial sub-adult fossils have been found—the full picture of Aquilops remains unclear.
To understand the true appearance of this mysterious dinosaur with the “Eagle Face,” further fossil discoveries are essential.