Therizinosaurs are an unusual group of Therapod Dinosaurs known from the Cretaceous of Asia and North America (with one dubious fossil from the Early Jurassic of China), usually placed within the Maniraptors, which makes them closely related to the early Birds. Unlike most Therapods they had well developed forelimbs with a wide range of movement and strongly curved claws and dentition suited to a vegetarian diet.
In a paper published in the journal PLoS One on 29 August 2012, Phil Senter of the Department of Biological Sciences at Fayetteville State University and James Kirkland and Donald DeBlieux of the Utah Geological Survey describe a new species of Therizinosaur from the Early Cretaceous Cedar Mountain Formation of western Utah.
The new dinosaur is named Martharaptor greenriverensis, or Martha's Raptor from Green River, in honour of Martha Hayden, who co-discovered the site that produced Martharaptor greenriverensis (now named the Hayden-Corbett Site) and has served as the assistant to three successive state paleontologists of Utah over a period of about 25 years (including the current office holder, James Kirkland).
Martha Hayden at the Hayden-Corbett Site. Utah Geological Survey.
The new dinosaur is described on the basis of three partial vertebrae, a radius and partial ulna (lower arm bones) a number of hand bones, the left scapula (shoulder blade), part of the ischium (part of the hip), a bone which might be part of the pubis (also part of the hip), several foot bones and a large amount of fragmentary bone material.
Vertebrae, scapula, forelimb bones, and pelvic bones of Martharaptor greenriverensis. (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. Senter et al. (2012).
Manual bones of Martharaptor greenriverensis. (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. Senter et al. (2012).
Metatarsals of Martharaptor greenriverensis. (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. Senter et al. (2012).
Pedal phalanges of Martharaptor greenriverensis). (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. Senter et al. (2012).
See also New species of Dromaeosaur from the Early Cretaceous of Utah, How did raptors use their claws? (and did it help them learn to fly?), A new Troodontid Dinosaur with an injured toe, The Ashdown Maniraptoran and Dinosaurs on Sciency Thoughts YouTube.
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