Shen C.,Yunnan University |
Pratt B.R.,University of Saskatchewan |
Lan T.,Yunnan University |
Hou J.-B.,Yunnan University |
And 3 more authors.
Palaeoworld | Year: 2013
Orsten-type fossils, mainly arthropod juveniles and even tiny embryos exquisitely preserved in apatite, have been well documented from several localities in southern China. This particular type of Lagerstätte is known from just a few places around the world but has led to significant breakthroughs in the understanding of the early diversity of animals and evolution of metazoans. The original 'orsten' from southern Sweden are limestone concretions within black shales, whereas in China this kind of preservation occurs in lime mudstone thin beds and nodules interbedded with shale. Thus there is a taphonomic bias in that this kind of preservation is localized to a deeper water carbonate facies which can be regarded as concretionary due to early cementation under shallow burial. Nonetheless, we observe that even within a laterally extensive bed of the seemingly appropriate lithofacies, preservation may be highly localized. Thus, in addition to the extreme rarity of Orsten-type preservation globally, serendipity in discovering fossiliferous localities plays a significant role. Because of their predominant occurrence in the Cambrian they are also a temporally restricted window. To extract Orsten-type material from the limestone matrix, mild acetic acid digestion has been widely applied, but certain procedures can be employed to aid recovery by limiting damage to these delicate but fragile specimens. Here, we describe our method for etching out specimens and review some of the discoveries recently made in southern China. © 2013 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS.
Carbon isotope stratigraphy of terrestrial organic matter for the turonian (upper cretaceous) in northern Japan: Implications for oceanatmosphere δ13C trends during the mid-cretaceous climatic optimum
Uramoto G.-I.,Japan Agency for Marine - Earth Science and Technology |
Tahara R.,McGill University |
Sekiya T.,Zigong Dinosaur Museum |
Hirano H.,Waseda University
Geosphere | Year: 2013
Carbon isotope data of terrestrial organic matter (δ13CTOM) obtained in Hokkaido, northern Japan, from the marine Cretaceous Yezo Group along the northwestern Pacifi c margin elucidated a detailed chemostratigraphy for the Turonian Stage in this region of East Asia. Chemostratigraphic intra-basin correlation reveals three positive δ13CTOM events in the Middle-Upper Turonian of the Yezo Group. δ13CTOM fl uctuations in these events show similar patterns in the Yezo Group, indicating that terrestrial organic matter is mixed suffi ciently before deposition in the Yezo Basin. These δ13CTOM events are correlated with previously documented δ13Ccarbonate events in Europe (the Lulworth-Round Down, Glynde-Pewsey, and Late Turonian Events) based on global biostratigraphy. Our chemostrati graphic correlations strengthen the use of these δ13C events for global correlation of the Turonian marine successions. In addition, global correlation of Turonian marine and terrestrial δ13C events identifi es changes in isotopic difference between δ13CTOM and δ13Ccarbonate (ΔTOM-carbonate), which are interpreted to refl ect changes in atmospheric pCO2 levels, and climate-driven stresses of humidity and soil processes. In earlier stages of Turonian, ΔTOM-carbonate values are increased. Elevated atmospheric pCO2, and increased humidity and soil processes in enhanced greenhouse conditions during mid-Turonian, are interpreted to enlarge ΔTOM-carbonate values. In later stages of Turonian, ΔTOM-carbonate values are at a constant level, and the loweringof atmospheric pCO2 or decrease of climate stress related to the diverse paleoclimatic cooling is interpreted to have restored the ocean-atmosphere δ13C trends. © 2013 Geological Society of America.
Xing L.D.,China University of Geosciences |
Lockley M.G.,University of Colorado at Denver |
Klein H.,Saurierwelt Palaontologisches Museum |
Gierlinski G.D.,JuraPark |
And 5 more authors.
Palaeoworld | Year: 2014
Deposits from the Ordos Basin of mid-western China are rich in body fossils and ichnofossils of Early Cretaceous vertebrates. Thousands of Early Cretaceous sauropod, theropod and bird tracks described since 1958 have been found at several localities in the basin. We report two new sites (Dijiaping and Bawangzhuang) in the Luohe Formation of the Ordos Basin, Shaanxi Province, which contain small theropod footprints that are here referred to the ichnogenus Jialingpus. The assignment is based on pad configurations including (1) the large metatarsophalangeal area positioned in line with the axis of digit III, (2) the subdivision of this part into a small pad behind digit II, which in some specimens is close to the general position of the hallux (digit I), and a large metatarsophalangeal pad behind digit IV, and (3) a distinct inter-pad space between metatarsophalangeal pads and proximal phalangeal pads of digits II and III. We re-describe the type material of the type ichnospecies Jialingpus yuechiensis from the Upper Jurassic Penglaizhen Formation of Sichuan Province, proposing a largely amended diagnosis for this ichnotaxon. The presence of a digit I trace in the holotype, indicating a relatively long hallux, and the large metatarsophalangeal area positioned in line with digit III distinguishes Jialingpus from the ichnogenus Grallator and similar tracks that all lack these features. The only difference between Jialingpus specimens from the Cretaceous of the Ordos Basin and those of the Jurassic Penglaizhen Formation is the larger digit divarication in the Cretaceous taxon. This is the fourth record of Jialingpus in China and the second in Cretaceous strata, with the first being those from the Huangyangquan locality in Xinjiang, China. © 2014 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS.
Sekiya T.,Zigong Dinosaur Museum
Memoir of the Fukui Prefectural Dinosaur Museum | Year: 2011
The present study re-evaluates Chuanjiesaurus anaensis Fang et al., 2000 from the Middle Jurassic of Lufeng, Yunnan, Southwest China. The holotype and a new referred specimen are described in detail, and re-examined osteologically and phylogenetically. In this report, the author proposes several emended diagnoses based on close observations and comparisons of the specimens. Some osteological features reveal that Chuanjiesaurus belongs to Mamenchisauridae. Compared to other mamenchisaurid dinosaurs, C. anaensis possesses relatively primitive characters. The phylogenetic position of C. anaensis was determined according to the present analysis. In addition, the data sets of some taxa of Mamenchisauridae from southwestern China are modified in the present research. The present analysis reveals that C. anaensis, Mamenchisaurus, Tienshanosaurus and Yuanmousaurus constitute a monophyletic group that belongs to relatively derived Eusauropoda. This suggests that Mamenchisauridae could be positioned at a more derived part of Eusauropoda than previously thought. This study confirms that C. anaensis is a member of Mamenchisauridae. © by the Fukui Prefectural Dinosaur Museum.
Sekiya T.,Zigong Dinosaur Museum |
Jin X.,Zhejiang University of Science and Technology |
Zheng W.,Zhejiang University of Science and Technology |
Shibata M.,Fukui Prefectural Dinosaur Museum |
Azuma Y.,Fukui Prefectural Dinosaur Museum
Historical Biology | Year: 2014
An almost complete skeleton with partial cranial material (ZMNH-M8739) is recovered from the Early or Middle Jurassic of southwest China. ZMNH-M8739 is identified as a juvenile individual of basal sauropodomorph dinosaur, Yunnanosaurus robustus Young, 1951. The revised diagnoses are as follows: absence of anteroposterior expansion on the medial end of astragalus and dorsoventrally compressed medium shaft of the metatarsal IV. Unfused neural arch and finely grooved long bone surface texture indicate that this individual is in the immature growth stage. ZMNH-M8739 possesses the tooth-tooth wear facet on its mesial maxillary and dentary teeth. However, the distal maxillary teeth have coarse serrations. Such a characteristic dentition could represent a unique feeding mechanism of this animal. Finally, ZMNH-M8739 constitutes a monophyletic group with Y. robustus (holotype), and Y. huangi is nesting this clade in the phylogenetic tree of the present analysis. Comparison of juvenile and adult specimen reveals distinctive growth changes of Y. robustus. This clade is positioned in an unnamed clade at a sister taxon of Sauropoda. Finally, some members of the so-called prosauropod dinosaurs constitute a monophyletic group in the present result. © 2013 Taylor & Francis.