Aorun, a Theropod dinosaur from the Late Jurassic Period, stands as a remarkable testament to the diversity of prehistoric life. Named after the Dragon King from Chinese mythology, this carnivorous creature was first discovered in Wucaiwan, China in 2006. Its discovery has provided valuable insights into the Alvarezsauroid family to which it belongs, and the broader ecosystem of its time.

This dinosaur, pronounced “Aw-roon”, lived approximately between 166.1 to 163.5 million years ago. The significance of this carnivore lies not just in its unique characteristics as a member of the Theropod group but also in the light it sheds on the evolutionary pathways and ecological dynamics of the Late Jurassic Epoch.

Aorun Key Facts

Aorun Origins, Taxonomy and Timeline

This name, derived from Mandarin Chinese, resonates with mythical grandeur. It’s a nod to Ao Run, the Dragon King of the West Sea in the epic “Journey to the West.” This name not only reflects the dinosaur’s Asian roots but also adds a touch of mystique to its scientific identity.

As a member of the Theropod group, it shares a lineage with some of the most well-known dinosaurs, including the fearsome Tyrannosaurus rex. However, Aorun’s closer family ties lie within the Alvarezsauroid family, a group known for their small size and peculiar physical characteristics. The type species, Aorun zhaoi, further distinguishes it within this intriguing family.

This timeline is a journey back to the Late Jurassic, specifically the Callovian Epoch. This era spanned from 166.1 to 163.5 million years ago and was a period of significant geological and biological changes. The world Aorun inhabited was vastly different from ours, with shifting continents and evolving ecosystems providing a backdrop to its existence.

Discovery & Fossil Evidence

The story of discovery is as intriguing as the dinosaur itself. In 2006, a team led by James Clark, the Professor of Biology at GW’s Columbian College of Arts and Sciences, and his doctoral student Jonah Choiniere, made a remarkable find in a remote region of Xinjiang, China. Their expedition included international researchers. Here, they stumbled upon a portion of a leg bone protruding from the ground. This initial find led to an exciting excavation that revealed a skull with numerous teeth, some vertebrae, and additional leg bones.

The fossilized remains of Aorun, including its skull and partial skeleton, provided a rare glimpse into the life of this Late Jurassic predator. The discovery was significant not just for the well-preserved state of the fossils but also for the insights they offered into the Alvarezsauroid family.

In 2013, the team, comprising of Jonah Choiniere, James Clark, Catherine Forster, Mark Norell, David Eberth, Gregory Erickson, Chu Hongjun and Xu Xing, formally described the species Aorun zhaoi. The specific name, “zhaoi”, honors Professor Zhao Xijin, a prominent figure in vertebrate paleontology who led several expeditions to the Junggar Basin. Aorun zhaoi is currently the only species classified under its genus, making it monotypic.

Aorun Size and Description

The type specimen of Aorun, indicative of a juvenile individual, was a bipedal predator. Its skeletal structure suggests agility and speed, traits essential for a carnivorous lifestyle. The presence of a nearly complete sclerotic ring in the skull also provides insights into its possible sensory capabilities, which would have been crucial for hunting or scavenging.

Size and Weight of Type Species

The only specimen of Aorun, despite being a juvenile, gives us a glimpse into the size of this dinosaur. It measured approximately 3.3 feet in length and weighed around 3.3 pounds. This small stature indicates that it was one of the smaller theropods of its time.

Histological analysis of the femur and tibia, as noted by Choiniere and colleagues in 2013, confirms that the specimen was about one year old and not a newborn. This analysis is crucial as it provides a more accurate picture of the growth and development stages of this theropod, contributing to our understanding of its life cycle and physical development.

The Dinosaur in Detail

This small but fascinating carnivore presents a unique combination of features that set it apart from other dinosaurs of its time. The holotype, IVPP V15709, includes a skull with a nearly complete sclerotic ring in the right orbit, composed of overlapping ossicles. It also includes lower jaws, a neck vertebra, a dorsal vertebra, three tail vertebrae, the left ulna and hand, the lower ends of both pubes, and both lower legs. One of the most striking aspects of Aorun is its gracile hand, particularly the thin metacarpals III and IV. These closely resemble the hands of derived non-avian coelurosaurs rather than those of more basal theropods.

The teeth have no serrations, which is very distinctive for theropods. However, because this individual is a juvenile, the teeth may have a different morphology for adults. It most likely hunted for lizards and small mammals.

Interesting Points about Aorun

Aorun in its Natural Habitat

The Callovian Epoch, home to this predator, was a period of dynamic ecological change. The landscape was likely dominated by lush vegetation and diverse ecosystems, which provided a fertile hunting ground for this carnivorous dinosaur. The climate likely varied and would have influenced the types of prey and competition Aorun faced.

As a carnivore, its diet would have consisted primarily of smaller animals. Its bipedal locomotion suggests a capacity for bursts of speed that were essential for hunting or scavenging. Its social behavior, whether it was a solitary hunter or part of a pack, remains a subject of speculation.

Contemporary Dinosaurs

Imagine a world millions of years ago where the young, feisty Aorun roamed the ancient landscapes. This small, agile predator, no bigger than a modern-day fox, was a sight to behold. With its sharp teeth and keen eyes, it was always on the lookout for an opportunity. In this prehistoric world, Aorun wasn’t the only player; it shared its home with a variety of other fascinating Asian dinosaurs, each playing a unique role in the ecosystem.

One of its contemporaries was Tianchiasaurus. This fellow carnivore was slightly larger and bulkier. While Aorun was quicker and more agile, darting through the underbrush, Tianchiasaurus might have dominated larger prey and more open areas. Their interactions could have ranged from competitive stand-offs over kills to avoiding each other entirely, each respecting the other’s hunting prowess.

Then there was Kileskus, another contemporary. It was roughly the same size as Tianchiasaurus but with a different hunting style. Kileskus, possibly more of a stealth hunter, might have crossed paths with Aorun in the dense forests. These encounters could have been tense, with each assessing whether to compete or retreat. With its youthful energy and speed, Aorun might have chosen to steer clear of direct confrontations and perhaps preferred to rely on its agility to escape or outmaneuver Kileskus.

Lastly, imagine the gentle giant Shunosaurus–a large, herbivorous contemporary. This massive creature was likely not a direct competitor for Aorun, but their paths must have crossed. Aorun, curious and opportunistic, might have scavenged around Shunosaurus, maybe even daring to nip at the giant’s heels. These interactions paint a vivid picture of Aorun’s life: a small but fearless predator navigating a world of giants and rivals, each day a new adventure in survival and coexistence.

Frequently Asked Questions

Sources

The information in this article is based on various sources, drawing on scientific research, fossil evidence, and expert analysis. The aim is to provide a comprehensive and accurate overview of Aorun. However, please be aware that our understanding of dinosaurs and their world is constantly evolving as new discoveries are made.

This article was last fact-checked: Joey Arboleda, 11-30-2023

Featured Image Credit: The Nanotyrant, CC BY-SA 3.0, via Wikimedia Commons