Ankylosauridae

Ankylosauridae is a family of armored dinosaurs that lived long ago. They were part of a larger group called Ankylosauria and were related to another group known as Nodosauridae. The oldest members of this family appeared about 122 million years ago and disappeared around 66 million years ago.

These plant-eating dinosaurs always walked on all four legs. They had special leaf-shaped teeth and their bodies were covered with tough, bony plates called scutes. They had strong defenses, like a rounded head, bony pieces on their skull, armored plates along their bodies, and a big bony club at the end of their tail for protection.

Ankylosaurids have been found in the northern part of the world, in places like North America, Europe, and Asia. The first of these dinosaurs to be discovered was named Ankylosaurus by Peter Kaiser and Barnum Brown in Montana in 1906. Barnum Brown later named this group Ankylosauridae and also named a smaller group within it called Ankylosaurinae in 1908.

Anatomy

Ankylosaurids were strong dinosaurs with heavy armor. They had special bony pieces on their skulls that looked like horns and thick plates along their bodies that acted like a shield. They had only two layers of armor around their necks.

The most famous feature of these dinosaurs was their tail club—a large, bony ball at the end of their tails. This helped protect them from predators. Scientists found a well-preserved ankylosaur named Zuul, named after a monster from Ghostbusters, which showed more details about their bodies.

History of study

In 1906, Barnum Brown and Peter Kaisen found the first ankylosaurid dinosaur, called Ankylosaurus, in Montana. They found parts of its skull, teeth, vertebrae, and ribs, and many bony plates on its body. At first, some scientists were unsure and thought it might be another dinosaur called Stegopelta.

Scientists have wondered if the shape of ankylosaurid tail clubs might be related to the genders of these dinosaurs. This idea suggests the tail clubs could have been used in behaviors between dinosaurs of the same species. However, clear evidence for this has not been found.

Phylogeny

In 1978, a scientist named W.P. Coombs, Jr. grouped many armored dinosaurs into two families: Nodosauridae and Ankylosauridae. This helped scientists learn more about these dinosaurs.

Later, in 1998, another scientist named Paul Sereno described Ankylosauridae as all ankylosaurs more closely related to Ankylosaurus than to Panoplosaurus. More details were added in 2001 and 2021 to better explain this group of dinosaurs. The basal subfamily Shamosaurinae was defined to include certain ankylosaurs like Gobisaurus and Shamosaurus.

In 2004, a study found that some early ankylosaurids included Gargoyleosaurus, Gastonia, and Minmi, along with others from China, Mongolia, and North America.

In 2012, scientists studied many known ankylosaurs and found that Gargoyleosaurus and Gastonia belonged to a different group, while Cedarpelta and Liaoningosaurus were early ankylosaurids.

In 2016, a new study looked at many ankylosaurids, including Gastonia, Cedarpelta, Chuanqilong, and others, but some relationships between certain ankylosaurids were still not clear.

Paleobiology

Ankylosaurids were probably slow movers. Their legs show they put most of their weight on one bone, with another bone helping muscles hold on. This means they moved in a steady, elephant-like way.

They had strong muscles in their back legs and tail. Their tail could swing from side to side but not up and down easily, which helped them use their tail club to stay safe. Their teeth looked like leaves, showing they mostly ate plants. Some scientists think a few kinds might have eaten insects or fish, but we are not sure. There are different ideas about why they had tail clubs, like for fighting or keeping away attackers.

Timeline of genera

The image shows when different groups of the Ankylosauridae family lived. It helps us see how these armored dinosaurs changed over millions of years. The timeline starts around 122 million years ago and ends when they went extinct 66 million years ago.