High-precision 40Ar/39Ar age for the Jehol Biota

Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA; State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences), Nanjing 210008, China; Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, USA; Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
Palaeogeography, Palaeoclimatology, Palaeoecology 01/2009; DOI: 10.1016/j.palaeo.2009.06.021

ABSTRACT Abundant fossils of the terrestrial Jehol Biota, including plants, insects, dinosaurs, birds, mammals and freshwater invertebrates, were discovered from the Yixian Formation and the overlying Jiufotang Formation in Inner Mongolia, Hebei Province and Liaoning Province, northeastern China. Because of the exceptional preservation of fossils, the Jehol Biota is one of the most important Mesozoic lagerstätten and is referred to as a “Mesozoic Pompeii”. The Jehol Biota has provided a rare opportunity to address questions about the origin of birds, the evolution of feathers and flight, the early diversification of angiosperms and the timing of placental mammal radiation. Six tuff samples and two basalt samples collected from the Tuchengzi, the Yixian and the Jiufotang formations near the classic outcrops in western Liaoning, NE China yielded high-precision 40Ar/39Ar ages. We obtain an age of 129.7 ± 0.5 Ma for a basaltic lava from the bottom of the Yixian Formation and an age of 122.1 ± 0.3 Ma for a tuff from the lowermost part of the overlying Jiufotang Formation. Our age results provide an age calibration of the whole Yixian Formation and show that the whole formation was deposited entirely within Early Cretaceous time over an interval of ~ 7 Ma.

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    ABSTRACT: Abundant Mesozoic terrestrial plant, fish and invertebrate fossils have been discovered from the Lishugou Formation and the underlying Xiaolin Formation in the eastern Liaoning province of NE China since the 1970s. These discoveries have great potential for substantially increasing our knowledge on the evolution of paleoecosystems and paleoenvironments in East Asia. However, previous geological and geochronological studies for these fossil-bearing formations are rare because the fossil outcrops are near the border between China and North Korea. Here we present robust 40Ar/39Ar ages of 99.9 ± 0.4 Ma for one sample from the Lishugou Formation and 109.1 ± 0.2 Ma and 122.4 ± 0.2 Ma for two samples from the upper and lower parts of the Xiaolin Formation from Dandong City, Liaoning, China. Our new age data indicate that the Lishugou and Xiaolin Formations were deposited contemporaneously with the Jiufotang Formation from the classic Jehol outcrops in western Liaoning. Therefore, our results provide an accurate age calibration for the fossils discovered from the Liaodong Peninsula and suggest that the hypothesis of the Jehol migration should be reappraised.
    Palaeogeography Palaeoclimatology Palaeoecology 01/2014; · 2.75 Impact Factor
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    ABSTRACT: New fossil genus with a new species, Stellularis longirostris Chen, Yao and Ren, gen. et sp. nov., from the family Procercopidae, are described. New specimens were collected from the Lower Cretaceous non-marine sedimentary strata from the Yixian Formations of northeast China. The exceptionally well-preserved materials reveal fine details of the body structure and morphology including rostrum, legs, abdomen, anteclypeus and ovipositor. The genera Luanpingia Hong, 1983 and Cathaycixius Ren, Lu, and Guo, 1995 are discussed.
    Cretaceous Research 01/2014; · 1.63 Impact Factor
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    ABSTRACT: Here we report the first ichthyodectiform in the Jinju Biota from the Lower Cretaceous Jinju Formation, Shindong Group, at Hyojagyo, Jinju City, South Korea. It shows the following ichthyodectiform characters: 1) jaw teeth in single series; 2) coracoid expanded ventrally; 3) dorsal fin situated posteriorly, with its origin opposite to that of long anal fin. Besides, its caudal skeleton also exhibits certain features often seen in basal ichthyodectiforms and some other primitive teleosts. The fish is noticeably similar to the species referred to Chuhsiungichthys from the upper Lower Cretaceous Dobaru and Kumagai formations of the Wakino Subgroup of Kanmon Group in Kyushu, Japan, and Chuhsiungichthys tsanglingensis from the Jiangdihe Formation of similar age from Chuxiong, Yunnan Province, China. Chuhsiungichthys was, in turn, comparable with Mesoclupea showchangensis from the upper Lower Cretaceous Shouchang Formation in Shouchang and Linhai, and Guantou Formation in Zhuji, Zhejiang Province, China. The latter two genera also show the ichthyodectiform characters mentioned above. Nevertheless, the fish from Korea, those referred to Chuhsiungichthys from Japan and China, and Mesoclupea can easily be distinguished from other ichthyodectiforms in their higher body depth and shorter length; proportionally longer head; longer dorsal and anal fins; lower number of vertebrae, with abdominal less than caudal; vertebrae deeper than long. Among them the Jinju fish is distinct from the other two genera in even higher and shorter body, and presence of urodermal. In addition, the Jinju fish is different from Mesoclupea showchangensis in having a much longer dorsal fin and lower number of vertebrae, but different from Chuhsiungichthys tsanglingensis in having a much higher number of vertebrae and more ridges and grooves on the lateral face of vertebrae. Thus, the Jinju fish cannot be referred to either Chuhsiungichthys or Mesoclupea, and establishing a new genus and species for it is warranted. The Asian ichthyodectiforms, Mesoclupea, Chuhsiungichthys, and Jinjuichthys, may most probably form a monophyletic group – Chuhsiungichthyidae, known so far restricted to the upper Lower Cretaceous fresh and/or brackish waters of East Asia. The new ichthyodectiform materials from Korea are better preserved than those from Japan, thereby allowing a relatively complete description of the fish, providing more information for discussion of its phylogenetic position, enriching the diversity of the local fish fauna, and helping us better understand the paleobiogeographical distribution of the group and its geological background.
    Cretaceous Research 01/2014; 47:117–130. · 1.63 Impact Factor


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