Ornitholestes

Name

Ornitholestes means "bird robber" because its name comes from Ancient Greek words for "bird" and "robber." It was a small meat-eating dinosaur that lived about 154 million years ago during the late Jurassic period.

Discovery

Scientists found the only known fossils of Ornitholestes in 1900 near Medicine Bow, Wyoming. These fossils included a partial skeleton, but the skull was badly crushed. A scientist named Henry Fairfield Osborn described this dinosaur in 1903.

At first, another incomplete hand was thought to belong to Ornitholestes, but it is now believed to belong to a different dinosaur called Tanycolagreus. The only recognized species of Ornitholestes is called O. hermanni, named in honor of Adam Hermann, a preparator at the American Museum of Natural History.

Discovery and naming

Ornitholestes was the first of its kind found in the 1900s. The main skeleton (AMNH 619) was dug up in July 1900 at the Bone Cabin Quarry in Wyoming by a team from the American Museum of Natural History. It includes parts of the spine, arms, pelvis, and legs, along with a skull. Henry Fairfield Osborn named and described this dinosaur in 1903. The name Ornitholestes comes from Ancient Greek words for "bird" and "robber". The species name (O. hermanni) honors Adam Hermann, a museum worker who helped prepare the skeleton.

At first, another incomplete hand (AMNH 587) was thought to belong to Ornitholestes, but later studies showed it likely belongs to a different dinosaur, Tanycolagreus, found nearby. Since then, scientists have relied only on the main skeleton for information about Ornitholestes. Some pieces from another quarry might also be from this dinosaur, but they have not been fully studied yet. Over time, some experts have suggested Ornitholestes might be the same as Coelurus, but others have kept it as a separate name.

Description

Ornitholestes was a small, two-legged dinosaur that lived about 154 million years ago. Early guesses said it was about 2.22 meters long, but newer studies say it was closer to 2 meters. It weighed around 12 to 15 kilograms.

This dinosaur had a smaller head than other meat-eating dinosaurs, with big eye sockets. Its front teeth were cone-shaped, and the back teeth were curved and sharp, like other theropods. Ornitholestes had a short neck and a long, whip-like tail. Its arms were relatively long, with strong upper arm bones. The legs were not very long, but its feet had three toes with claws, typical of theropods.

Classification

The group Coelurosauria was named in 1914 by Friedrich von Huene. It was used for many small meat-eating dinosaurs. Because Ornitholestes was small, it was often placed in this group.

In 1986, Jacques Gauthier changed how these dinosaur groups were defined. He created the group Tetanurae for dinosaurs more closely related to modern birds than to ceratosaurs. Coelurosauria now included those in Tetanurae more closely related to birds than to carnosaurs.

In 1988, Gregory S. Paul thought Ornitholestes looked like Proceratosaurus, a dinosaur from England. He suggested they were related to the big Allosaurus. But later studies showed this was not correct. All recent studies show that Ornitholestes belongs to Coelurosauria.

Some studies suggest it might be one of the earliest members of the group Maniraptora. Others think it is related to Juravenator starkii.

In 2021, a study suggested that Ornitholestes might be the earliest member of another group called oviraptorosaur.

Paleobiology

Scientists studied the foot bones of Ornitholestes and found no signs of injury.

A study showed how Ornitholestes could move its arms. Its forearm could bend in many directions, helping it grab things. This was special compared to other dinosaurs from the same time.

When Ornitholestes was first found, scientists thought it might have eaten birds. But later ideas suggest it probably ate small land animals like frogs, lizards, and baby dinosaurs. Some scientists think it might have hunted at night, while another dinosaur named Coelurus hunted during the day.

One scientist guessed that Ornitholestes might have had simple feathers to stay warm, similar to a short coat. These feathers might have also helped when taking care of its eggs.