A Middle Jurassic dinosaur trackway site from Oxfordshire, UK

The Middle Jurassic (Bathonian) Ardley trackway site in Oxfordshire, UK is described in detail. The track site is extensive, containing over 40 more-or-less continuous theropod and sauropod trackways preserved together on a single bedding plane with some trackways up to 180 m in length. The trackways display reasonable preservation, with claw marks discernible. Sauropod trackways are by far the most abundant and are representative of taxa that exhibit both narrow and wide-gauge styles of locomotion. Theropod trackways are represented by large tridactyl prints and claw impressions that display exceptionally low pace angulation values during their walking phase. One theropod trackway is unique in that it reveals a gait transition associated with a temporary increase of speed. These dinosaurs were walking over a lime-mud firmground to hardground that was emergent, or locally very shallowly submerged. GPS (Global Positioning Satellite) data reveal that the tracks, preserved during a short time interval, trend in a north-easterly direction. Multi-herding behaviour is suggested for the sauropods of differing size. The discovery of this site adds significantly to our knowledge of the taxonomic composition of Middle Jurassic ecosystems. Evidence concerning locomotor styles employed by saurischian dinosaurs, footprint identification, potential trackmaker, social interactions and observations concerning estimates of Middle Jurassic faunal diversity, as well as aspects of dinosaur locomotor evolution are discussed.     

Sauropod trackways from site el sobaquillo (Munilla,La Rioja,Spain) indicate amble walking

Values of hindlimb height and glenoacetabular length are estimated in two ways: a) from an Aptian age sauropod trackway 13 meters long at a site (El Sobaquillo) in La Rioja Province (Spain), and b) from published skeletal reconstructions in Norman (1985), McIntosh (1990) and Farlow (1992). Results that best fit the presently available data are obtained using formulae suggested by Ishigaki (1988) and Lockley et al. (1986) for hindlimb height, and that employed by Far‐low et al. (1989) for glenoacetabular length. Our estimate of the glenoacetabular lengths of trackmakers from El Sobaquillo is consistent with a hypothesis that the sauropods were moving by amble walking. This interpretation is supported by data from other trackways found in La Rioja.     

Middle Triassic horseshoe crab reproduction areas on intertidal flats of Europe with evidence of predation by archosaurs

A systematically excavated track site in a 243.5 Myr old Middle Triassic (Karlstadt Formation, Pelsonian, middle Anisian) intertidal carbonate mud‐flat palaeoenvironment at Bernburg (Saxony‐Anhalt, central Germany) has revealed extensive horseshoe crab trackways attributable to the Kouphichnium Nopsca, 1923 ichnogenus. The exposed track bed of a Germanic Basin‐wide spanned intertidal megatrack site is a mud‐cracked biolaminate surface on which detailed tracks have been preserved because of rapid drying and cementation as a result of high temperatures, followed by rapid covering with a protective layer of arenitic storm or tsunami sediments. The different trackway types and their orientations have allowed a tidal sequence to be reconstructed, with the initial appearance of swimming horseshoe crabs followed by half‐swimming/half‐hopping limulids under the shallowest water conditions. The Bernburg trackways, which have mapped lengths of up to 40 m, were all produced by adult animals and exhibit a variety of shapes and patterns that reflect a range of subaquatic locomotion behaviour more typical of mating than of feeding activities. The closest match to the proportions and dimensions of the horseshoe crab tracks at Bernburg is provided by the largest known Middle Triassic limulid Tachypleus gadeai, which is known from the north‐western Tethys in Spain. The horseshoe crab body fossils recognized in the German Mesozoic intertidal zones, instead, are from juveniles. The uniformly adult size indicated by the trackways therefore suggests that they may record the oldest intertidal reproductive zones of horseshoe crabs known from anywhere in the world, with the track‐makers having possibly migrated thousands of kilometres from shallow marine areas of the north‐western Tethys to reproduce in the intertidal palaeoenvironments of the Germanic Basin. Chirotherium trackways of large thecodont archosaurs also appeared on these flats where they appear to have fed on the limulids. With the tidal ebb, smaller reptiles such as Macrocnemus (Rhynchosauroides trackways) appeared on the dry intertidal flats, probably feeding on marine organisms and possibly also on horseshoe crab eggs. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 76–105.     

Trackway Ratio: A New Look at Trackway Gauge in the Analysis of Quadrupedal Dinosaur Trackways and its Implications for Ichnotaxonomy

A new parameter, the Trackway Ratio (TR), is proposed to supplement the previously used trackway gauge to describe and quantify the relative width of trackways in dinosaur quadrupedal gaits. It is expressed as the ratio of the width of the tracks relative to the total width of the trackway (both measured perpendicular to the long axis of the trackway). The ratio may be used with either pes (PTR) or manus (MTR) tracks. The PTR range of values for wide-, medium- and narrow-gauge trackways of previous authors are provisionally suggested to be ≤35%, 36–49% and ≥50%, respectively. The application of such a ratio would permit a more consistent ichnotaxonomy to be adopted where both track morphology and trackway parameters are used to define ichnotaxa.

Determination of the TR, as well as other parameters, will be affected by track preservation quality. Recent experiments on track simulation in the laboratory have shed further light on observations made in the field concerning the value of track measurements (in particular track length and width) recorded from below the surface on which the maker was moving. Experimental track simulations in the laboratory have shown that the dimensions of transmitted tracks preserved below the surface on which the foot was impressed may vary from 65% to 135% of the true dimensions of the indenter. Two case studies are presented that quantify the errors that may be made on calculating TR and the size, gait and speed of the maker, from trackways if the preservation of the tracks are not fully understood.

It is shown that in individual trackways the PTR may vary along the length of the trackway; so that part of the trackway may be classified as wide-gauge and other parts medium-gauge. There is a relationship between variation in PTR and that of pace angulation along the length of a single trackway. An analysis of 42 trackways, principally sauropod, shows a temporal distribution that does not agree closely with previous suggestions relating to narrow- and wide-gauge trackways.     

Tracking a Legend: An Early Cretaceous Sauropod Trackway from Zhaojue County,Sichuan Province,Southwestern China

Cretaceous tetrapod (dinosaur and pterosaur) tracks from Zhaojue County in Sichuan Province are locally very abundant. Large scale quarrying operations at the Sanbiluoga Copper Mine site have produced extensive exposures, and track material for detailed study. However, natural track-bearing outcrops also occur at a site in Jiefang Township. The traditions of the local Yi people, indigenous to the area, attribute such tracks to Zhigealu, a central creator hero-ancestor, who made the footprints while riding his heavenly steed through the area. Through seeing tracks exposed by quarrying the local people offered these legend-based interpretations, and reported the Jiefang site which was previously unknown to scientists from outside the area. Thus, it is important to pay attention to local legends about track makers since they may lead directly to significant fossil footprint discoveries. Thereby paleontology and ichnological research can benefit largely from archeological sciences as well as from oral narratives from the local people. The recently discovered sauropod trackway from Jiefang is an excellent example. It comprises 16 pes-manus sets arranged in a narrow-gauge pattern. A peculiarity is the combination of this feature with morphological characteristics known from typical wide-gauge Brontopodus trackways suggesting a tentative assignment to cf. Brontopodus. The discovery enlarges the distribution and diversity of Brontopodus-like trackways and their producers in the Cretaceous Sichuan Basin.     

Bushmen Cave Paintings of Ornithopod Dinosaurs: Paleolithic Trackers Interpret Early Jurassic Footprints

Remnants of Bushmen cave paintings showing representations of dinosaurs evidently reconstructed from footprints, trackways and skeletal remains have been found in Lesotho. This is a region of prolific dinosaur trackways preserved in Lower Jurassic sedimentary rocks, and the Bushman culture is renowned for extraordinary skill in the tracking of modern animals. It is probable that the track and trackmaker representations depict ornithopod dinosaurs. The track drawings are accurate, and the trackmaker representations show that Bushman artists anticipated modern reconstructions of bipedal dinosaurs and produced depictions that are more realistic than many paleontological reconstructions that endured until quite recently.     

Hominid Ichnotaxonomy: An Exploration of a Neglected Discipline

Although more than 60 ancient hominid track sites ranging in age from 3.7 million to less than 500 B. P. are recorded from all continents except Antarctica, no ichnotaxonomic names have ever been formally proposed for hominid tracks. There is no prohibition to the naming of fossil footprints of species that created tracks and trackways similar to those of living species. On the contrary, there is precedent for the naming of ichnotaxa corresponding to the dominant extant vertebrates classes: mammals = Mammalipedia and birds = Avipeda. The hominid track site sample includes only about a dozen sites where footprint preservation is good enough to show details of diagnostic foot morphology and typical trackway morphology. We infer that the Acahualinca Footprint Museum site in Nicaragua represents the most important ancient hominid track site that combines accessibility, a large sample of well-preserved trackways and reliable dating. For this reason, we select the Nicaraguan tracks as the type sample for the new ichnotaxon Hominipes modernus ichnogen., and ichnsp. et ichnosp. nov., which we infer to represent fully modern Homo sapiens. Our preliminary investigations of other track sites suggest that the majority also yield H. modernus. However, at many sites preservation is insufficient to make an ichnotaxonomic designation at the species level or to infer that the trackmaker was H. sapiens. Thus, at many sites including the famous Laetoli site, we apply the more general label of Hominipes isp. indet.     

Simulating sauropod manus-only trackway formation using finite-element analysis

The occurrence of sauropod manus-only trackways in the fossil record is poorly understood, limiting their potential for understanding locomotor mechanics and behaviour. To elucidate possible causative mechanisms for these traces, finite-element analyses were conducted to model the indentation of substrate by the feet of Diplodocus and Brachiosaurus. Loading was accomplished by applying mass, centre of mass and foot surface area predictions to a range of substrates to model track formation. Experimental results show that when pressure differs between manus and pes, as determined by the distribution of weight and size of respective autopodia, there is a range of substrate shear strengths for which only the manus (or pes) produce enough pressure to deform the substrate, generating a track. If existing reconstructions of sauropod feet and mass distributions are correct, then different taxa will produce either manus- or pes-only trackways in specific substrates. As a result of this work, it is predicted that the occurrence of manus- or pes-only trackways may show geo-temporal correlation with the occurrence of body fossils of specific taxa.     

New Data on Therangospodus oncalensis from the Berriasian Fuentesalvo Tracksite (Villar del Río,Soria, Spain): An Example of Gregarious Behaviour in Theropod Dinosaurs

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.     

Pliocene Animal Trackways at Laetoli: Research and Conservation Potential

Laetoli, a paleoanthropological site in Northern Tanzania, is perhaps best known for its famous fossil hominid footprints that were discovered by Mary Leakey and her co-workers in 1978. The site not only preserves the hominid footprints but also trackways, which provide a snapshot of Pliocene faunal communities from East Africa and their inferred environments. Unlike the hominid footprints at site G, which have received tremendous attention, the animal trackways, especially at Localities 7, 8 and 10 have been neglected and are fast disappearing. In this paper, we discuss animal tracks at a newly discovered exposure and provide preliminary data on the tracks at this exposure and other sites. We also discuss the importance of the animal trackways as ecological indicators, which we have investigated as part of ongoing research and conservation efforts initiated by the Tanzania Field School in Paleoanthropology and the Associated Colleges of the Midwest (ACM) Tanzania Semester Abroad programs.     

Orientation and Characteristics of Theropod Trackways from the Las Losas Palaeoichnological Site (La Rioja,Spain)

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.     

America's Most Famous Human Footprints: History,Context and First Description of Mid-Holocene Tracks from the Shores of Lake Managua,Nicaragua

Human tracks discovered in 1874 at a site named El Cauce or Acahualinca near the shores of Lake Managua, Nicaragua, are the most famous and abundant human tracks in the Americas. They represent a landmark ichnological discovery during the late 19th century that generated much debate regarding their age and origins. Reported dates for the tracks range from 2,120 to 6,500 B.P. The site, which is now situated within the limits of Nicaragua's capital city of Managua, forms the basis of the Acahualinca Tracks Museum (Huellas de Acahualinca) and has been in place since 1953. However, it is still little known and has not been systematically studied, despite being an important window into Meso-American prehistory. Two exposures of a surface of volcanic ash reveal hundreds of human tracks comprising a minimum of 12 clearly defined trackways, and a trampled zone or path representing at least three more individuals, all heading in the same northwesterly direction. Tracks of deer, opossum and at least one bird are also present. Bison tracks collected from another nearby site (El Recreo) that is no longer accessible are on display at the museum. The Acahualinca tracks are noteworthy for the exceptional quality of preservation. We herein present the first maps of the two exposures, which combine to tell a story of human and animal activity along the shores of ancient Lake Managua several thousand years ago.     

Preliminary Report on the Courtedoux Dinosaur Tracksite from the Kimmeridgian of Switzerland

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 paleontologie” 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.     

Early evidence for complex social structure in Proboscidea from a late Miocene trackway site in the United Arab Emirates

Many living vertebrates exhibit complex social structures, evidence for the antiquity of which is limited to rare and exceptional fossil finds. Living elephants possess a characteristic social structure that is sex-segregated and multi-tiered, centred around a matriarchal family and solitary or loosely associated groups of adult males. Although the fossil record of Proboscidea is extensive, the origin and evolution of social structure in this clade is virtually unknown. Here, we present imagery and analyses of an extensive late Miocene fossil trackway site from the United Arab Emirates. The site of Mleisa 1 preserves exceptionally long trackways of a herd of at least 13 individuals of varying size transected by that of a single large individual, indicating the presence of both herding and solitary social modes. Trackway stride lengths and resulting body mass estimates indicate that the solitary individual was also the largest and therefore most likely a male. Sexual determination for the herd is equivocal, but the body size profile and number of individuals are commensurate with those of a modern elephant family unit. The Mleisa 1 trackways provide direct evidence for the antiquity of characteristic and complex social structure in Proboscidea.     

THREE-DIMENSIONAL MODELLING AND ANALYSIS OF DINOSAUR TRACKWAYS

Abstract:  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.     

Footprint on a coprolite: A rarity from the Eocene of Vietnam

A rare ichnological example of a crocodilian footprint on an Eocene crocodilian coprolite has been discovered. The enigmatic specimen, measuring 4 cm in length, was found among 100 coprolites at the Na Duong coal mine in Lang Son province, northern Vietnam. Almost all the discovered coprolites were ascribed to a potential crocodilian producer, suggesting the existence of an ancient lacustrine environment. Furthermore, neoichnological analyses of extant crocodilian footprints also corroborate the inference of a crocodilian as the producer of the footprint. We concluded that the 4-cm-long Na Duong fingerprints most likely belonged to a 2-m-long crocodilian whose IV or V finger of the right manus might have made the fingerprints. Since no other records of foot traces or trackways were identified during the fieldwork in the fall of 2018, the Na Duong fossil site should be investigated for further ichnofossil analysis.     

A theropod–sauropod track assemblage from the ?Middle–Upper Jurassic Shedian Formation at Shuangbai,Yunnan Province,China, reflecting different sizes of trackmakers: Review and new observations

A dinosaur tracksite at Hemenkou (Shuangbai County, Yunnan Province) in the ?Middle–Upper Jurassic Shedian Formation that consists mainly of gray-purple feldspathic quartz sandstones was previously reported incorrectly as being in the Lower Cretaceous Puchanghe Formation. The previous assignment is also inconsistent with two regional geological maps. Although mostly yielding poorly preserved tracks, the site nevertheless indicates a diversity of theropod and sauropod trackmakers partly consistent with the Late Jurassic body fossils from the region. Purported ornithopod are re-evaluated here as those of theropods. The theropod tracks and trackways show distinct similarities to those of the Grallator–Eubrontes plexus and can be subdivided into three morphotypes that may reflect different pes anatomy and/or substrate conditions. Two sizes of tracks (small, large) indicate the presence of different size classes or species in this area in the Late Jurassic. Similarly, the sauropod trackways document three differently sized trackmakers (small–medium–large) showing a typical wide-gauge (Brontopodus) pattern. The track record is the first evidence of theropods in the ?Middle–Late Jurassic of central Yunnan, whereas the sauropod tracks suggest a relation to the coeval basal eusauropods known from this region by skeletal remains.