The authors have declared that no competing interests exist.
Analyzed the data: PS. Contributed reagents/materials/analysis tools: JIK DDD. Wrote the paper: PS. Field work: JIK DDD. Lab work: DDD.
The Yellow Cat Member of the Cedar Mountain Formation (Early Cretaceous, Barremian?) of Utah has yielded a rich dinosaur fauna, including the basal therizinosauroid theropod
Here we describe a fragmentary skeleton of the new theropod and perform a phylogenetic analysis to determine its phylogenetic position. The skeleton includes fragments of vertebrae, a scapula, forelimb and hindlimb bones, and an ischium. It also includes several well-preserved manual unguals. Manual and pedal morphology show that the specimen is distinct from other theropods from the Cedar Mountain Formation and from previously described therizinosauroids. It is here named as the holotype of a new genus and species,
The new specimen adds to the known dinosaurian fauna of the Yellow Cat Member of the Cedar Mountain Formation. If the phylogenetic placement is correct, it also adds to the known diversity of Therizinosauroidea.
The Cedar Mountain Formation (Lower Cretaceous) of Utah, USA, preserves a rich theropod paleofauna. The paleofauna of the Ruby Ranch Member includes a large carnosaur similar to
Here we describe a new theropod specimen from the upper Yellow Cat Member.
The specimen is from the Hayden-Corbett Quarry, Utah state Loc. # Gr.287v, approximately eight miles southeast of the city of Green River, Utah. The specimen is a possible therizinosauroid.
The clade Therizinosauroidea is part of the clade Coelurosauria within the dinosaurian clade Theropoda. Therizinosauroids are known from the Lower and Upper Cretaceous of Asia and North America
One possible therizinosauroid,
We entered data from the new specimen into an updated version (
The electronic version of this document does not represent a published work according to the International Code of Zoological Nomenclature (ICZN), and hence the nomenclatural acts contained in the electronic version are not available under that Code from the electronic edition. Therefore, a separate edition of this document was produced by a method that assures numerous identical and durable copies, and those copies were simultaneously obtainable (from the publication date noted on the first page of this article) for the purpose of providing a public and permanent scientific record, in accordance with Article 8.1 of the Code. The separate print-only edition is available on request from PLoS by sending a request to PLoS ONE, 1160 Battery Street, Suite 100, San Francisco, CA 94111, USA along with a check for $10 (to cover printing and postage) payable to “Public Library of Science”.
In addition, this published work and the nomenclatural acts it contains have been registered in ZooBank, the proposed online registration system for the ICZN. The ZooBank LSIDs (Life Science Identifiers) can be resolved and the associated information viewed through any standard web browser by appending the LSID to the prefix “
Stratigraphic section of the basal Cedar Mountain Formation of eastern Utah, showing that
Systematic hierarchy.
Dinosauria Owen, 1841
Saurischia Seeley, 1887
Theropoda Marsh, 1881
Coelurosauria von Huene, 1914
Therizinosauroidea Maleev, 1954
urn:lsid:zoobank.org:act:9F589210-60D8-4971-95A5-6ACE4D0BA361
urn:lsid:zoobank.org:act:5065191E-53CD-4B48-8C95-8DC7E405F9CB
The holotype specimen is UMNH VP 21400 (Natural History Museum of Utah, Salt Lake City, Utah).
The species name refers to the city of Green River in Emery County, Utah. The genus name honors Martha Hayden, who co-discovered the site and has served as the assistant to three successive state paleontologists of Utah over a period of about 25 years.
(A)–
The Hayden-Corbett Site (Gr287v) is at the top of an approximately 20 cm thick sandstone, interpreted to represent a crevasse splay deposit, in the Yellow Cat Member of the Cedar Mountain Formation approximately 8 miles southeast of Green River, Utah in the immediate vicinity of the Suarez and Crystal Geyser sites, both of which are bone beds yielding abundant specimens of the basal therizinosauroid
Bone | Figure | Dimension | Measurement |
Cervical neural arch | 3A | Total length | 72.70 |
Prezygapophysis: transverse width | 13.76 | ||
Cranial dorsal vertebra | 3B–E | Centrum: length | 62.07 |
Centrum: transverse width | 20.5 | ||
Centrum: height of cranial face | 41.47* | ||
Centrum: height of caudal face | 45.77 | ||
Distal caudal centrum | 3F, G | Length | 32.41* |
Height | 17.6* | ||
Presumed ulna | 3H | Length | 159* |
Diameter | 40.36 | ||
Radius | 3I | Length | 118.11* |
Shaft: diameter at proximalend, in plane of flattened distaltip | 22.39 | ||
Shaft: diameter at proximalend, perpendicular to plane offlattened distal tip | 22.98 | ||
Distal tip: greatest breadth | 56.88 | ||
Distal tip: width perpendicular to greatest breadth | 10.74 | ||
Scapula | 3J, K | Greatest length of proximal fragment | 150.03* |
Shaft: width | 32.01 | ||
Length of distal fragment | 186.3* | ||
Ischium | 3L | Length | 98.65* |
Possible distal pubis | 3M | Greatest length | 104.18* |
Width perpendicular to greatest length | 5019* | ||
Presumed metacarpal I | 4A | Length | 19.15* |
Distal transverse width | 23.3 | ||
Presumed manual phalanx I-1 | 4B | Length | 22.40* |
Proximal height | 18.95 | ||
Proximal transverse width | 19.12 | ||
Penultimate manual phalanx | 4C | Length | 25.4* |
Distal height | 20.1 | ||
Distal transverse width | 18.23 | ||
Penultimate manual phalanx | 4D | Length | 25.48* |
Distal height | 16.23* | ||
Distal transverse width | 15.95 | ||
Manual phalanx | 4E | Length | 18.77* |
Distal height | 18.22 | ||
Distal transverse width | 19.06 | ||
Manual phalanx | 4F | Length | 22.09* |
Distal height | 14.38* | ||
Distal transverse width | 14.96* | ||
Manual ungual (digit I) | 4G | Height of articular facet | 43.07 |
Height of proximal end including flexor tubercle | 43.07 | ||
Length perpendicular to articular facet | 55.09* | ||
Greatest transverse width | 15.93 | ||
Manual ungual (digit I) | 4H | Length approximately perpendicular to articular facet | 33.25* |
Height approximately parallel to articular facet | 28.58* | ||
Manual ungual (digit II) | 4I | Height of articular facet | 28.76 |
Height of proximal end including flexor tubercle | 37.93 | ||
Length perpendicular to articular facet | 44.44* | ||
Greatest transverse width | 16.18 | ||
Manual ungual (digit II) | 4J | Height of articular facet | 29.09 |
Height of proximal end including flexor tubercle | 36.53 | ||
Length of proximal fragment perpendicular to articular facet | 40.04* | ||
Greatest transverse width | 15.90 | ||
Greatest length of distal fragment | 18.25* | ||
Manual ungual (digit III) | 4K | Height of articular facet | 24.55 |
Height of proximal end including flexor tubercle | 36.21 | ||
Length perpendicular to articular facet | 49.95* | ||
Greatest transverse width | 14.03 | ||
Manual ungual (digit III) | 4L | Height of articular facet | 24.92 |
Height of proximal end including flexor tubercle | 35.65 | ||
Length perpendicular to articular facet | 51.05* | ||
Greatest transverse width | 9.56 | ||
Metatarsal I | 5A | Greatest length | 46.41* |
Distal width | 19.09 | ||
Distal depth | 15.03 | ||
Metatarsal II | 5B | Length | 55.42* |
Proximal transverse width | 31.22 | ||
Proximal depth | 30.89 | ||
Metatarsal II | 5D | Length | 37.76* |
Distal transverse width | 30.72 | ||
Distal depth | 38.73 | ||
Presumed metatarsal III | 5C | Length | 23.22* |
Proximal transverse width | 25.22* | ||
Proximal depth | 29.98 | ||
Metatarsal IV | 5E | Length | 50.48* |
Distal transverse width | 29.24* | ||
Distal depth | 28.07* | ||
Pedal phalanx | 6A | Length | 20.62* |
Proximal transverse width | 27.84 | ||
Proximal depth | 24.52 | ||
Pedal phalanx | 6B | Length | 31.14* |
Proximal transverse width | 29.03 | ||
Proximal depth | 23.32 | ||
Pedal phalanx | 6C | Length | 27.20.41* |
Proximal transverse width | 25.17* | ||
Proximal depth | 27.51 | ||
Pedal phalanx | 6D | Length | 41.98* |
Proximal transverse width | 23.98* | ||
Proximal depth | 30.89 | ||
Pedal phalanx | 6E | Length | 32.21* |
Proximal transverse width | 26.15 | ||
Proximal depth | 32.88 | ||
Pedal phalanx | 6F | Length | 46.17* |
Proximal transverse width | 25.43* | ||
Proximal depth | 19.71* | ||
Pedal phalanx | 6G | Length | 30.54* |
Distal transverse width | 25.81 | ||
Distal depth | 20.64 | ||
Pedal phalanx | 6H | Length | 25.15* |
Distal transverse width | 27.37 | ||
Distal depth | 18.71* | ||
Pedal phalanx | 6I | Length | 25.86* |
Proximal transverse width | 28.59 | ||
Proximal depth | 25.09 | ||
Pedal phalanx | 6J | Length | 16.87* |
Proximal transverse width | 23.45 | ||
Proximal depth | 20.51* | ||
Pedal phalanx | 6K | Length | 27.67* |
Distal transverse width | 25.61* | ||
Distal depth | 20.00* | ||
Pedal ungual (digit I) | 6L | Length, approximately perpendicular to articular facet | 29.88* |
Height approximately parallel to articular facet | 26.95* | ||
Pedal ungual | 6M | Height of articular facet | 26.75 |
Height of proximal end including flexor tubercle | 29.01* | ||
Length perpendicular to articular facet | 26.99* | ||
Greatest transverse width | 13.63 |
Measurements are in mm. For cases in which the total measurement cannot be given because part of the bone is missing, the measurement of the preserved portion is given and marked with an asterisk. For pedal bones, “depth” refers to the dorsoplantar dimension.
The bones of the holotype of
(A)–Partial cervical neural arch, dorsal view. (B–E)–Cranial dorsal centrum in cranial (B), caudal (C), right lateral (D), and left lateral (E) views. (F–G)–Distal caudal centrum in lateral (F) and ventral (G) views. (H)–Possible ulna. (I)–Possible radius. (J–K)–Left scapula in lateral (J) and medial (K) views. (L)–Proximal end of ischium. (M)–Possible distal end of pubis Scale bar = 50 mm. acr = acromium process, ar = acetabular rim, gl = glenoid, hyp = hypapophysis, poz = postzygapophysis, pnp = pneumatopore, prz = prezygapophysis.
Theropod dinosaur with the following combination of character states: cervical prezygapophyses not flexed; cranial dorsal vertebrae with hypapophyses and a single pair of pneumatopores; manual unguals without proximodorsal lips and with prominent flexor tubercles and strong curvature; manual unguals in which total length perpendicular to the articular facet is subequal to total height parallel to the articular facet; ungual of manual digit III nearly as large as that of digit II; distal end of scapula expanded; proximal end of ischium laterally compressed; metatarsal I proximally attenuated and distally reduced in transverse width relative to the other metatarsals; all metatarsals distally non-ginglymoid; fourth metatarsal distally attenuated immediately proximal to condyles; pedal unguals laterally compressed and strongly curved; first pedal ungual smaller than the others.
(A)–Presumed metacarpal I. (B)–Presumed phalanx I-1. (C)–Penultimate phalanx. (D) Penultimate phalanx. (E)–Unidentified phalanx. (F)–Unidentified phalanx. (G)–Ungual of digit I. (H)–Ungual of digit I. (I)–Ungual of digit II. (J)–Ungual of digit II. (K)–Ungual of digit III. (L)–Ungual of digit III. Scale bar = 50 mm. Numbers on sub-figures refer to proximal (1), distal (2), dorsal (3), palmar (4), and side (5) views; for side views, whether the side is medial or lateral cannot be determined.
No other theropod dinosaur exhibits this combination of character states. However, because of the fragmentary nature of the specimen, it is important to be specific about how this combination of character states distinguishes the specimen as a new taxon. Therefore, below we show how these character states distinguish the new specimen from other theropods of the Cedar Mountain Formation and from previously described therizinosauroids.
(A)–Left metatarsal I. (B)–Left metatarsal II. (C)–Presumed left metatarsal III. (D)–Right metatarsal II. (E)–Right metatarsal IV. Scale bar = 50 mm. Numbers on sub-figures refer to proximal (1), distal (2), dorsal (3), plantar (4), medial (5), and lateral (6) views.
(A–K)–Unidentified phalanges. (L)–Ungual of digit I. (M)–Ungual of unidentified digit (II, III, or IV). Scale bar = 50 mm. Numbers on sub-figures refer to proximal (1), distal (2), dorsal (3), plantar (4), and side (5) views; for side views, whether the side is medial or lateral cannot be determined. Phalanx H articulates well with phalanx J, and phalanx G articulates well with phalanx I.
In the known material of
Genus names in green are Asian therizinosauroids, and those in red are North American therizinosauroids. Numbers at therizinosauroid clades indicate decay indices (Bremer values).
Other therizinosauroids differ from
Preserved bones of
A partial neural arch from a cervical vertebra preserves the left zygapophyses and the lateral lamina connecting them (
The centrum of one cranial dorsal vertebra is preserved (
The ventral part of another centrum with a nearly flat ventral surface is relatively small, suggesting that it is from the tail (
The distal end of a bone is interpreted as a radius (
The partial shaft of another long bone is interpreted as an ulna (
The distal tip of a manual element, interpreted as metacarpal I from the right hand, is preserved (
The proximal tip of a manual element that may be phalanx I-1 is preserved (
Five nearly complete manual ungual phalanges are preserved, each with its tip broken off (
The left scapula is preserved, with a piece missing from the middle of its shaft (
The proximal end of the ischium is preserved (
The flattened, expanded end of a bone with a shaft is preserved (
The first metatarsal of the left foot is missing its proximal tip (
The preserved proximal end of the left second metatarsal has a nearly square proximal surface (
The proximal end of another metatarsal (
The distal end of the right fourth metatarsal (
Several partial pedal phalanges are preserved (
Only one pedal phalanx preserves its whole length (
Two pedal unguals are present (
In addition to the material described above, the sample includes many bone shards and tiny fragments that are too incomplete to identify.
The phylogenetic analysis found 1444 trees of 1303 steps. For these trees the consistency index is 0.3761, the homoplasy index is 0.6239, the retention index is 0.8136, and the rescaled consistency index is 0.3059. The strict consensus tree places
Synapomorphies of Therizinosauroidea or its sub-clades that are demonstrably present on
(DOC)
(DOC)
Synapomorphies of clades within Therizinosauroidea.
(DOC)
Martha Hayden and Cari Corbett (North Carolina State University) co-discovered the site. The site was collected under BLM paleontological permit # UT-S-04-011. Volunteers from the Utah Friends of Paleontology helped excavate the site together with Lindsay Zanno and Robert Bakker. Lindsay Zanno and two anonymous reviewers provided input that improved this manuscript.