[D] Falcarius utahensis [Su] [sG] [T]
Describer
Kirkland, Zanno, Sampson, Clark, DeBlieux, 2005
Time
Cretaceous Early Barremian Aptian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Therizinosauroidea Therizinosauridae
Diet
Omnivore
Fossilsite
Cedar Mountain Formation, Crystal Geyser Quarry, basal Yellow Cat Member, Utah, US.
Length
4 meter
Info
Genus - Typespecies - Skull
Etymology
From Falcarius (Latin, a sickle-maker) and utahensis (refers to Utah as its place of origin)
90% of the skeleton is represented (but disarticulated). Falcarius is a gracile, small- to medium-sized theropod, approximately 1 m in height at hips. The dentary is downturned snout and lacks a lateral shelf. The hands are long and gracile (as in Beipiaosaurus inexpectus and most oviraptorosaurs. The wrist is very interesting: \\\\\\\"Distal carpals are preserved in two morphs: one fused into a semilunate that caps metacarpals I and II, and the other as unfused pairs of distal carpals as in other therizinosauroids.\\\\\\\" The pelvis is not opisthopubic, with the pubis restored in a subvertical orientation.
The anatomy of Falcarius indicates that the teeth (small, leaf-like) and pelvis were among the first things to change in the transition from carnivory to herbivory in therizinosauroid evolution. Nevertheless, \\\\\\\"similarities between the dentition of the basal therizinosaur Falcarius and the basal oviraptorosaur Incisivosaurus gautheri, raises the possibility that the common ancestor of the Oviraptorosauria and Therizinosauroidea had already undertaken the initial steps in this transition.\\\\\\\"
The skull material is underrepresented and includes a left maxilla, right postorbital, paired frontals, two braincases, isolated juvenile basiocciput, left and right quadrates, one left and two right dentaries, and a right splenial. The vertebral column is well represented with the exception of the axis. Anterior cervical centra are amphicoelous, elongate (length four times height) and highly pneumatized, with multiple, small pneumatic foramina. The pelvis is primitive in that the ilium is relatively elongate anteroposteriorly, with a parasagittal dorsal margin lateral to the sacral transverse processes the pubis has not rotated to an opisthopubic condition, and the obturator process does not contact the pubis. The pubic peduncle is also primitive, being wide and dorsoventrally shallow.
Holotype
Utah Museum of Natural History; UMNH VP 15000 partial braincase. Referred specimens (paratypes). Utah Museum of Natural History; UMNH VP 12279-12443, 14524-14999, 15001-15149.
Zanno, L. & Erickson, G. (2006) Ontogeny and life history of Falcarius utahensis, a primitive Therizinosauroid from the Early Cretaceous of Utah. JVP 26(3) Abstracts pp. 143
The type locality of the recently named basal therizinosaur Falcarius utahensis is known as the Crystal Geyser Quarry (CGQ)—a dense, paucispecific bonebed within the Cedar Mountain Formation that is notable for being the largest known maniraptoran mass death assemblage. Over 2000 elements have been recovered from the CGQ, representing individuals of a minimum of five growth stages. Recent excavations at the site have generated novel elements from the smallest known size class (estimated to belong to a minimum of one individual of approximately 0.5 m in length) as well as previously unknown elements from individuals of intermediate growth stages (i. e. smaller than 4 m in length).
Recovered juvenile specimens include dorsal, sacral, and caudal vertebrae, an ischium, pubis, femur, fibula, astragalus, proximal scapula, proximal humerus, metacarpals, and multiple phalanges. Thus far less than five percent of the CGQ has been excavated and only a small amount of the bones removed from this area have been prepared. The MNI based on femora is eight, therefore extrapolation of this value suggests an MNI for the quarry of approximately 300.
Falcarius bones from the CGQ are excellently preserved, displaying well-developed LAGS. From the femoral and fibular ontogenetic series thus far recovered, we are generating the first detailed histological analysis for this clade. This study aims to: 1) characterize the microstructure of major long bones for use in phylogenetic analyses; 2) construct a growth curve for comparison with other non-avian dinosaur taxa; and 3) identify possible physiological and/or metabolic changes correlated with modification of the therizinosaur diet. Initial results are promising, offering a nearly complete LHC from hatchling to adult.
Kirkland, Zanno, Sampson, Clark, DeBlieux, 2005
Time
Cretaceous Early Barremian Aptian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Therizinosauroidea Therizinosauridae
Diet
Omnivore
Fossilsite
Cedar Mountain Formation, Crystal Geyser Quarry, basal Yellow Cat Member, Utah, US.
Length
4 meter
Info
Genus - Typespecies - Skull
Etymology
From Falcarius (Latin, a sickle-maker) and utahensis (refers to Utah as its place of origin)
90% of the skeleton is represented (but disarticulated). Falcarius is a gracile, small- to medium-sized theropod, approximately 1 m in height at hips. The dentary is downturned snout and lacks a lateral shelf. The hands are long and gracile (as in Beipiaosaurus inexpectus and most oviraptorosaurs. The wrist is very interesting: \\\\\\\"Distal carpals are preserved in two morphs: one fused into a semilunate that caps metacarpals I and II, and the other as unfused pairs of distal carpals as in other therizinosauroids.\\\\\\\" The pelvis is not opisthopubic, with the pubis restored in a subvertical orientation.
The anatomy of Falcarius indicates that the teeth (small, leaf-like) and pelvis were among the first things to change in the transition from carnivory to herbivory in therizinosauroid evolution. Nevertheless, \\\\\\\"similarities between the dentition of the basal therizinosaur Falcarius and the basal oviraptorosaur Incisivosaurus gautheri, raises the possibility that the common ancestor of the Oviraptorosauria and Therizinosauroidea had already undertaken the initial steps in this transition.\\\\\\\"
The skull material is underrepresented and includes a left maxilla, right postorbital, paired frontals, two braincases, isolated juvenile basiocciput, left and right quadrates, one left and two right dentaries, and a right splenial. The vertebral column is well represented with the exception of the axis. Anterior cervical centra are amphicoelous, elongate (length four times height) and highly pneumatized, with multiple, small pneumatic foramina. The pelvis is primitive in that the ilium is relatively elongate anteroposteriorly, with a parasagittal dorsal margin lateral to the sacral transverse processes the pubis has not rotated to an opisthopubic condition, and the obturator process does not contact the pubis. The pubic peduncle is also primitive, being wide and dorsoventrally shallow.
Holotype
Utah Museum of Natural History; UMNH VP 15000 partial braincase. Referred specimens (paratypes). Utah Museum of Natural History; UMNH VP 12279-12443, 14524-14999, 15001-15149.
Zanno, L. & Erickson, G. (2006) Ontogeny and life history of Falcarius utahensis, a primitive Therizinosauroid from the Early Cretaceous of Utah. JVP 26(3) Abstracts pp. 143
The type locality of the recently named basal therizinosaur Falcarius utahensis is known as the Crystal Geyser Quarry (CGQ)—a dense, paucispecific bonebed within the Cedar Mountain Formation that is notable for being the largest known maniraptoran mass death assemblage. Over 2000 elements have been recovered from the CGQ, representing individuals of a minimum of five growth stages. Recent excavations at the site have generated novel elements from the smallest known size class (estimated to belong to a minimum of one individual of approximately 0.5 m in length) as well as previously unknown elements from individuals of intermediate growth stages (i. e. smaller than 4 m in length).
Recovered juvenile specimens include dorsal, sacral, and caudal vertebrae, an ischium, pubis, femur, fibula, astragalus, proximal scapula, proximal humerus, metacarpals, and multiple phalanges. Thus far less than five percent of the CGQ has been excavated and only a small amount of the bones removed from this area have been prepared. The MNI based on femora is eight, therefore extrapolation of this value suggests an MNI for the quarry of approximately 300.
Falcarius bones from the CGQ are excellently preserved, displaying well-developed LAGS. From the femoral and fibular ontogenetic series thus far recovered, we are generating the first detailed histological analysis for this clade. This study aims to: 1) characterize the microstructure of major long bones for use in phylogenetic analyses; 2) construct a growth curve for comparison with other non-avian dinosaur taxa; and 3) identify possible physiological and/or metabolic changes correlated with modification of the therizinosaur diet. Initial results are promising, offering a nearly complete LHC from hatchling to adult.