Keqin Gao

New Specimens of Microraptor zhaoianus (Theropoda: Dromaeosauridae) from Northeastern China

Abstract New specimens of the diminutive theropod dinosaur Microraptor zhaoianus are described. These specimens preserve significant morphological details that are not present or are poorly preserved in the holotype specimen, including aspects of the manus, pectoral girdle, dorsal vertebrae, ilium, and sacrum. These specimens were coded into a current matrix of theropod morphological characters. Microraptor is found to be the sister taxon to other dromaeosaurs. Dromaeosaurids are monophyletic and together with a monophyletic troodontid group form a monophyletic Deinonychosauria, which is the sister taxon to Avialae. Apparently small size is primitive for Deinonychosauria, which has implications for bird origins.

Exceptional fossil material of a semi-aquatic reptile from China: the resolution of an enigma

The lacustrine deposits of the Yixian Formation, western Liaoning, China, are renowned for producing remarkable vertebrate fossils, including primitive birds (e.g., Hou et al., 1995) and feathered dinosaurs (e.g., Ji et al., 1998). However, the first tetrapod described from these beds was a small reptile, Monjurosuchus Endo, 1940, whose relationships have remained problematic because key features of its morphology have been poorly understood. The discovery of five finely-preserved Monjurosuchus specimens from the Lingyuan area has resolved the mystery; it is a primitive member of the Choristodera, a clade of distinctive but poorly known aquatic reptiles. For more than a century, knowledge of this group was limited to two highly specialized gavial-like genera, Champsosaurus and Simoedosaurus, from the Late Cretaceous/Early Tertiary of North America and Europe (Cope, 1877; Gervais, 1877). Over the last two decades, an additional nine genera have been recognized. Choristoderes had a temporal range spanning at least 190 million years from the Late Triassic to the late Oligocene; a geographical distribution from western North America, across Europe and Asia, to Japan, and from subtropical latitudes to the Arctic (Tarduno et al., 1998). Choristoderes were the only major group of Mesozoic reptiles that survived the K-T transition event and then became extinct. Choristodera are beginning to emerge from the shadows as a group of unexpected phylogenetic and ecological diversity. The newly recovered Monjurosuchus specimens from western Liaoning show unique integumentary structures of this aquatic reptile for the first time. The skin appears to have been rather soft, with the ventral scales smaller than those of the dorsal surface, but there is also a double row of enlarged ovoid and keeled scutes running along the dorsum of the body. The feet are webbed as an adaptation for swimming. In addition, one specimen has preserved intestinal contents. The new specimens thus provide important new information on the soft anatomy and lifestyle of choristoderes.

A new lizard from the Lower Cretaceous of Shandong, China

ABSTRACT A new squamate taxon is described from the Lower Cretaceous Doushan Formation, Qingshan Group, Laiyang, Shandong Province, China. Two incomplete mandibles represent a morphologically peculiar lizard taxon, which has heavily built jaws and highly specialized crushing teeth in a greatly shortened tooth row. Results of phylogenetic analysis show that the new taxon is a member of the Scincomorpha, and can be grouped with the Lacertiformes on the basis of character states related to jaw structures.

New Lizards from the Middle Eocene Mergen Formation, Mongolian Gobi Desert

ZusammenfassungAus der mitteleozänen Mergen-Formation der Gobi/Mongolei werden neue Funde fossiler Echsen beschrieben. Ungefähr 30 isolierte, zahntragende Kiefer sind repräsentativ für mindestens sechs verschiedene Taxa. Darunter befinden sich drei neue Iguania im Sinne nonchamaeleontider Acrodonta, zwei scincomorphe Vertreter mit unsicherer phylogenetischer Stellung und ein Fragment eines recht großwüchsigen Anguimorphen, bei dem es sich um einen Vertreter der Platynota handeln könnte. Diese neuen Echsenfunde tragen zur verbesserten Kenntnis der großen paläogenen Faunenänderung bei, für deren Verständnis besonders die hinzukommenden Daten der fossilen Nonmammalier wichtig sind.AbstractNew lizard fossils are described from the middle Eocene Mergen Formation, eastern Gobi Desert in Mongolia. Some 30 isolated tooth-bearing jaws represent at least six lizard taxa. These include three new iguanians that are nonchamaeleonid acrodontans; two scincomorphs having uncertain relationships within the group; and one large anguimorph that may represent a platynotan taxon. Discovery of these fossil lizards is important for accumulating nonmammalian vertebrate data, in attempting to understand a major faunal change that took place in relation to the drastic uplifting of the Mongolian Plateau in Palaeogene time.