Table of Content

15 March 2012, Volume 50 Issue 1

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A NEW GENUS OF EUGALEASPIDIFORMS (AGNATHA: GALEASPIDA) FROM THE LUDLOW, SILURIAN OF QUJING, YUNNAN,SOUTHWESTERN CHINA

ZHU Min, LIU Yu-Hai. JIA Lian-Tao, GAI Zhi-Kun

2012, 50(1):  1-7. 

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A new genus and species of the Eugaleaspidiformes (Agnatha: Galeaspida), Dunyu longiforus gen. et sp. nov., is described from the Ludlow (Silurian) Kuanti Formation of Qujing, Yunnan, southwestern China, in association with the oldest near-complete gnathostome Guiyu oneiros of the Xiaoxiang Vertebrate Fauna. The new genus is most suggestive of Eugaleaspis of the Eugaleaspidae by the absence of inner corners, in addition to the diagnostic features of the family, such as only 3 pairs of lateral transverse canals from lateral dorsal canals, and the U-shaped trajectory of median dorsal canals. They differ in that the new genus possesses a pair of posteriorly extending corners, the breadth/length ratio of the shield smaller than 1.1, and the posterior end of median dorsal opening beyond the posterior margin of orbits. Eugaleaspis xiushanensis from the Wenlock Huixingshao Formation of Chongqing is re-assigned to Dunyu, based on the new examination of the type specimen which shows a pair of posteriorly extending lobate corners and three (instead of four in the original description) pairs of lateral transverse canals. The new species differs from Dunyu xiushanensis in its large cephalic shield which is longer than broad, spine-shaped corners, anteriorly positioned orbits, the length ratio between preorbital and postorbital portions of the shield less than 0.75, and large polygonal, flat-topping tubercles exceeding 2.0 mm in length.

A NEW BASAL BEAKED ORNITHURINE BIRD FROM THE LOWER CRETACEOUS OF WESTERN LIAONING, CHINA

ZHOU Shuang, ZHOU Zhong-He, Jingmai O’CONNOR

2012, 50(1):  9-24. 

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We report a new species of basal ornithurine bird, Schizooura liigen. et sp. nov., based on a well-preserved specimen from the Lower Cretaceous Jiufotang Formation in Jianchang, western Liaoning, China.Phylogenetic analysis indicates that it is more derived than Jianchangornis andArchaeorhynchus, but more basal than all other known Jehol ornithurines. The new specimen preserves a unique suite of characters that differentiate it from other known taxa, including several features previously unreported in Early Cretaceous ornithurines, including a V-shaped furcula with a short hypocleidium, a rostrocaudally elongate unperforated sternum with deep caudal notches absent, and a deltopectoral crest that extends for half the length of the humerus. The specimen preserves a nearly perfectly articulated skull that indicates the species was beaked and preserves details of the skull anatomy such as the premaxilla-frontal articulation. The most notable feature of this new specimen is the preservation of a feathered tail morphology previously unknown among Mesozoic birds. It is the second tail morphology known among early ornithurines, which have until now only preserved fan-shaped tails. The new specimen preserves a forked tail composed of elongate rectrices medially separated by a deep notch. This tail feather morphology in modern birds decreases aerodynamic efficiency relative to the fan-shaped tail, but increases chance of sexual reproduction. This discovery suggests that this tradeoff convergently evolved in basal members of Ornithurae, and is consistent with the wooded environment inferred for the Jehol. 

A REVISED LOOK AT LIAONINGORNIS LONGIDIGITRUS (AVES)

Yixian Formation, Enantiornithes, Ornithurae,Ornithuromorpha, Liaoningornis

2012, 50(1):  25-37. 

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Many of the earliest discovered ornithurine birds from the Jehol Group in northeastern China are highly fragmentary; this current study on the only known specimen of Liaoningornis longidigitrus, first described by Hou in 1997, indicates the taxon is in fact a member of Enantiornithes. Although based on fragmentary and poorly preserved material, the absence of a well-developed sternum,lack of developed cnemial crests on the tibiotarsi and reduced pedal unguals suggests Liaoningornis should be excluded from the more advanced ornithothoracine clade. The taxon remains distinct from all known enantiornithines, although it shows similarity to the Spanish taxon Eoalulavis hoyasi; shared features of the sternum suggest a close relationship between these two, although disparity from other enantiornithines suggests this may be an artifact of ontogeny. TheLiaoningornis specimen is too fragmentary to be able to make strong inferences about its placement within the diverse enantiornithine clade.

MASS ESTIMATE AND EVOLUTIONARY TREND IN CHINESE MESOZOIC FOSSIL BIRDS

LIU Di, ZHOU Zhong-He, ZHANG Yu-Guang

2012, 50(1):  39-52. 

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Body mass or weight is a crucial biological parameter for an organism. It is influenced by development, reproduction, physiology and evolution. Therefore, mass estimates for fossil species are important for many kinds of analyses. In this project, eighteen bivariate regression analyses of different measurements of the appendicular skeleton plotted against body weight in a data set of 422 individual birds, representing 229 species in 21 orders, revealed high correlations between several skeletal parameters and body mass. R-squared values of eighteen bivariate equations are ranged from 0.50 for tibiotarsal length, indicating a relative poor fit, to 0.91 for humeral diameter. To test the 18 equations empirically, they were used to predict the body weight of an additional 64 extant bird specimens, and the accuracies of various equations were compared. This predictive test showed that three parameters are generally most accurate as predictors of body mass: humerus length, ulna diameter, and tibiotarsal diameter. However, the humeral length and ulna diameter tended to give accurate results for particularly songbirds, raptors and climbing birds. The tibiotarsal diameter tended to give accurate results for terrestrial birds, such like chicken and doves. It is probable that humerus length and ulna diameters are the more accurate parameter for arboreal taxa, while tibiotarsal diameter is more accurate for terrestrial ones. Closer examination of the results showed that different measurements correlated best with body mass in different avian orders. This variation appeared to result from differences in habitat and functional morphology across the avian orders represented in the data set. The weights of some Chinese Mesozoic fossil birds were estimated using the equations generated for humeral length and tibiotarsal diameter, because ulnar diameter was frequently difficult to measure. Humeral length and tibiotarsal diameter yielded dramatically different mass estimates for some taxa, with estimates based on humerus length generally being lower. The result shows that these Early Cretaceous birds experienced a significant diversification in body weight during evolutionary process.

A NEW SPECIES OF CHALICOTHERIINAE (PERISSODACTYLA, MAMMALIA) FROM THE LATE MIOCENE IN THE LINXIA BASIN OF GANSU, CHINA

CHEN Shao-Kun, DENG Tao, HE Wen, CHEN Shan-Qin

2012, 50(1):  53-73. 

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Chalicothere fossils are rare in Chinese Neogene deposits.A new chalicothere species from the Linxia Basin of Gansu Province, Nestoritherium linxiaense sp. nov., is described and studied here. This species represents the most primitive Nestoritherium known. Based on this new species, the generic name Nestoritherium is revalidated and the species N. wuduense(Xue and Coombs,1985) is referred to this genus. Hesperotherium is nested within Nestoritherium.

A SKULL OF HIPPARION (PROBOSCIDIPPARION)SINENSE (PERISSODACTYLA, EQUIDAE) FROM LONGDAN, DONGXIANG OF NORTHWESTERN CHINA —Addition to the Early Pleistocene Longdan Mammalian Fauna (3)

DENG Tao

2012, 50(1):  74-84. 

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A skull of Hipparion (Proboscidipparion) sinense is reported from the Longdan locality in Dongxiang, Gansu Province, northwestern China. The previously known material of H. (P.) sinensein the Early Pleistocene Longdan fauna was only a Metacarpal III. The discovery of this skull not only confirms the specific identification of Hipparion in this fauna, but also increases the understanding of the cranial and dental characters of this species. The holotype specimen of H. sinense belongs to a senile individual, and no other complete skull of this species has been found. As a result, the new material from Longdan provides more key information for the diagnoses of H. sinense, and the structure of the nasal notch of this species becomes clear. The lower part of the nasal bone is a tenuous strip that extends far forward, comprises the posterior part of the lower margin of the nasal notch, and has a sharp anterior end reaching the level of the P2/P3 boundary, at a 30 mm distance from the posterior end of the nasal process of the premaxillary bone. The recognition of these characters is of great interest in determining the phylogenetic relationship of Proboscidipparion.