Table of Content

20 May 2021, Volume 59 Issue 2

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A new pteranodontoid pterosaur forelimb from the upper Yixian Formation, with a revision of Yixianopterus jingangshanensis

JIANG Shun-Xing, ZHANG Xin-Jun, CHENG Xin, WANG Xiao-Lin

2021, 59(2):  81-94.  DOI: 10.19615/j.cnki.1000-3118.201124

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Pterosaurs in the Jehol Biota have been found in the Yixian and Jiufotang formations. The Jingangshan bedding is in the upper part of the Yixian Formation. The first two pterosaur embryos ever discovered in the world, two archaeopterodactyloid specimens, and the questionable Yixianopterus jingangshanensis have been reported in previous literature. Here, we describe a forelimb from this horizon and confirm its phylogenetic position in the Pteranodontoidea. The holotype of Y. jingangshanensis, now housed at Benxi Geological Museum, has been examined. The diagnosis of this taxon has been revised without the consideration of the artificial parts as following, a pteranodontoid pterosaur with a distinguished combination of characters: triangular and labiolingually compressed teeth with the first two more slender and longer than the others; teeth vertical to the occlusal surface; the second wing phalanx about 93% the length of the first wing phalanx. In the Jehol Biota, archaeopterodactyloid specimens have been mainly discovered from the Yixian Formation, while tapejaroids are almost found from the Jiufotang Formation. Including the new forelimb and Y. jingangshanensis, the pteranodontoids from the Jiufotang Formation are slightly greater in number than those from the Yixian Formation in species and specimens, differing from the previous thoughts on the distribution.

Reanalysis of Oculudentavis shows it is a lizard

LI Zhi-Heng, WANG Wei, HU Han, WANG Min, YI Hong-Yu, LU Jing

2021, 59(2):  95-105.  DOI: 10.19615/j.cnki.1000-3118.201020

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The recent finding of a fossil entombed in a Late Cretaceous amber - Oculudentavis khaungraae - was claimed to represent a humming bird-sized dinosaur. Regardless of the intriguing evolutionary hypotheses about the bauplan of Mesozoic dinosaurs (including birds) posited therein, this enigmatic animal demonstrates various morphologies resembling lizards. If Oculudentavis was a bird, it challenges several fundamental morphological differences between Lepidosauria and Archosauria. Here we reanalyze the original computed tomography scan data of the holotype of Oculudentavis khaungraae (HPG-15-3). Morphological evidences demonstrated here highly contradict the avian or even archosaurian phylogenetic placement of the species. In contrast, our analysis revealed multiple skull morphologies of HPG-15-3 resembling those of squamates, including pleurodont marginal teeth, an open infratemporal fenestra, and the presence of palatal dentition. Based on these new morphological information, the phylogenetic position of Oculudentavis was analyzed in a data matrix sampling across the Diapsida. Taxon sampling of the data matrix included multiple species of lizards, birds, and major clades in Lepidosauromorpha and Archosauromorpha. In the strict consensus tree, Oculudentavis is nested within Squamata. These results show that morphology of the Oculudentavis khaungraae holotype supports a squamate rather than avian or dinosaurian affinity of the species.

Cartilage on the furculae of living birds and the extinct bird Confuciusornis: a preliminary analysis and implications for flight style inferences in Mesozoic birds

WU Qian, Jingmai K. O’CONNOR, LI Zhi-Heng, Alida M. BAILLEUL

2021, 59(2):  106-124.  DOI: 10.19615/j.cnki.1000-3118.201222

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The early evolution of flight is one of the most studied topics in vertebrate paleontology. Living birds have evolved to utilize a variety of flight styles, but studies focused on inferring flight strategies in Mesozoic birds are often contradictory and without a clear consensus, making it necessary to find additional informative characteristics that can be useful for inferences in fossils. Virtually nothing is known about the histology of the avian pectoral girdle, even though skeletal and joint tissues are key candidates to solve form-function relationships. Avian secondary cartilage found on the dermal bones of the avian skeleton is influenced by epigenetics and only forms when joints are stimulated by muscle contractions. As the only dermal bone in the avian postcranium, the furcula is a potential site for the formation of furcular secondary cartilage and merits further attention. It is still unknown whether adult living birds and fossil birds have furcular secondary cartilage. Here we present histological analyses conducted on the furcula-coracoid articulation in three living birds (Spilopelia chinensis, the Spotted dove; Passer montanus, the Eurasian tree sparrow; and Apus apus, the Common swift), taxa that utilize different flight styles, and one of the most common fossil birds of the Jehol Biota, Confuciusornis. Secondary cartilage was identified on the furculae of the living birds and of Confuciusornis, representing the first report of furcular secondary cartilage in the fossil record. Clear differences in secondary cartilage morphologies were observed in the living species, but additional data is required to establish a strong form-function relationship that could be useful for making inferences in Mesozoic birds.

An Upper Miocene “Hipparion fauna” locality sandwiched by basalt in Hanjiaying, Nei Mongol

WANG Qian, LIU Yan, WANG Li-Hua, Mikael FORTELIUS, ZHANG Zhao-Qun

2021, 59(2):  125-137.  DOI: 10.19615/j.cnki.1000-3118.210323

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Here we report a Hipparion fauna locality discovered in between two basalt layers near Hanjiaying Village, Jining District, Wulanchabu City, Nei Mongol. K-Ar isotopic dating of the lower and upper level of the basalt constrains the age of the fauna from 7.2 to 6.8 Ma. Compared with classical Hipparion fauna from northern China, the Hanjiaying fauna is closer to those from Baode of Shanxi, Siziwang Banner of Nei Mongol and the Linxia Basin of Gansu. It is similar to the Loc. 43, 44 and 49 from Baode by faunal composition, confirming their age to be ~7.0 Ma rather than 5.5 Ma. The high similarity with the fossils from Wulanhua, Siziwang Banner, Nei Mongol, verified the age of Wulanhua fauna at about 7 Ma. Compared with faunas from the Linxia Basin, Gansu, it is more similar to those from the upper part of the Liushu Formation, especially the Yangjiashan fauna. Based on the faunal composition and their tooth morphology, the Hanjiaying fauna could be included in the “Gazella dorcadoides” fauna, which is supposed to be at the west paleobiome in northern China during the Late Miocene.

Climate change and evolution of early lagomorphs (Mammalia): a study perspective based on new materials of Ordolagus from Nei Mongol (northern China)

Chiara ANGELONE, ZHANG Zhao-Qun

2021, 59(2):  138-168.  DOI: 10.19615/j.cnki.1000-3118.210325

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The Early Oligocene is a critical time for global climate changes in the Cenozoic. This epoch witnessed severe mammalian faunal turnovers known as “Grande Coupure” in Europe and “Mongolian Remodelling” in Asia. However, insights about morphological changes in Oligocene mammal lineages have not been explored in detail. One of the least diversified groups of recent mammals, lagomorpha, is globally common in the fossil records, especially in Asia. During the Oligocene, many Eocene archaic lagomorph taxa died out and were replaced by more advanced forms. New findings from Nei Mongol and re-examination of the specimens from older collections enabled a revision of a common Asian lagomorph genus, Ordolagus, which possibly has a close affinity with the Middle-Late Eocene genus Gobiolagus. In Nei Mongol, we recognized the presence of Ordolagus during the basal Early Oligocene. Comparisons with coeval and slightly older lagomorph taxa from Asia and North America show that Ordolagus attained some salient tooth morphological characters (i.e., development of anteroconid on p3, full hypselodonty of cheek teeth, and lingual connection of trigonid and talonid on p4-m2), which are also the key features of modern leporids. The appearance of those morphologic features in Ordolagus is coeval to major global or regional climatic changes. Further investigations on Asian early lagomorphs compared with the study of other small mammals and local climatic factors will be essential to refine the role of lagomorphs as palaeoclimatic proxies.