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new papers in Acta Geologica Sinica: Ningchengopterus,Shidaisaurus, Nyctosaurus and dentary diastemae in
Junchang LÜ. 2009. A Baby Pterodactyloid Pterosaur from the Yixian
Formation of Ningcheng, Inner Mongolia, China. Acta Geologica Sinica,
Volume 83 Issue 1, 1-8.
A new baby pterodactyloid pterosaur with soft tissue preserved,
Ningchengopterus liuae gen. et sp. nov., is erected based on a nearly
complete skeleton with a skull. It was characterized by the skull,
slightly longer than the combined length of the dorsal and sacral
vertebrae; 50 teeth (including upper and lower jaws); short
mid-cervical vertebrae; the humerus and the scapula, equal to that of
the wing metacarpal in length; the ulna and the femur, equal to that
of the first and third wing phalanx in length, respectively. The
similar ratio of the wing phalanx 2 to wing phalanx 1 of
Ningchengopterus and Eosipterus implies that Ningchengopterus may be
close to the ctenochasmatid pterosaur. However, it may also imply that
the isometrically growing of the first two wing phalanges exists among
Xiao-chun WU, Philip J. CURRIE, Zhiming DONG, Shigang PAN, Tao WANG.
A. 2009. New Theropod Dinosaur from the Middle Jurassic of Lufeng,
Yunnan, China. Acta Geologica Sinica, Volume 83 Issue 1, 9-24.
A new theropod dinosaur, Shidaisaurus jinae gen. et sp. nov., has been
described on the basis of an incomplete skeleton. The specimen was
found near the base of the Upper Lufeng Formation (early Middle
Jurassic) in Yunnan, China. It is the first theropod dinosaur from the
Middle Jurassic of Yunnan. Shidaisaurus jinae is distinguishable from
other Jurassic theropods by certain features from the braincase, axis,
and pelvic girdle. The absence of any pleurocoels in the axis or in
any anterior dorsal vertebrae suggests that the new Lufeng theropod is
relatively primitive and more plesiomorphic than most of the Middle to
Late Jurassic theropods from China. Most Chinese taxa of Jurassic
theropod dinosaurs have not been well described; a further detailed
study will be necessary for us to determine their phylogenetic
relationships with Shidaisaurus jinae.
Lida XING, Jianghao WU, Yi LU, Junchang LÜ, Qiang JI. 2009.
Aerodynamic Characteristics of the Crest with Membrane Attachment on
Cretaceous Pterodactyloid Nyctosaurus. Acta Geologica Sinica, Volume
83 Issue 1, 25-32.
The Nyctosaurus specimen KJ1 was reconstructed under the hypothesis
that there is a membrane attached to the crest; the so-called headsail
crest. The aerodynamic forces and moment acting on the headsail crest
were analyzed. It was shown that KJ1 might adjust the angle of the
headsail crest relative to the air current as one way to generate
thrust (one of the aerodynamic forces, used to overcome body drag in
forward flight) and that the magnitude of the thrust and moment could
vary with the gesture angle and the relative location between the
aerodynamic center of the headsail crest and body's center of gravity.
Three scenarios were tested for comparison: the crest with membrane
attachment, the crest without membrane attachment and the absence of a
cranial crest. It was shown that the aerodynamic characteristics
(increasing, maintaining and decreasing thrusts and moment) would have
almost disappear in flight for the crest without membrane attachment
and was non-existent without the cranial crest. It is suggested from
aerodynamics evidence alone that Nyctosaurus specimen KJ1 had a
membrane attached to the crest and used this reconstructed form for
auxiliary flight control.
Katsuhiro KUBOTA, Yoshitsugu KOBAYASHI. 2009. Evolution of Dentary
Diastema in Iguanodontian Dinosaurs. Acta Geologica Sinica, Volume 83
Issue 1, 39-45.
The dentary diastema of iguanodontians has been considered to be
related to its unique jaw mechanism for herbivorous adaptation. The
dentary and diastema lengths of iguanodontians were measured and
compared to elucidate the evolution of iguanodontian diastema. A gap
in ratios between most non-hadrosaurid iguanodontians and hadrosaurids
was observed, suggesting that all non-hadrosaurid iguanodontians,
expect for Ouranosaurus nigeriensis and Protohadros byrdi, lack a
diastema or have a short diastema, although some other taxa have been
considered to have a long diastema in previous studies. In
non-hadrosaurid iguanodontians, some large-sized forms, such as
Iguanodon bernissartensis, Shuangmiaosaurus gilmorei, and possibly
Eolambia caroljonesa, had a short diastema through ontogeny, whereas
Ouranosaurus nigeriensis and Protohadros byrdi developed a long
diastema convergently. The development of a long diastema of
hadrosaurine hadrosaurids may be different from that of lambeosaurine
hadrosaurids. Some hadrosaurunes (Edmontosaurus annectens,
Edmontosaurus regalis, and Saurolophus angustirostris) may have
developed a long diastema in the subadult stage and showed little
elongation of dentary diastema through ontogeny. Lambeosaurines
(Corythosaurus casuarius and Lambeosaurus lambei) tend to have a short
diastema in the embryonic and subadult stages, and an elongated
diastema from the subadult to adult stages.
Jose Ignacio Ruiz-Omeñaca
Museo del Jurásico de Asturias (MUJA)
E-33328 Colunga, Spain