Timing of the earliest known feathered dinosaurs and transitional pterosaurs older than the Jehol Biota

Palaeogeography, Palaeoclimatology, Palaeoecology 323–325 (2012) 1–12

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Timing of the earliest known feathered dinosaurs and transitional pterosaurs older than the Jehol Biota Yong-Qing Liu a,⁎, Hong-Wei Kuang a, Xiao-Jun Jiang a, Nan Peng b, Huan Xu a, Hui-Yi Sun c a b c

Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China China University of Geosciences,Beijing,100083, China Beijing SHRIMP II Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China

a r t i c l e

i n f o

Article history: Received 28 March 2011 Received in revised form 17 December 2011 Accepted 20 January 2012 Available online 2 February 2012 Keywords: Age The feathered dinosaurs Transitional pterosaurs The Daohugou Biota,the Jehol Biota,China

a b s t r a c t The Early Cretaceous Jehol Biota in China has produced numerous well preserved fossils of feathered theropods and early birds. Recent discoveries of feathered dinosaurs, as well as transitional pterosaurs and a sexually mature individual of Darwinopterus preserved together with an egg from the Daohugou Biota of an earlier age than the Jehol Biota, in northeastern China, have greatly enriched our knowledge of the transition from dinosaurs to birds and primitive to derived pterosaurs. The age estimate of fossils or host strata, however, has proven to be contentious and varies widely from the Middle Jurassic to the Early Cretaceous. Here, we report a SHRIMP U–Pb zircon date unambiguously associated with the fossil horizons, and thus, for the first time, provide an age calibration for the earliest appearance of feathered dinosaurs and transitional pterosaurs. Date results indicate that the feathered dinosaurs of China were present more than 161 Ma ago, unquestionably older than Archaeopteryx in Germany, and are the earliest known feathered dinosaurs in the world. Furthermore, feathers appeared in ornithischians before 159 Ma rather than late in the Early Cretaceous. The known transitional pterosaurs first emerged before 161 Ma. The Daohugou Biota, containing mammals, primitive pterosaurs, insects and plants, in addition to the feathered dinosaurs, was living in Inner Mongolia ,western Liaoning and northern Hebei in northeastern China during the Middle Jurassic. © 2012 Elsevier B.V. All rights reserved.

1. Introduction The Early Cretaceous Jehol Biota (Grabau, 1928; Gu, 1962; Chen, 1988) of northeastern China has revealed a plethora of extraordinarily well preserved fossils of feathered theropods and early birds over the past 10 years (Chen et al., 1998; Ji et al., 1998; Xu et al., 1999a,b, 2001, 2002, 2003, 2004, 2010; Zhou et al., 2003). However, the Daohugou Biota (Zhang, 2002), which is older than the Jehol Biota and estimated to be of Jurassic age, was discovered in recent years at Ningcheng, Inner Mongolia, and in northeastern China, and has yielded spectacular fossil mammals (Ji et al., 2006; Meng et al., 2006; Luo et al., 2007a, 2007b, 2011), pterosaurs (Ji and Yuan, 2002; Lü et al., 2009, 2011), and insects (Ren et al., 2009), in addition to feathered dinosaurs (Hu et al., 2009; Xu and Zhang, 2005; Xu et al., 2009; Zheng et al., 2009; Zhang et al., 2000), which have greatly expanded our knowledge of the diversity and palaeobiology of a time before the Jehol Biota and contributed to our understanding of the origin of the Jehol Biota. Though the feathered dinosaur species (Zheng et al., 2009; Hu et al., 2009; Xu and Zhang, 2005; Xu et al., 2009, 2011) and transitional

⁎ Corresponding author. E-mail address: [email protected] (Y.-Q. Liu). 0031-0182/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.palaeo.2012.01.017

pterosaurs (Lü et al., 2009, 2011) were discovered more recently in China, their age and that of the Daohugou Biota has been contentious. Some authors concluded that it belongs to the Early Cretaceous (He H., 2004a, 2004b, 2005; Wang et al., 2005b; Xu et al., 2009; Zheng et al., 2009) and others describe it as Jurassic (Zhang J, 2002; Zhang H, 2008a, 2008b, 2009; Liu et al., 2004; Liu and Liu, 2005; Liu et al., 2006; Duan et al., 2009; Hu et al., 2009; Lü et al., 2009; Chen et al., 2004). The timing of their earliest emergence and evolution remains to be confirmed. Feathered theropods from the Jehol Biota previously date to 125 Ma (Swisher et al., 1999,2002) and were deemed to be younger than Archaeopteryx lithographica at 150 Ma from Solnhofen, Germany (Wellnhofer, 1992). In terms of evolutionary biology, feathered dinosaurs and associated birds older than 150 Ma or of Jurassic age should exist if in fact birds evolved from theropods. More recently, ornithischians (Tianyulong confuciusi) with feathers of “the early Cretaceous ” were reported at Yaolugou, Jianchang, western Liaoning, China (Zheng et al., 2009), which challenges the evolution of dinosaur feathers and implies that hairlike structures may be common for either the early dinosaurs or their descendents, or both. In addition, another new, feathered theropod, Anchiornis huxleyi (Hu et al., 2009), was also reported in 2009 from the same locality. Based on its well preserved morphology, it is thought to be closely related to basal birds. The two abovementioned important discoveries expand our knowledge of the

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origin and evolution of feathers, but an accurate timing of the emergence of feathered theropods and ornithischians remains unclear. More recently, Xu et al.(2011) reported an Archaeopteryx-like therpod (Xiaotingia zhengi) from China, and concluded that Archaeopteryx was an animal very closely related to the featured therpod and not a bird. These current dates will help palaeontologists to understand when the ancestors of modern birds or closely related cousins appeared. Over the years, both primitive and derived species of pterosaurs, separated by a large time gap that had never been filled before, were frequently discovered in China and abroad (Wang et al., 2002, 2005a, b; 2009; Wang and Zhou, 2006). Transitional pterosaur specimens, however, were not found in these expeditions. One transitional form (Darwinopterus) from the same locality and horizon yielding A. huxleyi was reported (Lü et al., 2009), which fills a gap in pterosaur evolution. In addition, a sexually mature individual of Darwinopterus, preserved together with an egg, was reported from the same horizon as Darwinopterus and A. huxleyi (Lü et al., 2011). Feathered theropods and ornithischians and transitional forms of pterosaurs were all excavated from sediments interbedded with volcanic rocks from the Jurassic Lanqi Formation (called the Tiaojishan Formation in Hebei Province) in Jianchang, western Liaoning, China. Though many dated results have previously been attained for this formation elsewhere (Gao et al., 2004; Davis, 2005, Davis et al., 2001; Zhang et al., 2005, 2008a, 2008b, 2008c; Liu and Liu, 2005; Liu et al., 2004, 2006; Liu J et al., 2006; Hu et al., 2007; Chang et al., 2009) with a rough estimation of 152–165 Ma, a precise date for the fossils has not been determined. Here, this study reports SHRIMP U–Pb zircon ages for the fossil horizons and for the feathered species of theropods and ornithischians and transitional forms of pterosaurs, emphasizing the timing of the first appearance of feathered dinosaurs and transitional pterosaurs previously not well determined. 2. Geological background During the Late Mesozoic period, the sampling location and the surrounding area were located in northeastern part of the North China Craton, in a terrestrial environment at a paleolatitude of approximately 45°N (Smith et al., 1994). The Late Mesozoic terrestrial strata of the northeastern China , in ascending order, are the Middle Jurassic Haifanggou Formation (called the Jiulongshan Formation in

Hebei Province) and Lanqi/Tiaojishan Formation, the Upper JurassicLower Cretaceous Tuchengzi Formation (called the Houcheng Formation in Hebei Province), the Lower Cretaceous Zhangjiakou Formation (called as Tamulangou Formatio in the Great Xinganling Mountain, and Maketouebo,Manitu and Baiyingaolao Formations in an ascendering order in southeastern Inner Mongolia), the Dabeigou Formation, the Yixian Formation and the Jiufoutang Formation, which are widely distributed in western Liaoning, northern Hebei, and southern Inner Mongolia of northeastern China (Fig. 1,Table 1) and contain two well preserved terrestrial biotas (the Daohugou Biota and the Jehol Biota). Both the Haifanggou Formation and Lanqi/Tiaojishan Formation yielded fossils of the Daohugou Biota. The fossils of the Jehol Biota occurred within the Lower Cretaceous Zhangjiakou Formation, Dabeigou Formation, Yixian Formation and Jiufoutang Formation. The Haifanggou/Jiulongshan Formation of western Liaoning and northern Hebei of China, containing fauna including conchostracans Euestheria ziliujingensis, bivalves Ferganoconcha spp., insects Mesoneta beipiaoensis Wang, Mesoblattina sp., Sinoplecia protansa Wang, Platyperla plotypoda B. R. et G., and Lycoriomimodes ruida Wang, and abundant plants (Chen, 2003), is mainly composed of sandstones, conglomerates, shales, and interbedded pyroclastic rocks (tuffs) and occasional poor coal seams and has a thickness of more than 200 m. The Lower Haifanggou/Jiulongshan Formation has more conglomerates, and the proportion of pyroclastic rocks increases upward. Limited radioisotopic studies for the Haifanggou/Jiulongshan Formation have been reported. K/Ar whole rock analyses from the Haifanggou/Jiulongshan Formation yielded ages of 146 Ma for a volcanic rock at 900 m depth, 162 Ma for one at 1300 m depth and 178 Ma for one at the base (Chen et al., 1997). Wu et al. (2004) reported Rb/Sr isochron ages of 177 Ma from three samples and 188 Ma from four samples. The large uncertainties of most of these data and the incomplete stratigraphic descriptions of the samples limit their value for high-resolution chronostratigraphy (Chang et al., 2009). The 200–800 m thick Lanqi/Tiaojishan Formation of western Liaoning and northern Hebei, mainly consists of basalts, with andesites in the lower and middle of the formation and rhyolites, acid tuffs, and purple-red tuffaceous siltstones, sandstones, and conglomerates. Besides the abundant conchostracans and plants (Zhang, 2002; Duan et al.,

Fig. 1. Distribution of Late Mesozoic terrestrial strata and tectonics in northeastern China.

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Table 1 Generalized stratigraphic succession, biotas, sedimentary background, and lithology from the Middle Jurassic to the Early Cretaceous in northeastern China. Age/Ma

Stratigraphic succession, thickness/m

Lithology and fossil assemblages

Early Cretaceous

Fuxin Formation, 500–800

Grey, purple red siltstone, sandstone and conglomerates with thinner coal intercaltions. Haizhoulepis, Teichardosaurus, Endotherrium; Sinaeschnidia, Psittacosaurus, Chaangichthys; Ruffordia-Onychiopsisi Yellowish sandstones and siltstone, mud and shale interbeded with tuffs. Jinanichthys longicephalus-Shenzhouraptor sinensis-Hyphalosaurus baitaigouensis AZ Basic volcanic lavas, tuff and yellowish tuffaceous sandstones, siltstone, mudstone. The earliest Angiospermae Feathered dinosaurs, mammals, Pterosaur. "Lycoptera" muroii-Eosestheria jingangshanensis-Ephemeropsis trisetalis AZ. Archaefructus liaoningensis-Zhangheotherium quinquecuspidens-Changchengornis hengdaoziensis AZ; Sinosauropteryx-Confuciusornis-Eomaia AZ Acid volcanic lavas, tuff and tuffaceous sandstones, siltstones, mudstone or shale. Ephemeropsis trisetalis; Peipiaosteus pani; Nestoria pissovi AZ Mainly conglomerates and tuffaceous sandstones, siltstone, mudstone. Chaoyangosaurus liaoxiensis-Pseudongrapta aff. Murchisoniae-Wolburgia polyphema AZ Mainly basic volcanic rocks and tuffaceous with interclations of sandstones, siltstone. Feathered dinosaurs, mammals, Pterosaur, salamander.

Shahai Formation, 500–1700.

110 120

Jiufotang Formation, 800–1200

123

Yixian Formation, 790–1400

125

Middle-Late Jurassic

130

Dabeigou Formation and Zhangjiakou Formation, 200–1000.

140

Tuchengzi Formation, 500–2000

152

Tiaojishan Formation, 200–800.

165

Jiulongshan (Haifanggou) Formation, >200

2009), a fauna including the abundant insects (Ren et al., 2009; Zhang J, 2002, 2004, 2005, 2006, 2007; Zhang and Klugc, 2007) and vertebrates such as salamanders (Gao and Shubin, 2003), pterosaurs (Ji and Yuan, 2002; Lü et al., 2009, 2011), feathered dinosaurs (Hu et al., 2009; Zheng et al., 2009; Xu and Zhang, 2005; Xu et al., 2009, 2010, 2011) and mammals (Ji et al., 2006; Meng et al., 2006; Luo et al., 2007a, 2007b, 2011) were found from the Lanqi/Tiaojishan Formation in northern Hebei, western Liaoning and southern Inner Mongolia as well. The radioisotopic ages for the Lanqi/Tiaojishan Formation obtained by different methods presented various results such as ( 40Ar/ 39Ar) 175–147 Ma (Davis, 2005), (ICP-MS)163 Ma (Zhang et al., 2005) , (SHRIMP U/Pb and 40Ar/ 39Ar)166-153 Ma(Yang and Li, 2008), ( 40Ar/ 39Ar)160 Ma (He H et al., 2004b, 2005), (SHRIMP U/Pb)168-152 Ma (Liu and Liu, 2005; Liu Y et al., 2006) and ( 40Ar/ 39 Ar )161-159 Ma (Chang et al., 2009). Although most samples of the Lanqi/Tiaojishan Formation for the previous radioisotopic works were collected from Hebei and Inner Mongolia, the correlations of the Mesozoic formations between Hebei and Liaoning are clear. Estimates of the Lanqi/Tiaojishan Formation have ranged from the Middle Jurassic (Toarcian) to the latest Jurassic (Tithonian). The Tuchengzi/Houcheng Formation referred to the latest Jurassic (Tithonian) to the earliest Cretaceous (Berriassian) terristrail deposits is widely distributed in the northern area of the North China. Generalized lithologic associations of it, in a varied thickness -ca. 160–4425 m, is similar across north China, and mainly consists of purplish red conglomerate with interclations of tuffaceous sandstone, siltstone and tuffs in the lower member, grey-purple siltstone,

Biotas

Palaeogeography and palaeoecology River, lake marsh with coal beds; insects, invertebrates, vertebrates and plants Dry-hot alluvial, mud flows and fans, rare fossils

Jehol biota

Mainly lakes, wet and hot, vertebrates.

Alluvial fans, volcanic mud flows, rare fossils. Wet-hot, lakes and rivers, high CO2, basic volcanic eruptions, Insects, invertebrates, vertebrates and plants

Lakes during volcanic eruptions, rare fossils

Daohugou biota

Alluvial fans, river and mud flows, rare fossils Lakes during basic magmas eruptions and flow. Rare fossils. Lakes and rivers, plants, invertebrates and plants

sandstone and conglomerate intercalated with sandstone in the middle member and grey-purple conglomerate intercalated with green tuffaceous sandstone in the upper member, occasionly, with interclations of andesitic, rhylotic, trachyandesitic and pyroclastic rocks in the middl or upper part. The Tuchengzi/Houcheng Formation rests unconformably on the Lani/Tiaojishan Formation or the Pre-Mesozoic units. Previously, based on K–Ar, SHRIMP U–Pb and LA-ICP-MS dates, ages of 156–139 Ma of the Tuchengzi/Houcheng Formation were reported (He et al., 1998, 1999; Swisher et al., 2002; Cope, 2003; Shao et al., 2003; Zhang et al., 2005, 2009; Chang et al., 2009). Such, the Tuchengzi Formation have ranged from the Late Jurassic (Tithonian) to Early Cretaceous (Berriassian). Furthermore, the Tuchengzi/Houcheng Formation was deposited during a transition period from the Daohugou Biaota (Yanliao Biota, J2) (Zhang J, 2002) to the Jehol Biota (K1). Sediments in the Tuchengzi/Houcheng Formation is coarser in grained size, purplish red alluvial deposits of mainly fan and brainded river facies interbeded with lacustrine facies, occasionally, volcanic rocks and tuffs, which indicates a tropical, dry and hot climate and paleoenvironment compared with the subtropical, humid and seasonal climate in the early Middle Jurassic as the Daohugou Biaota (Yanliao Biota,J2) lived. The Daohugou Biaota was not adaptive to the poor terrestrial paleoecosystems in the period of the Tuchengzi/Houcheng Formation deposition, most than 90% genus and species of it were unfortunately died out until the next biota (the Jehol Biota) emerged in the earliest period of the Early Cretaceous. Such, except those scattered plants (Zheng and Zhang, 2001; Zheng S et al., 2001), dinosaur and bird tracks (Martin et al., 2006), an unearthed Dinosaur:

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Chaoyangosaurus liaoxiensis (Zheng and Zhang, 2001) or some freshwater invertebrates (Wang et al., 2004; Wang W et al., 2004; Wang and Li, 2008; Shen and Chen, 1984), generally, fewer fossils yielded in the Tuchengzi/Houcheng Formation. The Zhangjiakou Formation is distributed along a northeast trend in northeastern China. The main lithologic components of this formation, with a varied thickness between 200 and 1000 m, are rhyolites, dacite, rhyodacitic trachyandesitic tuffs, and pyroclastic rocks with intercalations of tuffaceous sandstones, siltstones and grey-purple shales, siltstones, sandstones, and conglomerates. The Zhangjiakou Formation either rests unconformably on Pre-Mesozoic units or overlies the underlying Tuchengzi Formation either conformably or unconformably, but field observations from this study indicate no significant break in time between the underlying Tuchengzi deposition. The Dabeigou Formation, interfingerings with the Zhangjiakou Formation, mainly consists of grey-purple shales, siltstones, sandstones, tuffaceous sandstones, and siltstones, yielding Nestoria conchostracans, Ephemeropsis trisetalis flies, and Peipiaosteus fish, indicating fossil traits of the earliest Cretaceous. A number of previous dates of the Zhangjiakou Formation and the Dabeigou Formation by various dates were published, which gives an age interval of 143 Ma–135 Ma(Shao et al., 2003; Zhang et al., 2008b, 2009; Yang and Li, 2008; Liu et al., 2003; Niu et al., 2004). The 790–1400-m-thick Yixian Formation, varying in thickness and lithology in different areas, is mainly composed of andesites, basalts and interbeds of tuffs, tuffaceous sandstones, shales, mudstones, siltstones, and conglomerates. The Jiufotang Formation, 800–1200 m thick, is mainly composed of mudstones, siltstones, shales, sandstones, and tuffs, and interfingers with the Yixian Formation. Both the Yixian Formation and Jiufotang Formation were previously dated by various dating methods, and yielded an age interval of 132 Ma to 121 Ma from the Yixian Formation (Smith et al., 1994; Peng et al., 2003; Swisher et al., 1999, 2002; Wang et al., 2001a, 2001b; Yang and Li, 2008; Zhu et al., 2007; He H et al., 2006; Ji et al., 2011) and 122 Ma-120 Ma from the lower Jiufotang Formation(He H et al., 2004a; Chang et al., 2009).Such, 40Ar/39Ar and zircon U/Pb data above mentioned about the Yixian Formation and the Jiufotang Formation containing the Jehol Biota in northeastern China indicates that two formations were deposited during the Early Cretaceous, the Barremian to early Aptian. Two well preserved Mesozoic terrestrial biotas, the Daohugou Biota ( J2–J3) and the Jehol Biota (K1), are widely distributed in eastern– northern Asia. Previous studies referred to fossils within the Jiulongshan and Tiaojishan Formations as the Daohugou Biota (Zhang J, 2002; Liu Y et al., 2004, 2006), which is mainly composed of terrestrial vertebrates and invertebrates, including dinosaurs (the earliest feathered dinosaurs), the earliest swimming and flying mammals, transitional pterosaurs, salamanders and plants, numerous well preserved insects, and freshwater invertebrates. The Jehol Biota, defined initially as the assemblage of Eosestheria–Ephemeropsis–Lycoptera (Grabau, 1928; Gu, 1962; Chen, 1988), is widely distributed in eastern and central Asia. Most fossils of the Jehol Biota were recently excavated from the Yixian Formation and the overlying or interfingering Jiufotang Formation in northeastern China, and include many fossils of dinosaurs (including feathered dinosaurs) (Chen et al., 1998; Ji et al., 1998; Chang et al., 2003; Zhou et al., 2003; Xu et al., 1999a, 1999b; 2001, 2002, 2004; Xu and Norell, 2004), birds (Zhang F et al., 2004; 2008 Zhang and Zhou, 2008; Zhou, 2004, 2006; Zhou and Zhang, 2002, 2003; Zhou et al., 2003), fish (Jin et al., 1995; Lu, 2002), mammals (Luo et al., 2003, 2007a, 2007b), pterosaurs (Wang et al., 2002, 2005a, 2006, 2009), and freshwater invertebrates, such as insects (Ren et al., 2009, conchostracans (Shen et al.,1984), and plants (Sun et al., 1993, 1998, 2001, 2002, 2011). Both the Daohugou biota and the Jehol Biota are important Mesozoic terrestrial biotas and have provided a rare opportunity to address questions about the origin and evolution of birds, mammals, and dinosaurs, the evolution of feathers and flight, the early diversification of angiosperms, the evolution of insects, and the timing of the placental mammalian radiation.

3. Measured sections, dating sample horizons, and localities The Lanqi Formation, in the Yaolugou and Daxishan fossil localities of western Liaoning, northeastern China, consists of a succession of basic and acidic volcanic rocks, tuff, tuffaceous sandstone, siltstone, and shale. It is about 435–100 m thick and a detailed measurement is given as bellow (Fig. 2). The Lanqi Formation in the Daxishan fossil locality of western Liaoning, GPS to the start of the section: 40°51′45″N, 119°59′59″E, 240 m elev., the end: 40°52′20″N, 119°59′03″E, 309 m elev., is 434.0 m thick and contains 28 beds, and details as follow (Fig. 2). 28. Shallow pink rhyolitic breccia, mainly andesites and trachandensite, 7.9 m thick. 27. Light greyish-green andesitic breccia, 6.3 m thick. 26. Greyish trachandensite, 23.7 m thick. Bottom volcanic rocks yielded a U–Pb zircon SHRIMP age of 158.5 Ma. 25. Light yellow-brown basaltic andesites, 15.8 m thick. 24. Light greyish, thin-bedded calcareous mudstone and shale, horizontal bedding, 44.6 m thick. This bed is thought to be the equivalent of the fossil horizon yielding Tianyulong confuciusi at the Yaolugou fossil locality. 23. Light greyish-green calcareous mudstone, 5.0 m thick. 22. Greyish, thin-bedded deposition of marl and greyish-green calcareous rock, 6.6 m thick. 21. Light greyish, medium-bedded, laminated calcareous siltstone, 10.7 m thick. 20. Greyish-green, thin-bedded, laminated silty shale with lens of tuffaceous siltstone, 1.7 m thick. 19. Greyish laminated mudstone, 2.5 m thick. 18. Yellow-green laminated siltstone, 1.7 m thick. 17. Light greyish, medium-bedded marl, 0.8 m thick. 16. Greyish-green, thin-bedded marl intercalated with muddy shale and a 0.3-m-thick tuff, from which dating specimen 091003–2 was collected (GPS: 40°52′16″N, 119°59′10″E, 260 m elev.), 2.5 m thick. 15. Greyish, medium-bedded marl with yellow-brown and grayishgreen muddy shale,1.6 m thick. 14. Greyish-green, thin-bedded tuffaceous mudstone with lens of 0.3-m-thick marl, 8.3 m thick. 13. Greyish-green and shallow grayish mudstone and muddy shale, occasionally tuffs and tuffaceous sandstone; poorly outcropped, yielding estherias, ostracods, bivalves, fishes, insects, vertebrate, and plant fossils; 119.0 m thick. Both Darwinopterus and A. huxleyi were unearthed from this bed. Dating specimen 091003–1 (GPS: 40°52′13″N, 119°59′17″E, 247 m elev.), dated at 160.5 Ma, was collected from the bottom tuff, and 091003–2, dated at 161.0 Ma, was from a 20-cm-thick tuff 100 m higher than the 091003–1 horizon. 12. Yellow-green-brown pebbly coarse sandstone, mainly breccias of middle-acid volcanic rocks, occasionally silica wood fossils, 29.45 m thick. 11. Shallow yellow siltstone with shale, 7.6 m thick. 10. Yellow-green, pebbly sandstone, 34.65 m thick. 9. Shallow, greyish-green silty mudstone with shale, yielding fishes: Ptycholepidae? insects: Aeschnoidae bivalves: Shaanxiconcha cliovata and Estheria: Euestheria sp., 7.44 m thick. 8. Yellow-green and greyish-green pebbly sandstone, 17.4 m thick. 7. Yellow-brown, rhythmic siltstone and silty mudstone, vertebrate fragments are common, 5.58 m thick. 6. Yellow-green and purple muddy siltstone interbedded with silty shale, 0.9 m thick. 5. Greyish and yellow-green pebbly sandstone, 0.54 m thick. 4. Purple, muddy sandstone, 5.58 m thick. 3. Yellow-brown sandstone interbedded with greyish-green siltstone, 2.56 m thick.

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Fig. 2. Succession, vertebrate fossils, U–Pb dates, and correlation of the Lanqi/Tiaojishan Formation at Daxishan and Yaolugou, Jianchang, western Liaoning Province, and Daohugou, Ningcheng, Inner Mongolia, China. Columnar stratigraphic section A is located in Daohugou, Ningcheng, Inner Mongolia, modified from Liu et al.(2004, 2005,2006) , and B is the section measured in current research in Daxishan, Jianchang, western Liaoning.Numbers beside the columnar section is bed numbers.Various genera and species of fossils of both in Daohugou and Daxishan section are referenced accordingly as the superscript references: 1. Ji et al., 2006; 2. Meng et al., 2006 ; 3. Luo et al., 2007a, 2007b ; 4 and 6. Wang et al., 2005a, 2005b ; 5. Xu and Zhang, 2005; 7. Wang et al., 2002 ; 8. Wang et al., 2005b ; 9. Gao and Shubin, 2003; 10. Zheng et al., 2009; 11–12. Xu et al., 2009; Hu et al., 2009; 13. Lü et al., 2009, 2011.Legend explanations: 1.basaltic andesite ;2. breccia andesite ; 3. andesite ;4. rhyolitic tuff ;5. rhyolite ;6. breccia rhyolite ;7. trachandensite ; 8. calcareous mud ; 9.mud shale ;10. marl ;11. fossil horizon ;12. sandy conglomerate ;13. pebbly sandstone ;14. coarse sandstone ;15. medium sandstone ;16. fine sandstone ;17. mudy siltstone ;18. silty mud ;19. mud ;20. shale ;21. tuffaceous shale ;22. interbeded shale and mud.

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Fig. 3. Locations of sample 091003-1 (left) and sample 091003-2 (right) from interbedded tuff in the Lanqi Formation at Daxishan, Linglongta, Jianchang, western Liaoning, China.

Fig. 4. Sample location for 091002-2 from dacite overlying calcareous siltstone on top of the Lanqi Formation at Yaolugou, Jianchang, western Liaoning, China.

2. Greyish-green andesite, 48.64 m thick. 1. Purple andesite. Three samples, including two tuffs and one lava, were collected for dating from both of the horizons containing fossils and the overlying lavas in the Tiaojishan Formation in the Yaolugou and Daxishan sections. Two samples are from the Daxishan (Fig. 2,B; Fig. 3) and the rest are from Yaolugou (Fig. 4). Sample 091003-1 is from a 1–2-cmthick clay-rich tuff, 30 cm above the horizon yielding feathered theropods (Fig. 2, B) and pterosaurs, and 091003-2 is from a 20-cm-thick tuff 100 m above 091003-1 (Fig. 2,B). Both samples were located within the middle lacustrine deposits of this formation in Daxishan. Sample 091002-2 was collected from dacite overlying clay-rich siltstone where Tianyulong was unearthed at Yaolugou (Fig. 4;Fig. 2,B, layer 26). 4. Methods and dating results Three dating samples, including two tuffs and one dacite, were successfully extracted from zircons (Fig. 5) for SHRIMP U–Pb dating. Zircons were separated from samples using standard density and magnetic separation techniques at the Institute of Geology and Mineral Resources, Hebei, China. Zircon grains, together with the zircon U–Pb standard TEMORA (Black et al., 2003), were cast in an epoxy mount, which was then polished to section the crystals in half for analysis. Zircons were documented with transmitted and reflected light micrographs, as well as cathodoluminescence (CL) images, to reveal their internal structures (Fig. 5), and the mounts were vacuum-coated with a 500-nm layer of high-purity gold. Under the guidance of zircon CL images, the zircons were analyzed for U–Pb isotopes and U, Th, and

Pb concentrations (Tables 2–4) using a SHRIMP II ion microprobe at the Beijing SHRIMP Center, Chinese Academy of Geological Sciences, Beijing, following the procedures reported by Liu D. (2006). The U–Th–Pb isotopic ratios were determined relative to the TEMORA standard zircon corresponding to 417 Ma 206Pb/238U =0.0668 (Black et al., 2003), and the absolute abundances of U–Th–Pb were calibrated to the standard zircon M257. Analyses of the TEMORA standard zircon were interspersed with unknown sample grains, following operating and data processing procedures described by Williams (1998). The reference zircon was analyzed after every fourth analysis. Measured compositions were corrected for Common Pb using the 204Pb method (Compston et al., 1984), and data processing was carried out using Isoplot (Ludwig, 2001). Uncertainties for individual analyses are reported at the 1-sigma level; mean ages for pooled 206Pb/ 238U results are quoted at the 2-sigma level. Errors are 1-sigma; Pbc and Pb⁎ indicate the common and radiogenic portions, respectively. Error in standard calibration was 0.25% (not included in the above errors but required when comparing data from different mounts). Age dates common Pb corrected using measured 204Pb, common Pb corrected by assuming 206Pb/ 238U– 207Pb/ 235U age-concordance, and common Pb corrected by assuming 206Pb/ 238U– 208Pb/ 232Th age-concordance. Zircons from tuffs and dacite samples show similar or different crystal forms of euhedral or long columnar with inherited cores and crystallization growth texture mostly at a size of about 100 μm (Fig. 5) and exhibit low to high uranium and thorium content, yielding Th/U ratios greater than 0.48 (Tables 2–4). All these features are consistent with the zircons being magmatic in origin (Compston et al., 1984). Thus, the interpretation of the zircon U–Pb isotopic data (see following) is straightforward, and the

Fig. 5. Cathodoluminescence (CL) images of zircon SHRIMP dating of rocks from the Lanqi Formation in Jianchang, western Liaoning, northeastern China.Circles indicate the locations for SHRIMP U–Pb dating, which was performed at the Beijing SHRIMP II Center, Chinese Academy of Geological Sciences. U/Th ratio plot (left, down) showing that all analyzed zircons are magmatic.

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Table 2 Dating results for sample 091003-1 from the Lanqi Formation, Jianchang, western Liaoning, China. Errors on individual spots are based on counting statistics and are at the 1σ level, but the average weighted ages are quoted at 2 s or 95% confidence. Pbc and Pb* indicate the common and radiogenic portions, respectively. The common lead is corrected by assuming 206Pb/238U–208Pb/232Th age-concordance. Spots

1.1 2.1 3.1 4.1 5.1 6.1 7.1 8.1 9.1 10.1 11.1 12.1 13.1 14.1 15.1 16.1 17.1 18.1 19.1 20.1 21.1 22.1 23.1 24.1

U ppm

Th ppm

232

%

206

1.59 0.39 0.50 0.50 0.23 1.18 1.05 3.63 1.63 3.37 0.82 0.54 3.14 1.68 1.99 2.45 0.27 0.99 0.32 1.69 0.23 0.12 0.82 0.85

174 300 427 369 386 304 269 423 144 165 422 719 1034 498 305 150 415 436 392 167 448 648 584 148

105 203 199 272 561 326 165 547 100 85 276 396 1701 750 191 72 224 272 205 118 631 397 382 80

0.62 0.70 0.48 0.76 1.50 1.11 0.63 1.34 0.72 0.53 0.68 0.57 1.70 1.56 0.65 0.49 0.56 0.65 0.54 0.73 1.45 0.63 0.67 0.56

Pbc

238

Th / U

206 Pb⁎ ppm

3.9 6.6 9.3 7.9 8.4 6.3 5.8 8.2 3.2 3.6 9.1 15.5 21.3 15.0 6.7 3.3 9.1 9.6 8.5 3.6 13.8 14.3 12.9 3.3

206

207

Pb/ U Age

Pb/ Pb Age

238

161.3 163.3 160.7 158.3 161.3 151.4 157.1 138.7 161.1 158.3 159.2 159.1 147.8 218.8 159.9 159.0 161.6 161.9 160.2 158.1 225.8 163.8 161.9 161.3

206

2.4 2.2 2.0 2.4 2.0 2.1 2.2 2.0 2.8 2.8 2.0 1.9 1.8 2.8 2.3 3.3 2.0 2.0 2.0 2.3 3.0 1.9 1.9 2.5

− 369 103 48 101 157 125 − 204 490 − 412 − 2552 − 58 − 22 290 221 − 618 − 769 − 37 105 129 170 205 164 − 169 − 13

obtained 206Pb/ 238U ages are interpreted as dating from the time of crystallization of the zircons and thus the time of deposition of the host rocks. Zircon U–Pb age data from actual analyses are given in Tables 2–4 and Fig. 5. All 19 points from 091003-1 yield a weighted mean 206Pb/ 238Pb date of 160.5 ± 0.99 Myr (MSWD = 0.71)(Fig. 6). Thirteen dated zircons from 091003–2 give a weighted mean 206Pb/ 238Pb age of 161.0 ± 1.44 Myr (MSWD = 1.18) (Fig. 6). A weighted mean 206Pb/238Pb age of 158.5 ± 1.6 Myr (MSWD = 0.57) is obtained from 11 dated zircons from sample 091002-2(Fig. 6). Dating results of 161 and 160.5 Myr (0910031 and 091003-2) provide a fine age constraint for both Anchiornis and

284 153 164 135 100 201 297 257 462 1835 95 110 180 205 375 921 129 151 135 172 60 52 189 281

Pb⁎ / Pb⁎

Discor dant/%

207

144 − 59 − 232 − 56 −3 − 21 177 72 139 106 374 811 49 1 126 121 536 − 55 − 24 7 − 10 0 196 1310

.0397 .0481 .0470 .0480 .0492 .0485 .0424 .0570 .0391 .0204 .0450 .0456 .0521 .0506 .0362 .0343 .0453 .0481 .0486 .0495 .0502 .0493 .0430 .0458

206

207

±%

235

11.0 6.5 6.9 5.7 4.3 8.5 11.8 11.7 17.7 42.7 3.9 4.6 7.9 8.9 13.7 32.7 5.3 6.4 5.7 7.4 2.6 2.2 7.6 11.6

Pb⁎ / U

0.14 0.17 0.16 0.16 0.17 0.16 0.14 0.17 0.14 0.07 0.16 0.16 0.17 0.24 0.13 0.12 0.16 0.17 0.17 0.17 0.25 0.18 0.15 0.16

±%

206 238

11.1 6.6 7.0 5.9 4.5 8.7 11.9 11.8 17.8 42.7 4.1 4.7 8.0 9.0 13.8 32.8 5.4 6.5 5.9 7.5 2.9 2.5 7.7 11.7

Pb⁎ / U

.0253 .0257 .0252 .0249 .0253 .0238 .0247 .0217 .0253 .0249 .0250 .0250 .0232 .0345 .0251 .0250 .0254 .0254 .0252 .0248 .0357 .0257 .0254 .0253

±%

err corr

1.5 1.3 1.3 1.5 1.3 1.4 1.4 1.5 1.7 1.8 1.3 1.2 1.2 1.3 1.5 2.1 1.2 1.3 1.3 1.5 1.4 1.2 1.2 1.6

.137 .203 .184 .257 .285 .160 .121 .125 .098 .042 .305 .253 .155 .144 .106 .063 .229 .197 .217 .198 .466 .458 .159 .135

Darwinopterus. Moreover, a date of 158.5 Myr for 091002-2 from volcanic rocks overlying the fossil horizon at Yaolugou suggests the youngest age estimation for Tianyulong. Previous dates for the Tiaojishan Formation in Daohugou, Ningcheng, Inner Mongolia, yielded an age of 152–165 Myr(Fig. 2,A) (Chen et al., 2004; He H, 2004b, 2005; Liu Y et al., 2004, 2006; Liu and Liu, 2005). 5. Discussion and implications Current date results indicate that tuffs from the horizon yielding Anchiornis and Darwinopterus in Daxishan, Jianchang, revealed two

Table 3 Dating results for sample 091003-2 from the Lanqi Formation, Jianchang, western Liaoning, China. Errors on individual spots are based on counting statistics and are at the 1σ level, but the average weighted ages are quoted at 2 s or 95% confidence. Pbc and Pb* indicate the common and radiogenic portions, respectively. The common lead is corrected by assuming 206Pb/238U -208Pb/232Th age-concordance. Spots

1.1 2.1 3.1 4.1 5.1 6.1 7.1 8.1 9.1 10.1 11.1 12.1 13.1 14.1 15.1 16.1 17.1 18.1 19.1 20.1

206

Pbc/ %

0.19 – 0.09 1.35 0.59 0.54 1.75 0.88 0.16 1.26 0.36 1.39 0.01 0.08 0.64 0.31 0.52 0.63 0.25 0.70

U/ ppm

Th/ ppm

232

393 212 398 881 208 760 1121 313 71 66 305 80 42 38 426 228 204 154 395 280

262 146 637 1310 162 763 1812 265 83 87 108 102 31 32 587 193 166 120 467 154

0.69 0.71 1.66 1.54 0.81 1.04 1.67 0.88 1.21 1.37 0.37 1.33 0.77 0.87 1.42 0.88 0.84 0.80 1.22 0.57

238

Th / U

206 Pb*/ ppm

206

Pb/ U/ Age

8.74 7.45 8.72 19.2 9.16 16.4 24.6 6.92 18.2 2.51 6.66 1.73 16.8 1.57 9.40 4.84 4.54 5.22 8.60 6.24

164.5 258.1 162.3 159.2 320.9 158.8 159.7 162.3 1,681 277.2 161.2 158.9 2.445 305.1 162.6 157.1 163.8 248.2 160.9 164.3

207

Pb/ Pb/ Age

238

206

± 2.0 ± 3.3 ± 2.4 ± 1.8 ± 4.1 ± 1.8 ± 1.8 ± 2.7 ± 25 ± 4.5 ± 2.0 ± 2.9 ± 32 ± 7.5 ± 1.9 ± 2.1 ± 2.5 ± 3.5 ± 2.0 ± 2.4

150 456 216 124 137 − 17 − 27 − 298 1,817 379 105 − 104 2,503 407 − 41 16 − 98 208 114 − 47

± 56 ±51 ±98 ±140 ±160 ± 73 ±150 ±150 ±26 ±110 ±110 ±310 ±21 ±520 ±87 ±180 ±320 ±91 ±85 ±130

Pb⁎ / Pb⁎

Dis cordant/ %

207

− 10 43 25 − 29 − 135 1056 686 154 7 27 − 54 253 2 25 499 − 880 267 − 20 − 42 450

0.0490 0.0561 0.0505 0.0485 0.0488 0.0457 0.0455 0.0408 0.1111 0.0542 0.0481 0.0441 0.1645 0.055 0.0453 0.0464 0.0442 0.0503 0.0483 0.0452

206

±%

207 235

2.4 2.3 4.2 5.9 6.8 3.0 6.0 5.8 1.4 4.7 4.7 13 1.2 23 3.6 7.3 13 3.9 3.6 5.2

Pb⁎ / U

0.1747 0.3160 0.1774 0.167 0.343 0.1572 0.1574 0.1435 4.56 0.328 0.1680 0.152 10.46 0.367 0.1594 0.158 0.157 0.272 0.1683 0.1607

±%

Pb⁎ / U

±%

err corr

0.02584 0.04085 0.02550 0.02500 0.05104 0.02494 0.02508 0.02549 0.2979 0.04394 0.02533 0.02496 0.4612 0.0485 0.02554 0.02467 0.02574 0.03926 0.02527 0.02581

1.3 1.3 1.5 1.2 1.3 1.1 1.1 1.7 1.7 1.7 1.3 1.8 1.6 2.5 1.2 1.4 1.5 1.4 1.2 1.5

.469 .490 .338 .193 .190 .355 .186 .274 .762 .333 .261 .143 .787 .109 .319 .185 .116 .339 .323 .273

206 238

2.7 2.6 4.5 6.0 7.0 3.2 6.1 6.1 2.2 5.0 4.9 13 2.0 23 3.8 7.4 13 4.2 3.8 5.5

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Table 4 Dating results for sample 091002-2 from the Lanqi Formation, Jianchang, western Liaoning, China. Errors on individual spots are based on counting statistics and are at the 1σ level, but the average weighted ages are quoted at 2 s or 95% confidence. Pbc and Pb* indicate the common and radiogenic portions, respectively. The common lead is corrected by assuming 206Pb/238U–208Pb/232Th age-concordance. Spots

1.1 2.1 3.1 4.1 5.1 6.1 7.1 8.1 9.1 10.1 11.1 12.1 13.1 14.1 15.1 16.1 17.1 18.1 19.1 20.1

U/ ppm

Th/ ppm

232

%

206

1.45 3.45 2.86 1.54 0.48 3.56 2.82 – – 4.58 1.20 0.21 3.79 2.78 4.68 0.70 – 1.00 1.06 1.93

54 185 76 51 214 97 119 73 71 63 111 108 60 202 52 252 204 83 182 118

42 207 64 42 294 77 113 65 53 47 122 80 47 287 39 306 279 84 171 100

0.79 1.16 0.86 0.85 1.42 0.82 0.98 0.91 0.77 0.78 1.13 0.77 0.81 1.47 0.77 1.25 1.42 1.04 0.97 0.88

Pbc

238

Th / U

206 Pb*/ ppm

206

Pb/ U Age

1.16 3.99 1.62 1.12 4.63 2.06 2.50 1.54 1.54 1.37 2.40 2.34 1.26 4.28 1.11 5.52 4.39 1.80 3.87 2.55

156.4 154.1 153.3 158.9 159.7 151.9 151.6 155.8 163.4 153.9 158.1 160.7 150.0 152.8 152.2 161.1 160.1 158.7 155.7 157.6

207

Discordant%

Pb/ Pb Age

238

206

±3.2 ±2.6 ±3.6 ±4.0 ±2.2 ±3.2 ±2.9 ±2.9 ±2.9 ±4.7 ±2.8 ±2.7 ±3.2 ±2.5 ±3.5 ±2.3 ±2.6 ±4.2 ±2.2 ±2.6

207 206

Pb⁎ / Pb⁎

±%

207 235

Pb⁎ / U

±%

±%

err corr

0.02456 0.02420 0.02407 0.02496 0.02509 0.02384 0.02379 0.02446 0.02567 0.02416 0.02483 0.02525 0.02353 0.02399 0.02388 0.02531 0.02515 0.02493 0.02444 0.02475

2.0 1.7 2.4 2.5 1.4 2.2 1.9 1.9 1.8 3.1 1.8 1.7 2.2 1.7 2.3 1.5 1.7 2.7 1.5 1.7

.181 .055 .064 .089 .172 .043 .059 .199 .372

238

226 − 1410 − 700 − 36 − 29 − 1990 − 1330 431 707

±260 ±1000 ±1000 ±690 ±200 ±1900 ±1000 ±200 ±96

31 111 122 544 650 108 111 64 77

0.0507 0.0277 0.035 0.045 0.0455 0.023 0.0284 0.0555 0.0630

11 31 37 28 8.1 50 33 9.2 4.5

0.172 0.092 0.116 0.156 0.157 0.077 0.093 0.187 0.223

11 32 37 28 8.2 50 33 9.4 4.9

35 261 − 1161 − 1457 − 2300 60 251 136 − 78 − 348

±370 ±210 ±820 ±920 ±1800 ± 200 ±72 ±520 ±180 ±350

− 358 38 113 110 107 − 170 36 − 17 299 145

0.0467 0.0514 0.0300 0.0273 0.0217 0.0472 0.0512 0.049 0.0446 0.0400

15 9.3 27 28 44 8.2 3.1 22 7.4 13

0.160 0.179 0.097 0.090 0.071 0.165 0.1777 0.168 0.150 0.137

16 9.4 27 28 44 8.3 3.5 22 7.6 14

ages of 160.5 and 161.0 Myr (091003-1 and 091003-2), respectively, which provides a fine age constraint for both Anchiornis and Darwinopterus. Furthermore, a date of 158.5 Myr (091002-2) from volcanic rock overlying a fossil horizon at Yaolugou, Jianchang, suggests an accurate age constraint for Tianyulong as well, and a youngest age estimation for Anchiornis and Darwinopterus. The recent dates are consistent with previous dates for the Tiaojishan Formation in Daohugou, Ningcheng, Inner Mongolia, where the earliest fossils from the Daohugou Biota were found and ages of 152–165 Myr (Liu and Liu, 2005; Liu Y et al., 2006) were reported, and be identical to the dating results of 152–165 Myr (Chen et al., 2004; Gao et al., 2004; He H et al., 2004b, 2005; Davis, 2005, Davis et al., 2001; Zhang H et al., 2005, 2008, 2009; Liu and Liu, 2005; Liu Y et al., 2006; Hu J et al., 2007), obtained from the Lanqi/Tiaojishan Formation in both northern Hebei and western Liaoning province rogionally and locality of Daohugou, Ningcheng, Inner Mongolia. Other Jurassic fossil beds that have produced unquestionable feathered dinosaur specimens are found in the Archaeopteryx-bearing strata near Solnhofen, Germany. The Solnhofen beds, however, were dated to less than 150 Ma and are therefore younger than the Tiaojishan Formation based on this study. The feathered dinosaurs of China were present more than 161 Myr ago and are unquestionably older than Archaeopteryx from Germany, and much older than Sinosauropteryx (125 Myr) from the Jehol Biota in China; they are thought to be the oldest known feathered theropods in the world. The known transitional pterosaurs first emerged before 161 Myr. Furtherly,Archaeopteryx has long been placed at the base of the bird evolutionary tree and is widely accepted as being the most basal bird, and accordingly it is regarded as central to understanding avialan origins (Xu et al.,2011).However, recent discoveries of derived maniraptorans i.e., a new Archaeopteryx-like theropod (Xiaotingia zhengi) from China, have weakened the avialan status of Archaeopteryx, and Xu et al.(2011) argued that identify Xiaotingia is an animal very closely related to Archaeopteryx and another feathery relative, Anchiornis (Xu et al., 2011). Such, current dates will help palaeontologists to understand when the ancestors of modern birds or closely related cousins appeared.

Pb⁎ / U

206

.117 .180 .081 .059 .053 .174 .470 .119 .192 .125

In addtionally, Zheng et al. (2009) reported a new heterodontosaurid, Tianyulong confuciusi gen. et sp. nov. from Jianchang County, western Liaoning Province, China. Although previous heterodontosaurid records are mainly from the Early Jurassic period (205–190 million years ago) of Africa, Zheng et al. (2009) concluded that the fossil was from “the Early Cretaceous horizon (i.e., Jehol Group, 144– 99 Ma interval)” and insisted that “Tianyulong extends the geographical distribution of heterodontosaurids to Asia and confirms the clade's previously questionable temporal range extension into the Early Cretaceous period.” The problem with much of this conclusion is that it provides no evidence to support the authors’ statement about the geochronology and stratigraphic horizon from which Tianyulong was collected. The present date results from lava overlying the Tianyulong horizon show clearly that feathers appeared in ornithischians before 159 Myr (perhaps Middle to Late Jurassic) earlier than the 144–99 Myr reported by Zheng et al. (2009). Therefore, according to new dating ages, the Tianyulong-bearing sequence is neither Jehol Group nor Early Cretaceous in age. Evolutionary implications of Tianyulong need to be reevaluated. Besides the main vertebrate fossils of Anchiornis, Darwinopterus, and Tianyulong, the other main vertebrates that were recovered from the lacustrine deposits of the Tiaojishan Formation at Daxishan include fish (Ptycholepidae indet), which are mainly from early Middle Jurassic sediments in western China (Hu et al., 2009). Associated invertebrate fossils include the conchostracan Euestheria sp., the ostracodans Darwinula sarytirmenensis, D. impudica, and D. magna, the bivalve Shaanxiconcha cliovata, and insects (Aeschnoidae indet.)(Duan et al., 2009), which are widely distributed in sediments containing fossils of Anchiornis, Darwinopterus, and Tianyulong, suggesting a Middle Jurassic age. Taken together, the vertebrates Anchiornis, Darwinopterus, and Tianyulong and associated invertebrate fossils at the Daxishan and Yaolugou localities are closely correlated to fossils (the Daohugou Biota) recovered from the Middle-Upper Jurassic Lanqi/Tiaojishan Formation in northeastern China. Recent discoveries from the middle Jurassic biota (or the Daohugou Biota) in northeastern China is beneficial to improves our understanding of the evolutionary history of several biota groups and to

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Fig. 6. Concordia diagrams for zircon analyses from tuffs and dacite samples, Lanqi Formation, Jianchang, western Liaoning, China.

Y.-Q. Liu et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 323–325 (2012) 1–12

reconstructs the Mesozoic ecosystem in terrestrial environment. However, controversy remains over the host stratigraphy and geochronology of the Daohugou Biota. Current new age data for the feathered dinosaurs and host Lanqi/Tiaojishan Formation suggest that the earliest known feathered dinosaurs and transitional pterosaurs is absolutely older than the Jehol Biota and equivalent to the Daohugou Biota as well. The Daohugou Biota was vast living, during the Middle Jurassic, in Inner Mongolia ,western Liaoning and northern Hebei in northeastern China. 6. Conclusions The newly obtained dating results for the fossil horizons containing the feathered dinosaurs and transitional pterosaurs provide, for the first time, an accurate age constraint for the appearance of feathered dinosaurs and transitional pterosaurs. Date results indicate that the feathered dinosaurs of China were present more than 161 Myr ago and are unquestionably older than Archaeopteryx from Germany and the Jehol Biota as well. Thus the feathered dinosaurs in China are the earliest known feathered dinosaurs in the world. Feathers appeared in ornithischians before 159 Myr rather than 144–99 Myr. The known transitional pterosaurs first emerged before 161 Myr. Furthermore, associated invertebrate fossils at the fossil localities in northeastern China, in addition to the main vertebrate fossil occurrences of Anchiornis, Darwinopterus, and Tianyulong, are closely correlated with fossils recovered from the Middle-Upper Jurassic Lanqi/ Tiaojishan Formation(the Daohugou Biota).The Daohugou Biota, containing mammals, primitive pterosaurs, insects and plants, in addition to the feathered dinosaurs, was living in Inner Mongolia ,western Liaoning and northern Hebei in northeastern China during the Middle Jurassic. Acknowledgments We thank Prof. Ji Shu'an, Lu Junchang and You Hailu for stimulating discussions, and Dr. Dong Chunyan and Dr. Wang Wei for their help with laboratory work and processing data for the zircon SHRIMP U–Pb ages. Financial support from the Natural Science Foundation of China (90914003), the China Geology Survey (1212010610421, 1212011085477, 1212010610421) special funds for Basic scientific research of Geology Institute of CAGS(J1106) are gratefully acknowledged. Constructive reviews by editor, Prof.Finn Surlyk, and two anonymous reviewers improved the manuscript substantially. References Black, L.P., Kamo, S.L., Allen, C.M., Aleinikoff, J.N., Davis, D.W., Korsch, R.J., Foudoulis, C., 2003. TEMORA 1: a new zircon standard for Phanerozoic U–Pb geochronology. Chemical Geology 200, 155–170. The Jehol Biota, the Emergence of Feathered Dinosaurs, Beaked Birds and Flowering Plants. In: Chang, M., Chen, P., Wang, Y. (Eds.), Shanghai Scientific & Technical Publishers,China, Shanghai. Chang, S., Zhang, H., Renne, P.R., Fang, Y., 2009. High-precision 40Ar/39Ar age constraints on the basal Lanqi Formation and its implications for the origin of angiosperm plants. Earth and Planetary Science Letters 279, 212–221. Chen, P., 1988. Distribution and migration of Jehol fauna with reference to nonmarine Jurassic–Cretaceous boundary in China. Acta Palaeontologica Sinica 27, 659–683 (in Chinese with English abstract). Chen, P., 2003. Jurassic Biostratigraphy of China. Biostratigraphy of China. Science Press, Beijing, pp. 423–463. Chen, Y., Chen, W., Zhou, X., Li, Z., Liang, H., Li, Q., 1997. Liaoxi and Adjacent Mesozoic Volcanic Rocks: Chronology, Geochemistry and Tectonic Setting. The Seismological Press, Beijing. (in Chinese with English abstract). Chen, P., Dong, Z., Zhen, S., 1998. An exceptionally well-preserved theropod dinosaur from the Yixian Formation of China. Nature 391, 147–152. Chen, W., Ji, Q., Liu, D., Zhang, Y., Song, B., Liu, X., 2004. Isotope geochronology of the fossil-bearing beds in the Daohugou area, Ningcheng, Inner Mongolia. Geological Bulletin of China 23 (12), 1166–1169 (In Chinese with English abstract). Compston, W., Williams, I.S., Meyer, C., 1984. U–Pb geochronology of zircons from Lunar Breccia 73217 using a sensitive high mass resolution ion microprobe. Journal of Geophysical Research 89, 525–534.

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