Falcarius – The Sickle-cutter of the Early Cretaceous

When we delve into the world of dinosaurs, it’s like opening a time capsule that takes us millions of years back. Today, let’s embark on a journey to discover a rather intriguing inhabitant of the Early Cretaceous Period – Falcarius. This dinosaur, whose name translates to “Sickle-maker,” offers a fascinating glimpse into a bygone era.

Falcarius Key Facts

Meaning of nameSickle Cutter
Type SpeciesFalcarius utahensis
When it Lived145 to 139.8 MYA
PeriodEarly Cretaceous
Length13.0 to 16.0 feet
HeightApproximately 4.0 feet
Weight220.0 lbs
MobilityMoved on two legs
First Discovery1999 by Lawrence Walker
First Described by2005 by James Kirkland, Scott Sampson, Donald DeBlieux, David Smith and Kent Sander
HolotypeUMNH VP 15000
Location of first findUtah, USA

Falcarius Origins, Taxonomy and Timeline

Falcarius, a name that conjures images of sharp tools and ancient predators, is indeed a fascinating creature. Its etymology, rooted in the Latin language, means “sickle-maker”. This dinosaur belongs to the Theropoda, specifically within the Therizinosauroidea. Its type species, Falcarius utahensis, pays homage to its discovery location.

Artistic restoration of Falcarius, a feathered dinosaur from the Early Cretaceous period. The illustration depicts the dinosaur in a side profile, showing its long, feathered body, tail, and limbs, with a bird-like head.

Taxonomically, Falcarius places in the Coelurosauria and as an early diverging Therizinosauroidea. It shares a common ancestor with the Oviraptorosauria (such as Avimimus, Caudipteryx and Oviraptor). On a larger scale, as a member of the Theropoda, it shares a common ancestor with some of the most formidable predators, yet it carves out its own identity as a herbivore.

The timeline of Falcarius is set in the Barremian Age of the Early Cretaceous Period, approximately 145 to 139.8 million years ago. This era saw Falcarius in the current North America thrive and leave its mark in the fossil record.

How to Pronunciate Falcarius Utahensis

For those curious about the correct pronunciation of this ancient creature.

Discovery & Fossil Evidence

The story of Falcarius unfurled in 1999 when commercial fossil collector Lawrence Walker made a groundbreaking discovery at the Crystal Geyser Quarry site in Grand County. This initial find, seemingly unassuming, was the gateway to one of the most extraordinary paleontological revelations in recent history. Paleontologist James Kirkland, alerted to the find, spearheaded an excavation with a team from the Utah Geological Survey starting in 2001. Their efforts unveiled a two-acre area within Utah’s Cedar Mountain Formation (Yellow Cat member), rich with Falcarius remains dating back to the Barremian, Early Cretaceous.

The excavation sites, particularly the extensive bone beds, were nothing short of remarkable. They contained the remains of thousands of individual Falcarius specimens. By 2006, the minimum number of individual animals was estimated at three hundred, but this was just the tip of the iceberg. As of 2005, over two thousand specimens had been excavated, predominantly consisting of disarticulated bones, including those of juvenile animals, offering a comprehensive glimpse into the life cycle of Falcarius.

In 2008, a second site, the Suarez Quarry, was reported. This site mainly contained adult individuals but hinted at a slightly different type of Falcarius. The discoveries continued to mount. By 2010, the number of specimens from the original quarry had surged to over 2,700, and later that year, it was reported to have risen to over three thousand.

Among these thousands of specimens, UMNH VP 15000 stands out as the type specimen, playing a crucial role in defining the species. The sheer volume and quality of the specimens found in these bone beds are astounding. Each bone, each fragment, adds a piece to the puzzle, helping us reconstruct a world that existed over 135 million years ago and providing invaluable insights into the life and times of Falcarius. Particularly, it recorded one of the earliest known transition from carnivory to herbivory in the Therizinosauroidea.

Falcarius Size and Description

Falcarius, with its distinctive body shape, offers a glimpse into the adaptability of prehistoric life. The skull of Falcarius was small and elongated, complemented by a long neck that allowed it to reach about 4.9 feet off the ground, likely to munch on leaves or fruit. Its teeth, numbering at least sixteen in the upper jaw (remains of the upper jaw are incomplete) and twenty-eight in the lower jaw, were small, leaf-shaped, and finely serrated, indicating a diet of plant material. Falcarius might have possessed a keratinized beak.

Scale diagram comparing the size of Falcarius utahensis to a human. The silhouette of Falcarius utahensis is shown in blue, standing next to a human figure, indicating the dinosaur's length of approximately 3 meters.
Slate Weasel, Public domain, via Wikimedia Commons

The neck of Falcarius was notably long, featuring elongated cervical vertebrae. Its tail, too, was relatively long. The arms were moderately long with a somewhat robust humerus. The hand, while long, was not particularly robust, featuring an elongated metacarpus, though the first metacarpal was short. The first finger diverged from the second, the longest in the hand, while the third finger was very thin. The hand claws of Falcarius were moderately curved, rather pointed, and moderately long, measuring 4.0 to 5.0 inches. These claws, slightly recurved and pointed, were likely used in self-defense.

Size and Weight of Type Species

Falcarius, a dinosaur known from multiple specimens at different stages of growth, showcases a remarkable range in size. The smallest specimens measured less than 3.5 feet, indicating a significant size variation within the species. Average adults of Falcarius reached lengths of about 13.0 to 16.0 feet, weighing approximately 220.0 pounds. This size suggests a moderately-sized dinosaur, neither the largest nor the smallest of their era. Their physical features, coupled with their size, indicate a lifestyle adapted to a herbivorous diet and possibly a degree of agility in navigating their environment.

Contemporary Dinosaurs

In the ancient, lush landscapes where Falcarius roamed, life was a constant dance of survival, a delicate balance between predator and prey, hunter and hunted. Picture Falcarius, a relatively small theropod, about the size of a modern horse, moving nimbly through the underbrush. Its size made it neither the titan of its realm nor its weakest link. It shared its world with some fascinating contemporaries, each playing a unique role in the tapestry of their prehistoric ecosystem. Among them, Utahraptor and Nedcolbertia where found alongside Falcarius.

Imagine a day in the life of Falcarius, foraging for food amidst the towering presence of Cedarosaurus. This gentle giant, significantly larger than Falcarius, would have been like a moving mountain in comparison, peacefully browsing on high vegetation. While Cedarosaurus posed no direct threat to Falcarius, it’s easy to envision how the smaller dinosaur might have had to navigate around these colossal herbivores, perhaps even competing indirectly for plant resources or navigating through territories delineated by these massive creatures.

Not far from this scene, you might find Venenosaurus, another sizable herbivore, roughly the same size as Cedarosaurus. The presence of Venenosaurus added another layer to Falcarius’ world, possibly creating a dynamic where Falcarius had to be ever-watchful and strategic about its movements and feeding grounds. The competition for resources, though indirect, was a real aspect of Falcarius’ daily life.

Then there was Gastonia, a dinosaur found in the same geological Formation than Falcarius that could have brought a more direct form of interaction. This heavily armored dinosaur, though smaller than Cedarosaurus and Venenosaurus, was still larger than Falcarius. With its protective bony plates and spikes, Gastonia was like a walking fortress. It’s fascinating to imagine the cautious curiosity that might have marked the encounters between Falcarius and Gastonia. While not direct competitors, their coexistence in the same environment would have been a remarkable display of nature’s diversity and the intricate web of relationships that defined their ancient world.

Interesting Points about Falcarius

  • Falcarius’ herbivorous diet is a notable deviation from the typically carnivorous theropod group.
  • Its name, meaning “Sickle Cutter,” suggests unique physical traits that distinguish it from its contemporaries.
  • The discovery of Falcarius in Utah, USA, adds to the rich tapestry of North American dinosaur finds.
  • Falcarius lived during the Valanginian Epoch, a period of significant evolutionary changes.
  • The holotype UMNH VP 15000 plays a crucial role in our understanding of Falcarius’ anatomy and lifestyle.

Falcarius in its Natural Habitat

Imagine the world of Falcarius, a landscape shaped by the climate and geography of the Early Cretaceous. The vegetation, lush and diverse, provided sustenance for this herbivorous creature. Falcarius, with its bipedal locomotion, navigated this terrain, possibly influencing the ecosystem around it.

As a herbivore, Falcarius had a diet that was in harmony with its environment. Its food sources, likely abundant, played a role in its survival and social behavior. Whether Falcarius was a solitary wanderer or a social creature remains a topic of intrigue.

The senses of Falcarius, attuned to its surroundings, would have been crucial for its survival. From detecting predators to finding food, these senses were key to its existence in a dynamic and ever-changing world.

Frequently Asked Questions

What does the name of this dinosaur mean?

The name Falcarius translates to “Sickle-maker,” hinting at its unique physical traits.

When was this dinosaur discovered?

Falcarius was discovered in 1999 by commercial fossil collector Lawrence Walker at the Crystal Geyser Quarry site, Cedar Mountain Formation  in Grand County, Utah.

What type of diet did it have?

Falcarius was a herbivore, feeding on the vegetation of its time.

In which period did it live?

It lived during the Early Cretaceous Period, specifically in the Barremian Age.

What makes this dinosaur unique?

Its herbivorous diet and possible sickle-like claws set Falcarius apart from other Theropods.


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 Falcarius. 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, 11-04-2023; Alienor Duhamel 11-10-2023


Featured Image Credit: PaleoNeolitic, CC BY 4.0, via Wikimedia Commons