Track-bearing Surface Research Articles

First discovery of dinosaur tracks from the Lower Cretaceous Duoni Formation in eastern Tibet, China

Dinosaurs are known to have been abundant and diverse in eastern Tibet, and roamed the region from the Early Jurassic to the Late Cretaceous. Even though the evidence of dinosaurs is known throughout this interval, there are still many stratigraphic gaps that lack evidence, such as the Upper Jurassic and the Lower Cretaceous successions. Here, we report a new dinosaur tracksite from the Lower Cretaceous Duoni Formation of Basu County, where 28 track-bearing surfaces were discovered, which document a flourishing dinosaur community. Of these, three track layers with a high abundance of dinosaur tracks are described here, including sauropod, ornithopod and theropod trackways. These tracks suggest a possible exchange of trackmakers between this region and with adjacent areas of East Asia. The trackmakers' size, gait, and speed were inferred. The paleoenvironment is interpreted as ephemeral lakes bordered by conifer dominated forests. Palynological analysis conducted along the Duola stratigraphic section suggests that the tracksite is Aptian-Albian (Lower Cretaceous) in age, and the paleoclimate of the Basu area was relatively warm and dry.

First dinosaur tracks found in the Mulichinco Formation (Lower Cretaceous), Neuquén Basin, Argentina: Paleoenvironmental implications

This study focuses on the analysis of the first dinosaur tracks discovered in the Mulichinco Formation, Neuquén Basin, Argentina. The deposition of this unit occurred during the early Valanginian, Early Cretaceous, making it the oldest known record of dinosaur tracks for that period in the basin. The aim of this study is to provide a paleoenvironmental interpretation of the area and potential trackmakers based on the morphology of the tracks and the facies analysis of the depositional system. The depositional system evolved from a moderately sinuous fluvial system in the lower interval to a braid distal plain system with the development of bodies of water without marine influence, culminating in an estuary with marine influence in the upper interval. The paleoenvironmental conditions during the deposition of the unit were favourable for the presence and interaction of diversity large continental vertebrates. The track-bearing surfaces in the lower interval suggest that the organisms exploited the temporary gaps created between channel migration and floodplain formation as areas for transit or water sources. In the middle interval, the abundant presence of traces fossils of invertebrates and symmetrical ripples suggest a more stable depositional system where fluctuations in the water column were common. The co-occurrence of various track-makers and remains of large vertebrates described in the Mulichinco Formation is unusual among track sites at the basin. Overall, this study provides new insights into the Early Cretaceous paleoenvironmental conditions of the Neuquén Basin and the diversity of large vertebrates that inhabited the region during this time.

Lower Cretaceous dinosaur footprints from the Molfetta tracksite (Apulia, southern Italy)

The lower Albian track-bearing surface of the San Leonardo quarry (Molfetta, Apulia) is characterised by more than 800 footprints, produced by both quadrupedal and bipedal dinosaurs. Six well-preserved bipedal trackways, composed of tridactyl footprints are attributed to medium-to large-sized theropod dinosaurs. Only one clear but poorly preserved trackway and numerous isolated manus-pes couples have been attributed to quadrupedal dinosaurs. The tridactyl ichnoassemblage, analysed using both traditional methods and close-range photogrammetry, is represented by weakly mesaxonic and robust specimens. Morphological comparison with Upper Jurassic and Lower Cretaceous theropod tracks from surrounding areas, supported by morphometric analyses, points out a highest affinity with the specimens from Switzerland and North Africa. Nevertheless, a set of unique characters appears to justify the establishment of a new ichnospecies, Jurabrontes melphicticus. Additionally, the photogrammetric models of the quadrupedal trackway and four isolated manus-pes sets suggest they belong to the same morphotype, represented by asymmetrical tetradactyl pes and highly digitigrade tetra- or pentadactyl manus. These tracks share numerous morphological characters with both the ichnogenera Tetrapodosaurus and Metatetrapodus and thus can be attributed to a medium-sized ankylosaurian trackmaker.

Geothematic map of the Altamura dinosaur tracksite (early Campanian, Apulia, southern Italy)

In 2019 a multidisciplinary study of the Altamura dinosaur tracksite (Apulia, southern Italy; early Campanian) was carried out to meticulously document its geological and palaeontological features. The goal was to pave the way for projects aimed at long-term conservation and valorisation of the geo-palaeontological heritage. For this purpose, a mapping of the whole track-bearing surface was performed, which led to the production of the first geothematic map (1:200) of the whole ichnosite. During the field activities, the surface was subdivided into 34 distinct sectors. For each sector, the work started with accurate manual and mechanical cleaning of the surface (industrial vacuum cleaner). The ichnological survey was carried out using standard methods (interpretative drawings with chalks to highlight outline and morphological features of each track). This approach was combined with close-range photogrammetry to obtain detailed 3D models of the best-preserved specimens. Finally, each sector was surveyed through aerial-based photogrammetry by means of sUAS (small Unmanned Aerial System). The aerial survey allowed us to gain a high-resolution and georeferenced orthophoto processed by using specific software. The field ichnological drawings occurring on each orthophoto were then traced and vectorised. The final step was the overlapping of each digitised sector and the processing of the tracksite map. The products of our study (geothematic map and 3D models of dinosaur tracks) highlight the extraordinary richness of the Altamura tracksite (26,000 footprints and 12 distinct trackways), confirming the high impact of new methodologies (close-range and aerial- based photogrammetry) as useful tools both for ichnological studies and future activities of public fruition of the geosite.

Dinosaur footprints from the Early Jurassic of Le Mazel (Lozère, Southern France)

During the 20th century, the first dinosaur tracks of the Causses Basin were identified at Saint-Laurent-de-Trèves, in the Parc National des Cévennes (southern France). A recent excavation reveals a new theropod tracksite in the Hettangian deposits from Le Mazel, 2km from the historical tracksite at Saint-Laurent-de-Trèves. The tracks are here described combining a biometric approach and 3D imaging photogrammetry. The main track-bearing surface bears 64 in situ tridactyl footprints preserved as concave epireliefs. Two morphotypes were identified, a “Grallatorid” morphotype and a “Kayentapus” morphotype. Footprints belonging to the first morphotype are closely similar to Grallator lescurei, Grallator minusculus, and Grallator sauclierensis. This study shows the difficulty to distinguish quite similar tridactyl tracks from an ichnotaxonomic point of view and highlights the importance of detailed biometric comparisons. Tracks are preserved in a brown to yellowish dolomudstone showing abundant cryptalgal laminites and mud cracks. These deposits were accrued in shallow environments such as intertidal and supratidal zones of a tidal flat.

Late Triassic dinosaur tracks from Penarth, south Wales

AbstractEvidence of Late Triassic large tetrapods from the UK is rare. Here, we describe a track-bearing surface located on the shoreline near Penarth, south Wales, United Kingdom. The total exposed surface is c. 50 m long and c. 2 m wide, and is split into northern and southern sections by a small fault. We interpret these impressions as tracks, rather than abiogenic sedimentary structures, because of the possession of marked displacement rims and their relationship to each other with regularly spaced impressions forming putative trackways. The impressions are large (up to c. 50 cm in length), but poorly preserved, and retain little information about track-maker anatomy. We discuss alternative, plausible, abiotic mechanisms that might have been responsible for the formation of these features, but reject them in favour of these impressions being tetrapod tracks. We propose that the site is an additional occurrence of the ichnotaxon Eosauropus, representing a sauropodomorph trackmaker, thereby adding a useful new datum to their sparse Late Triassic record in the UK. We also used historical photogrammetry to digitally map the extent of site erosion during 2009–2020. More than 1 m of the surface exposure has been lost over this 11-year period, and the few tracks present in both models show significant smoothing, breakage and loss of detail. These tracks are an important datapoint for Late Triassic palaeontology in the UK, even if they cannot be confidently assigned to a specific trackmaker. The documented loss of the bedding surface highlights the transient and vulnerable nature of our fossil resources, particularly in coastal settings, and the need to gather data as quickly and effectively as possible.

A reevaluation of the Late Jurassic dinosaur tracksite Barkhausen (Wiehengebirge, Northern Germany)

A restudy of the Barkhausen dinosaur tracksite shows that the track-bearing surface reveals considerably more detail than previously indicated, and a new map is presented, showing the trackways of nine sauropods, traveling north, possibly as a group. These are among the smallest sauropod tracks recorded in Europe. There is also evidence of two large theropods crossing the area, one moving to the south and the other to the west. Evidence of at least three other sauropods is registered in the form of isolated manus traces that represent larger individuals. Previous interpretations inferred that sauropod trackways trended south, and therefore suggested a predator chasing its prey as in the purported but controversial attack scenario claimed for the famous Paluxy River site in Texas. Based on the present study, this scenario is no longer tenable for the Barkhausen tracksite. The description of Elephantopoides barkhausensis (Kaever and Lapparent, 1974) shows that it represents a moderately wide gauge, but small manus sauropod and can be assigned under the ichnofamily label Parabrontopodidae. E. barkhausensis as originally defined was a nomen dubium, but it has since been re-described semi-formally, without renaming, we emend the description and assigned them to the ichnotaxon Parabrontopodus barkhausensis comb. nov. These tracks could have been produced by the small sauropod dinosaur taxon Europasaurus. The problematic ichnotaxon Megalosauropus teutonicus (Kaever and Lapparent, 1974), which represents a large three-toed theropod, is assigned to the recently described ichnogenus Jurabrontes from the Late Kimmeridgian of the Swiss Jura mountains as Jurabrontes teutonicus comb. nov. Furthermore, we attribute the theropod tracks from the time equivalent Langenberg quarry to the same ichnotaxon.

Small bird and mammal tracks from a mid-Cenozoic volcanic province in Southern Colorado: implications for palaeobiology

ABSTRACT The surprise discovery of two small assemblages of well-preserved, small bird and small mammal tracks in a thin unit of reworked tuff in the mid-Cenozoic volcanic field of southwestern Colorado represents the first significant report of tetrapod tracks in the region. The bird tracks are represented by a new ichnospecies of Avipeda (A. circumontis ichnosp. nov.), which differs from other Avipeda ichnospecies in representing a trackmaker with a narrower foot and comparatively robust digit traces and digital pads. The mammal tracks which are also well preserved are small (< 1.5 cm long and wide) tetradactyl-pentadactyl and rodent like. They are arguably unique and among the best-preserved small mammal tracks presently known from the Cenozoic, and are here assigned to the new ichnotaxon Musvestigium minutus ichnogen et ichnosp nov. The track-bearing surface represents a very thin unit of reworked tuff sandwiched between massive ignimbrite flows, and therefore represents a localised window into a brief period of biotic activity in local phase of quiescence in a large, active volcanic province.

A Review of two Middle Jurassic Theropod Tracksites Discovered in the 1980s from Sichuan Basin

Tracks from two sites in the Middle Jurassic Xintiangou Formation in the Wuma Village area, Wuhuang Township, Zizhong have been known and intermittently studied and excavated since the 1980s. The track-bearing surfaces were exposed by a combination of natural weathering and deliberate excavation by residents in a rural agricultural area. The surfaces were used as “threshing floors” for the processing of agricultural crops in an area subject to weathering under a humid sub-tropical climatic regime. Despite the negative effects of weathering on the quality of track preservation, the sites are historically significant in Chinese ichnology as the type areas for many controversially named theropod ichnotaxa. Subsequent researchers challenged the ichnotaxonomy as provincial and over-split, suggesting that many of the tracks, belong to well-known Lower Jurassic ichnogenera. The present study reviews these two sites, providing new information, and confirming that the tracks belong to the ichnogenera Grallator, Eubrontes and Kayentpus which are typical of the globally widespread Lower Jurassic tetrapod biochron. This suggests the Middle Jurassic ichnofauna in Sichuan is like Lower Jurassic ichnofaunas elsewhere. Previous efforts to transfer the ichnospecies to globally, better-known ichnogenera were important in reducing ichnogenus diversity, but did not reduce ichnosepcies diversity. Herein the ichnotaxa are reviewed and it is shown that the ichnospecies names have no utility for comparative study or in assessing assemblage diversity, or biochron composition. It is therefore proposed that the multiple ichnospecies names proposed based on tracks from these two localities can mostly be accommodated under the labels Grallator isp. indet., and Eubrontes isp. indet.

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.

Uncommon preservation of dinosaur footprints in a tidal breccia: Eubrontes giganteus from the Early Jurassic Mongisty tracksite of Aveyron, southern France

AbstractA recent excavation yielded 118 large tridactyl footprints in the Lower Jurassic Dolomitic Formation of the Causses Basin, at Mongisty in southern France. Most of the tracks are ascribed to Eubrontes giganteus Hitchcock, 1845. They are preserved on a surface of 53 m2 and form parallel rows with a preferential orientation towards the north. Such an abundance and density of E. giganteus is observed for the first time in the Early Jurassic from the Causses Basin. Sedimentological and ichnotaphonomical analyses show that the footprints were made at different time intervals, thus excluding the passage of a large group. In contrast to all other tracksites from the Dolomitic Formation, where tracks are preserved in fine-grained sediments corresponding to low-energy depositional palaeoenvironments, the tracks from Mongisty are preserved in coarse-grained sediment which is a matrix- to clast-supported breccia. Clasts consist of angular to sub-rounded, millimetric to centimetric-scale (up to 2 cm), poorly sorted, randomly oriented, homogeneous dolostone intraclasts floating in a dolomudstone matrix. Sedimentological analysis shows that the depositional environments of Mongisty varied from subtidal to intertidal/supratidal settings in a large and protected flat marsh. The lithology of the track-bearing surfaces indicates that the mudflat of the Causses Basin was sporadically affected by large mud flows that reworked and redeposited mudstone intraclasts coming from the erosion of upstream, dry and partially lithified mud beds. Throughout the world, this type of preservation of dinosaur tracks in tidal matrix- to clast-supported breccias remains rare.

TRACKING DINOSAURS IN COARSE-GRAINED SEDIMENTS FROM THE UPPER TRIASSIC OF ARDÈCHE (SOUTHEASTERN FRANCE)

ABSTRACTCoarse-grained sediments deposited in high-energy environments are usually considered unfavorable to the preservation of fossil tracks. Here we report dinosaur footprints showing good physical preservation, despite being found in coarse-grained sandstones of alluvial origin from the Upper Triassic of Ardèche, southeastern France. The ichnoassemblage, dominated by Grallator isp., raises questions about the processes leading to the formation and preservation of tracks in coarse-grained sediments. The track-bearing surface is a medium- to coarse-grained quartz arenite that is microconglomeratic locally. The tracking surface grain size ranges from 0.2 to 2 mm and numerous pebbles are present. It is overlain by a succession of thin, intercalated layers of claystones and siltstones, themselves covered by a mix of siltstones and coarse-grained sandstones. We interpret this succession as a progressive decrease in energy due to channel migration culminating in channel abandonment, and the establishment of a lower energy setting where the tracking surface formed. Sedimentological and taphonomic observations indicate that the trackmakers walked on fine-grained layers (clay, silt) in which true tracks formed. The passage of the animals along the tracking surface deformed the older coarse-grained sand layers and resulted in the formation of the transmitted undertracks. The fine-grained layer helped record the pedal anatomy of the trackmakers and contributed to protecting the transmitted undertracks from destruction. Overall, we suggest that the fossil footprints were preserved by abiotic processes only, the main factor being the lithological contrast between successive sedimentary layers. The exceptional preservation of those relatively high quality undertracks in coarse-grained deposits contrasts sharply with the prevailing models of true track formation involving fine-grained sediments and microbial mats present in low-energy environments. This mode of undertrack formation may have been relatively frequent elsewhere but potentially overlooked in previous studies.

A new ichnofauna from the Permian of the Zat Valley in the Marrakech High Atlas of Morocco

A new ichnofauna from the Permian of Morocco is described in details: it is the first Palaeozoic ichnofauna from the Zat Valley in Marrakech High Atlas. The new tracksite was found in the Tighdouine region, in the middle-upper Permian of the Cham-el-Houa Siltstone Formation. An abundant and diverse ichnoassemblage composed of both protostomian (probably arthropods and annelids) traces and vertebrate tracks is recorded. The presence of protostomian burrows and traceways, associated with tetrapod tracks corresponds to the Scoyenia ichnofacies. Protostomian traces are ascribed to Diplichnites gouldi, Diplopodichnus biformis, Scoyenia cf. gracilis and Spongeliomorpha carlsbergi. Tetrapod tracks include more than 70 tracks attributed to Amphisauropus, Erpetopus, Hyloidichnus, Characichnos, and indeterminate tracks. The co-occurrence of tetrapod tracks (both walking and swimming tracks), protostomian traces, mudcracks, ripple marks, as well as the lithological features of the track-bearing levels, indicate regularly inundated depositional environments during periods of high discharge under a local seasonal climate. A sedimentological analysis shows that the depositional environments evolved from braided-meandering systems to alluvial floodplains. The track-bearing surfaces are mainly preserved in crevasse splays, levees and pond deposits. This newly discovered ichnofauna helps to better reconstruct the palaeoenvironments of the Marrakech High Atlas in Morocco during the Permian, and enlarges the palaeogeographic distribution of important ichnotaxa.

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.

Early Jurassic basal sauropodomorpha dominated tracks from Guizhou, China: Morphology, ethology, and paleoenvironment

The newly discovered large (350 m2) Yantan dinosaur tracksite, in the Lower Jurassic Ziliujing Formation of Guizhou Province, China, reveals at least 250 footprints of which ∼97 can be resolved into trackways of sauropodomorphs. All the trackways are sub parallel likely indicating gregarious behavior. One theropod track (cf. Grallator) was recorded. The sauropodomorph tracks predominantly represent quadrupedal progression (Morphotype A), and footprint morphology is similar to the ichnospecies Liujianpusshunan, characterized by outward pes rotation. Three trackways indicate bipedal progression, and two of these (Morphotype B) indicate inward pes rotation, accompanied by elongate pes digit scratch marks. For the latter phenomenon three possible scenarios are discussed: (1) significant rotation changes accompanying changes in gait, (2) swimming behavior, (3) formation of undertracks.Sedimentological evidence indicates the tracks were made on a linguloid rippled, muddy, immature sandstone substrate characterized by significant differences in substrate consistency across the track-bearing surface. Microbially induced sedimentary structures (MISS) characterized by distinctive wrinkle marks indicate a stressed, probably semi-arid, paleoenvironment that was not conducive to habitation by invertebrate organisms. This is consistent with other evidence that Lower Jurassic sauropodomorph tracks are often associated with semi-arid paleoenvironments.

Les pistes d’archosauriens : Kayentapus ubacensis nov. isp. (théropodes) et crocodylomorphes du Bathonien des Grands-Causses (France). Conséquences paléo-biologiques, environnementales et géographiques

Two tracksites yielding tridactyl footprints II-IV of theropods as well as supposedly sauropod tracks from the Causses Basin, briefly described in 2006 are reinvestigated. They are the Capelan tracksite (Meyrueis, Lozère) and the Garène tracksite (La Roque-Sainte-Marguerite, Aveyron), both Bathonian in age. In 2012, one of them (Le Capelan) was excavated and enlarged, allowing the discovery of numerous new tracks. In the Capelan tracksite, 102 concave epireliefs, 11 to 36cm long, represent at least 21 trackways; the longest being visible along 37 meters. Footprints are almost as long as wide and show a large divarication angle II-IV (up to 70°). The largest of them (more than 24cm long) were statistically compared with different Middle and Upper Jurassic ichnotaxa for which a synthesis is proposed. Tracks from the Causses Basin as well as those from the Capelan and the Garène tracksites can be ascribed to the ichnogenus Kayentapus. We propose a new ichnospecies K. ubacensis nov. isp. Whose trackmakers were tetanurian theropods, probably megalosaurids. At the Capelan, some marks are tentatively interpreted as swim tracks of crocodylomorphs. The supposedly sauropod tracks are here reinterpreted and considered as erosion cups and as concavities indicating the location of tree trunks. The sedimentological analysis indicates a paralic environment including lagoons and freshwater to brackish bays. They were separated from dysoxic lagoons by calcarenitic coastal barrier spits, and by tidal flats where microbial mats contributed to the good preservation of trackways. Despite the presence of “mangroves”, the main track-bearing surface from the Capelan was quite open and visited by megalosaurid dinosaurs of various sizes, moving in all directions but preferably to the North. The regional palaeogeography of the early-middle Bathonian is in accordance with a coastal area with low relief, bordering the “Seuil Cévenol”, which was probably emerged.

Diverse sauropod-theropod-dominated track assemblage from the Lower Cretaceous Dasheng Group of Eastern China: Testing the use of drones in footprint documentation

The use of drones in the exploration and documentation of track surfaces in steep terrain, otherwise only accessible by time intensive climbing activity, is tested. Location is the Nanquan site, one of many now known footprint localities from the Lower Cretaceous Dasheng Group that has been recently exposed by local industrial excavation. It reveals an ichnofauna of sauropod, theropod, and ornithopod tracks and trackways occurring at multiple stratigraphic levels (at least 10) in a thin sequence of fine grained purple mudstones with thin sandstone units that are steeply inclined by >45°. It was therefore necessary and most efficient to map the track-bearing surfaces using drone photography. The majority of track-bearing levels reveal sauropod tracks (cf. Brontopodus, cf. Parabrontopodus), which on some surfaces are very abundant. Large theropod tracks (cf. Grallator) and ornithopod tracks (Caririchnium) also occur, but only on single horizons. The ichnofauna is evidence of repeated activity by large dinosaurs in a fluvio-lacustrine floodplain setting susceptible to periodic desiccation. The Naquan site forms part of an extensive Dasheng Group outcrop belt with multiple tracks sites, most of these containing multiple track-bearing levels. As a result of the investigation, drone techniques can be recommended as an additional tool for quick documentation, in order to get a general overview and map of the track surface. Details are relatively distinct on the achieved photographs, however, a precise study still needs direct examination and documentation by classical outline drawings or photogrammetry.

Late Jurassic dinosaur footprints from Chassiron–La Morelière (Oléron Island, western France)

A new dinosaur tracksite was recently discovered in the Upper Jurassic deposits from the Oleron Island (Atlantic Ocean, western France). Tracks are located along the coastline in the tidal area of La Moreliere near “Pointe de Chassiron”. They were observed in situ in an evaporitic interval from the “Purbeck beds” Unit. Sediments consist of calcite recrystallised after gypsum dissolution within limestone layers which are composed of thin laminites. The track-bearing surface shows abundant mud cracks and some ripple marks. Ichnofossils consist of medium-sized tridactyl footprints of theropods forming a narrow trackway. In order to obtain 3D reconstructions of the track-bearing surface, the trackway was scanned with a resolution of 0.5 mm using an Artec Eva 3D white-light scanner. As indicated by the track dimensions, the probable trackmaker is assigned to a medium-sized non-coelurosaur tetanuran, such as a megalosauroid or an allosauroid theropod. The palaeoenvironmental context is interpreted as a tidal flat in an evaporitic basin. In addition to the tridactyl tracks, we report sauropod- and thyreophoran-like tracks on two other surfaces from Chassiron–La Moreliere.

Re-description of the partially collapsed Early Cretaceous Zhaojue dinosaur tracksite (Sichuan Province, China) by using previously registered video coverage

A re-description of the Early Cretaceous Zhaojue dinosaur tracksite (Sichuan Province, China) is the major focus of the present work. The tracksite is located in an active copper mine, and a dinosaur track-bearing surface of about 1500 m2 (named tracksite I) initially discovered in 1991, has since almost completely collapsed due to ongoing quarry activities. Only about 5% of the initial surface still remains in place (named “remaining tracksite”), while due to the collapse a few new but rather poorly-preserved tracks were unearthed on an underlying level. While the tracks still in place were studied using common field techniques, a schematic tracksite map of the collapsed surface was drawn based on a “corrected orthophotograph” that was generated from overview photographs and from video frames. Fortunately, the resolution of some of the close-up video frames is sufficiently high to observe general track morphology, and to re-interpret previously wrongly identified trackways. Here, we report a quite diverse ichnocoenosis consisting of sauropod, ornithopod, theropod, and pterosaur trackways and isolated tracks. The sauropod trackways belong to the Brontopodus-type and were possibly left by medium-sized titanosaurs. One of the sauropod trackways turns around and makes an astonishingly narrow turn of more than 180° with very pronounced “off-tracking” of the manus with respect to the pes. Such unusual trackways are important for the reconstruction of sauropod locomotion. The theropod trackways were left by small and medium-sized animals with the imprint morphology being similar to that of the ichnogenera Grallator and Eubrontes. Large tridactyl tracks with blunt toes are tentatively identified as ornithopod tracks and may be described as Caririchnium-type tracks. Pterosaur tracks can be assigned to Pteraichnus. The association of pterosaur with small theropod tracks is rather unusual, and this tracksite further corroborates the frequent presence of large ornithopods in inland environmental settings.

Diverse sauropod-, theropod-, and ornithopod-track assemblages and a new ichnotaxon Siamopodus xui ichnosp. nov. from the Feitianshan Formation, Lower Cretaceous of Sichuan Province, southwest China

Copper mining activities in a huge quarry in the fluvial–lacustrine Lower Cretaceous Feitianshan Formation near Zhaojue, Sichuan Province have temporarily exposed large track-bearing surfaces that require rapid documentation before they are subject to erosion or damage from collapse or destruction by mining. Due to the urgent need to document these sites several preliminary studies of representative material have been completed, and more than 1000 tracks have been observed. Here we present maps of two large surfaces, with a combined area of ~1000m2, representing the same stratigraphic level, and yielding multiple trackways of measurable quality, including at least 8 theropod, 7 sauropod, and 22 ornithopod trackways. Additional trackmakers of the two latter groups are also well-represented by natural casts derived from an overlying unit disturbed by quarrying. The sauropod tracks are assigned to the ubiquitous ichnogenus Brontopodus. The ornithopod tracks belong to the ichnogenera Caririchnium, attributed to quadrupeds or facultative bipeds, and Ornithopodichnus, corresponding to smaller bipeds. Based on size and morphology the theropod trackways appear to represent diverse morphotypes, including one attributed to the new ichnospecies Siamopodus xui. The Feitianshan Formation ichnofauna, which also includes pterosaur tracks from other nearby surfaces, is moderately diverse and indicates an abundant presence of archosaurs in the region during the Early Cretaceous.