[D] Zuolong salleei [sG] [T]
Describer
Choiniere, Clark, Forster & Xu 2010
Time
Jurassic Late Oxfordian
Classification
Saurischia Theropoda Tetanurae Coelurosauria
Diet
Carnivore
Fossilsite
Shishugou Formation, Wucaiwan, Xinjiang, China
Info
Abstract
We describe a new coelurosaurian theropod, Zuolong salleei, gen. et sp. nov., from exposures of the upper part of the Shishugou Formation at the Wucaiwan locality, Xinjiang Autonomous Region, People’s Republic of China. Zuolong has a large, inclined quadrate foramen that extends onto the medial surface of the quadratojugal, an unusually large fovea capitis on the femoral head, and an apomorphically large distal condyle of metatarsal III with a medially projecting flange on the extensor surface.
Radiometric dating of the Shishugou Formation constrains the age of the specimen to the beginning of the Late Jurassic (Oxfordian). A cladistic analysis of Zuolong salleei in a broadly sampled theropod data matrix recovers it as a basal coelurosaur. These data make Zuolong one of the oldest coelurosaur fossils yet known that preserves both cranial and postcranial bones.
Holotype
IVPP V15912, consisting of the following bones: left premaxilla; left maxilla; left quadrate; right and left quadratojugals; left squamosal; right and left ectopterygoids; left pterygoid; left lacrimal; partial frontal; partial parietal; left postorbital; one premaxillary and two maxillary or dentary teeth; five cervical, four dorsal, five sacral, and eight caudal vertebrae; right humerus; left radius and ulna; one complete manual ungual; left ilium; right and left pubes; right and left femora; right tibia; proximal right fibula; right metatarsals II–IV; three pedal phalanges, pedal ungual.
Age and Distribution
Upper part of the Shishugou Formation, Wucaiwan, Xinjiang, People’s Republic of China. Extensive 40Ar/39Ar dating of feldspars from intercalated tuffaceous layers of volcanic tuffs at Wucaiwan constrains the age of the specimen to between 158.7 ± 0.3 and 161.2 ± 0.2 Ma, approximately at the Oxfordian/Callovian boundary (Gradstein et al., 2004; Clark et al., 2006b). Because the holotype is from the upper part of the sediments between these dated tuffs, we consider the age of Zuolong to be Oxfordian.
Etymology
The generic name Zuolong refers to General Zuo Zongtang (also known as General Tso), who conquered portions of Xinjiang during the Qing dynasty, and the Chinese long,meaning dragon. The species epithet salleei is for Hilmar Sallee, whose bequest partially funded excavations at Wucaiwan.
Diagnosis
Differs from all other theropods in possessing: large, slit-like quadrate foramen inclined medially at approximately 45◦ with associated deep fossa on the quadrate; sacral centrum 5 with an obliquely oriented posterior articular surface that is angled anterodorsally; fovea capitis very large, occupying almost the entire posterodorsal surface of the femoral head; distal condyle of metatarsal III large relative to that of other metatarsals and bearing an anteromedially projecting flange on its anteromedial margin.
Differs from the co-occurring species Guanlong wucaii in having a square premaxillary body in lateral view; an external naris oriented at almost 45◦ to the horizontal; a triangular anterior end of the maxilla; an antorbital fossa that does not deeply emarginate the ascending process of the maxilla; a postorbital with frontal and jugal processes at right angles to each other; a short postacetabular wing of the ilium; and absence of a pubic tubercle.
Differs from the basal coelurosaur Tanycolagreus in having a square, rather than rectangular, premaxillary body; a postorbital without an anterior process; a ventrally directed anterior process of the lacrimal; a straight ulna and radius; and a lateral ridge on cnemial crest of tibia.
Differs from the basal coelurosaur Coelurus in having cervical vertebrae that lack paired lateral foramina and are not anteroposteriorly elongate; dorsal centra without a fossa on the lateral surface of the centrum; a straight, rather than sigmoidal, humeral shaft; a high and rounded, rather than low and squared, ilium; and a straight, rather than curved, femoral shaft.
Choiniere, Clark, Forster & Xu 2010
Time
Jurassic Late Oxfordian
Classification
Saurischia Theropoda Tetanurae Coelurosauria
Diet
Carnivore
Fossilsite
Shishugou Formation, Wucaiwan, Xinjiang, China
Info
Abstract
We describe a new coelurosaurian theropod, Zuolong salleei, gen. et sp. nov., from exposures of the upper part of the Shishugou Formation at the Wucaiwan locality, Xinjiang Autonomous Region, People’s Republic of China. Zuolong has a large, inclined quadrate foramen that extends onto the medial surface of the quadratojugal, an unusually large fovea capitis on the femoral head, and an apomorphically large distal condyle of metatarsal III with a medially projecting flange on the extensor surface.
Radiometric dating of the Shishugou Formation constrains the age of the specimen to the beginning of the Late Jurassic (Oxfordian). A cladistic analysis of Zuolong salleei in a broadly sampled theropod data matrix recovers it as a basal coelurosaur. These data make Zuolong one of the oldest coelurosaur fossils yet known that preserves both cranial and postcranial bones.
Holotype
IVPP V15912, consisting of the following bones: left premaxilla; left maxilla; left quadrate; right and left quadratojugals; left squamosal; right and left ectopterygoids; left pterygoid; left lacrimal; partial frontal; partial parietal; left postorbital; one premaxillary and two maxillary or dentary teeth; five cervical, four dorsal, five sacral, and eight caudal vertebrae; right humerus; left radius and ulna; one complete manual ungual; left ilium; right and left pubes; right and left femora; right tibia; proximal right fibula; right metatarsals II–IV; three pedal phalanges, pedal ungual.
Age and Distribution
Upper part of the Shishugou Formation, Wucaiwan, Xinjiang, People’s Republic of China. Extensive 40Ar/39Ar dating of feldspars from intercalated tuffaceous layers of volcanic tuffs at Wucaiwan constrains the age of the specimen to between 158.7 ± 0.3 and 161.2 ± 0.2 Ma, approximately at the Oxfordian/Callovian boundary (Gradstein et al., 2004; Clark et al., 2006b). Because the holotype is from the upper part of the sediments between these dated tuffs, we consider the age of Zuolong to be Oxfordian.
Etymology
The generic name Zuolong refers to General Zuo Zongtang (also known as General Tso), who conquered portions of Xinjiang during the Qing dynasty, and the Chinese long,meaning dragon. The species epithet salleei is for Hilmar Sallee, whose bequest partially funded excavations at Wucaiwan.
Diagnosis
Differs from all other theropods in possessing: large, slit-like quadrate foramen inclined medially at approximately 45◦ with associated deep fossa on the quadrate; sacral centrum 5 with an obliquely oriented posterior articular surface that is angled anterodorsally; fovea capitis very large, occupying almost the entire posterodorsal surface of the femoral head; distal condyle of metatarsal III large relative to that of other metatarsals and bearing an anteromedially projecting flange on its anteromedial margin.
Differs from the co-occurring species Guanlong wucaii in having a square premaxillary body in lateral view; an external naris oriented at almost 45◦ to the horizontal; a triangular anterior end of the maxilla; an antorbital fossa that does not deeply emarginate the ascending process of the maxilla; a postorbital with frontal and jugal processes at right angles to each other; a short postacetabular wing of the ilium; and absence of a pubic tubercle.
Differs from the basal coelurosaur Tanycolagreus in having a square, rather than rectangular, premaxillary body; a postorbital without an anterior process; a ventrally directed anterior process of the lacrimal; a straight ulna and radius; and a lateral ridge on cnemial crest of tibia.
Differs from the basal coelurosaur Coelurus in having cervical vertebrae that lack paired lateral foramina and are not anteroposteriorly elongate; dorsal centra without a fossa on the lateral surface of the centrum; a straight, rather than sigmoidal, humeral shaft; a high and rounded, rather than low and squared, ilium; and a straight, rather than curved, femoral shaft.