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Table of Content

    20 January 2019, Volume 57 Issue 1
    A taxonomical revision of the Confuciusornithiformes (Aves: Pygostylia)
    WANG Min, Jingmai O’CONNOR, ZHOU Zhong-He
    2019, 57(1):  1-37.  DOI: 10.19615/j.cnki.1000-3118.180530
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    The Confuciusornithiformes is a basal clade of Early Cretaceous birds that includes the oldest and most basal birds with a toothless beak and an abbreviated bony tail. Over the last two decades, thousands of specimens have been collected, more than for any other group of Mesozoic birds or non-avian dinosaurs. Ten species separated into four genera have been erected with limited taxonomic phylogenetic scrutiny. Here, we perform a comparative study of these ten species, and demonstrate that most of these taxa were originally diagnosed by characters that prove to be either preservational artifacts, intraspecific variations, subject to ontogenetic variation, or widely distributed among the Confuciusornithiformes or a more phylogenetically inclusive group. Our results suggest that ‘Confuciusornis suniae’, ‘C. feducciai’, ‘Jinzhouornis yixianensis’, ‘J. zhangjiyingia’, and ‘C. jianchangensis’ are all junior synonyms of C. sanctus. ‘C. chuonzhous’ lacks autapomorphies of C. sanctus and is referred to Confuciusornithiformes incertae sedis. Our taxonomic reappraisal of published materials indicates that the Confuciusornithiformes consists of one family, three genera, and four species: C. sanctus, C. dui, Changchengornis hengdaoziensis, and Eoconfuciusornis zhengi, for which we provide revised diagnoses.

    Negligible effect of tooth reduction on body mass in Mesozoic birds
    ZHOU Ya-Chun, Corwin SULLIVAN, ZHANG Fu-Cheng
    2019, 57(1):  38-50.  DOI: 10.19615/j.cnki.1000-3118.180307
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    Tooth reduction and loss was an important evolutionary process in Mesozoic birds. Analysis of evolutionary trends in the total mass of the dentition, a function of tooth size and tooth number, has the potential to shed light on the evolutionary pattern of tooth reduction and loss, and on the causes of this pattern. Because modern birds lack teeth, however, they cannot provide the basis for a model that would allow estimation of tooth masses in their Mesozoic counterparts. We selected the teeth of crocodilians as analogues of those in Mesozoic birds because the former are the closest living relatives of the latter, and the two groups are similar in tooth morphology, tooth implantation, and tooth replacement pattern. To estimate tooth masses in Mesozoic birds, we formulated four regression equations relating tooth mass to various linear dimensions, which were measured in 31 intact isolated teeth from eight individual crocodiles (Crocodylus siamensis). The results for Mesozoic birds show that dental mass as a proportion of body mass was negligible, at least from the perspective of flight performance, suggesting that selection pressure favoring body mass reduction was probably not the primary driver of tooth reduction or loss. Variations in dental mass among Mesozoic birds may reflect the different foods they ate, and the different types of feeding behavior they displayed.

    Evidence of diphyodonty and heterochrony for dental development in euharamiyidan mammals from Jurassic Yanliao Biota
    MAO Fang-Yuan, ZHENG Xiao-Ting, WANG Xiao-Li, WANG Yuan-Qing, BI Shun-Dong, MENG Jin
    2019, 57(1):  51-76.  DOI: 10.19615/j.cnki.1000-3118.180803
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    Evidences for tooth replacement of known euharamiyidans are reported based on eight specimens of four species from the Jurassic Yanliao Biota, Liaoning Province, China. Tooth morphologies, eruptional and wear condition, and tooth germs are directly observed and/or revealed by Micro CT or slab CL scan. The euharamiyidan dentition has definite number of cheek teeth and monophyodont molars that are related to precise occlusion. Incisor germs are found in three specimens of Arboroharamiya but not in Shenshou lui and Xianshou linglong. The incisor germs in the upper jaw, presumably I2, have a large crown with two or three cusps; those in the lower jaw, interpreted as the permanent i2, are positioned dorsal to the root of the erupted incisor, interpreted as di2. Comparing dental development within various ontogenetic stages, the incisor tooth germs in Arboroharamiya and Vilevolodon would replace the deciduous incisors in a much later time than when ultimate molars became fully erupted and functional, if it did happen. The available evidence indicates presence of diphyodonty in the loci of the ultimate lower premolar and incisor, which are common mammalian features potentially related to lactation and parental care. The prolonged or delayed eruptions of incisors and ultimate molars in Arboroharamiya and Vilevolodon are probably associated with the specialization of dentition, with emphasis on the P4/p4 chewing function, which should be an autapomorphy and represent a heterochronic shift of tooth replacement in terms of ontogenetic timing comparing to other “haramiyidians”. The heterochronic incisor replacement is probably owing to developmental suppression related to expansion of the premolars, and may have evolved independently multiple times within mammaliaforms.

    The first Stalicoolithus shifengensis discovered in a clutch from the Sanshui Basin, Guangdong Province
    ZHU Xu-Feng, FANG Kai-Yong, WANG Qiang, LU Xiao-Hong, WU Wei-Qiang, DU Yan-Li, HUANG Zhi-Qing, WANG Xiao-Lin
    2019, 57(1):  77-83.  DOI: 10.19615/j.cnki.1000-3118.180110
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    The first clutch of Stalicoolithus shifengensis is described here. This incomplete dinosaur egg clutch in which three nearly complete eggs and two egg prints were preserved was discovered in the red deposits of the Sanshui Formation at a construction site near the sluice of North Village, Dali Town, Nanhai District, Foshan City, Guangdong Province, China. The eggs in the clutch are stacked with various ranges. Based on the characteristics of the eggshell, these eggs can be assigned to S. shifengensis. The discovery of S. shifengensis in the Sanshui Formation complements the clutch information about the oospecies as well as expands its paleogeographic distribution, and sets the foundation for discussing the diversity of dinosaur eggs in the Sanshui Basin.

    Development and applications of paleontological computed tomography
    WANG Yan-Fang, WEI Cun-Feng, QUE Jie-Min, ZHANG Wen-Ding, SUN Cui-Li, SHU Yan-Feng, HOU Ye-Mao, ZHANG Jiu-Chang, SHI Rong-Jian, WEI Long
    2019, 57(1):  84-92.  DOI: 10.19615/j.cnki.1000-3118.170921
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    The traditional serial grinding method used to investigate the internal structure of fossils cannot be readily applied to valuable fossil specimens due to its destructive and time-consuming nature. Computed tomography (CT) is an ideal non-destructive technique for investigating the internal structure of fossils, in which thousands of serial images are obtained and used to produce an accurate reconstruction of the internal morphology. This paper reviews the design, development and applications of the first CT system in China dedicated exclusively to scanning fossils. The 225 kV three-dimensional (3D) fossil micro-CT (225-3D-μCT) is capable of high-resolution volumetric imaging, with a resolution up to 5 μm, and can accommodate specimens measuring up to 100 mm in diameter and 100 mm in length. The 450 kV ordinary fossil CT (450-TY-ICT) can produce high signal-to-noise ratio (SNR) images of specimens ranging up to 800 mm in diameter and 1000 mm in length, with a resolution up to 200 μm. Two paleontological CT facilities represent a high-performance platform offering the functional diversity needed to meet the demands of studying fossils at a variety of different scales. The two machines have become indispensable for paleontological research in China.