|Name Meaning||Digging runner||Height||2–3 feet (0.6 to 0.9 meters)|
|Pronunciation||oh-rik-toh-DROH-mee-us||Length||6–9 feet (1.8 to 2.7 meters)|
|Era||Mesozoic –Late Cretaceous||Weight||22–32 kilograms (50–70 pounds)|
|Classification||Dinosauria, Ornithischia, Ornithopoda||Location||USA (North America)|
One of the last things anyone would ever expect to find is a burrowing dinosaur, but it did exist.
The Oryctodromeus is a genus of Ornithischia known to have exhibited burrowing behavior.
The genus name translates as “digging runner,” which alludes to the dinosaur’s ability to dig and live in burrows.
Oryctodromeus lived in North America during the Late Cretaceous Period.
It was the first non-avian dinosaur known to have shown evidence of burrowing behavior.
The first fossil of this dinosaur was discovered in 2007.
It was the fossil of an adult individual buried inside a burrow with two juveniles.
The fact that this dinosaur was found buried in a burrow and some of its anatomical similarities to burrowing animals led scientists to conclude that the Oryctodromeus was an active burrower.
In this article, we’ll explore some of the other interesting aspects of the Oryctodromeus’ life to better understand how it lived.
Oryctodromeus was a relatively small ornithopod dinosaur.
It is often compared to modern-day wallabies in terms of its size and digging behavior (without the hopping, of course).
Oryctodromeus measured about six to nine feet (1.8–2.7 meters) in length and stood about two to three feet (0.6–0.9 meters) tall at the hips.
The estimated weight for an adult is about 22 to 32 kilograms (50–70 pounds).
Oryctodromeus had a slender and elongated body with long hind limbs that were well-adapted for running.
This dinosaur’s tail was flexible, fitting for an animal that lived underground.
A lack of ossified tendons would make it possible for the dinosaur to curl up its tail in its small burrow, as is the case with many burrowing animals.
However, subsequent studies have shown that contrary to earlier thoughts, the Oryctodromeus’ tail did have thick tendons, but they were still flexible enough to be folded.
Unlike many modern animals adapted to a burrowing lifestyle, Oryctodromeus had relatively modest arms and legs.
But while its limbs were not long, they were still quite robust and specialized for digging.
It also had an extra pelvis-backbone connection which helped to strengthen its hips during digging.
Habitat and Distribution
Oryctodromeus lived during the Late Cretaceous Period, around 95 million years ago.
Its fossils have been discovered in the western part of North America, primarily in what is now Montana, United States.
Since no fossils of this dinosaur have turned up elsewhere on the continent, the geographic range of Oryctodromeus appears to have been limited to this region.
Oryctodromeus was a burrowing dinosaur.
It is worth noting that this dinosaur wasn’t the only one that exhibited this kind of behavior, but it was the first one identified with evidence of burrowing behavior.
Others discovered after it include the Australian Leaellynasaura and Asian Koreanosaurus.
A burrowing behavior suggests that this dinosaur likely lived in an area with a lot of soft soil and sediments it could easily dig through.
Habitats that may have had this soil type include floodplains, lowland areas, and coastal regions.
The Blackleaf Formation, where fossils of this dinosaur were found, shows evidence of a forested area near a lake, river, or sea.
It was a dynamic ecosystem with different layers of sedimentary deposits.
This is consistent for an area with fluctuating conditions, most likely influenced by changing sea levels.
The Late Cretaceous Period was generally characterized by a warm but relatively mild global climate.
This led to a high sea level that created shallow seas in some parts of the continent periodically.
The region of North America where this dinosaur lived had distinct wet and dry seasons.
Oryctodromeus lived underground during harsh conditions and probably to raise its young or escape prey.
The underground den measured two meters (6.6 feet) long and was about 70 centimeters (2.3 feet) wide.
The burrow had two 90 degrees bends in different directions near the middle.
This was big enough for the dinosaur to fit in but would have been too small for a large predator.
The bones in the burrow were densely packed and disarticulated.
This means the animal lived and died in the burrow rather than its remains being brought in by a scavenger.
The Oryctodromeus’s burrow is very similar to that of present-day hyenas or puffins.
Behavior and Diet
Oryctodromeus was an agile biped.
Although the forelimbs and hindlimbs of this dinosaur were modified for digging, they were not modified enough to affect the dinosaur’s ability to run.
In fact, the “dromeus” part of this dinosaur’s name references its swiftness.
The social behavior of the Oryctodromeus is comparable to that of large burrowing animals like hyenas or rabbits.
They lived in small family groups or colonies.
It isn’t certain if the different burrowing families interacted with each other or lived independently without significant interaction.
Oryctodromeus was primarily a herbivore.
The structure of its teeth and jaw suggest a diet suited for cropping and grinding vegetation.
During the Late Cretaceous, the environment in which Oryctodromeus lived would have provided a range of plant resources, including ferns, cycads, conifers, and early flowering plants that served as food for this small dinosaur.
Oryctodromeus would have leveraged its agility to forage for food efficiently in these environments.
Agile running also helped to escape from prey species in its ecosystem.
Like other dinosaurs, Oryctodromeus reproduced by laying eggs.
They most likely laid their eggs in burrows, using them as protective nesting sites to incubate eggs and raise their young.
This also means that this dinosaur exhibited parental care, staying near the eggs to provide warmth and caring for the young until they were old enough to be independent.
The juvenile fossil of this dinosaur was about 1.3 meters (4.3 feet) long.
The size of the young Oryctodromeus suggests that they remained with the parent for an extended period of parental care, becoming independent only after attaining maturity.
Evolution and History
Oryctodromeus is a member of the ornithischian group of dinosaurs.
The ornithischians, or bird-hipped dinosaurs, were a diverse group of herbivores that evolved during the Triassic Period and diverged in various forms.
They evolved from dinosaur-like animals that lived during the Late Triassic, known as silesaurians.
The ornithischian family includes some well-known dinosaur groups, such as the hadrosaurs (duck-billed dinosaurs) and iguanodontids.
Ornithischian dinosaurs evolved the most bizarre anatomy of all the different dinosaur families.
They ranged from large dinosaurs with giant armored plates on their back to small burrowing forms like the Oryctodromeus.
Oryctodromeus evolved a unique combination of attributes that made a burrowing lifestyle possible while retaining its ability to move swiftly and navigate terrestrial terrains effectively.
Most notably, the forelimbs and hindlimbs of this dinosaur were well-developed to allow digging but not too long to get in the way of its walking on land.
Oryctodromeus also developed a bipedal stance which allowed it to move swiftly using its muscular hindlimbs alone without involving the forelimb.
Oryctodromeus is commonly classified as a hypsilophodontid, along with other small to medium-sized ornithischian dinosaurs such as the Orodromeus and Zephyrosaurus.
Members of this group were small gracile dinosaurs with a bipedal posture and unique adaptations for efficient running.
Oryctodromeus shared many anatomical similarities with other hypsilophodontids.
However, it was unique because of its adaptation for burrowing.
This distinctive trait sets it apart from other hypsilophodontid dinosaurs.
Interactions With Other Species
As a small burrowing herbivore, Oryctodromeus was at the bottom of the food chain.
Any of the large predators in the North American dinosaur ecosystem could have preyed on this dinosaur, including large theropod dinosaurs like the tyrannosaurids.
But the biggest threat to small dinosaurs like this came from smaller predators like the dromaeosaurs that most likely targeted smaller prey like this.
The Oryctodromeus’ adaptation for running and its ability to hide away in burrows would have helped it evade these predators.
The dinosaur’s burrow was big enough to fit into but would have been too small for large predators to get in.
Although there’s no direct evidence of symbiotic partnerships for this dinosaur, it’s possible that the Oryctodromeus engaged in some form of mutualistic relationship with other species.
For instance, burrowing behaviors could have created habitats that benefited other smaller creatures, such as insects or small mammals.
These small creatures may have helped clean the burrows or acted as commensals (species benefiting from the burrows without causing harm).
One piece of evidence for this is the presence of smaller secondary cylinders leading to the dinosaur’s burrow.
The smaller channels were most likely made by a smaller animal sharing the burrow with the Oryctodromeus.
When the digging runner was discovered entombed in a burrow in 2007, it was the first of its kind.
Prior to this discovery, burrowing behavior was unknown in dinosaurs, and no one could have imagined that the dinosaurs once occupied a niche that many small mammals currently occupy.
The recent discovery has opened up the possibility that burrow-dwelling dinosaurs may have been a common part of the Mesozoic environment in North America and other parts of the world.
It’s even likely that many more burrowing dinosaurs similar to the Oryctodromeus have been discovered from unrecognized burrows in the past.
But they were not identified as burrowers because the behavior was unexpected for dinosaurs.
Its discovery further expands our knowledge of the diversity of the dinosaurs and the fascinating world they lived in.
Although it is not very well-known to the general public, Oryctodromeus has been featured in various scientific and educational materials, including books, documentaries, and museum exhibitions.
Its unique adaptations make it an intriguing example to convey the diversity of prehistoric life to the public.
Also known as the “burrowing runner,” Oryctodromeus is a genus of ornithopod dinosaur that was alive in North America about 95 million years ago.
It was a small agile dinosaur known for a unique combination of traits, including an ability to dig burrows.
Oryctodromeus lived in burrows to escape from harsh environmental conditions and to raise its young.
This dinosaur relied on its speed and swiftness as well as its burrowing ability to escape from predators in its ecosystem.
Although other burrowing dinosaurs have since been discovered, Oryctodromeus was the first dinosaur with confirmed evidence of burrowing behavior and one of the most notable of them all.
Where was Oryctodromeus found?
Fossils of the Oryctodromeus were discovered in 95-year-old rocks of the Blackleaf Formation located in Montana, United States.
It was found in a burrow that contained an adult individual with two juveniles.
Did Oryctodromeus have feathers or scales?
No evidence of preserved soft tissue has been found for this dinosaur, so it’s difficult to determine if it had feathers on its body.
A few ornithopods are known to have had feathers, so it isn’t unlikely that the Oryctodromeus had it too.
Jerry Young is a self-proclaimed prehistoric animal nerd. He has been fascinated with these ancient creatures for as long as he can remember, and his passion for them continues to this day. With his extensive knowledge and love for prehistoric animals, he is the perfect fit for Gage Beasley Prehistoric.