FALCARIUS
an omnivorous therizinosaurian dinosaur from the Early Cretaceous of North America.
Pronunciation: fal-cuh-RYE-us
Meaning: Sickle maker
Author/s: Kirkland
et al. (
2005)
Synonyms: None known
First Discovery: Utah, USA
Discovery Chart Position: #573
Falcarius utahensis
(Utah Sickle Maker)Etymology
The Latin term "Falcarius" means "sickle (or scythe) maker", referring to the huge sickle-like claws that adorn its hands.
The
species epithet,
utahensis, means "from Utah" in Latin.
Discovery
The first fossils of
Falcarius were discovered in 1997 in the Cedar Mountain Formation at Crystal Geyser Quarry, 12 miles southeast of the town of Green River, Utah, USA, by commercial fossil collector Larry Walker of Moab. Under cover of darkness, Walker removed the fossils from public land without the required permit. Although he later led paleontologists to the near impossible-to-find site in a bout of guilty conscience, he was indicted in 2002 for theft of government property and sentenced to five months in prison, along with a $15,000 fine
The
holotype (UMNH VP 15000) is a partial braincase, but
Falcarius is almost completely known thanks to hundreds of individuals that have been excavated since 2001. A second quarry has also yielded many specimens which are significantly larger than those from the first, but palaeontologists are not sure whether these represent fully adult versions of
Falcarius or a new species of therizinosaur.
Estimations
Timeline:
Era: Mesozoic
Epoch: Early Cretaceous
Stage: Barremian
Age range: 130-125 mya
Stats:
Est. max. length: 5 meters
Est. max. hip height: 1.5 meters
Est. max. weight: 120 Kg
Diet: Herbivore
References
• Zanno LE (2004) "The Pectoral Girdle and Forelimb of a Primitive Therizinosauroid (Theropoda, Maniraptora) with Phylogenetic and Functional Implications".
(PhD diss.). Department of Geology and Geophysics, University of Utah.
• Kirkland JI, Zanno LE, Sampson SD, Clark JM and DeBlieux DD (2005)
"
A primitive therizinosauroid dinosaur from the Early Cretaceous of Utah".
Nature, 435: 84–87. DOI: 10.1038/nature03468.
• Zanno LE and Erickson GM (2006) "Ontogeny and life history of
Falcarius utahensis, a primitive therizinosauroid from the Early Cretaceous of Utah".
Journal of Vertebrate Paleontology, 26(sup003): 143. Abstracts of Papers. Society of Vertebrate Paleontology Sixty-Sixth Annual Meeting. Canadian Museum of Nature. October 18-21, 2006. DOI: 10.1080/02724634.2006.10010069.
• Zanno LE (2006) "The pectoral girdle and forelimb of the primitive therizinosauroid
Falcarius Utahensis (Theropoda, Maniraptora): analyzing evolutionary trends within Therizinosauroidea".
Journal of Vertebrate Paleontology, 26(3): 636?650. DOI: 10.1671/0272-4634(2006)26[636:tpgafo]2.0.co;2.
• Long J and Schouten P (2009) "
Feathered Dinosaurs: The Origin of Birds".
• Sampson SD (2009) "
Dinosaur Odyssey: Fossil Threads in the Web of Life".
• Zanno LE (2010) "A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora)".
Journal of Systematic Palaeontology, 8(4): 503–543. DOI: 10.1080/14772019.2010.488045.
• Paul GS (2010) "
The Princeton Field Guide to Dinosaurs".
• Zanno LE (2010) "
Osteology of Falcarius utahensis (Dinosauria: Theropoda): characterizing the anatomy of basal therizinosaurs".
Zoological Journal of the Linnean Society 158(1): 196-230. DOI: 10.1111/j.1096-3642.2009.00464.x.
• Smith DK, Zanno LE, Sanders RK, Deblieux DD and Kirkland JI (2011) "New information on the braincase of the North American therizinosaurian (Theropoda, Maniraptora)
Falcarius utahensis".
Journal of Vertebrate Paleontology, 31(2): 387?404. DOI: 10.1080/02724634.2011.549442.
• Lautenschlager S, Rayfield EJ, Altangerel P, Zanno LE and Witmer LM (2012) "
The Endocranial Anatomy of Therizinosauria and Its Implications for Sensory and Cognitive Function".
PLoS ONE, 7(12): e52289. DOI: 10.1371/journal.pone.0052289
• Smith DK (2014) "
Craniocervical myology and functional morphology of the small-headed therizinosaurian theropods Falcarius utahensis and Nothronychus mckinleyi".
PLoS ONE, 10(2): e0117281. DOI: 10.1371/journal.pone.0117281.
• Paul GS (2016) "
The Princeton Field Guide to Dinosaurs: Second Edition".
• Smith DK (2023) "Hindlimb Musculature of the Lower Cretaceous (Barremian) Therizinosaur
Falcarius utahensis (Maniraptora, Theropoda) with Implications for Evolution, Stance, and Stride".
Cretaceous Research: 105557. DOI: 10.1016/j.cretres.2023.105557.
• Smith DK (2025) "Pectoral Girdle and Forelimb Muscle Reconstruction in the Basal Therizinosaur Falcarius utahensis From Central Utah".
Journal of Morphology, 286(7): e70067.
DOI: 10.1002/jmor.70067.
• Freimuth WJ and Zanno LE (2025) "New craniodental materials of
Falcarius utahensis (Theropoda: Therizinosauria) reveal patterns of intraspecific variation and cranial evolution in early coelurosaurians".
The Anatomical Record.
DOI: 10.1002/ar.70080.
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Atkinson, L.
"
FALCARIUS :: from DinoChecker's dinosaur archive".
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