Cervical and anterior dorsal vertebrae of <i>Jianchangosaurus yixianensis</i> gen. et sp. nov.

<p>A, Atlas, axis and cervical vertebrae 3 and 8 in left lateral view. Cervical 8 is repositioned, but others are in the original position. B, Cervical vertebrae 5 and 6 in right lateral view and cervical vertebra 9 in left lateral view. Cervical 5 and 6 are articulated and repositioned on the opposite side. Cervical 9 is also repositioned. C, Cervical vertebra 10 and dorsal vertebrae 1–3. All are in the original position. See caption of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0063423#pone-0063423-g001" target="_blank">Figure 1</a> for abbreviations. Scale bar is 5 cm for A–C.</p

Feathers of <i>Jianchangosaurus yixianensis</i> gen. et sp. nov.

<p>The distal halves of the feathers are preserved as carbonized impressions, dorsal to the first to fourth dorsal vertebrae. These features are similar to the elongated broad filamentous feathers along the neck of <i>Beipiaosaurus</i>. See caption of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0063423#pone-0063423-g001" target="_blank">Figure 1</a> for abbreviations. Scale bar is 5 cm.</p

A, Reconstruction the skeleton of <i>Jianchangosaurus yixianensis</i> gen. et sp. nov. The hip height is approximately 1 meter.

<p>It is 1880 mm long from the skull to the eleventh caudal vertebra. B, Reconstruction of the skull. The ventral lacrimal, postorbital, posterior jugal, anterior edge of the quadrate, anterior surangular are missing. A rhamphotheca is reconstructed in grey based on edentulous area and a series of foramina. C, Cross section of the right upper and lower jaws, showing dental arrangement and rhamphotheca. Anterior portion (right) may have been used for plucking food by a rhamphotheca in the upper jaw and anterior dentary teeth with the normal dental morphology (convex labial and concave lingual surfaces). Posterior portion (left) shows the opposite dental morphology (concave labial and convex lingual surfaces) in the dentary, which allows the tips of the upper and lower teeth to abut each other. Abbreviations: an, angular; d, dentary; f, frontal; j, jugal; l, lacrimal; lat, lateral; m, maxilla; med, medial; n, nasal; pf, prefrontal; pm, premaxilla; q, quadrate; rham, rhamphotheca; sa, surangular; sq, squamosal.</p

An Unusual Basal Therizinosaur Dinosaur with an Ornithischian Dental Arrangement from Northeastern China

<div><p>Therizinosauria are an unusual group of theropod dinosaurs, found mostly in the Cretaceous deposits in Mongolia, China and western USA. The basal forms of this group are represented by incomplete or disarticulated material. Here, we report a nearly complete, articulated skeleton of a new basal therizinosaur from the Early Cretaceous Yixian Formation of Jianchang County, western part of Liaoning Province, which sheds light on our understanding of anatomy of basal therizinosaurs. This new dinosaur shows some typical therizinosaur features, such as neural spines of the anterior caudal vertebrae that possess anterior and posterior alae, a rectangular buttress on the ventrolateral side of the proximal end of metacarpal I, and appressed metatarsal shafts. Our phylogenetic analysis suggests that it is a basal therizinosaur (sister taxon to Therizinosauroidea) because it bears many basal therizinosaur characters in the dentition, pelvis and hind limbs. The new therizinosaur described here has unique tooth and jaw characters such as the offsetting of the tooth row by a shelf and dentary teeth with labially concave and lingually convex dentary teeth, similar to ornithopods and ceratopsians.</p></div

A photograph of the skeleton of <i>Jianchangosaurus yixianensis</i> gen. et sp. nov. (41HIII-0308A) (A) and line drawing (B).

<p>Abbreviations: at, atlas; ax, axis; cav, caudal vertebra; cv, cervical vertebra; co, coracoid; dc, distal carpal; dv, dorsal vertebra; l., left; f, femur; fi, fibula; fur, furcula; hu, humerus; il, ilium; is, ischium; pu, pubis; ra, radius; sc, scapula; ti, tibia; ul, ulna; mc, metacarpal; mt, metatarsal; mxf, maxillary fenestra; pat, proatlas; r., right; sr, sacral rib; sv, sacral vertebra; ung, ungual. All elements of the skeleton are preserved except the distal half of the caudal vertebrae. Dashed lines of metatarsals indicate areas that have been reconstructed. The middle portion of the neck, from the fourth to ninth cervical vertebrae, and the pedal phalanges have been repositioned. The rest of elements of this specimen are in the original position.</p

Measurements in millimeters of vertebrae of <i>Jianchangosaurus yixianensis</i> gen. et sp. nov.

<p>Measurements in millimeters of vertebrae of <i>Jianchangosaurus yixianensis</i> gen. et sp. nov.</p

Hind limbs of <i>Jianchangosaurus yixianensis</i> gen. et sp. nov.

<p>A, Right (above) and left (bottom) femora in posterior and anterior views, respectively. B, Both tibiae and right fibula. The distal half of the fibula is missing. C, Metatarsals and pedal unguals. The metatarsals are covered in part by thick coatings, and the distal half of most metatarsals may not be real (reconstructed). The specific identification of most phalanges is not possible because most are crushed. Five bones are identified as pedal phalanges and have been labeled. Abbreviations: lt, lesser trochanter; pph, pedal phalanx; see caption of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0063423#pone-0063423-g001" target="_blank">Figure 1</a> for abbreviations. Scale bar is 3 cm for A–C.</p

Pelvis and femora of <i>Jianchangosaurus yixianensis</i> gen. et sp. nov.

<p>A, Left ilium in lateral view. The ilium is low and dorsal edge is nearly horizontal in lateral view. B, Left pubis in lateral view and right femur in posterior view. The fourth sacral centrum is preserved next to the right femur. C, Left ischium in lateral view. A triangular obturator process is positioned at the mid-length of the element. See caption of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0063423#pone-0063423-g001" target="_blank">Figure 1</a> for abbreviations. Scale bar is 5 cm for A–C.</p

Photograph of the skull of <i>Jianchangosaurus yixianensis</i> gen. et sp. nov. (A) and line drawing (B).

<p>The right side of the skull is better exposed than the left side. The braincase and palatal bones are displaced. The seventh cervical vertebra is preserved next to the hyoids. Abbreviations: ect, ectopterygoid; hy, hyoids; mxf, maxillary fenestra; A, a large foramen at the base of the internarial bar of the premaxilla; B, a large foramen within the narial fossa of the premaxilla; C, a maxillary foramen above the eighth maxillary tooth; see captions for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0063423#pone-0063423-g001" target="_blank">figures 1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0063423#pone-0063423-g002" target="_blank">2</a> for other abbreviations. Scale bars are 3 cm.</p

Dorsal vertebrae and cervical vertebra 4 of <i>Jianchangosaurus yixianensis</i> gen. et sp. nov.

<p>All neurocentral sutures are unfused. A, Articulated dorsal vertebrae 2–5 and ribs in left lateral view. B, Cervical vertebra 4 in dorsal view and dorsal vertebra 7 in left lateral view. A partial semilunate carpal can be observed next to dorsal vertebra 7. C, Semi-articulated dorsal vertebrae 8–12, likely displaced post-mortem. Abbreviations: slc, semilunate carpal; see caption of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0063423#pone-0063423-g001" target="_blank">Figure 1</a> for other abbreviations. Scale bar is 5 cm for A–C.</p