鹦鹉嘴龙的研究进展及CT应用

鹦鹉嘴龙作为亚洲东部地区早白垩世时期中所特有的原始角龙类群,对研究角龙类的起源和演化有着重要意义。近年来在辽宁西部地区发现大量鹦鹉嘴龙化石,大大推进了该类恐龙的骨骼解剖学和古生物学研究。结合最新研究进展,对鹦鹉嘴龙科内的属种分异度进行了剖析,并对该科的地史地理分布特征和演化历史进行了讨论。此外,本项研究应用医学CT扫描和计算机辅助三维图像重建技术,对辽西新发现的一件完整的鹦鹉嘴龙头骨进行了CT扫描和三维图像的复原。这一手段的应用揭示了该头骨腭面的形态结构,为鹦鹉嘴龙类的解剖和生物学研究提供了新的特征信息。     

Discovery of a pterodactylid pterosaur from the Yixian Formation of western Liaoning, China

A well-preserved pterosaur with nearly complete skull is described from the Lower Cretaceous Yixian Formation at Sihetun in western Liaoning. It is characterized by a low and long crestless skull, slender and pointed teeth, long metacarpal, nearly equal length of metatarsals I–III and short pedal digit V. It is referred to a new genus and species of the family Pterodactylidae:Haopterus gracilis gen. et sp. nov. This is the first pterosaur with a nearly complete skull from the Jehol Biota; it also represents the first non-controversial fossil record of Pterodactylidae in Asia.Haopterus is more derived thanPterodactylus from the Late Jurassic Solnhofen in Germany. This discovery extends the distribution of the family Pterodactylidae from Europe and Africa to Asia and its latest occurrence from the Late Jurassic to the Early Cretaceous. The discovery ofHaopterus gracilis provides further evidence for the study of the origin and radiation of the Jehol Biota; it also sheds new light on the evolution and distribution of pterosaurs in the late Mesozoic.     

Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids

Tyrannosauroids are one of the last and the most successful large-bodied predatory dinosaur groups, but their early history remains poorly understood. Here we report a new basal tyrannosauroid from the Early Cretaceous Yixian Formation of western Liaoning, China, which is small and gracile and has relatively long arms with three-fingered hands. The new taxon is the earliest known unquestionable tyrannosauroid found so far. It shows a mosaic of characters, including a derived cranial structure resembling that of derived tyrannosauroids and a primitive postcranial skeleton similar to basal coelurosaurians. One of the specimens also preserves a filamentous integumentary covering similar to that of other coelurosaurian theropods from western Liaoning. This provides the first direct fossil evidence that tyrannosauroids had protofeathers.     

Occurrence of Sciadopitys-like fossil wood （Coniferales） in the Jurassic of western Liaoning and its evolutionary implications

The genus Sciadopitys, containing a single species (S. verticillata), is the only extant representative of the Family Sciadopityaceae (Coniferales), and is a remarkable living fossil. Although some leafy fossils have been ascribed to Sciadopityaceae, fossil xylem material with a close affinity to this family is very rare, and there have been no fossils found showing both pith and primary xylem structures, which are of great importance for wood identification. Thus, it has been difficult to use fossils for the understanding of wood anatomy evolution in the sciadopityaceous plants over geological time. In this note we briefly report on Sciadopitys-like fossil wood found in the Middle Jurassic of western Liaoning, which bears well-preserved Protosciadopityoxylon-type secondary xylem, endarch primary xylem and heterogeneous pith. This is the first report of fossil specimens of the Sciadopityaceae with such detailed preservation of wood structures. The discovery provides precise anatomical evidence for reconstructing the evolu- tionary history and geographical distribution of Sciadopityaceae, as well as contributing to understanding of the fossil diversity of the Jurassic Yanliao Flora in northern China.     

The most primitive osteichthyan braincase?

Most living vertebrates, from teleosts to tetrapods, are osteichthyans (bony fishes), but the origin of this major group is poorly understood. The actinopterygians (ray-finned bony fishes) are the most successful living vertebrates in terms of diversity. They appear in the fossil record in the Late Silurian but are poorly known before the Late Devonian. Here we report the discovery of the oldest and most primitive actinopterygian-like osteichthyan braincase known, from 400-million-year-old limestone in southeastern Australia. This specimen displays previously unknown primitive conditions, in particular, an opening for a cartilaginous eyestalk. It provides an important and unique counterpart to the similarly aged and recently described Psarolepis from China and Vietnam. The contrasting features of these specimens, and the unusual anatomy of the new specimen in particular, provide new insights into anatomical conditions close to the evolutionary radiation of all modern osteichthyan groups.     

New fossil elaterids （Insect： Coleoptera： Polyphaga： Elateridae） from the Middle Jurassic of Inner Mongolia, China

A new genus with a new species of fossil elaterid, Paraprotagrypnus superbus gen. et sp. nov., from the Middle Jurassic Jiulongshan Formation in Daohugou Village (N41°18.979′, E119°14.318′), Shantou Township, Ningcheng County, Inner Mongolia, China is described and illustrated. The genus Paraprotagrypnus belongs to the family of Elateridae, subfamily of Protagrypninae and tribe of Protagrypnini. Some primitive characters of the new genus and new species shed light on the ages between the Jiulongshan Formation in Inner Mongolia and the Yixian Formation in the western Liaoning Province of China. The habitat of the new species is briefly discussed.     

First discovery of fossil Diplothrix (Muridae, Rodentia) outside the Ryukyu Islands, Japan

The first Diplothrix (Muridae, Rodentia) fossils of the early Early Pleistocene are described as D. yangziensis sp. nov., which were collected from the Renzidong Cave deposits in Anhui Province, Eastern China. Diplothrix was previously represented by a single species, D. legata, whose geographical distribution during the Late Pleistocene is restricted to the Ryukyu Islands, Japan. With straight chevrons on M1, distinct t3 and t9 on upper molars, primitive M3, mlc on m1, and developed a-lab on m2 and m3, the new species is morphologically distinct from other large murids in East Asia, and should belong to the genus Diplothrix. There are also differences in molar morphology between the new species and D. legata, the type species of Diplothrix, as well as other known fossils. For example, D. yangziensis sp. nov. has a smaller size, a more elongated crown, developed precingulum and pc on M1, more primitive M3, weaker mlc and more primitive pc on m1, and stronger plc and pc on m3. In short, Diplothrix yangziensis sp. nov. is evidently more primitive than D. legata, suggesting that the former is likely the ancestor of the latter. Diplothrix yangziensis sp. nov. is the first discovery of the genus outside the Ryukyu Islands, Japan and is also the earliest and most primitive species of the genus in Eurasia. Its discovery has significant implications for reconstructing the evolution and dispersal pattern of Diplothrix, as well as for discussing its palaeoecological variation.     

New frog family from India reveals an ancient biogeographical link with the Seychelles

About 96% of the more than 4,800 living anuran species belong to the Neobatrachia or advanced frogs. Because of the extremely poor representation of these animals in the Mesozoic fossil record, hypotheses on their early evolution have to rely largely on extant taxa. Here we report the discovery of a burrowing frog from India that is noticeably distinct from known taxa in all anuran families. Phylogenetic analyses of 2.8 kilobases of mitochondrial and nuclear DNA unambiguously designate this frog as the sister taxon of Sooglossidae, a family exclusively occurring on two granitic islands of the Seychelles archipelago. Furthermore, molecular clock analyses uncover the branch leading to both taxa as an ancient split in the crown-group Neobatrachia. Our discovery discloses a lineage that may have been more diverse on Indo-Madagascar in the Cretaceous period, but now only comprises four species on the Seychelles and a sole survivor in India. Because of its very distinct morphology and an inferred origin that is earlier than several neobatrachian families, we recognize this frog as a new family.     

Paleornithology of China: A general review

Study of fossil birds in China was first conducted by western scholars in last century, and extensive study of Cenozoic birds by Chinese scholars since the 1970s. However, it is the finding of Mesozoic birds, mostly from northeast China since the 1990s, that has become the focus and highlight of paleornithology of China. Enantiornithine birds from the Late Jurassic-Early Cretaceous of China provide the most complete record of the early evolution of this extinct group. The co-existence of the most primitive ornithurine bird Liaoningornis with the oldest known Confuciusornis indicates an earlier and more significant diversification of birds than previously recognized. Evidence from the Chinese Mesozoic birds seems to support the arboreal hypothesis of the origin of avian flight. Despite the controversy, the recent discovery of various feathered dinosaurs in China may provide the most compelling evidence for the hypothesis of the dinosaurian origin of birds.     

Two new ornithurine birds from the Early Cretaceous of western Liaoning, China

We describe two new ornithurine birds from the Early Cretaceous Jiufotang Formation of western Liaoning, northeast China: Yanornis martini gen. et sp. nov. and Yixianornis grabaui gen. et sp. nov. They represent the best fossil record of ornithurine birds known from the Early Cretaceous. They are more advanced than the most primitive ornithurine Liaoningornis, and are more similar to the other two Chinese Early Cretaceous ornithurines Chaoyangia and Songlingornis. Compared with Confuciusornis, Liaoxiornis and Eoenantiornis from the same age, the two new birds show remarkable advanced characteristics and suggest the presence of powerful flight capability like modern birds. Compared with Yixianornis and Chaoyangia, Yanornis is larger, with a more elongated skull and relatively long wings. The new discoveries indicate that by the Early Cretaceous both enantiornithine and ornithurine birds had already radiated significantly. The flight structures of Yanornis and Yixianornis are hardly distinguishable from those of modern birds; however, both retain a few primitive traits such as teeth on the jaws, wing claws and pubic symphysis, which exclude them from being the most recent ancestor of all extant birds.     

Primitive deuterostomes from the Chengjiang Lagerst?tte (Lower Cambrian, China).

Cambrian fossil-Lagerst?tten (sites of exceptional fossil preservation), such as those from Chengjiang (Lower Cambrian) and the Burgess Shale (Middle Cambrian), provide our best window into the Cambrian 'explosion'. Such faunas are known from about 40 localities, and have yielded a widely disparate series of taxa ranging from ctenophores to agnathan fish. Recent excavations of the Chengjiang fossil-Lagerst?tte, known from a series of sites near Kunming in Yunnan, south China, have resulted in the discovery of several new forms. In conjunction with material described earlier, these provide evidence for a new group of metazoans, the vetulicolians. Several features, notably a series of gill slits, suggest that this group can throw light on an early stage of deuterostome diversification.     

First discovery of Promimomys （Arvicolidae） in East Asia

Promimomys asiaticus sp. nov., the first known species of the genus in East Asia, is described. The material was collected from the early Pliocene cave deposit in Dajushah Hill, Huainan, Anhui Province. Promimomys was first found in Europe and considered as the ancestor of the family Arvicolidae. The new species from China is distinct from the type species, P. cor, and other known species in its thicker enamel of uniform thickness, simple anterior loop of ml, and blunt, salient angles. It is more primitive than other known species in Europe and North America and also more primitive than Mimomys bilikeensis of early Pliocene of Inner Mongolia. It is thus the earliest and the most primitive arvicolid rodent known. The discovery of Promimomys asiaticus sp. nov. is significant to the study on the origin and the phylogeny of arvicolids, and to the discussion of the intercontinental dispersal events of arvicolids.     

On the horizon of Protopteryx and the early vertebrate fossil assemblages of the Jehol Biota

Protopteryx, a monotypic fossil bird discovered from the Sichakou basin in Fengning, Hebei, is the most primitive enantiornithine currently known. The bird-bearing strata do not contain the index fossils of the Yixian Formation in western Liaoning; the fish and bird fossils have more primitive features than the related forms found in the Yixian Formation, and the conchostracans are those usually distributed in the Dabeigou and Dadianzi formations in northern Hebei. Besides, the Protopteryx-bearing strata underlie the deposits bearing the index fossils of the Yixian Formation in the neighboring basin. Thus, it could be confirmed that the horizon of Protopteryx should be lower than the Yixian Formation, and is approximately equivalent to the Dadianzi Formation in northern Hebei. This is the lowest horizon of the known fossil birds in China and Mesozoic enantiornithine birds in the world. Accompanying Protop- teryx, there are other birds, acipenseriform fishes, salamanders, and mammals, which compose the Peipiaosteus fengningensis-Protopteryx fengningensis assemblage. This new assemblage traces the vertebrate evolution history of the Jehol Biota back to 130.7 Ma before. It is suggested that the de- marcation of the Jehol Biota should be based on the large-scale tectonic-sedimentary cycles, and Peipiaosteus, instead of Lycoptera, could be taken as the vertebrate representative of the Jehol Biota.     

东北鸟类分布新记录-高山兀鹫

2002年6月，在辽宁省朝阳地区发现了3只高山兀鹫，这是首次在我国东北地区发现高山兀鹫，为东北鸟类分布的新记录种．     

A Cretaceous terrestrial snake with robust hindlimbs and a sacrum

It has commonly been thought that snakes underwent progressive loss of their limbs by gradual diminution of their use. However, recent developmental and palaeontological discoveries suggest a more complex scenario of limb reduction, still poorly documented in the fossil record. Here we report a fossil snake with a sacrum supporting a pelvic girdle and robust, functional legs outside the ribcage. The new fossil, from the Upper Cretaceous period of Patagonia, fills an important gap in the evolutionary progression towards limblessness because other known fossil snakes with developed hindlimbs, the marine Haasiophis, Pachyrhachis and Eupodophis, lack a sacral region. Phylogenetic analysis shows that the new fossil is the most primitive (basal) snake known and that all other limbed fossil snakes are closer to the more advanced macrostomatan snakes, a group including boas, pythons and colubroids. The new fossil retains several features associated with a subterranean or surface dwelling life that are also present in primitive extant snake lineages, supporting the hypothesis of a terrestrial rather than marine origin of snakes.     

A new iguanodontid (Jinzhousaurus yangi gen. et sp. nov.) from the Yixian Formation of western Liaoning, China

A new iguanodontid,Jinzhousaurus yangi gen. et sp. nov., is erected based on the cranial and dental morphology of a specimen from the Yixian Formation of western Liaoning. Although a few primitive characteristics remain,Jinzhousaurus yangi display a number of characteristics similar to those seen in derived iguanodontids. Other interesting characteristics include the absence of antorbital fenestra and the frontal excluded from the participation in orbit, which are closer to the condition in hadrosaurids. The unusual combination of the characteristics provides important data for assessing morphological evolution toward hadrosaurs. The new discovery also represents the first reported large-sized dinosaur from Jehol fauna in western Liaoning, and increases the diversity of this famous fauna. Furthermore, the discovery of a derived iguanodontid from the Yixian Formation provides further evidence supporting a Cretaceous age of the Jehol fauna, which is consistent with an isotopic age.     

A euprimate skull from the early Eocene of China

The debut of undoubted euprimates (primates of modern aspect) was in the early Eocene, about 55 Myr ago. Since their first appearance, the earliest euprimates can be distinguished as Cantius, Donrussellia and Teilhardina. Nonetheless, the earliest euprimates are primarily known from isolated teeth or fragmentary jaws. Here we describe a partially preserved euprimate skull with nearly complete upper and lower dentition, which represents a new species of Teilhardina and constitutes the first discovery of the genus in Asia. The new species is from the upper section of Lingcha Formation, Hunan Province, China, with an estimated age of 54.97 Myr ago. Morphology and phylogeny analyses reveal that the new species is the most primitive species of Teilhardina, positioned near the root of euprimate radiation. This discovery of the earliest euprimate skull known to date casts new light on the debate concerning the adaptive origin of euprimates, and suggests that the last common ancestor of euprimates was probably a small, diurnal, visually oriented predator.     

A new family of primitive mammal from the Mesozoic of western Liaoning, China

A fairly well-preserved specimen of a new primitive mammal, Repenomamus robustus gen. et sp. nov., has been described from the Yixian Formation (Lower Cretaceous), western Liaoning, China. This animal has several derived characteristics, such as well-developed den-tary/squamosal articulation, reduced number of tooth, differentiation of premolars and molars in postcanine teeth, presence of a dorsal process of the premaxilla that is not in contact with the nasal, closed medial wall of the orbit, and presence of fingerlike promontorium on the petrosal. It also retains some primitive reptile-like features. It is the most primitive taxon among the three mammals known from the Jehol Biota, and also represents the largest mammal of Mesozoic age over the world.     

A new species of Gobiconodon （Triconodonta, Mammalia） and its implication for the age of Jehol Biota

A new species of Gobiconodon is found from the Yixian Formation of western Liaonlng, China. The new taxa,G zofiae sp. nov., has a confluent opening for branches Ⅱand Ⅲ of the trigeminal nerve on the anterior lamina of the petrosal. G zofiae sp. nov. is similar to Repenomamus in having an ossified Meckel‘s cartilage connecting the lower jaws and ear region. The new species, with enlarged I^1/I1, posteriorly located infraorbital foramen and four mental foramina,distinctly differs from the other species of Gobiconodon. The new material indicates that Gobiconodon has four, not five,upper molariforms. The presence of Gobiconodon in Jchol Biota makes it possible to correlate Jehol Biota with faunas in eastern Asia and North America, and suggests the age of the Yixian Formation to be Early Cretaceous.