A Review of the Tetrapod Track Record in China,with Special Reference to Type Ichnospecies:Implications for Ichnotaxonomy and Paleobiology

＂Splitting＂ and ＂lumping＂ are perpetual problems in vertebrate, especially dinosaur, ichnotaxonomy. Chinese dinosaur ichnotaxonomy, which began in 1940, provides a series of interesting case studies, highlighting the dual problems of historical and dubious ichnotaxonomy. Chinese Mesozoic tetrapod track types have been placed into 63 ichnospecies （one Triassic, 28 Jurassic, and 34 Cretaceous）, exclusive of other, non-type ichnospecies or ichnotaxa identified from China. Fifty-two （~83%） of these 63 tetrapod ichnospecies were placed in monospecific ichnogenera. At the ichnogenus level, we prune---either by recognizing nomina dubia or by synonymy--17 from the list of 53 dinosaurian ichnogenera （a 32% reduction）, leaving 36 ichnotaxa that we consider valid. Most of the cuts affect Jurassic theropod ichnotaxa, which are reduced from 23 to only nine because most ichnogenera are subjective junior synonyms of Grallator and Eubrontes. Fewer Chinese Cretaceous ichnotaxa （only six of 21 ichnogenera） are obvious nomina dubia or subjective synonyms, suggesting greater east Asian endemism during this time. Because ichnospecies differences are subtle, we provisionally retain ichnospecies as valid pending detailed comparative analyses of congeneric ichnospecies. This synthesis is long overdue and is necessary to address problems of historical and provincial ichnotaxonomy, which severely hamper comparisons of tetrapod ichnofaunas in space and time.

An Important Ornithischian Tracksite in the Early Jurassic of the Shenmu Region,Shaanxi,China

A large track site with multiple, well-preserved trackways of an Early Jurassic quadrupedal ornithischian dinosaur is the first report of Moyenisauripus-like trackways from Asia, herein named Shenmuichnus youngteilhardorum. The tracks occur in a clastic fluvial sequence in the Fuxian Formation in Shenmu County, Shaanxi Province, which is in the same general region as the discovery site of Sinoichnites, the first dinosaur track reported from China. Based on size and morphology, it is likely that Sinoichnites, which is now lost, also represents an ornithischian. The Shenmuichnus youngteilhardorum trackways show two modes of preservation： the first representing deeper tracks, with sediment rims, results in Deltapodus-like tracks, with indistinct pes digit traces and sub-circular manus traces, the second produces Moyenosauripus-like tracks, with clear tridactyl and pentadactyl digit traces in the pes and manus respectively. Thus the Shenmu trackways play a key role in resolving globally significant ichnotaxonomic problems surrounding the nomenclature of Sinoichnites, Moyenosauripus, Deltapodus and other named （Ravatichnus） and unnamed trackways from Asia, Africa and Europe. In addition they shed important light on the paleogeographical and paleoecological distribution of quadrupedal ornithischians in the Early Mesozoic. The track site has been the focus of a major excavation to transfer the trackways from their original remote location to the new Shenmu Museum, in Shenmu City. Other tracksites in the area which reveal Anomoepus, Grallator and the Deltapodus morphotype, together with Shenmuichnus and plant fossil evidence, suggest an Early Jurassic age for the tracksite.

Theropod assemblages and a new ichnotaxon Gigandipus chiappei ichnosp.nov.from the Jiaguan Formation,Lower Cretaceous of Guizhou Province,China

A newly discovered Jiaguan Formation(Lower Cretaceous) tracksite from the Linjiang region of Guizhou Province, China, reveals the first example of a Cretaceous track morphotype attributable to the non-avian theropod ichnogenus Gigandipus, here named Gigandipus chiappei ichnosp nov. The theropod dominated locality also reveals the second report of the avian theropod ichnogenus Wupus, one of the largest avian traces currently known from the Lower Cretaceous. The Linjiang site provides evidence to support previous interpretations of a distinctive Lower Cretaceous theropod-dominated ichnofauna that was widespread in China and East Asia and highlights the similarity between Lower Cretaceous theropod ichnotaxa in East Asia and those found in the Lower Jurassic both in East Asia and elsewhere. These similarities in turn create various ichnotaxonomic challenges familiar to researchers working on theropod tracks, and we recommend caution in the naming of new theropod ichnotaxa at the ichnogenus level.

New Early Cretaceous Pterosaur-Bird Track Assemblage from Xinjiang, China:Palaeoethology and Palaeoenvironment

A pterosaur-bird track assemblage from a sandstone-siltstone-mudstone sequence of the Lower Cretaceous Tugulu Group of Xinjiang comprises the first pterosaur track record from this province and the largest specimen thus far known from China.The pterosaur tracks are assigned to the ichnogenus Pteraichnus based on the triangular overall-shape,the four elongate digit traces and the robust manual digit trace Ⅲ.Supposed trackmakers were dsungaripterid pterodactyloids whose skeletal remains are well known from the Tugulu Group.The bird tracks that occur on the same surface,are those of typical shorebirds,known from different other localities in southeast Asia.The congruence with Koreanaornis dodsoni described from the same stratigraphic level justifies an assignment to this ichnospecies.This is a further evidence of the co-occurrence of pterosaurs and birds in a typical iakeshore environment with possible seasonal alteration of water supply and aerial exposure indicated by wave ripples,mudcracks and repeated cycles of coarse to fine sediment.Pterosaurs and birds frequented the shoreline and may have fed also on the numerous invertebrates such as the Scoyenia tracemaker that left abundant burrows.

Unusual dinosaur trackway preservation as clues to paleo-landscape and behavior from the Lower Cretaceous Luohe Formation,Shaanxi Province,China

Poorly preserved tracks have limited ichnotaxonomic or biotaxon utility,but may reveal useful information about the paleoenvironment,behavior and track taphonomy.Eight mostly parallel to sub parallel trackway segments(T1–T8)were registered on a truncation surface in the Lower Cretaceous Luohe Formation of Shaanxi Province.These attest to the passage of several bipeds,probably all theropods,in a paleo-contour-parallel,south-north direction in an arid setting.Quality of preservation in these trackways is poor,but notably superior in two additional trackways(T9–T10)on a foreset surface.Trackway T9 indicates a didactyl trackmaker,probably a deinonychosaurian,heading north to south.This is the 13th report of deinonychosaurian tracks from the Lower Cretaceous of China.If any or all the eight south-north oriented trackway segments represent continuations of other segments in the same trackways,the total number of individual trackmakers heading in this direction may have been as lowas three.Although the trackway pattern and sedimentological evidence could indicate a physically controlled pathway influencing the direction taken by these trackmakers,the possibility that the trackways also represented small social or gregarious group cannot be ruled out.

Largest dinosaur tracksite in China (Cretaceous, Zhaojue area, Sichuan Province): On the verge of destruction

The Zhaojue(ZJ)tracksites represent multiple steeply-inclined,track-bearing exposures in the clastic Feitianshan Formation of Sichuan Province that have been sequentially,excavated,mapped,expanded and destroyed,by quarrying,erosion or collapse,for almost three decades.The quarried area extends for more almost 1.0 km from north to south and-0.5 km from east to west.Four important track-bearing surfaces have been identified and identified as ZJ-Ⅰ,ZJ-Ⅱ,ZJ-ⅡN and ZJ-Ⅲ,some of which are newly exposed surfaces or expanded surfaces that were previously partially described.Others represent surfaces lost since they were first reported in papers published in 2014-2016.The ZJ-Ⅱ site represents a hugely expanded continuation of a much smaller track-bearing surface described in 2014.It was mapped using drone technology,and now represents the largest tracksite in China,with a minimum count of 933 recognizable tracks,and the longest recorded sauropod and ornithopod trackways from China(-80 m and-52 m respectively),which also reveal a pronounced change in the direction of trackmaker movement.The ZJ-Ⅱ surface represents the best Zhaojue paleo-census sample giving a count of 68 individuals from 61 trackways(37 ornithopod,10 theropod,14 sauropod)and isolated tracks(representing 7 individuals).Thus,ornithopods(both large and small trackmakers)represent-54%of the total number of trackways.The smaller ZJ-Ⅲ surface was mapped using traditional methods,and reveals at least 6 ornithopod-and 4 theropod trackways.Both the ZJ-Ⅱ and ZJ-Ⅲ surfaces reveal parallel ornithopod trackways suggestive of social or gregarious behavior.The combined data from all four Zhaojue surfaces reveal a total of 1928 tracks,and include a few previously reported pterosaurs and theropod swim tracks.The Zhaojue quarry complex provide a good example of multiple track-bearing sites(surfaces)that require long term study and monitoring to extract as much trackway data as possible before in situ physical evidence is lost.

First Report of Avian Tracks from the Cretaceous of Tibet, China

Objective Despite a large number of bird fossils in the Jehol Biota, Mesozoic bird records from other parts of China are dominated by tracks. Late Cretaceous bird tracks are rarely found in China. Reliable reports so far include a Dongyangornipes and Koreanaornis assemblage of early Late Cretaceous age from Dongyang City, Zhejiang Province, China （Azuma et al., 2013）. Buckley et al. （2016） consider Dongyangornipes sinensis a subjective junior synonym of Uhangrichnus chuni. Type Uhangrichnus chuni （Yang et al. 1995; Lockley et al., 2012） from the Uhangri Formation, Hwangsan Basin of South Korea is Late Cretaceous in age, and the trackrnaker was a web-footed avian.

山东莒南早白垩世新类型鸟类足迹化石

在山东省莒南县后左山早白垩世大盛群田家楼组(巴列姆-阿普特期)发现保存在泥质粉砂岩层面上的5个连续的足迹.经研究, 认为是一新类型鸟类足迹化石, 命名为Shandongornipes(山东鸟足迹).足迹中大型、四趾, 宽约5.8 cm, 全长(含拇指)8.7 cm.趾迹纤细, 末端均有细长的爪迹.拇指(Ⅰ趾)向后, 趾印清晰, 各趾趾垫通常为3个.Ⅱ～Ⅳ趾间角变化范围128°～142°.趾间无蹼状构造.足迹最显著的特征是: Ⅱ, Ⅲ, Ⅳ三趾中轴不对称, Ⅱ-Ⅲ趾间角较大(范围91°～118°), 以及足迹长(不含拇指)与宽近等.该足迹是中国最早的鸟类足迹之一, 也是迄今为止在中国境内发现的惟一的新遗迹属.它形成于河漫滩环境, 与大量兽脚类、鸟脚类恐龙足迹共生.

白垩纪四足动物足印的生物地层学、生物年代学与遗迹相

从全球范围来看,白垩纪四足动物的足印多数是非鸟恐龙与鸟类留下的痕迹;少量足印来自翼龙、鳄鱼、龟、哺乳动物和其他四足动物。白垩纪的足迹化石以东亚(尤其是中国和朝鲜)和北美西部的最为人所知。南美(主要是阿根廷和巴西)也有一定数量广泛分布的足迹化石,欧洲、非洲与澳大利亚的白垩纪足迹组合则鲜为人知。以白垩纪四足动物的足印记录为基础,我们对两个全球足印生物年代重新进行了检查。早白垩世生物年代以蜥脚类与鸟脚类的足迹为特征。晚白垩世生物年代中的蜥脚类足迹较少,但是鸭嘴龙、暴龙和角龙的足迹增多了。另外,白垩纪足印化石的记录中记载了许多重要的生物地层学信息,如北美白垩纪中期蜥脚类恐龙的消失,以及白垩纪末恐龙的绝灭。越来越多来自东亚的白垩纪足印记录使我们对更精细的地方性白垩纪足印生物年代学有了初步印象。因此,以地方性四足恐龙(包括鸟类)遗迹属的地层分布为基础,可以识别出三个或四个足印生物年代。种类丰富并具有地方性特色的东亚的白垩纪鸟类动物的遗迹群,可能指示白垩纪时东亚存在着一个独特而繁盛的鸟类动物群。以足印化石为基础的这一假说有待进一步的验证。

Early Cretaceous dinosaur and other tetrapod tracks of southwestern China

In recent years the Lower Cretaceous red beds of southwestern China have yielded more than 20 significant dinosaur-dominated tracksites. More than half occur in the Jiaguan Formation with the remainder in the Feitianshan and Xiaoba formations. Collectively these sites provide evidence of at least 13 distinct dinosaurian trackmaker morphotypes, in addition to two avian theropod(bird)morphotypes and pterosaur and turtle tracks. Together these total 17 morphotypes provide a data base of 479 potential trackmakers, probably representing the same number of individuals. Such an ichnological database provides a useful proxy paleoecological census of tetrapod communities in the area during the Early Cretaceous, and is especially significant given the complete absence or scarcity of skeletal remains reported from these formations.The composition of ichnofaunas in all three formations is heavily saurischian(theropod and sauropod) dominated with a high diversity of distinctive theropod morphotypes,mostly assignable to known ichnogenera. Moreover, ichnofaunal data from multiple sites are generally consistent between sites and an indication of the reliability and repeatability of track census data. Such regionally-widespread data are rapidly superseding the information available from the skeletal record in the corresponding area, and must therefore be considered of high paleontological value.

A probable tyrannosaurid track from the Upper Cretaceous of southern China

A large number of Upper Cretaceous(Maastrichtian)dinosaur skeletal fossils have been found in the Nanxiong Basin and adjacent Ganzhou area,including those of theropods,sauropods and hadrosaurids.However,known dinosaur ichnoassemblages from the Nanxiong Basin partly indicate a different fauna,with dominating large-and medium-sized ornithopods,theropods,and pterosaurs(1,2)This is one of many known examples where trace and body fossil assemblages from the same formation or geologically discrete region show a different composition.Palecological and paleobiogeographical analyses therefore should consider data from both,before any conclusions can be drawn.Formations can be classified according to the relative degree of similarity or congruity(or difference/incongruity)between trace and body fossils into the 5 categories proposed by Lockley[3].

Late Triassic sauropodomorph and Middle Jurassic theropod tracks from the Xichang Basin,Sichuan Province,southwestern China:First report of the ichnogenus Carmelopodus

Upper Triassic and Middle Jurassic strata of the Xichang Basin in Sichuan Province, southwestern China, yielded important dinosaur ichnofossils. From the Xujiahe Formation of the Yiguojiao tracksite, we report a Late Triassic footprint assemblage in China and the first discovery of diagnostic Triassic sauropodomorph tracks in this region. The tracks share a number of features in common with the ichnogenera Eosauropus(Late Triassic) and Liujianpus(Early Jurassic). The neighboring Bingtu tracksite is stratigraphically younger(Shaximiao Formation, Middle Jurassic) and preserves small tridactyl theropod tracks that represent the first occurrence of the ichnotaxon Carmelopodus in China and Asia. While these tracks are morphologically comparable to those from the Middle Jurassic type locality in North America, the specimens from China show the proximal margin of the digit IV impression in a more cranial position, which may indicate a trackmaker with a relatively short metatarsal IV. In addition to the skeletal record, the Carmelopodus footprints document the presence of small theropods in the dinosaur fauna of the Middle Jurassic Shaximiao Formation.

The first theropod tracks from the Middle Jurassic of Gansu,Northwest China:new and rare evidence of quadrupedal progression in theropod dinosaurs

A new Middle Jurassic tracksite dominated by non-avian theropod footprints from the Wangjiashan Formation in Pingchuan District,Baojishan Basin,Gansu Province has yielded a unique trackway with four consecutive manus-pes sets.Only three previous examples,all Early Jurassic in age,of theropod trackways are known with convincing examples of manus tracks and in each case,only two tracks were recorded in association with pes tracks with metatarsal impressions and pelvic traces indicating crouching behavior.Thus,this is the first example of manus tracks registered while a theropod trackmaker was walking.This unique configuration is here designated as Grallator pingchuanensis ichnosp.nov.which shows the trackmaker forelimbs registering in a wide straddle gait,much wider than the pes trackway width.G.pingchuanensis confirms previous reports that theropods could occasionally register tridactyl,ectaxonic manus traces.In the case of the Pingchuan trackway,the short step indicates an animal moving at a slow speed,probably due to a soft substrate.

A redescription of the ichnospecies Koreanaornis anhuiensis(Aves) from the Lower Cretaceous Qiuzhuang Formation at Mingguang city, Anhui Province, China

The Cretaceous bird trackway originally labeled Aquatilavipes anhuiensis, in 1994, had previously been examined, photographed and replicated, but never described or illustrated in detail. However, it has been part of a widening discussion about the distribution of Aquatilavipes and Koreanaornis in China(and Korea). Here we illustrate and formally describe the holotype in detail and assign it to Koreanaornis(Koreanaornis anhuiensis) as informally proposed by previous authors. We also demonstrate that most authenticated reports of Koreanaornis, including the Anhui occurrence, are from the Lower Cretaceous, not from the Upper Cretaceous as previously reported.

Lower Cretaceous sauropod trackways from Lishui City and an overview of dinosaur dominated track assemblages from Zhejiang Province, China

A relatively small number of tetrapod tracksites from Zhejiang Province fills out the fossil record from that region,which is also known to have yielded both saurischian（titanosauriform, coelurosaur） and ornithischian（basal ornithopod, ankylosaurian） body fossils as well as dinosaurian eggs. We use photogrammetry and 3 D imaging to reinterpret the sauropod tracks from Lishui City, which revealed the existence of trackways. The track record from three documented sites in Zhejiang Province includes avian and non-avian theropod, sauropod, ornithopod and pterosaur tracks. Previous work showed that the purported new bird ichnospecies Dongyangornipes sinensis is a synonym of Uhangrichnus chuni, while we here consider Pteraichnus dongyangensis as a nomen dubium. Such ＂provincial ichnotaxonomy＂ may mask similarities in the ichnofauna across large regions. In fact, we show that the ichnofauna is similar to that found in the Early Cretaceous elsewhere in China.

The Middle-Upper Jurassic dinosaur-pterosaur fauna in Shandong Province,China:Evidence from ichnology

Tracks previously examined between 2002 and 2015 from an incompletely-studied,and now partially lost tracksite site in the Santai Formation of Shandong Province were restudied based on new ex-cavations of additional surfaces.In contrast to the previous reports of tridactyl tracks,including Grallator,the present study discovered an additional assemblage of unequivocal pterosaur tracks(Pteraichnus)and a possible didactyl deinonychosaurian track.The age of the Santai Formation is controversial but it is probably Late Jurassic,which corresponds to the epoch when pterosaur tracks appear worldwide.Age interpretations,based on palynology and isotopic data,tentatively suggests an earlier Middle-Late Jurassic age and might suggest that the pterosaurian tracks are as old or somewhat older than any previously reported.

The new ichnotaxon Eubrontes nobitai ichnosp. nov. and other saurischian tracks from the Lower Cretaceous of Sichuan Province and a review of Chinese Eubrontes-type tracks

The Jiaguan Formation and the underlying Feitianshan Formation(Lower Cretaceous) in Sichuan Province yield multiple saurischian(theropod–sauropod) dominated ichnofaunas. To date, a moderate diversity of six theropod ichnogenera has been reported, but none of these have been identified at the ichnospecies level. Thus, many morphotypes have common "generic" labels such as Grallator, Eubrontes, cf. Eubrontes or even "EubrontesMegalosauripus" morphotype. These morphotypes are generally more typical of the Jurassic, whereas other more distinctive theropod tracks(Minisauripus and Velociraptorichnus) are restricted to the Cretaceous. The new ichnospecies Eubrontes nobitai ichnosp nov. is distinguished from Jurassic morphotypes based on a very wellpreserved trackway and represents the first-named Eubrontes ichnospecies from the Cretaceous of Asia.