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The Upper Cretaceous Cantwell Formation in Denali National Park and Preserve (DENA) preserves an abundant and diverse ichnofossil record of high latitude dinosaurs. Field-based investigations of the formation remain limited due to its wide areal extent and remoteness, leaving questions concerning its temporal and faunistic relationships to other units unaddressed. Here we describe the largest tracksite known in DENA and all of Alaska – a 7500 square metre outcrop of steeply dipping beds known as the Coliseum. The site exposes 66.3 metres of vertical section consisting of laterally extensive fine- to medium-grained sandstone, mudstone, calcareous shale, and bentonite. Vertebrate trace fossils include true tracks, transmitted tracks, natural casts, and trackways documented via handheld and UAV-assisted photogrammetry, enabling three-dimensional mapping of the site. Facies analysis reveals a depositional environment of crevasse splay and overbank deposits within a fluvial floodplain. U-Pb dating of bentonite collected from the site returned an age of 69.3 ± 0.9 Ma, improving the limited temporal constraints of the formation. We document several ichnotaxa, some new to the formation, representing ornithopods, ceratopsids, and large and small-bodied avian and non-avian theropods. The Coliseum provides a rare window into a high latitude, Late Cretaceous forested ecosystem deposited in a Greenhouse World. [ABSTRACT FROM AUTHOR]

The Coniacian non-marine portion of the Frontier Formation in southwestern Montana has been primarily studied stratigraphically, whereas its trace fossil record and relative sedimentological significance have remained overlooked so far. We present the first description of a trace fossil assemblage reported from Frontier Formation deposits exposed in the western Centennial Mountains, Beaverhead County, Montana. Three main lithofacies groups with distinctive trace fossil assemblages have been recognised at the locality of Price Creek: (1) coarse-grained, thin and laterally extensive cross-bedded sandstone channel bodies characterised by rare vertical, passively filled burrows; (2) fine-grained overbank sandstones and siltstones, with abundant horizontal, meniscated, and unwalled burrows, sinusoidal trails, vertical burrows, and dinosaur tracks, and (3) fining-upward, planar cross-bedded silty sandstones, associated with carbonaceous plant material and bone fragments. The trace fossil assemblage is ascribed to the pre-desiccation suit of the Scoyenia ichnofacies. The occurrence of theropod, ornithopod, and thyreophoran dinosaur tracks, and invertebrate trace fossils suggests considerable diversity of terrestrial and aquatic fauna. Tracks described here represent the first dinosaurian record reported from Coniacian deposits in Montana and one of the few fossil records reported from non-marine Coniacian deposits in North America. [ABSTRACT FROM AUTHOR]

The morphology of fossil footprints is the basis of vertebrate footprint ichnology. However, the processes acting during and after trace fossil registration which are responsible for the final morphology have never been precisely defined, resulting in a dearth of nomenclature. Therefore, we discuss the concepts of ichnotaphonomy, ichnostratinomy, taphonomy, biostratinomy, registration and diagenesis and describe the processes acting on footprint morphology. In order to evaluate the morphological quality of tetrapod footprints, we introduce the concept of morphological preservation, which is related to the morphological quality of footprints (M-preservation, acronym MP), and distinguish it from physical preservation (P-preservation, acronym PP), which characterizes whether or not a track is eliminated by taphonomic and diagenetic processes. M-preservation includes all the morphological features produced during and after track registration prior to its study, and may be divided into substages (ichnostratinomic, registrational, taphonomic, stratinomic, diagenetic). Moreover, we propose an updated numerical preservation scale for M-preservation. It ranges from 0.0 (worst preservation) to 3.0 (best preservation); intermediate values may be used and specific features may be indicated by letters. In vertebrate footprint ichnotaxonomy, we regard the anatomy-consistent morphology and to a lesser extent the trackway pattern as the only acceptable ichnotaxobases. Only footprints showing a good morphological preservation (grade 2.0–3.0) are useful in ichnotaxonomy, whereas ichnotaxa based on poor morphological preservation (grade 0.0–1.5) are considered ichnotaphotaxa (nomina dubia) characterized by extramorphologies. We applied the preservation scale on examples from the Palaeozoic to the present time, including three ichnotaphotaxa and 18 anatomy-consistent ichnotaxa/morphotypes attributed to several vertebrate footprint producers. Results indicate the utility, feasibility and suitability of this method for the entire vertebrate footprint record in any lithofacies, strongly recommending its use in future ichnotaxonomic studies. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Diplocraterion, a U-shaped burrow attributed to infaunal invertebrates, is normally a shallow-marine trace fossil and not part of a continental vertebrate ichnoassemblage. Hence, the Glen Rose Formation (Aptian–Albian) of Texas (USA) presents an opportunity to studyDiplocraterionassociated with a world-class dinosaur tracksite. MostDiplocraterionare in a bioclastic wackestone–packstone bed just above the Taylor Tracklayer, a significant dinosaur track horizon.Diplocraterionare consistently sized, but with variable depths; most have protrusive spreiten and northeast–southwest trends. SmallerArenicolitesco-occur withDiplocraterion, and other trace fossils includeRhizocoralliumand a large theropod trackway. Based on our analysis, a sea-level rise buried the Taylor Tracklayer, with a shallow-marine carbonate mud colonised byDiplocraterionandArenicolitestracemakers. ProtrusiveDiplocraterion, eroded burrow tops,Rhizocorallium, and other criteria point towards firming and net erosion of the bed caused by a stillstand. The depositional environment of theDiplocraterionbed was possibly a subtidal lagoon that covered shoreward sediments impacted by large theropods. Burrow orientations suggest bidirectional currents consistent with trends of theropod trackways, implying each were controlled by a shoreline. The results of our study demonstrate how marine invertebrate and continental vertebrate trace fossils can be used together to define fine-scale changes in former carbonate shorelines. [ABSTRACT FROM AUTHOR]

Dinosaur tracksites recently discovered in exposures of the Belly River Group in the Milk River Natural Area (MRNA) and Dinosaur Provincial Park (DPP) of southern Alberta represent a novel type of ichnofossils. The tracks, all referable to hadrosaurs, occur as sideritic or calcareous concretions protruding above fine-grained deposits and are here termed concretionary tracks. Detailed sedimentological, petrographic, and geochemical analyses reveal that, although the MRNA and DPP tracks are of different mineralogical compositions (calcium carbonate versus siderite, respectively), they display similar internal structures (microscopic convoluted laminations) and occur in depositional settings indicative of wet paleoenvironments, where the ground was soft and water saturated. These characteristics suggest that concretionary tracks are footprint casts that formed as groundwater rich in dissolved carbonates flooded depressions left in the soft substrate. As the ponded water evaporated, minerals began to precipitate and mix with clastic material transported into the depressions, settling as finely laminated mud within the tracks and filling them either completely or partially. The geochemical composition of the precipitate would depend on the prevalent groundwater conditions (e.g., pH, dissolved carbonate and sulphate concrentrations). Cementation of the tracks occurred relatively soon after burial (<100 years), possibly in response to microbial activity and saturation by mineral-rich groundwater, and modern erosion exposed the concretionary tracks by removing the softer host unit. Recognition of this novel type of ichnofossils suggests dinosaur tracks may be more common than previously thought. Unfortunately, concretionary tracks tend to break apart rapidly when the encasing and underlying substrate erodes away, altering their diagnostic shape and rendering them indistinguishable from nonichnogenic concretions. As such, concretionary tracks may be transient ichnofossils in the badlands, explaining why they are rarely recognized. [ABSTRACT FROM AUTHOR]

The new ichnospeciesCubiculum levisis described as a bowl-shaped bioerosion trace fossil in dinosaur bone from the Upper Cretaceous of western Argentina. The systematic description is based on specific ichnotaxobases for bioerosion trace fossils in bones. The main characteristics of the new ichnospecies are its general bowl-shaped morphology with marked concavity of the flanks and bottom, marked constriction of walls in the upper area, and the absence of bioglyphs in the interior surface. To establish a hierarchical approach to the taxonomy ofCubiculum, we propose an emended diagnosis for this ichnogenus. Based on comparative analysis with structures of fossil pupal chambers and results of actualistic experiments with carrion insects, the ethology ofC. levisis interpreted as Pupichnia. Paleoenvironmental conditions at the paleontological site, taphonomic data and the morphology ofC. levisindicate a continental arthropod producer with the biological and anatomical ability to bore bone. The producer was probably a Cretaceous coleopteran with a heavily sclerotized body and well-developed biting mouthparts. We emphasize the importance of establishing paleoethologic and paleobiologic inferences based on testable data provided by multiple sources, such as biology, physiology, sedimentology, and forensic sciences. Finally, we cite some relevant reports of traces fossils in bones interpreted as pupal chambers and we discuss the conflicting interpretations of their producers and ecological significance. [ABSTRACT FROM AUTHOR]

Abstract: The study of the uppermost section of the Early Cretaceous Agrio Formation in northern Patagonia (Neuquén Basin) where dinosaur tracks assigned to cf. Therangospodus pandemicus are exposed (tracksites I and II) evidence mixed marginal marine siliciclastic-carbonate deposits. The succession was divided in two intervals. A lower one containing theropod tracks, recorded on top of subtidal oolithic limestones with tiny wave ripples suggesting shoreline fluctuations and subaerial exposure. Tidal influence is recognised by fining upward and prograding cycles starting with subtidal carbonates and ending with fine-grained siliciclastic deposits at the top, or rarely laminites. Dolomitization affects subtidal deposits generated in an alkaline media stressful for tracemakers. Intertidal facies include abundant heterolithic deposits, coquinas composed of gastropods encrusted by multilayered bryozoans and muddy levels with incipient mud cracking. Invertebrate ichnofossils recognized from tidally dominated deposits include Arenicolites, Kouphichnium, and Rhizocorallium. The upper interval is a transgressive–regressive cycle that starts with dark shales, deficiently oxygenated, and covered by prograding sandstones and finally sand flat deposits. This interval contains Gyrochorte, Hillichnus, and Ophiomorpha documented in wave-influenced sandstones. Dinosaur tracks as well as Hillichnus, attributed to tellinoid bivalves, and Kouphichnium assigned to xiphosurans, imply the activity of producers rarely recorded previously as body fossils in marginal marine deposits of southern South America. Previous paleogeographic schemes are questioned by our analysis, which shows evidence of extremely shallow and tide-controlled sedimentation, sometimes with subaerial exposure, with high cyclicity related to a marginal marine depositional setting and lack of significant erosion by the overlying unit, as traditionally was suggested. [Copyright &y& Elsevier]

Light Detection And Range (LiDAR) imaging provides a means to model the 3D geometry of fossil tracks in the field with high accuracy. This represents a considerable advance for the science of vertebrate ichnology in which traditional field methods suffer from a significant degree of abstraction and lack the resolution required to interpret tracks quantitatively. Three-dimensional LiDAR models provide additional morphometric information and allow the application of new analytical tools unique to the digital environment. The method will enable fossil track morphometrics to develop into an iterative process that combines 3D visualization and multivariate statistical methods, blending qualitative and quantitative approaches and allowing track morphologies to be compared holistically. Modelling of trackways from Fumanya (south-east Pyrenees) using LiDAR has enabled variation in linear track dimensions to be explained by the varied contribution of different modes of shear with increasing depth below the foot/sediment interface. Features in the relief of pes traces indicate that subsurface zones within their track volumes are defined by the interaction of puncture and local shear, below a surface zone of liquefaction failure now lost to erosion. This model of mechanical failure enables a preliminary review of the pedal kinematics of titanosaurid sauropod dinosaurs and suggests multiphase loading of the sediment by the titanosaurid pes. However, from inspection of these 3D surfaces alone it is not possible to differentiate between the possibility of one or two discrete phases of pedal motion preceding the toe-off event at the maximum height of the support phase. By integrating LiDAR models with analogue modelling within a 3D digital environment it will be possible to clarify such interpretations of fossil tracks and the locomotor mechanics of extinct animals. [ABSTRACT FROM AUTHOR]

Background: The evolutionary history of Mesozoic terrestrial vertebrates from the Arabian Peninsula is virtually unknown. Despite vast exposures of rocky outcrops, only a handful of fossils have yet been described from the region. Here we report a multi-taxon dinosaur track assemblage near Madar village, 47 km north of Sana'a, Republic of Yemen. This represents the first dinosaur tracksite from the Arabian Peninsula, and the only multi-taxon dinosaur ichnosite in the Middle East. Methodology/Findings: Measurements were taken directly from trackway impressions, following standard ichnological conventions. The presence of bipedal trackmakers is evidenced by a long series of pes imprints preserving smoothly rounded posterior margins, no evidence of a hallux, bluntly rounded digit tips and digital divarication angles characteristic of ornithopod dinosaurs. Nearby, eleven parallel quadrupedal trackways document a sauropod herd that included large and small individuals traveling together. Based on the morphology of manus impressions along with a narrow-gauged stance, the quadrupedal trackways were made by non-titanosauriform neosauropods. Additional isolated tracks and trackways of sauropod and ornithopod dinosaurs are preserved nearby. Conclusions/Significance: Taken together, these discoveries present the most evocative window to date into the evolutionary history of dinosaurs of the Arabian Peninsula. Given the limited Mesozoic terrestrial record from the region, this discovery is of both temporal and geographic significance, and massive exposures of similarly-aged outcrops nearby offer great promise for future discoveries. [ABSTRACT FROM AUTHOR]

A fundamental question remaining unanswered in dinosaur behavior is whether they had the ability to swim. We report the discovery of an exceptional swimming dinosaur trackway, with 12 consecutive footprints, in lacustrine nearshore sediment from the Early Cretaceous Cameros Basin, La Rioja, Spain. The singular morphology of these footprints strongly suggests a floating animal clawing the sediment as it swam. Diagnostic traits of theropod dinosaur footprints are identifiable in these peculiar elongated S-shaped ichnites. Paleoenvironmental reconstruction indicates an upper shoreface setting with a maximum water depth of ∼3 m, substantiating the swimming hypothesis. Ichnological analysis of the trackway shows that this theropod used a pelvic paddle motion, similar to that of modern bipeds, and swam with amplified asymmetrical walking movements to maintain direction into a leftward water current. After recent hints of swimming dinosaurs, this new evidence persuasively demonstrates that some non-avian theropod dinosaurs were swimmers. [ABSTRACT FROM AUTHOR]

Globally, skeletal remains of dinosaurs are particularly rare throughout much of the Middle Jurassic. Thus, other sources of evidence, and most importantly ichnofaunas, are important indicators of the contemporary terrestrial vertebrate communities. The outcrops of the Ravenscar Group (Aalenian—Bajocian) within the Cleveland Basin of Yorkshire, UK, which have recently been recognised as a megatracksite of global significance, provide one such major source of ichnofaunal information of this age. A comprehensive database on the variety and occurrence of dinosaur and other vertebrate traces within the Ravenscar Group has been built from a long-term and detailed study of the sequence. Thirty different and distinct morphotypes of vertebrate traces have been recognised and are being analysed and further differentiated morphometrically. Some of the morphotypes represent behavioural, preservational and perhaps ontogenetic variants of other morphotypes, but nevertheless the range of quadrupedal and bipedal prints allows an overall fauna of sauropod, stegosaurian, ornithopod and theropod dinosaurs along with crocodiles, pond turtles and fish to be reconstructed. The distribution and abundance of prints and print types within the succession shows evidence of environmental control on the behaviour and distribution of the vertebrates. Case studies highlight both the advantages and disadvantages of this type of data in reconstructing palaeocommunities. [ABSTRACT FROM AUTHOR]

Therangospodus oncalensis is a Berriasian theropod ichnotaxon from the Cameros Basin (Soria Province, Spain). We discovered new trackways assigned to this ichnotaxon during cleaning and conservation works at the type locality (Fuentesalvo), enabling us to describe it more precisely. Therangospodus oncalensis was made by a medium-sized theropod dinosaur and is characterized by a single tapering pad on each toe, a rounded heel impression and a narrow trackway. In addition to having similar morphometric characteristics, most of the trackways at the Fuentesalvo site show comparable size and biometric features. This indicates that, in terms of size and age, a homogeneous population of a single theropod species could have produced these tracks. Moreover, the similar orientation (lying within a range of only 15°) and estimated speed suggested by most of the trackways, lend weight to the hypothesis that the trackmaker of Therangospodus oncalensis was able, at least at times, to move in structured packs displaying gregarious behaviour. Furthermore, this is the first structured pack of theropods to be described. [ABSTRACT FROM AUTHOR]

Digital models of the tracks of bipedal theropod and ornithopod dinosaurs, and the quadrupedal tracks of a sauropod, were computationally eroded to investigate the effects of erosion on the shapes, sizes, and diagnostic details of fossil tracks. Narrow and (or) angular details, such as claw marks, interdigital ridges, and internal ridges, are removed early in erosion, creating the potential for misidentification of eroded theropod tracks as those of ornithopods. However, with the erosion models presented here, all tracks retain their basic shapes as indicated by the relative constancy of their interdigital angles and by the relative constancy of their footlength:footwidth ratios. Surface lengths of tracks did not increase significantly with erosion, so that dinosaurian hip height and speed estimates derived from trackways would not be greatly in error if based on eroded surface tracks. Synthetic undertracks from the surface tracks were also produced using information from published physical models of track formation. The differences between a weathered surface track and a freshly exposed, simulated undertrack are sufficient so that the two model tracks would not be confused. Large, rounded tracks are much better at retaining their characteristics than small, angular tracks, with the implication that large tracks may be over-represented in the fossil record, but they may be more reliably attributed to the appropriate trackmaker. This would bias estimates of dinosaur taxonomic diversity and body size ranges based on trackway evidence. [ABSTRACT FROM AUTHOR]

The origin of manus-only and manus dominated sauropod trackways has been a matter of intense debate since two hyphothesis exist: (a) manus-only and manus-dominated trackways result from a ‘swimming’ sauropod, and (b) they result from a selective underprint phenomenon that only leaves the manus recorded. Several new sauropod trackways are reported in the Fumanya tracksite area (Maastrichtian), in SE Pyrenees, where both tracks and undertracks are found on the same stratigraphic bedding surface. In one of the trackways, footprint morphology together with the trackway pattern displays a clear succession of manus-only impressions attributed to a sauropod dinosaur in a walking gait. The ichnological comparison between the manus-only trackway with the other complete trackway (manus-pes) display an identical distribution of the manus pattern. This fact clearly points towards an underprint phenomenon as the origin for manus-only trackways, since it is rather unlikely that the same pattern would completely match different locomotion behaviours such as walking and swimming. Therefore, we suggest an interpretation based on the differential loading between the hindfoot and the forefoot on an upper stratigraphic track-level, for the studied manus-only trackway. □ Fumanya tracksite, manus-only trackways, titanosaurs, trackway pattern, underprint, Upper Cretaceous . [ABSTRACT FROM AUTHOR]

Dinosaur traces are well known from the western United States in the Colorado Plateau region (Utah, Colorado, New Mexico, and Arizona). Utah contains the greatest abundance of known and documented dinosaur footprints and trackways. Far less well known, however, is the occurrence and distribution of dinosaur footprint-bearing horizons in Wyoming. Scientific studies over the past 10 years have shown that three of the four Middle and Upper Jurassic formations in northern Wyoming contain dinosaur footprints. Two of the footprint-bearing horizons are located in geologic intervals that were once thought to have been deposited in offshore to nearshore marine settings and represent rare North American examples of Middle Jurassic (Bajocian and Bathonian) dinosaur remains. Some of these new Wyoming sites can be correlated to known dinosaur footprint-bearing horizons or intervals in Utah. Wyoming has a great potential for additional discoveries of new dinosaur footprint-bearing horizons, and further prospecting and study is warranted and will ultimately lead to a much better understanding of the geographic distribution and behavior of the potential footprint-makers. [ABSTRACT FROM AUTHOR]

Dinosaur tracks and swimming traces have been discovered at three localities in the latest Albian Sarten Member of the Mojado Formation, Bisbee Group (="Anapra Sandstone"), at Cerro de Cristo Rey in Sunland Park, southernmost Doña Ana County, New Mexico. These localities preserve footprints of ornithopod (Caririchnium) and theropod (Magnoavipes) dinosaurs, ?reptilian swimming traces and possible tracks of an ankylosaurian dinosaur. The Sarten Member is of the latest Albian age, so the Cerro de Cristo Rey tracks are slightly younger than the wellknown late Albian tracksites of northeastern New Mexico. At Cerro de Cristo Rey, the dominance of ornithopod tracks and absence of sauropod tracks fit regional patterns of late Albian-early Cenomanian track distribution consistent with North American extirpation of sauropods before the end of Albian time. The deltaic/coastal plain depositional setting of the Sarten Member is also remarkably similar to the track-bearing late Albian-Cenomanian sandstones of NE New Mexico, Oklahoma, Nebraska, and SE Colorado, which also have a tetrapod footprint ichnofacies dominated by ornithopod (Caririchnium) and theropod (Magnoavipes) tracks throughout the so-called "dinosaur freeway." Keywords Dinosaur footprints; lower Cretaceous; Mojado Formation; New Mexico. [ABSTRACT FROM AUTHOR]

The Las Losas site (approximately 500 m²) was cleared in July 1998 and revealed 375 theropod dinosaur footprints. Statistical surveys of their biomorphical and morphometrical data are congruent with a continuous morphological transition among the theropod footprints—a transition which does not allow us to differentiate ichnogroups. Certain footprints show a longitudinal groove in their toes. The foot movement of their trackmakers can be inferred from these grooves. There are also, in this outcrop, i) trackways whose ichnites are either regular or anomalous according to the position of crossing, ii) semiplantigrade trackways with digitigrade sections and iii) trackways that cross the footprint site without variation in their footprints. These facts allow us to infer that: i) the substrate hardness was different in different zones at particular moments, and ii) the variation in the regularity and shape of the footprints depended upon the mud conditions at the moment they were made. Three preferential directions of march are shown by the trackways, suggesting different phases of activity. Keywords Dinosaur; footprints; semiplantigrade; shape variations; mud conditions; Lower Cretaceous. [ABSTRACT FROM AUTHOR]

A newly discovered dinosaur tracksite in the Upper Cretaceous Dakota Group of southeastern Colorado preserves tracks attributable to ornithopod, theropod, and possibly ankylosaurid dinosaurs. Minimally 79 tracks occur at the site, and are comprised predominantly of ornithopod prints preserved as natural sandstone casts. Nine ornithopod tracks are preserved in situ, and all but one of these trends in a northeasterly direction. The high density of ornithopod tracks coupled with the similar trend of those in situ suggest gregarious behavior. Size distribution of the ornithopod tracks indicates that some juveniles are present, with subadults most abundant and lesser numbers of mature adults. Considerable size variation exists within the nine in situ tracks with similar trends. Thus, the site could record the passage of a mixed herd composed of several age classes. This may be the only reported Dakota tracksite where ornithopod, theropod, and ankylosaurid prints occur together. Keywords Caririchnium, Magnoavipes, gregarious, herd. [ABSTRACT FROM AUTHOR]

A new ichnotaxon is described from the Lower Jurassic (Upper Hettangian—Lower Sinemurian) carbonate tidal fiats on the central-eastern Italian Alps. The narrow-gauge trackway is that of a large quadrupedal dinosaur. The pes is functionally tetradactyl with three rounded antero—medially directed digits, and the manus is pentadactyl. This quadrupedal form is close to Otozoum and Pseudotetrasauropus jaquesi both traditionally related to sauropodomorph trackmakers. The similarity with Otozoum is so marked that Lavinipes and Otozoum could be cogeneric. But the overall evidence today is that the Otozoum trackmaker was generally bipedal, whereas the trackmaker of L. cheminii is fully quadrupedal. The manual prints of L. cheminii show five short clawless digits and are different from the tetradactyl slender toed manual prints of Otozoum. The possible sauropodomorph affinity of the L. cheminii trackmaker is here discussed with an attempt to a revision of the Late Triassic—Jurassic tracks which have been traditionally related to sauropod and prosauropod. Keywords Dinosaur footprints; ornithischian tracks; sauropod tracks; Otozoum; Lower Jurassic; Italian Alps. [ABSTRACT FROM AUTHOR]

The upper part of the Chinle Group (Late Triassic) of the Gateway area in western Colorado is extraordinarily rich in fossil footprint assemblages. Dominant track types include small Grallator tracks, generally attributed to Coelophysis-like theropods, which often occur in high densities of 50 to 100 per m². Other abundant ichnotaxa that are attributable to dinosaurs or dinosaur-like archosaurs include Pseudotetrasauropus and Tetrasauropus, attributed to prosauropods and sauropods, respectively. Several Pseudotetrasauropus-like tracks appear to be functionally didactyl and may indicate a new ichnotaxon that represents an animal that shows certain unusual features that are convergent with dromeosaurs and certain birds. Such convergence may reflect inherent growth programs as much as functional adaptations. Non-dinosaurian ichnotaxa include Brachychirotherium (probably of aetosaur affinity) and Rhynchosauroides, attributed to a sphenodontid/lizardlike form. Other ichnotaxa include probable therapsid (dicynodont) tracks labeled Pentasauropus sp., mammaloid (non-therian mammal and/or mammal-like reptile) tracks, and the trails of arthropods. Excellent preservation and high track densities mark the Gateway assemblages in a thin stratigraphic interval in the upper part of the Chinle Group (Rock Point Formation). The track assemblages are similar to those reported from the Chinle Group in other parts of the Colorado Plateau and Rocky Mountain region, extending over most of Colorado, Utah, northern Arizona and northern and eastern New Mexico. Some of the Chinle ichnotaxa (Grallator and Brachychirotherium) are found in the overlying Wingate Formation, indicating that it is also Late Triassic in age, at least in the lower part. However, overall the Chinle and Wingate assemblages are quite different, most notably in the rarity of mammaloid/mammal-like tracks in the Chinle Group. Keywords Upper Triassic; Chinle Group; Grallator; Brachychirotherium; Rhynchosauroides; didactyl tracks. [ABSTRACT FROM AUTHOR]

The Los Cayos dinosaur tracksite is located at the eastern sector of the Cameros Basin (Cornago Township, La Rioja province), NE Spain. The sediments consist of interbedded terrigenous siliciclastics and carbonates belonging to the Enciso Group (Early Cretaceous, Aptian in age). The sedimentological and faunal evidence suggests that these sediments were deposited in a low gradient lacustrine environment. Los Cayos constitutes a relatively wide area with at least 6 localities that have yielded dinosaur tracks. More than 2,000 dinosaur tracks have been discovered to date. Medium to large theropod dinosaurs constitute about 95% of the ichnofauna. Ornithopod dinosaur tracks have been reported from only one of the outcrops (Los Cayos D). Los Cayos S has yielded theropod and sauropod tracks. One sauropod trackway shows a narrow-gauge locomotion pattern and a manus print morphology suggesting that the trackmaker was a titanosaurid, or at least a titanosauriform sauropod. Some pterosaur manus impressions, avian-like footprints of small size and possible turtle tracks complete the assemblage of one of the most impressive and best-preserved dinosaur tracksites of the European Lower Cretaceous. Keywords Paleoichnology; dinosaurs; aves; turtles; pterosaurs; Lower Cretaceous; Cameros Basin. [ABSTRACT FROM AUTHOR]

Studies of dinosaur tracks have benefited from a distinction between true tracks and those made in subsurface layers—undertracks. However, the straightforward definition of true tracks becomes problematic when dealing with deep tracks, which often perforate or incise surface layers rather than simply distort them. Deep tracks from the Late Triassic of Greenland were made by theropods moving their feet through a volume of sediment along a complex three-dimensional trajectory. I suggest that designating different portions of the track as direct or indirect features is fruitful for reconstructing foot motion. Identifying which sedimentary grains, rather than which layers, were touched by the foot avoids dismissing deep tracks as undertracks and overlooking a valuable source of kinematic data. Keywords Dinosaur track; locomotion; true tracks. [ABSTRACT FROM AUTHOR]

Until now dinosaur tracks from Switzerland were only known from Triassic and Late Jurassic strata. We report here for the first time the occurrence of ornithopod tracks from the Schrattenkalk Formation (Late Aptian) from the Swiss Central Alps. The locality is situated in an abandoned quarry on the shore of Lake Lucerne close to the village of Beckenried. The steeply inclined surface has more than 50 tracks (in three trackways) of ornithopod dinosaurs that are attributed to iguanodontids. Three trackways can be followed for distances of 25 to 35 m. The lengths the footprints (mean: 30 cm) point to animals ranging in size of from 4 to 6 m, with estimated hip heights between 1.8 and 2 m (hip height 6 FL) and 1.4 to 1.7 m (hip height 5 FL). One of the trackways shows two successive manus impressions, indicating facultative quadrupedal gait. The track bearing layer consists of shallow water micrites with traces of emersion, and it is overlain by bioclastic grainstones. Previously the Upper Schrattenkalk Member in the Helvetic realm was thought to have formed on a large shelf far away from any continents. The present discovery will shed new light on the paleogeographic position of the Helvetic nappes. Keywords Dinosaur tracks; Iguanodontids; Late Aptian. [ABSTRACT FROM AUTHOR]

In 2002 a new dinosaur tracksite was discovered in calcareous laminites of early Late Kimmeridgian age along the future course of the "Transjurane" highway in Courtedoux, Canton Jura, Northern Switzerland. The site has an extraordinary scientific potential, as the laminites, which have been deposited in an intertidal to supratidal environment, contain at least 6 track-bearing levels in a total thickness of about 1 m. The laminites are being systematically excavated by the "Section de paléontologie" over an area of approximately 1500 m². So far the main track level has been uncovered over an area of about 650 m², which reveals 2 trackways of theropods and 17 trackways of sauropods. The sauropod tracks are the smallest known in the Kimmeridgian so far, and the trackways belong to the ichnogenus Parabrontopodus, which has been revealed for the first time in Switzerland. The tracksite belongs to the "Middle Kimmeridgian megatracksite" sensu Meyer (2000), and represents the most important dinosaur tracksite in Switzerland, perhaps with the potential for development into one of the world's largest sauropod tracksites. It will be protected in situ underneath an especially constructed highway-bridge, thus offering opportunities for future research and the development of an interpretative center for education and tourism. Keywords Sauropoda; Diplodocoidea; Theropoda; dinosaur track; Parabrontopodus; Brontopodus; megatracksite; Reuchenette Formation; Canton Jura; Switzerland. [ABSTRACT FROM AUTHOR]

Ardley Quarry, Oxfordshire, central England, preserves a most remarkable ichnological record of dinosaur activity on a single 168 Ma old trackway-bearing horizon. This horizon reveals over 40 dinosaur trackways, most of them sauropod, but including several giant theropod trackways tentatively attributed to Megalosaurus, the first creature of its kind recognized and assigned to Dinosauria. A 60 meter-long portion of one theropod trackway (#80) is systematically characterized in terms of pitch, yaw, and roll of successive footprints. Variations among these parameters correspond closely with acceleration/deceleration intervals in the trackway, impressed by the animal in wet calcareous mud within the tidewater zone of a mid-Jurassic coastal plain. Energy expended (1.4 watts) by the animal in making each footprint in the trackway is comparable to the resting metabolic rate of modern birds and mammals. Efforts by the theropod to accelerate are reflected by intervals of forward pitch of footprints; here the backward component of the force exerted upon the ground exceeds the forward component. Conversely, during braking (deceleration) intervals, footprints tend to exhibit a backward pitch in which the forward component of the force will have exceeded the backward component. Maximum positive yaw (outward from the midline of the trackway) generally corresponds with forward pitch. Positive yaw is greatest where positive (outward) roll is maximum. Measurements of pitch, yaw, and roll of dinosaur footprints hold potential for revealing fundamental locomotor characteristics of dinosaurs and for estimating acceleration and speed of an animal from its footprint record. Keywords Paleoichnology; Jurassic; Megalosaurus; trackway; locomotion; energy; speed. [ABSTRACT FROM AUTHOR]

Tracks and traces of crouching theropods are rare, known from only three specimens from the Lower Jurassic of New England and the Lower to ?mid Jurassic of China. The New England specimens reveal manus, metatarsal and sub-crescentic ischial callosity impressions associated with Grallator-like tracks. The Chinese traces reveal metatarsal traces and a sub-triangular ischial callosity impression associated with Eubrontes-like tracks. All reveal symmetrical crouching postures. Theropod crouching traces should not be confused with ornithopod crouching traces, often assigned to Anomoepus. The ichnotaxonomy surrounding all these traces and associated footprints is very complex, and over split. Suggestions for simplification allow recognition that the North American and Chinese ichnofaunas have many similarities. The ichnotaxonomy is not as complex and confused as it may at first appear. Keywords Lower Jurassic; crouching theropod traces; metatarsal traces; ischial callosity traces. [ABSTRACT FROM AUTHOR]

The tracks ascribed to pterosaurs from the Late Jurassic limestones at Crayssac, France, must be pterosaurian because the manus prints are so far outside those of the pes, the pes print is four times longer than wide, and the manus prints appear to preserve distinct traces of a posteromedially directed wing-finger. These tracks are different in important ways from previously described Pteraichnus trackways, which have been variably considered pterosaurian, crocodilian, or indeterminate. No Pteraichnus (sensu stricto: those not from Crayssac) tracks have diagnostic features of pterosaurs and in none can a complete phalangeal or digital formula be reconstructed; however, all published Pteraichnidae tracks fulfill the criteria of poor preservation, and some have some diagnostic features of crocodile tracks. Reconstructions of pterosaurs walking in pteraichnid tracks do not fit those tracks well, but crocodiles do. In contrast, the Crayssac tracks demonstrate the erect stance and parasagittal gait previously reconstructed for pterosaurs. They also demonstrate that the footfall pattern was not as in typical reptiles (LH-RF-RH-LF), but that the manus must have been raised before the next forward step of the ipselateral foot (LH-LFRH-RF), suggesting that the quadrupedal pattern was secondary. The metatarsus in pterosaurs was set low at the beginning of a stride, as it is in crocodilians and basal dinosaurs. The diagnosis of the Ichnofamily Pteraichnidae comprises features of possible crocodilian trackmakers, but not of possible pterosaurian trackmakers. Trackways considered for attribution to pterosaurs should show (1) manus prints up to three interpedal widths from midline of body, and always lateral to pes prints, (2) pes prints four times longer than wide at the metatarso-phalangeal joint, and (3) penultimate phalanges longest among those of the pes. Keywords Pteraichnus; Pteraichnidae; Pterosauria; Crocodylia. [ABSTRACT FROM AUTHOR]

A reptile footprint fauna was recovered at Lerici, near La Spezia (northern Apennines, Italy) from Triassic sediments, belonging to the upper portion of the Montemarcello Formation. These sediments, of Mid to Late Triassic age, were deposited on a flood plain, during an early stage of rifting. The footprint-bearing levels are Carnian in age and the ichnofauna is unexpectedly diverse, including two chirotherian- and three dinosaur-related forms; consequently our findings are among the more ancient records of a true dinosaur-based ichnocoenosis. Due to the emerging complexity of systematic and stratigraphical problems, we restrict this paper to the description of a new prosauropod-related ichnotaxon named Evazoum siriguii igen. et isp. nov. In attempting to include this ichnotaxon into a convincing systematic framework we were obliged to examine the present confused situation of some different ichnotaxa. The conclusion of this attempt was that an integrated study is urgently needed to shed light on the systematics of quite a large number of prosauropod-related ichnotaxa. Keywords Dinosaur footprints; Prosauropods; Late Triassic. [ABSTRACT FROM AUTHOR]

Upper Cretaceous (Turonian–Santonian) tracksites at Barreales Lake, Neuquén Province, Argentina are described. Tracksites studied for the last 20 years on the northern and northeastern coasts of the lake mainly contain theropod and sauropod tracks preserved as either natural molds, concave epireliefs, concave hyporeliefs, or convex hyporeliefs. Sauropod tracks and trackways represent taxa that exhibited wide-gauge locomotor styles. Based on their morphology and evidence from body fossils, they are interpreted as having been produced by titanosaurs. Theropod tracks are represented by tridactyl prints with claw impressions. Some of the theropod tracks are inferred as having been made by megaraptorids. The dinosaur track record of the Barreales Lake region spans several formations: the Portezuelo Formation yielded theropod tracks at the Baal, Punta Motorhome, Aguas Claras, and South Loma de la Lata sites; the Plottier Formation preserves sauropod and ornithopod tracks at the Proyecto Dino and Middle Loma de la Lata sites, respectively; and the Bajo de la Carpa Formation yielded sauropod and theropod tracks at the Querubín site. Here we describe all these dinosaur tracksites and make inferences regarding their paleoenvironments. A brief description of some invertebrate traces from the Querubín tracksite is also provided. The description of these tracks and trackways adds to knowledge of Late Cretaceous continental paleoecosystems of southern South America. • Upper Cretaceous dinosaur tracks from Barreales Lake, Neuquén, Argentina. • Dinosaur tracks from Barreales Lake, Neuquén, Argentina. • Barreales Lake, Dinosaur Tracks, Argentina. • An overview on dinosaur tracks from Barreales lake, Argentina. • Cretaceous Dinosaur tracks, Barreales Lake, Argentina. [ABSTRACT FROM AUTHOR]

Updates that map of the Apatopus trackway and other footprints from the Chinle Group of Southern Utah. Skin impressions preserved in the Apatopus trackway of MWC 5141; Rhynchosauroides tracks on the track slab collected in 2002.

The article elaborates on the dinosaur footprints found in the Arabian Peninsula in the Middle East. Such fossils were uncovered from a 150-million-year-old rock formation, formerly a coastal mud flat. Anne Schulp of the Maastricht Museum of Natural History in the Netherlands and her colleagues from the U.S. and Yemen examined the fossils and they concluded that the track which was 15 56-centimeter-wide were made by a bipedal, plant-eating ornithopod. They also found footprints of a herd of 11 sauropods.