Scansoriopterygidae

Long ago, small dinosaurs lived in big forests.

These dinosaurs were great at climbing trees. They had very long fingers on their hands. They also had long arms to help them move.

Some of them even had skin to help them glide. They were covered in soft feathers. Some had long feathers on their tails. These tiny dinosaurs were only as big as birds. They were very special climbers.

Scansoriopterygidae is a family of small dinosaurs. Their name means "climbing wings."

These dinosaurs lived in China a long time ago. They lived in warm, wet forests with many trees.

These dinosaurs were great at climbing. They had very long arms. Their third finger was also very long. This helped them grip tree branches. Some species had a special bone in their wrist. This bone helped hold a skin membrane. This membrane worked like a bat wing to help them glide.

They were very small animals. Some were only the size of a sparrow. Others were the size of a pigeon. Most of them had feathers on their bodies. The dinosaur *Epidexipteryx* had long, ribbon-like feathers on its tail. These feathers might have been used to show off. Other dinosaurs, like *Yi qi*, had feathers that looked like paintbrushes. They used these feathers to cover their bodies.

Scansoriopterygidae is a unique family of extinct dinosaurs. Their name means "climbing wings."

These small animals lived a long time ago. They belonged to a group called maniraptorans. Scientists believe they lived in trees or spent much of their time there. This lifestyle made them very different from many other dinosaurs.

They were very small creatures. Some were only the size of a house sparrow. Others were about the size of a pigeon.

These dinosaurs had special ways to move through the trees. They had very long arms and long third fingers. In most other dinosaurs, the second finger is the longest. These long fingers helped them grip branches. Some species, like *Yi qi* and *Ambopteryx*, had a special bone in their wrist. This is called a styliform bone. This bone helped support a skin membrane. This membrane worked like a bat wing to help them glide.

They also had feathers covering their bodies.

Researchers have worked hard to learn about these animals. Stephen Czerkas and Yuan Chongxi first named the family in 2002. They described the first species, *Scansoriopteryx heilmanni*. Later, in 2008, scientists found *Epidexipteryx hui*. In 2015, a new adult specimen of *Yi qi* was discovered. This discovery helped show how they used their wings to glide.

Finding an adult specimen was a big step for science.

Most fossils come from the Tiaojishan Formation in China. These fossils were found in places like Liaoning and Hebei.

This area was a humid, temperate forest long ago. It had trees like ginkgos and conifers. The forest floor had ferns and mosses. These dinosaurs lived alongside many other things. They shared the forest with early mammals and flying pterosaurs. They even lived near insects like beetles and mayflies.

Learning about these dinosaurs helps us understand how flight began. They show us how climbing might lead to gliding. Some had short tails with long feathers, like *Epidexipteryx*. Others had very long tails, like *Scansoriopteryx*. Their feathers were sometimes simple and down-like. Others looked like paintbrushes or long ribbons.

By looking at these bones, we see how life changes over time. These small dinosaurs help us picture a very different world.

Scansoriopterygidae is a unique family of extinct dinosaurs. Their name means "climbing wings."

These small animals belonged to a group called maniraptorans. Scientists believe they were arboreal or semi-arboreal. This means they lived in trees or spent much of their time there. They are important because they show how climbing might lead to gliding.

These dinosaurs had very specific body parts for life in the trees. Most theropod dinosaurs have a second finger that is the longest. In scansoriopterygids, the third finger is extremely long. This long finger helped them grip branches. Some species, like *Yi qi* and *Ambopteryx*, also had a styliform bone. This is a long bone growing from the wrist. It worked with the long finger to support a skin membrane. This membrane was used for gliding, much like a bat.

Scansoriopterygids were among the smallest non-avian dinosaurs ever found. Their sizes varied depending on the species and age. Juvenile *Scansoriopteryx* specimens were only about the size of house sparrows. The subadult *Epidexipteryx* was roughly the size of a pigeon.

These small sizes helped them navigate through dense forest branches. They also had short, high skulls. Their jaws turned downward and they possessed large front teeth.

Scientists have worked for decades to understand these animals. Stephen Czerkas and Yuan Chongxi created the family name in 2002. They first described *Scansoriopteryx heilmanni*. For a long time, it was hard to place them in the dinosaur family tree. In 2008, the discovery of *Epidexipteryx hui* helped define the group more clearly. The 2015 discovery of an adult *Yi qi* was a major breakthrough. It provided the first evidence of adult gliding adaptations in this group.

Their tails were not all the same. This shows how different species adapted to their environments. *Epidexipteryx* had a short tail. It was only about 70% of the length of its torso. This tail held long, ribbon-like feathers for display. In contrast, *Scansoriopteryx* had a very long tail. It was over three times as long as its torso. This tail had a small spray of feathers at the very tip.

All known scansoriopterygids had feathers covering their bodies.

These feathers were often quite simple. *Epidexipteryx* had long feathers on its tail with a central shaft called a rachis. *Yi qi* had "paintbrush-like" feathers. These had long quill-like bases with thin filaments on top. They also had a semilunate carpal. This is a half-moon shaped wrist bone. It allowed them to fold their hands in a bird-like motion.

Most fossils come from the Tiaojishan Formation in China. This area includes the provinces of Liaoning and Hebei.

These fossils date to the mid-to-late Jurassic Period. The formation was likely between 165 and 153 million years old. During this time, the area was a humid, temperate forest. It was filled with ginkgo trees and conifers. The ground was covered in ferns, cycads, and horsetails.

These dinosaurs lived in a very busy ecosystem. They shared the forest with many other creatures. They lived alongside early mammals like *Castorocauda*. They also lived near gliding mammals and pterosaurs. Insects like beetles and mayflies were everywhere.

By studying these fossils, scientists can see how different animals shared the same forest. Scansoriopterygids help us piece together the complex history of life on Earth.