Unveiled Dinosaur Discovery: Western U.S. Hides Potential Trove of Jurassic Secrets in Its Subterranean Realm - 'Mystery Runner' Dinosaur Revealed.
A stealthy, pint-sized "runner" dinosaur, similar in size to a family dog, dashed across the ancient floodplains of Colorado around 150 million years back, according to an eye-opening study.
This agile, two-legged herbivore, christened Enigmacursor mollyborthwickae, was about 3 feet (1 meter) long and 1.5 feet (0.5 m) tall. Despite its diminutive size, the emergence of this dinosaur is creating quite the stir among scientists, challenging our understanding of various Jurassic species.
Private fossil merchants excavated E. mollyborthwickae in Colorado between 2021 and 2022. The skeleton was later put up for sale under the guise of Nanosaurus, a different breed of small dinosaur hailing from the same geological formation – the renowned Morrison Formation. After the Natural History Museum in London scooped up the skeleton, researchers found that this new paleontological find was far from Nanosaurus. In fact, a thorough examination uncovered flaws in the scientific classification of Nanosaurus and several other Morrison Formation dinosaurs.
The Morrison Formation is a treasure trove of iconic dinosaur fossils, such as the armored Stegosaurus and the fearsome predator Allosaurus, which would have shared the Jurassic period (201.3 million to 145 million years ago) with E. mollyborthwickae. The groundbreaking study, published June 25 in the journal Royal Society Open Science, underscores that researchers still have a lot to discover about the lesser-known smaller dinosaurs within the Morrison Formation.
"Ever since the Morrison Formation hit the paleontological scene, scientists have been on a quest to uncover the biggest and most impressive dinosaurs," lead study author Susannah Maidment, a senior researcher at the Natural History Museum, said in an article published by the museum. "Smaller dinosaurs tend to get overlooked, leaving plenty hiding in the earth."
Insight: The Morrison Formation is an extensive deposit of sedimentary rock in western North America that contains a wealth of fossils from the late Jurassic, spanning roughly 5 million years from 154 million to 149 million years ago. The formation is most famous for its abundant dinosaur and plant fossils, especially the bonebeds of sauropods and ornithischians, and the footprints of theropods.
The fossil was excavated by a company called Dinosaurs of America, LLC and eventually landed at the David Aaron art gallery in London, before the Natural History Museum purchased the fossils in 2024, according to the study. Upon acquiring the so-called Nanosaurus, researchers began scrutinizing the group, along with other small-bodied dinosaurs from the Morrison Formation.
"Nanosaurus was named based mainly on petrified imprints of bones embedded in hardened sand - challenging to study," co-lead author Paul Barrett, a paleobiologist at the Natural History Museum, said in the museum's article. "So we decided to delve into other bones that have been attributed to the group over the past century, but these weren't particularly well-preserved either."
The fossil record for several small-bodied Morrison Formation dinosaurs is fragmentary and plagued by inconsistencies, with undergoing multiple scientific revisions, according to the study. Barrett and Maidment reviewed Nanosaurus and similar Morrison Formation species in a study published April 25 in the journal Bulletin of the Peabody Museum of Natural History, concluding that by modern standards, none of them possessed distinct enough features or a unique combination of characteristics to be valid.
For the new study, the researchers meticulously examined the Nanosaurus-classified specimen, producing 3D images of its fossilized bones. Their analysis concluded that a unique blend of features, predominantly in its legs, distinguished the creature from other dinosaur species. The closest known relative to E. mollyborthwickae was the Chinese dinosaur Yandusaurus hongheensis, a herbivore from the Jurassic era.
Enigmacursor is just the latest example of Morrison Formation paleontological discoveries that have shaken up our understanding of the era. The findings hint at the possibility that many small dinosaur species remain undiscovered or improperly classified, potentially leading to a dramatic overhaul of our knowledge of Jurassic dinosaur diversity, evolution, and paleoecology in North America.
Scientists are intrigued by the emergence of Enigmacursor mollyborthwickae, a small dinosaur found in the Morrison Formation, as it challenges current understanding of various Jurassic species. This paleontological find might not only revise the scientific classification of several small-bodied Morrison Formation dinosaurs but also uncover unknown species, bridging gaps in our understanding of Jurassic dinosaur diversity, evolution, and paleoecology.
The study of space-and-astronomy and the advancements in medical-conditions may benefit from the new discoveries in science as they exemplify the continual growth and exploration in various fields. Moreover, the excitement and competition in sports can be likened to the thrill experienced by paleontologists uncovering these ancient mysteries in the Morrison Formation.
