[D] Xixianykus zhangi ~/~
Describer
Xu, Wang, Sullivan, Hone, Han, Yan, & Du 2010
Time
Cretaceous Late Coniacian Santonian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Avialae Alvarezsauridae [Parvicursorinae]
Diet
Carnivore
Fossilsite
Majiacun Formation, Zhoujiagou, Yangcheng, Xixia County, Henan Province, China
Info
Abstract
A new alvarezsaurid theropod, Xixianykus zhangi gen. et sp. nov., is described based on a partial postcranial skeleton collected from the Upper Cretaceous Majiacun Formation of Xixia County, Henan Province. The new taxon can be diagnosed by the following autapomorphies: sacral rib-transverse process complexes and zygapophyses fused to form separate anterior and posterior laminae; distinct fossa dorsal to antitrochanter on lateral surface of ilium; short ridge along posterior surface of pubic shaft near proximal end; distinct depression on lateral surface of ischium near proximal end; sharp groove along posterior surface of ischium; distal end of femur with transversely narrow ectocondylar tuber that extends considerable distance proximally as sharp ridge; transversely narrow tibial cnemial crest with sharp, ridgelike distal half; lateral margin of tibiotarsus forms step near distal end; fibula with substantial extension of proximal articular surface onto posterior face of posteriorly curving shaft; distal tarsals and metatarsals co-ossified to form tarsometatarsus; and sharp flange along anteromedial margin of metatarsal IV near proximal end. Cladistic analysis places this taxon as a basal parvicursorine within the Alvarezsauridae, a position consistent with the presence of several incipiently developed parvicursorine features in this taxon and also with its relatively early geological age. A brief analysis of vertebral functional morphology, together with data from the hindlimb, suggests that parvicursorines represent extreme cursors among non-avian dinosaurs.
Holotype
XMDFEC V0011 (Xixia Museum of Dinosaur Fossil Eggs of China), a partial, articulated postcranial skeleton including five posterior dorsal vertebrae, a complete synsacrum, two anterior caudal vertebrae, a few dorsal ribs and gastralia, both ilia, the right pubis and ischium, and most of the right hindlimb. A cast of the holotype is housed at the Institute of Vertebrate Paleontology & Paleoanthropology,Beijing (cast catalog number: IVPP FV1788
Etymology
Generic name from Xixia (area of origin), and onyx (Greek), claw; specific name is in honor of rof. Zhang Wentang, who has contributed greatly to the study of paleontology in Henan Province. The taxon name is pronounced as ‘SHEE-shya-nye-kus jong-eye’.
Type locality and horizon
Zhoujiagou, Yangcheng, Xixia County, Henan Province. Majiacun Formation. The fossil-bearing beds are considered to be late Coniacian to Santonian in age based on invertebrate and plant fossils, including bivalves, gastropods, conchostracans, and ostracods (Wang et al.2008).
Diagnosis
Xixianykus zhangi differs from other known alvarezsaurids in possessing the following autapomorphies: sacral rib-transverse process complexes and zygapophyses fused to form separate anterior and posterior laminae; distinct fossa dorsal to antitrochanter on lateral surface of ilium; short ridge along posterior surface of pubic shaft near proximal end; distinct depression on lateral surface of ischium near proximal end; sharp groove along posterior surface of ischium; distal end of femur with transversely narrow ectocondylar tuber that extends considerable distance proximally as sharp ridge; transversely narrow tibial cnemial crest with sharp, ridge-like distal half; lateral margin of tibiotarsus forms step near distal end; fibula with substantial extension of proximal articular surface onto posterior face of posteriorly curving shaft; distal tarsals and metatarsals co-ossified to form tarsometatarsus; and sharp flange along anteromedial margin of metatarsal IV near proximal end.
Xu, Wang, Sullivan, Hone, Han, Yan, & Du 2010
Time
Cretaceous Late Coniacian Santonian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Avialae Alvarezsauridae [Parvicursorinae]
Diet
Carnivore
Fossilsite
Majiacun Formation, Zhoujiagou, Yangcheng, Xixia County, Henan Province, China
Info
Abstract
A new alvarezsaurid theropod, Xixianykus zhangi gen. et sp. nov., is described based on a partial postcranial skeleton collected from the Upper Cretaceous Majiacun Formation of Xixia County, Henan Province. The new taxon can be diagnosed by the following autapomorphies: sacral rib-transverse process complexes and zygapophyses fused to form separate anterior and posterior laminae; distinct fossa dorsal to antitrochanter on lateral surface of ilium; short ridge along posterior surface of pubic shaft near proximal end; distinct depression on lateral surface of ischium near proximal end; sharp groove along posterior surface of ischium; distal end of femur with transversely narrow ectocondylar tuber that extends considerable distance proximally as sharp ridge; transversely narrow tibial cnemial crest with sharp, ridgelike distal half; lateral margin of tibiotarsus forms step near distal end; fibula with substantial extension of proximal articular surface onto posterior face of posteriorly curving shaft; distal tarsals and metatarsals co-ossified to form tarsometatarsus; and sharp flange along anteromedial margin of metatarsal IV near proximal end. Cladistic analysis places this taxon as a basal parvicursorine within the Alvarezsauridae, a position consistent with the presence of several incipiently developed parvicursorine features in this taxon and also with its relatively early geological age. A brief analysis of vertebral functional morphology, together with data from the hindlimb, suggests that parvicursorines represent extreme cursors among non-avian dinosaurs.
Holotype
XMDFEC V0011 (Xixia Museum of Dinosaur Fossil Eggs of China), a partial, articulated postcranial skeleton including five posterior dorsal vertebrae, a complete synsacrum, two anterior caudal vertebrae, a few dorsal ribs and gastralia, both ilia, the right pubis and ischium, and most of the right hindlimb. A cast of the holotype is housed at the Institute of Vertebrate Paleontology & Paleoanthropology,Beijing (cast catalog number: IVPP FV1788
Etymology
Generic name from Xixia (area of origin), and onyx (Greek), claw; specific name is in honor of rof. Zhang Wentang, who has contributed greatly to the study of paleontology in Henan Province. The taxon name is pronounced as ‘SHEE-shya-nye-kus jong-eye’.
Type locality and horizon
Zhoujiagou, Yangcheng, Xixia County, Henan Province. Majiacun Formation. The fossil-bearing beds are considered to be late Coniacian to Santonian in age based on invertebrate and plant fossils, including bivalves, gastropods, conchostracans, and ostracods (Wang et al.2008).
Diagnosis
Xixianykus zhangi differs from other known alvarezsaurids in possessing the following autapomorphies: sacral rib-transverse process complexes and zygapophyses fused to form separate anterior and posterior laminae; distinct fossa dorsal to antitrochanter on lateral surface of ilium; short ridge along posterior surface of pubic shaft near proximal end; distinct depression on lateral surface of ischium near proximal end; sharp groove along posterior surface of ischium; distal end of femur with transversely narrow ectocondylar tuber that extends considerable distance proximally as sharp ridge; transversely narrow tibial cnemial crest with sharp, ridge-like distal half; lateral margin of tibiotarsus forms step near distal end; fibula with substantial extension of proximal articular surface onto posterior face of posteriorly curving shaft; distal tarsals and metatarsals co-ossified to form tarsometatarsus; and sharp flange along anteromedial margin of metatarsal IV near proximal end.