Post by thesporerex on Dec 27, 2014 4:40:32 GMT
Xixianykus zhangi
Scientific classification:
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Theropoda
Superorder: Alvarezsauroidea
Order: Alvarezsauridae
Suborder: Parvicursorinae
Genus: Xixianykus
Species: Xixianykus zhangi
Scientific classification:
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Theropoda
Superorder: Alvarezsauroidea
Order: Alvarezsauridae
Suborder: Parvicursorinae
Genus: Xixianykus
Species: Xixianykus zhangi
Fossil range: Late Cretaceous Santonian-Coniacian, 83 million years ago
Length: ~50 cm long
Weight: (Unpublished)
Height: ~20 cm high
Location: Henan Province, China
Skull length: (Unpublished)
Name meaning: "polar bear lizard"
Description:
Xixianykus was a small animal, about 50 cm long and 20 cm high. It is one of the smallest known dinosaurs (not counting avians). It appears to have many adaptations towards a cursorial (running) lifestyle. It was about 50 centimetres (20 in) long but had 20 centimetres (7.9 in) long legs and a short femur combined with a long tibia and metatarsus, which are good indicators of it being a fast runner. It was probably covered in feathers. It is among the oldest of the derived alvarezsauroids, the parvicursorines, dated to the Santonian-Coniacian as opposed to other parvicursorines, which are either Campanian or Maastrichtian. The fossil, holotype XMDFEC V0011, was found in the Majiacun Formation in Henan Province, China. The fossil consists of a partial skeleton, without the skull. Parts of the hind legs, pelvis and spine has also been recovered.
Naming:
The type species is Xixianykus zhangi described in 2010 by Xu Xing. The genus name refers to Xixia County and to the Greek word for claw ("nyx"). The latter is a common element used in names for Alvarezsaurids. The species name is in honor of Zhang Xinglao; who has contributed greatly to the study of paleontology in Henan Province.
Papers:
1). A basal parvicursorine (Theropoda: Alvarezsauridae) from the Upper Cretaceous of China
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 end; sharp groove along posterior surface of ischium; distal end of femur with transversely narrow ectocondylar tuber end; sharp groove along posterior surface of ischium; 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. 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."
Link: www.davehone.co.uk/wp-content/uploads/2014/01/Xu-et-al.-2010-Xixianykus.pdf
Length: ~50 cm long
Weight: (Unpublished)
Height: ~20 cm high
Location: Henan Province, China
Skull length: (Unpublished)
Name meaning: "polar bear lizard"
Description:
Xixianykus was a small animal, about 50 cm long and 20 cm high. It is one of the smallest known dinosaurs (not counting avians). It appears to have many adaptations towards a cursorial (running) lifestyle. It was about 50 centimetres (20 in) long but had 20 centimetres (7.9 in) long legs and a short femur combined with a long tibia and metatarsus, which are good indicators of it being a fast runner. It was probably covered in feathers. It is among the oldest of the derived alvarezsauroids, the parvicursorines, dated to the Santonian-Coniacian as opposed to other parvicursorines, which are either Campanian or Maastrichtian. The fossil, holotype XMDFEC V0011, was found in the Majiacun Formation in Henan Province, China. The fossil consists of a partial skeleton, without the skull. Parts of the hind legs, pelvis and spine has also been recovered.
Naming:
The type species is Xixianykus zhangi described in 2010 by Xu Xing. The genus name refers to Xixia County and to the Greek word for claw ("nyx"). The latter is a common element used in names for Alvarezsaurids. The species name is in honor of Zhang Xinglao; who has contributed greatly to the study of paleontology in Henan Province.
Papers:
1). A basal parvicursorine (Theropoda: Alvarezsauridae) from the Upper Cretaceous of China
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 end; sharp groove along posterior surface of ischium; distal end of femur with transversely narrow ectocondylar tuber end; sharp groove along posterior surface of ischium; 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. 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."
Link: www.davehone.co.uk/wp-content/uploads/2014/01/Xu-et-al.-2010-Xixianykus.pdf