Dromaeosauridae

Some dinosaurs had soft feathers.

These animals were fast runners. They were often small or medium in size. Many lived a long time ago.

They had big claws on their toes. These claws were shaped like a sickle. The claws helped them catch food. They also helped them climb trees.

They had long tails too. The tails helped them stay steady. This helped them when they ran fast.

These dinosaurs look a lot like birds. Some might have even been able to glide.

Dromaeosaurids were a family of feathered dinosaurs. Their name means "running lizards."

These animals were mostly small or medium in size. Some, like Utahraptor, were very large. They lived during the Cretaceous Period.

Most dromaeosaurids walked on two legs. They had a very special foot. The second toe had a large, curved claw. This is called a sickle claw. They held this claw off the ground while walking. They likely used it to catch prey or climb trees.

These dinosaurs also had feathers. Some had long feathers on their arms and tails. Others had short, soft feathers on their bodies.

This made them look much like birds. In fact, many scientists think they are close cousins to birds. Some may have even used feathers to glide through the air. Their long tails helped them stay steady while they moved.

Dromaeosaurids were a family of feathered dinosaurs. Their name means "running lizards" in Greek.

These carnivores lived during the Cretaceous Period. They flourished until a major extinction event 66 million years ago. Some fossils might even date back to the Middle Jurassic. Most were small or medium in size. However, some species grew to be very large.

These dinosaurs had a very unique way of moving. Most walked on two legs, which is called being bipedal. They did not walk on three toes like other theropods. Instead, they held their second toe off the ground. This is called functional didactyly. This toe carried a large, curved, sickle-shaped claw.

Scientists think they used this claw to climb trees or catch prey. Some species, like Balaur bondoc, even had a modified first toe with a claw too.

Many scientists have studied how these animals looked. In 1969, John Ostrom wrote about the dinosaur Deinonychus. His work helped people see dinosaurs as fast and active. Later, in 1999, researchers found Sinornithosaurus in China. This was the first dromaeosaurid with clear evidence of feathers.

These fossils changed how we think about dinosaur skin. We now know many of them had a full coat of feathers.

There are many interesting facts about their bodies. A Velociraptor was quite small, but Utahraptor was much larger.

Their tails were long and helped them stay steady. Some tails had bony rods to make them stiff. Other fossils show tails that could bend from side to side.

Some small ones, like Microraptor, even had feathers on their legs. These feathers might have helped them glide through the air.

Because they had feathers, dromaeosaurids are closely related to birds. They share many features with the group called Avialae.

Some scientists even wonder if they came from flying ancestors. This idea is sometimes called "Birds Came First." In this view, large dromaeosaurids were flightless, like a modern ostrich.

Whether they could fly or not, they remain a key link to the birds we see today.

Dromaeosauridae is a family of feathered, coelurosaurian theropod dinosaurs. Their name comes from Greek words meaning "running lizards."

These carnivores were generally small to medium-sized animals. However, some species grew to be quite large. They flourished during the Cretaceous Period. They lived until the Cretaceous–Paleogene extinction event 66 million years ago.

Some fossil teeth suggest they may have existed as early as the Middle Jurassic. Definitive body fossils have been found in North America, Europe, and Asia.

The physical build of a dromaeosaurid is very distinct. They had relatively large skulls and narrow snouts. Their forward-facing eyes provided binocular vision. Most had an S-curved neck and a short, deep trunk. Their arms were long and could be folded against the body.

These arms ended in large hands with three long fingers. The middle finger was the longest, while the first finger was the shortest. Each finger ended in a large claw. They also featured a large pubic boot on the hip structure.

One of the most famous features is the specialized foot. Dromaeosaurids were bipedal, meaning they walked on two legs. Most theropods walked with three toes touching the ground. Dromaeosaurids practiced functional didactyly. This means they held the second toe off the ground in a hyperextended position.

This toe bore a large, recurved, sickle-shaped claw. Scientists believe this claw helped them catch prey or climb trees. In the species Balaur bondoc, even the first toe was modified with a similar claw.

The tail played a vital role in their movement and balance. Many dromaeosaurid tails were long and slender. Some species had bony, rod-like extensions called prezygapophyses.

John Ostrom proposed these features stiffened the tail like a rigid lever. However, a Velociraptor specimen shows a tail that could bend side to side. This suggests the tail could act as a stabilizer or counterweight. In Microraptor, the tail ended in a diamond-shaped fan of feathers.

This might have worked like a rudder for gliding.

Feathers are a defining characteristic of this family. Evidence shows they had long, pennaceous feathers on their arms and tails. They also had shorter, down-like feathers covering their bodies.

The first dromaeosaurid with definitive feather evidence was Sinornithosaurus, reported in 1999. Some fossils show quill knobs, which are attachment points for wing feathers. Even large species like Zhenyuanlong had a full feathered coat.

This suggests that feathers were a common trait across the whole family.

Size varied greatly among the different genera. Smaller members like Velociraptor were relatively tiny. In contrast, Utahraptor, Dakotaraptor, and Achillobator approached or exceeded 5 meters in length.

Large size actually evolved at least twice in this group. It appeared in the dromaeosaurines, such as Achillobator. It also appeared in the unenlagiines, like the 1.5-meter-long Austroraptor.

There may have even been a third lineage of giants on the Isle of Wight.

The relationship between dromaeosaurids and birds is a major topic in science. They share many features with the clade Avialae, which includes birds. Some researchers argue they are so bird-like they should be classified as birds. Others suggest they are cousins to birds. There is also a theory called "Birds Came First." This hypothesis suggests dromaeosaurids descended from flying ancestors.

In this view, large dromaeosaurids became flightless, much like modern ostriches.