Dinosaur Track Assemblage Research Articles

Late Jurassic–Early Cretaceous dinosaur track assemblages from northwestern Hebei Province, China: Implications for paleoenvironment and paleoecology

The relationship between the Middle–Late Jurassic Yanliao Biota and the Early Cretaceous Jehol Biota has long been unresolved due to an approximately 20 Ma “vertebrate fossil gap”. However, a large number of dinosaur tracks have been reported from the Tuchengzi/Houcheng Formation in northern Hebei–western Liaoning, which occupies the stratigraphic position between the Yanliao Biota and the Jehol Biota. This paper presents new discoveries of diverse dinosaur track assemblages from the Upper Jurassic–Lower Cretaceous Houcheng Formation in the Shangyi Basin, northwestern Hebei Province, China. Based on the ichnological analyses, tracks are assigned to the sauropod Parabrontopodus, theropod Grallator, Anchisauripus, Eubrontes, and Therangospodus. The theropod tracks were likely produced by small-sized feathered theropod dinosaurs (Coelurosauria) that thrived in both the Yanliao Biota and the Jehol Biota. These findings imply that these two biotas evolved successively, without evidence of a complete turnover or extinction of biotas. Sedimentological studies of the tracksites reveal their occurrence in diverse sedimentary environments, including braided sandbar, floodplain, and deltaic plain. The coexistence of highly diverse dinosaur tracks with various preservation environments indicates that the living environment during that time was relatively comfortable. The increased diversity of dinosaur tracks in the upper part of the Houcheng Formation closely aligns with the intense volcanic activity of the Zhangjiakou Formation in northwestern Hebei Province. This suggests that volcanic activity likely served a crucial function in the proliferation of the dinosaur fauna in the Shangyi Basin and northern North China during the earliest Cretaceous.

What do their footprints tell us? Many questions and some answers about the life of non-avian dinosaurs

Dinosaur tracks are considerably common in the fossil record and were described from many areas in the world. They provide a live picture of dinosaur behaviour and offer valuable data about different aspects of the trackmaker paleobiology. The dinosaur ichnological record allows gain information about autopod anatomy, functional adaptations, stance and gaits with which dinosaurs moved. This information, which is often difficult to obtain from the body-fossil record alone, allows making inferences not only concerning the single individuals who produced the footprints, but also within an evolutionary context. Footprints provide also evidences about the abilities that dinosaurs had to swim, run or live with certain pathologies. They also allowed inferring how they move in herds or even made courtship rituals. The study of tracks also enables the reconstruction of paleocommunities including predator–prey interaction. On the other hand, footprints are useful paleoenvironmental indicators, informing about moisture content, bathymetry, paleocurrents, subaqueous substrates, zonations in lacustrine margins, etc. In addition, it has been proposed that dinosaur track assemblages can be related to certain facies (ichnofacies), in order to refine paleoenvironmental reconstructions. Dinosaur tracks can sometimes be in the shadow with respect to the skeletal record. However, the data obtained from the ichnological record complements and completes the knowledge we have about the life of dinosaurs, even showing previously unknown aspects. This work is an overview of the information we can obtain from the study of non-avian dinosaur footprints, trying to answer some questions about their life.

The first dinosaur track assemblages from the Upper Cretaceous Shaxian Formation, Fujian Province, southeastern China

The record of Upper Cretaceous dinosaurs in China is dominated by skeletal body fossils, while the dinosaur track record has remained sparse. The new discovery of dinosaur tracks from the Shaxian Formation in Longxiang Village, Fujian Province, is the largest Upper Cretaceous ichnofauna known from China and the first recorded “evidence of” dinosaurs in Fujian Province. There are 247 tracks comprising 23 trackways and 14 isolated tracks. Ornithopod tracks showing three different sizes. Scarcely present are sauropod and small–medium tridactyl theropod tracks, while large form is missing. Remarkable is the presence of different deinonychosaur tracks. The unusual dinosaur tracks assemblage from Longxiang broadens the knowledge of the evolution of dinosaurs in the East Asian Late Cretaceous faunas.

A Preliminary Review of Dinosaur Track Assemblages from the Tuchengzi Formation in North China

In northern China, mainly within Western Liaoning, Northern Hebei and Beijing, vertebrate skeletons from the Tuchengzi Formation (Upper Jurassic to Lower Cretaceous) are scarce. However, a large number of new dinosaur track discoveries have made in past 10 years. So far, a total of 19 dinosaur track sites have been found in the Tuchengzi Formation, collectively containing 2,637 individual tracks and representing at least 2,091 trackmakers. This track record has become an important sample for understanding the Tuchengzi dinosaur fauna. The abundant Tuchengzi track record includes six non-avian theropod ichnogenera (Asianopodus, Eubrontes, Grallator, Menglongipus, Therangospodus, and Velociraptorichnus), three bird ichnogenera (Aquatilavipes, Pullornipes, and Koreanaornis), two sauropod ichnogenera (Brontopodus and cf. Parabrontopodus isp.), and a possible ornithopod ichnogenus (cf. Dinehichnu). This assemblage is saurischian-dominated, which is consistent with most Jurassic and Cretaceous track sites in China. The presence of deinonychosaurian tracks is consistent with the rich skeletal record from the Yanliao Biota or Jehol Biota, and the bird tracks are consistent with the record of shorebirds in Jehol Biota. The existence of ornithopod tracks is doubtful and needs further discoveries to be confirmed.

Theropod and ornithischian dinosaur track assemblages from Middle to ?Late Jurassic deposits of the Central High Atlas, Morocco

ABSTRACT Tridactyl theropod and ornithischian dinosaur tracks and trackways from Imilchil and Isli formations (Middle–?Late Jurassic, Bajocian–?) of the central High Atlas region (Morocco) are described. The Imilchil Formationconsists of brackish marine-continental deposits, and the Isli Formation is a continental red-bed succession. Considering numerous new footprint discoveries, including recently described Polyonyx sauropod trackways, tridactyl dinosaur tracks from the Imilchil-Tounfite region are revised. Dominating are theropod footprints resembling the ichnogenus Changpeipus and known from Lower-Middle Jurassic deposits of China. Other theropod ichnotaxa are Trisauropodiscus isp., cf. Wildeichnus isp.,Carmelopodus isp., Megalosauripus isp., Kayentapus isp. and an indeterminate small grallatorid. Ornithischians are represented by small indeterminate ornithischian tracks, large ornithischian footprints cf. Stegopodus isp. and a large indeterminate ornithopod form. Makers of the small theropod trackswere small coelurosaurs or basal tetanurans, larger forms belong toceratosaurs, megalosauroids, allosauroids or tyrannosauroids. Ornithischian tracks suggest dryomorphs, iguanodontians and thyreophorans as producers. Together with crocodylomorph and pterosaur tracks, invertebrate traces and plants, the Imilchil and Isli formations document a flourishing ecosystem and dinosaur habitat. Remarkable is the presence of Changpeipus theropod tracks known from abundant occurrences in East Asia. This suggests an exchange of dinosaur faunas between this region and northern Africa during the Middle Jurassic.

Diverse preserved dinosaur footprint assemblage from Jurassic–Cretaceous transition eolian dune deposits of western Shandong Province, China

Ancient desert, characterized by low biotic diversity as well as low preservation potential, has long been assumed as devoid of biotic activity. However, recent works from Mesozoic trace fossils preserved in the eolianites in North America, South America and East Asia indicate that the ancient desert can also have diverse inhabitants. This paper presents a diversified preserved dinosaur track assemblage from the Jurassic-Cretaceous transition eolian dune deposits in western Shandong Province, China. Based on the ichnological analysis, tracks are assigned to ichnogenus Anomoepus, Eubrontes-like and Ornithopodichnus-like forms, representing the oldest and second example of the Chelichnus ichnofacies reported from China as well as Asia. Sedimentological analysis of the tracksites indicates that tracks occurred in linear dunes under arid climatic conditions. Well-preserved tracks with detailed anatomical information are more likely to be preserved in moist sands, contrary to the dry cohesionless sands. Anomoepus and Ornithopodichnus-like tracks cooccurring with northwestward winds were made during summer wet season, while Eubrontes-like track was present during winter dry season characterized by strong northeastward wind, implying different habits between ornithopod and theropod dinosaurs. The preserved Jurassic-Cretaceous transition dinosaur tracks in eolian dune deposits not only expand the spatial-temporal distribution of dinosaur fauna in North China, but also greatly improve our understanding of the adaptive capacity of dinosaurs in severe living conditions, such as the desert environment.

The first record of Cretaceous non–avian dinosaur tracks from the Qinghai-Tibet Plateau, China

A dinosaur track assemblage from a remote, high altitude (~4500–5000 m) site on the is the first to be reported from this area. The location, here named the Yangguang tracksite, represents the Lower Cretaceous part of the Kezilesu Group consisting of feldspathic sandstones and dated as Hauterivian–Barremian on the basis of the palynoflora. As the site is a dangerous working environment, with a steep (65°) track-bearing surface and constant freeze-thaw-induced rock fall, a photographic survey was undertaken to obtain essential information, while the surface was exposed. The ichnofauna is saurischian-dominated consisting of more than 120 recognizable tracks comprising at least two diagnostic sauropod trackway segments (>90 tracks) and seven theropod trackways (>30 tracks). The sauropod trackways represent large animals (mean pes length ~92 cm) and resemble Brontopodus, although somewhat more narrow-gauge than typical. The theropod trackways also represent large animals (mean track lengths > 40 cm) and resemble Iberosauripus from the Kimmeridgian–Berriasian of Spain which is characterized by a relatively short wide footy with weak mesaxony.

First Upper Cretaceous dinosaur track assemblage from Jordan (Middle East) – preliminary results

Dinosaur tracks from Jordan (Middle East) have only been briefly reported in geological overview papers and books. We present here the first description and documentation of Jordanian dinosaur tracks based on a new tracksite from the south-central part of the country. The track-bearing strata belong to marginal marine (tidal flat) deposits of the Na’ur Formation (Upper Cretaceous, Cenomanian). This unit largely consists of well-bedded limestones, dolomites and marls that contain abundant marine invertebrate fossils such as bivalves, ammonites and foraminifers. The dinosaur ichnofauna occurs on four different levels and comprises abundant theropod tracks and trackways as well as isolated sauropod and ornithopod tracks. Theropod trackways consist of two different morphotypes. Morphotype 1 is tridactyl (26 cm pes length) and with a broad, but short metatarsal area and resembles the ichnogenus Picunichnus from the Lower Cretaceous (Albian) of Argentina. Morphotype 2 (36 cm pes length) has extensive and narrow metatarsal impressions continuously occurring along regularly-spaced trackways. This suggests either a plantigrade movement of the trackmaker or reflects preservational factors. By their overall-shape with thin digits, Morphotype 2 resembles described penetrative tracks suggesting a strong influence of the substrate. Sauropod tracks are relatively small (40 cm pes length) and show low heteropody with a kidney-shaped manus imprint, pointing to a Sauropodichnus -like form. The single ornithopod pes track (18 cm in length) is similar to material described as Ornithopodichnus from the Lower Cretaceous of Korea. Due to the incomplete material of sauropod and ornithopod prints, no concrete assignment is given to this material and further study is needed. The presence of dinosaur tracks proves a temporary subaerial exposure of the surface whereas the main part of the Na’ur Formation is dominated by subaqueous activity of marine faunas.

A mid-Cretaceous dinosaur track assemblage from the Hengshan Formation in central Zhejiang, China

ABSTRACT The Cretaceous Hengshan Formation at the Baxian tracksite, central Zhejiang has yielded more than 20 sauropod tracks with a considerable size range (pes length ranging from 22.7–83.7 cm). The assemblage consists of a more complete trackway of a large animal, a less complete trackway of a large animal with a similar orientation and, a small manus-pes set indicating a smaller trackmaker. Thus, it is a small ichnoassociation with tracks indicating different-sized trackmakers that moved in different directions. From a global perspective the assemblage is important, because it is another data point indicating the presence of different size-classes and mixed associations with very small and large sauropods, probably representing juvenile and adult individuals. These tracks are the first reported from the mid-Cretaceous of this region, being therefore slightly younger than those already known from Early Cretaceous sites, which are also attributed to sauropods.

A Lower Cretaceous dinosaur track assemblage from the Taoqihe Formation in Central Heilongjiang, China

An Early Cretaceous dinosaur ichnofauna is reported from the Taoqihe Formation (Aptian–Albian) in Heilongjiang Province, China. The assemblage, which comprises >70 tracks in 5 trackways, includes parallel sauropod trackways, a toe-trace dominated tridactyl ornithopod trackway and elongate tridactyl theropod tracks, the latter tentatively be attributed to swimming activity. The combination of possible swim and walking trackways suggest that they were formed at different times and in different environments. This is the first Lower Cretaceous tracksite reported from Heilongjiang Province with the exception of an historic record of a large pentadactyl track of probable thyreophoran (ankylosaurian) affinity. Ankylosaurian tracks are rare in China, and reported tentatively from only one other location. The dinosaur ichnofauna from the Taoqihe Formation is similar in composition to the skeletal assemblages of the Early Cretaceous Jehol Biota in the nearby Liaoning Province. The new track records are important for better understanding the palaeobiogeography and faunal developments of northeastern China and adjacent Russia.

An unusual dinosaur track assemblage from the Jurassic–Cretaceous boundary, Anning formation, Lufeng Basin, China

ABSTRACT Late Jurassic dinosaur track assemblages from China are much less common than those reported from the Lower and Middle Jurassic which are heavily dominated by well-known theropod ichnogenera such as Grallator, Eubrontes, Kayentapus, and a few sauropodomorph and ornithischian ichnotaxa. We here report two tridactyl dinosaur morphotypes from the Lufeng Basin in southern China that most closely resemble Late Jurassic Dinehichnus from North America, a probable gracile ornithopod morphotype, and an unnamed avian morphotype reported from rare occurrences in North America and Europe, which we here name as Tridentigerpes ichnogen. nov., accommodating two ichnospecies T. huasibanleei ichnosp. nov. from the Lufeng Basin, and T. pinuelai ichnosp nov., from Spain. These ichnites re-orient our understanding of Late Jurassic dinosaur track distributions in the Late Jurassic of China, which was previously based in large part on very poor material of presumed theropod affinity. Given the sparse body fossil record from southern China including very fragmentary sauropod remains, the ichnological record of diverse bipedal dinosaurs, suggestive of avian and non-avian dinosaurs and ornithopods, the Anning Formation represents a type 2b deposit where tracks are more common than skeletal remains and indicative of faunas not represented by the body fossil record.

A diversified dinosaur track assemblage from the Lower Cretaceous Xiaoba Formation of Sichuan Province, China: Implications for ichnological database and census studies

The rapid rate of discovery of Lower Cretaceous tetrapod tracksites in terrestrial sequences on the Sichuan Basin area is such that the 2016 report of 21 sites in the Xiaoba, Feitianshan and Jiaguan Formations is now increased by ∼24%–26 sites. Of these seven occur in the Xiaoba Formation, including two new sites (Luogan and Apuruha) described here. Likewise, there has been a similar increase in reports of sites from the Jiaguan Formation, from 12 to 15 sites (=25%) in the same period. The total of estimated trackmakers, based on trackways, not individual tracks, is ∼598 for all three formations, including∼150 from the Xiaoba Formation, and ∼325 from the Jiaguan Formation. This indicates a two-year increase in the database of ∼20%. To date all tracks from the Xiaoba formation represent saurischians (non-avian theropods and sauropods). However, as the database has increased for all three formations it has been possible to demonstrate that didactyl, presumably deinonychosaurian trackmakers, although rare and in some cases poorly preserved, occur in about 20% of assemblages. Thus, the data base helps differentiate between the relatively low abundance and relatively widespread distribution of deinonychosaurian trackmakers within the non-avian theropod track database. This difference between abundance and distribution is consistent with what is known of patterns in other parts of Asia.

Multiple parallel deinonychosaurian trackways from a diverse dinosaur track assemblage of the Lower Cretaceous Dasheng Group of Shandong Province, China

Many newly-discovered dinosaur tracksites have recently been reported from the Lower Cretaceous Dasheng Group of Shandong Province. These are proving valuable as tools for characterizing the fauna in deposits almost devoid of body fossils. Here we report on a new Cretaceous site, the 14th documented in recent years, with multiple track-bearing levels, that adds ∼300 tracks to a growing database. At least two morphotypes tentatively labelled as cf. Menglongpus isp., representing a deinonychosaur, and cf. Tatarornipes isp., representing an avian theropod, add to the list of at least seven named ichnogenera attributed to avian and non-avian theropods reported from the Dasheng Group in Shandong Province. Combined with two sauropodomorph and two ornithopod ichnogenera, and unnamed turtle tracks, the genus-level ichnodiversity (∼14) is one of the highest reported for any Cretaceous unit either regionally in China or globally.The tracks identified as cf. Menglongpus isp. occur in four parallel trackways indicating a group of small didactyl bipeds of inferred deinonychosaurian affinity. Despite the lack of body fossils from the Dasheng Group in Shandong Province, a high diversity of deinonychosaur body fossils is known from the contemporary Jehol Biota from northeastern China. This similarity underscores the importance of the Shandong track assemblage as indicators of regional, tetrapod biodiversity during the Cretaceous.

Mid-Cretaceous dinosaur track assemblage from the Tongfosi Formation of China: Comparison with the track assemblage of South Korea

A Yanji Basin tracksite in the Cretaceous Tongfosi Formation in the Yanbian Korean Autonomous Prefecture, Jilin Province was reinvestigated twenty years after the original study.The re-examination confirms the presence of tracks tentatively referred to ornithopods and theropod tracks including several not previously reported. In addition to the main track-bearing level, a second footprint horizon was identified from which a probable ornithopod track was collected. Some of the formerly identified tracks were documented using photogrammetry, whereas others that had been collected, eroded, buried or obscured by dense vegetation. The age of the track-bearing beds is inferred to be late Albian to early Cenomanian. Comparison with track-bearing units of the same age in Shandong, China, and Korea indicated quite different compositions of track assemblages. In the case of the Korean sites the differences may be facies related. While the Korean ichnofauna is characterized by the co-occurrence of ornithopod, sauropod and tridactyl theropod tracks with didactyl dromaeosaurid, Minisauripus (small theropod), pterosaur and avian tracks, the latter four are absent in the Tongfosi assemblage. This could reflect a restricted environment being not favourable for activities of these trackmakers or simply a preservational bias.

A dinosaur track assemblage from the Upper Hettangian (Lower Jurassic) marginal-marine deposits of Zapniów, Holy Cross Mountains, Poland

Upper Hettangian (Lower Jurassic) marginal-marine Przysucha Ore-bearing Formation exposed at Zapniow mine and clay-pit (northwestern part of the Holy Cross Mountains area, central Poland) revealed an interesting assemblage of dinosaur tracks. Although mostly yielding poorly preserved and isolated tracks probably left in shallow water conditions, the site nevertheless indicates a diversity of early saurischian (theropods and sauropodomorphs) and ornithischian (thyreophorans) dinosaur trackmakers. This new assemblage is partly consistent with the Lower-Middle Hettangian ichnorecord from the same region. The tracks are preserved in sediments of a barrier-foreshore origin within a barrier/lagoonal depositional system, belonging to the highstand systems tract, located below a marked erosional surface (sequence boundary), which is associated with a substantial fall in sea level at the end of Hettangian times. Here we described all previously and newly collected or observed in the field dinosaur tracks from both surface and underground exposures at Zapniow. Four ichnospecies: Grallator isp., Anchisauripus isp., cf. Tetrasauropus isp., and cf. Anomoepus isp. were identified. The theropod and ornithischian tracks show distinct similarities to those described from the richest in this region and most famous Gliniany Las dinosaur track assemblage, in age approximately coeval to Zapniow. Two sizes of theropod tracks (small and medium) indicate the presence of two different size classes or species of predators in this area. The described cf. Tetrasauropus isp. from Zapniow is the first unquestioned evidence of basal sauropodomorphs in the Upper Hettangian of the Holy Cross Mountains and first record of this ichnotaxa in the Lower Jurassic of Poland. Additionally, two theropod trackways ( Anchisauripus isp.) show evidence for trotting. The new finds suggest similarities between marginal-marine environments (delta-plain and foreshore-barrier/lagoon lithofacies) association of dinosaurs containing low-browsing thyreophorans accompanied by small or juvenile sauropodomorphs and small to medium sized theropods. Presence of the ornithischian footprints suggests their prominent role as a major component in Middle-Upper Hettangian dinosaur faunas in marginal-marine environments dominating in the region

Middle-Upper Triassic and Middle Jurassic tetrapod track assemblages of southern Tunisia, Sahara Platform

Three tetrapod track assemblages from the early-middle Mesozoic of southern Tunisia are reported. The strata exposed at the Tejra 2 clay-pit near the Medenine and Rehach site, located in the vicinity of Kirchaou, contain the first tetrapod tracks found in the Triassic of Tunisia. The Middle Jurassic (early Aalenian) dinosaur tracks are reported from the Mestaoua plain near Tataouine. In the Middle Triassic outcrop of the Tejra 2 clay-pit, tridactyl tracks of small and medium-sized dinosauromorphs, were discovered. These tracks represent the oldest evidence of dinosaur-lineage elements in the Triassic deposits of Tunisia. Similar tracks have been described from the Middle Triassic of Argentina, France and Morocco. An isolated set of the manus and pes of a quadrupedal tetrapod discovered in Late Triassic Rehach tracksite is referred to a therapsid tracemaker. The Middle Jurassic deposits of the Mestaoua plain reveal small and large tridactyl theropod dinosaur tracks (Theropoda track indet. A-C). Based on comparison with the abundant record of Triassic tetrapod ichnofossils from Europe and North America, the ichnofauna described here indicates the presence of a therapsid-dinosauromorph ichnoassociation (without typical Chirotheriidae tracks) in the Middle and Late Triassic, which sheds light on the dispersal of the Middle-Upper Triassic tetrapod ichnofaunas in this part of Gondwana. The reported Middle Jurassic ichnofauna show close similarities to dinosaur track assemblages from the Lower and Middle Jurassic of northwestern Africa, North America, Europe and also southeastern Asia. Sedimentological and lithostratigraphic data of each new tracksite have been defined on published data and new observations. Taken together, these discoveries present a tantalizing window into the evolutionary history of tetrapods from the Triassic and Jurassic of southern Tunisia. Given the limited early Mesozoic tetrapod record from the region, these discoveries are of both temporal and geographic significance.

Cretaceous saurischian tracksites from southwest Sichuan Province and overview of Late Cretaceous dinosaur track assemblages of China

Dinosaur tracks from Upper Cretaceous deposits of Sichuan Province, China have proved of great significance for two reasons: they (1) provide unambiguous evidence of dinosaurs from this epoch in this region, and (2) demonstrate that the track bearing units of the Leidashu Formation are not Paleocene-Eocene in age as previously claimed by some authors. We herein describe five small sites, from the Zhaojue area and the nearby Xide areas. Two sites are dominated by theropod tracks, including one with small tracks of Eubrontes-like morphology, and another with deep tracks revealing long metatarsal impressions, probably indicating a soft substrate. Three sites yield only sauropod tracks. Combined data from these five tracksites document a typical saurischian dominated ichnofauna, and based on present evidence these assemblages are less diverse than those from Lower Cretaceous sites in the region. However a larger sample is necessary to test this suggestion.

Upper Cretaceous dinosaur track assemblages and a new theropod ichnotaxon from Anhui Province, eastern China

Several noteworthy Cretaceous tracksites are known in the Huizhou District (Huangshan City) in the Yangtzee valley of southern Anhui Province. These include some that have been known since the late 1970s but have not been studied in detail until now. The footprints described here occur in siliciclastic fluvial deposits in three distinct horizons. The Xiaohutian tracksite in the Upper Cretaceous Xiaoyan Formation is the most interesting, being situated at a historically famous location used as a Taoist and Buddhist shrine. The Xiaohutian tracksite yields an assemblage with three different morphotypes of non-avian theropod tracks including the new ichnotaxon Paracorpulentapus zhangsanfengi that can be attributed to a theropod with relatively short “fleshy” toes showing convergence with the footprints of small ornithopods. A further diagnostic feature is the trackway pattern with relatively short steps. Associated ichnofossils are invertebrate traces that can be assigned to eurybathic forms such as Palaeophycus and ?Planolites or ?Scoyenia. Thus far skeletal remains from the Xiaoyan Formation have proved the pachycephalosaur Wannanosaurus and indeterminate sauropods. The ichnoassemblages enlarge the known dinosaur fauna by small- to medium-sized theropods that are identified here as the trackmakers and that are otherwise rare in Upper Cretaceous deposits of eastern China. The Shangshangen locality is another significant tracksite which has yielded small bird tracks (cf. Koreanaornis) in association with small tracks of non-avian theropods.

Theropod and possible ornithopod track assemblages from the Jurassic–Cretaceous boundary Houcheng Formation, Shangyi, northern Hebei, China

Dinosaur track assemblages from the Houcheng Formation in the small continental Shangyi Basin of northern Hebei Province, China bridge a gap in the record of vertebrates from this unit and enrich our knowledge of ichnofaunas from the Jurassic–Cretaceous boundary. Their stratigraphic position between the Middle Jurassic Yan-Liao Biota and the Lower Cretaceous Jehol Biota gives them a special importance. New discoveries allow a re-assessment of theropod and possible ornithopod tracks that are present with several trackways. Seventy-three footprints were examined and documented. Despite their smaller size, the tridactyl mesaxonic theropod tracks show morphological similarities with the ichnogenus Therangospodus known from the Upper Jurassic deposits of North America, Europe, and Central Asia. The possible ornithopod tracks lack an associated manus imprint, suggesting a bipedal trackmaker. These possible ornithopod tracks from the Houcheng Formation provide evidence for the presence of small basal ornithopods or basal Cerapoda in the Upper Jurassic–Lower Cretaceous in this region. The depositional environment was the margin of an extensive shallow lake with fluctuating water levels under seasonally dry climate.

Diverse dinosaur ichnoassemblages from the Lower Cretaceous Dasheng Group in the Yishu fault zone, Shandong Province, China

New dinosaur track assemblages were discovered recently in the Tianjialou Formation of the Lower Cretaceous Dasheng Group in Shandong Province, China. Theropods are represented by the trackways of two different medium-sized groups: (1) tridactyl tracks with a typical mesaxonic shape; (2) functionally didactyl tracks attributed to deinonychosaurian theropods. The latter report, the third from the Cretaceous of Shandong Province, enlarges the global record of didactyl theropod tracks, until now sparsely documented from only a few locations in Asia, North America and Europe. A number of features in the dromaeosaur trackway suggest the assignment to cf. Dromaeosauripus. Several medium-sized trackways resemble the narrow-gauge, small manus ichnogenus Parabrontopodus, and one large trackway is characterised by a wide-gauge and large manus, similar to Brontopodus. This suggests the co-occurrence of two different sauropod groups. A further component in these ichnoassemblages is a tetradactyl morphotype and trackways of ornithischian affinity that are tentatively attributed to psittacosaurs.