Description and Classification

Erlikosaurus belonged to a group of dinosaurs called Therizinosauria. These were unusual theropods, which are typically known for being meat-eaters, but therizinosaurs like Erlikosaurus were plant-eaters. Erlikosaurus was a medium-sized dinosaur, estimated to be about 4 to 5 meters (13 to 16 feet) long and weighing several hundred kilograms. It had a small head with a toothless beak at the front of its mouth, but it also had small, leaf-shaped teeth further back, suited for shredding plants. Like other therizinosaurs, it likely had a long neck, a bulky body, and walked on two legs. Its arms were relatively long and ended in three-fingered hands, each equipped with sharp, moderately long claws. Scientists believe that Erlikosaurus, similar to other maniraptoran dinosaurs, was likely covered in feathers.

In terms of classification, Erlikosaurus is placed within the family Therizinosauridae. This family includes other feathered, herbivorous theropods such as Segnosaurus, Nothronychus, and the gigantic Therizinosaurus, famous for its incredibly long claws. The discovery of Erlikosaurus, especially its complete skull, has been very important for understanding the anatomy and evolution of all therizinosaurs.

Distinguishing Features

Erlikosaurus had several features that help paleontologists identify it and distinguish it from other dinosaurs:

• It possessed a rhamphotheca, which is a horny beak, at the tip of its snout, similar to modern birds. This beak was likely used for cropping vegetation.
• Unlike many other therizinosaurs which are known from incomplete remains, Erlikosaurus is known from a very well-preserved skull. This provides crucial information about the head structure of its group.
• While it had claws on its hands, they were more slender and not as enormous as the famous claws of its relative, Therizinosaurus. These claws might have been used for pulling down branches or for defense.
• Its small, leaf-shaped cheek teeth were adapted for processing plant material, supporting the idea that it was an herbivore.
• The presence of a relatively long neck would have allowed it to browse on vegetation at various heights.

Paleoenvironment and Diet

Erlikosaurus lived in the region that is now Mongolia’s Gobi Desert during the Late Cretaceous. At that time, the environment of the Bayan Shireh Formation was quite different from today’s desert. It was likely a well-watered landscape with rivers, floodplains, and forests, supporting a diverse range of plant life. This ecosystem was home to many other dinosaurs, including armored ankylosaurs, large sauropods like Nemegtosaurus, duck-billed hadrosaurs, and other theropods such as the dromaeosaurid Achillobator.

The diet of Erlikosaurus was herbivorous. Its beak was well-suited for nipping off leaves and stems, while its cheek teeth were designed for shredding this plant material. Its pot-bellied appearance, typical of many herbivorous dinosaurs, likely housed a large digestive system needed to break down tough plant fibers. The long neck would have helped it reach a variety of plants, from low-growing ferns to higher branches.

Significance and Ongoing Research

Erlikosaurus holds considerable significance in paleontology primarily because of its exceptionally well-preserved skull. This fossil has provided scientists with invaluable insights into the anatomy of therizinosaurs, a group whose head structure was poorly understood before this discovery. It helped confirm that these unusual theropods were likely specialized herbivores and provided data for studying their brain structure through CT scans. The existence of Erlikosaurus contributes to our understanding of the great diversity within theropod dinosaurs, showing that they evolved a wide range of body forms and lifestyles beyond just being carnivores.

Ongoing research related to Erlikosaurus continues to refine our knowledge. Scientists are still studying its skull to learn more about its senses, such as smell and hearing, and the mechanics of how it fed. Its relationship to other therizinosaurs is also a topic of continued study, helping to build a more complete picture of their evolutionary tree. Each new analysis helps paleontologists better understand how these unique, feathered, plant-eating theropods lived and interacted with their environment millions of years ago.