Search

Limb phase, the timing of the footfalls in quadrupedal locomotion that describes common gaits such as the trot and the pace gait, 1 , We here present a fundamentally new approach that allows for estimating limb phase based on variation patterns in long trackways. The approach is tested on trackways of modern mammals, where the estimates generally correspond well with the actually employed limb phase. We then estimate limb phases of giant wide-gauged sauropod dinosaurs based on three long trackways from the Lower Cretaceous of Arkansas, US. 2 is widely believed to be difficult or even impossible to estimate for extinct tetrapods. 3-5 We here present a fundamentally new approach that allows for estimating limb phase based on variation patterns in long trackways. The approach is tested on trackways of modern mammals, where the estimates generally correspond well with the actually employed limb phase. We then estimate limb phases of giant wide-gauged sauropod dinosaurs based on three long trackways from the Lower Cretaceous of Arkansas, US. 6 , 7 Gait selection at the largest body sizes is of considerable interest given the lack of modern analogs. Contrary to previous assumptions, 8 , 9 our estimates suggest lateral sequence diagonal couplet walks, in which the footfalls of the diagonal limb pairs (e.g., right hind and left fore) are more closely related in time than those of the same side of the body (e.g., right hind and right fore). Such a gait selection allows for efficient walking while maintaining diagonal limb support throughout the step cycle, which is important for a giant, wide-gauged trackmaker. 10 Estimations of limb phase may help to constrain other gait parameters, body size and shape, and, finally, potential trackmaker taxa., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 The Authors. Published by Elsevier Inc.)

Two Early Cretaceous (Aptian) paleosol (fossil soil, FPS) profiles in the Northern Caucasus in the close vicinity of the City of Kislovodsk, that contain plant roots preserved in situ, are discussed. Geochemical characteristics and composition of microbiomorphs are obtained for the most representative paleosol profile FPS-D1. The dinosaur tracks are examined in the Valanginian deposits in the same area. The tracks are assigned to several morphotypes, i.e., the ichnogenera Iguanodontipus Sarjeant et al., Megalosauripus sensu Lockley et al., and Macropodosaurus Zakharov. The author's interpretation of paleogeographical and paleoecological environments of the dinosaur track localities and of paleosols is proposed. [ABSTRACT FROM AUTHOR]

Whilst bones present a static view of extinct animals, fossil footprints are a direct record of the activity and motion of the track maker. Deep footprints are a particularly good record of foot motion. Such footprints rarely look like the feet that made them; the sediment being heavily disturbed by the foot motion. Because of this, such tracks are often overlooked or dismissed in preference for more foot‐like impressions. However, the deeper the foot penetrates the substrate, the more motion is captured in the sediment volume. We have used deep, penetrative, Jurassic dinosaur tracks which have been naturally split into layers, to reconstruct foot motions of animals living over 200 million years ago. We consider these reconstructions to be hypotheses of motion. To test these hypotheses, we use the Discrete Element Method, in which individual particles of substrate are simulated in response to a penetrating foot model. Simulations that produce virtual tracks morphologically similar to the fossils lend support to the motion being plausible, while simulations that result in very different final tracks serve to reject the hypothesis of motion and help generate a new hypothesis. [ABSTRACT FROM AUTHOR]

Zhucheng, located in eastern Shandong Province, China, is well-known for its abundant Early Cretaceous dinosaur footprints and Late Cretaceous dinosaur bone fossils. Recently, Lockley et al. (2015) presented a sketch study on the Huanglonggou tracksite in the Zhucheng area, and critically commented on our paper (H. Xu et al., 2013), which conducted a detailed and comprehensive study of the tracksite. Here, we demonstrate that some of their assumptions and comments on our work are subjective and incorrect. Tracks at the Huanglonggou tracksite, including a dominant theropod (large theropod, Grallator yangi / Paragrallator , Corpulentapus lilasia ), and subordinate sauropod, suspected ornithopod, and turtle tracks were preserved in the Yangjiazhuang Formation with estimated ages of 129 to 122 Ma, rather than in the Longwangzhuang Formation as proposed by Lockley and his associates. Contrary to Lockley et al. (2015), our mapping of the Huanglonggou tracksite exhibits the previous work by Li et al. (2011) and focuses on the 50 well-preserved trackways and their orientations. Based on the stride length to footprint size index diagram and the Grallator–Anchisauripus–Eubrontes (GAE) plexus, our statistical constraints on the three species of theropods are better than those of Lockley et al. (2015). Lockley argued that tracks at the site were preserved on at least five levels, of which the majority on level 4 were of excellent preservation. In fact, the tracks identified throughout the site have been from only one level. The false appearance of multiple levels is interpreted as the result of sedimentation at the shoreline and differential excavation of the tracksite. [ABSTRACT FROM AUTHOR]

Extensive and well-preserved tracksites in the coastally exposed Lower Cretaceous (Valanginian–Barremian) Broome Sandstone of the Dampier Peninsula provide almost the entire fossil record of dinosaurs from the western half of the Australian continent. Tracks near the town of Broome were described in the late 1960s as Megalosauropus broomensis and attributed to a medium-sized theropod trackmaker. Brief reports in the early 1990s suggested the occurrence of at least another nine types of tracks, referable to theropod, sauropod, ornithopod, and thyreophoran trackmakers, at scattered tracksites spread over more than 80 km of coastline north of Broome, potentially representing one of the world's most diverse dinosaurian ichnofaunas. More recently, it has been proposed that this number could be as high as 16 and that the sites are spread over more than 200 km. However, the only substantial research that has been published on these more recent discoveries is a preliminary study of the sauropod tracks and an account of the ways in which the heavy passage of sauropod trackmakers may have shaped the Dampier Peninsula's Early Cretaceous landscape. With the other types of dinosaurian tracks in the Broome Sandstone remaining undescribed, and the full extent and nature of the Dampier Peninsula's dinosaurian tracksites yet to be adequately addressed, the overall scientific significance of the ichnofauna has remained enigmatic. At the request of the area's Goolarabooloo Traditional Custodians, 400C hours of ichnological survey work was undertaken from 2011 to 2016 on the 25 km stretch of coastline in the Yanijarri–Lurujarri section of the Dampier Peninsula, inclusive of the coastline at Walmadany (James Price Point). Forty-eight discrete dinosaurian tracksites were identified in this area, and thousands of tracks were examined and measured in situ and using three-dimensional photogrammetry. Tracksites were concentrated in three main areas along the coast: Yanijarri in the north, Walmadany in the middle, and Kardilakan– Jajal Buru in the south. Lithofacies analysis revealed 16 repeated facies types that occurred in three distinctive lithofacies associations, indicative of an environmental transgression between the distal fluvial to deltaic portions of a large braid plain, with migrating sand bodies and periodic sheet floods. The main dinosaurian track-bearing horizons seem to have been generated between periodic sheet floods that blanketed the preexisting sand bodies within the braid plain portion of a tidally influenced delta, with much of the original, gently undulating topography now preserved over large expanses of the present day intertidal reef system. Of the tracks examined, 150 could be identified and are assignable to a least eleven and possibly as many as 21 different track types: five different types of theropod tracks, at least six types of sauropod tracks, four types of ornithopod tracks, and six types of thyreophoran tracks. Eleven of these track types can formally be assigned or compared to existing or new ichnotaxa, whereas the remaining ten represent morphotypes that, although distinct, are currently too poorly represented to confidently assign to existing or new ichnotaxa. Among the ichnotaxa that we have recognized, only two (Megalosauropus broomensis and Wintonopus latomorum) belong to existing ichnotaxa, and two compare to existing ichnotaxa but display a suite of morphological features suggesting that they may be distinct in their own right and are therefore placed in open nomenclature. Six of the ichnotaxa that we have identified are new: one theropod ichnotaxon, Yangtzepus clarkei, ichnosp. nov.; one sauropod ichnotaxon, Oobardjidama foulkesi, ichnogen. et ichnosp. nov.; two ornithopod ichnotaxa, Wintonopus middletonae, ichnosp. nov., and Walmadanyichnus hunteri, ichnogen. et ichnosp. nov.; and two thyreophoran ichnotaxa, Garbina roeorum, ichnogen. et ichnosp. nov., and Luluichnus mueckei, ichnogen. et ichnosp. nov. The level of diversity of the main track types is comparable across areas where tracksites are concentrated: Kardilakan– Jajal Buru (12), Walmadany (11), and Yanijarri (10). The overall diversity of the dinosaurian ichnofauna of the Broome Sandstone in the Yanijarri–Lurujarri section of the Dampier Peninsula is unparalleled in Australia, and even globally. In addition to being the primary record of non-avian dinosaurs in the western half of Australia, this ichnofauna provides our only detailed glimpse of Australia's dinosaurian fauna during the first half of the Early Cretaceous. It indicates that the general composition of Australia's mid-Cretaceous dinosaurian fauna was already in place by the Valanginian–Barremian. Both sauropods and ornithopods were diverse and abundant, and thyreophorans were the only type of quadrupedal ornithischians. Important aspects of the fauna that are not seen in the Australian mid-Cretaceous body fossil record are the presence of stegosaurians, an overall higher diversity of thyreophorans and theropods, and the presence of large-bodied hadrosauroid-like ornithopods and very large-bodied sauropods. In many respects, these differences suggest a holdover from the Late Jurassic, when the majority of dinosaurian clades had a more cosmopolitan distribution prior to the fragmentation of Pangea. Although the record for the Lower Cretaceous of Gondwana is sparse, a similar mix of taxa occurs in the Barremian–lower Aptian La Amarga Formation of Argentina and the Berriasian–Hauterivian Kirkwood Formation of South Africa. The persistence of this fauna across the Jurassic-Cretaceous boundary in South America, Africa, and Australia might be characteristic of Gondwanan dinosaurian faunas more broadly. It suggests that the extinction event that affected Laurasian dinosaurian faunas across the Jurassic-Cretaceous boundary may not have been as extreme in Gondwana, and this difference may have foreshadowed the onset of Laurasian-Eurogondwanan provincialism. The disappearance of stegosaurians and the apparent drop in diversity of theropods by the mid-Cretaceous suggests that, similar to South America, Australia passed through a period of faunal turnover between the Valanginian and Aptian. [ABSTRACT FROM AUTHOR]

Although the type section of the Morrison Formation, near Denver Colorado, now also well-known as Dinosaur Ridge, has since 1877 been world famous as the source of iconic Late Jurassic dinosaurs like Stegosaurus , Apatosaurus , and Diplodocus , little detailed information has been published on fossil footprints from the formation in this area. Late Jurassic (Morrison) footprints were not reported from the type section at Dinosaur Ridge until the early 1990s. Since then, other footprints have been reported, and their precise stratigraphic occurrences documented. To date, diagnostic examples of theropod, sauropod, and thyreophoran (stegosaur) tracks have been documented from at least three different locations. The quality of preservation of these tracks ranges from moderately good to quite poor. Nevertheless, more than 25 individual footprints, including some undertracks, have been identified unequivocally, including several manus–pes sets of quadrupedal trackmakers. The track assemblages are typical of many small Morrison Formation ichnofaunas and are consistent with what is known of the body fossil assemblages. The track assemblage is reviewed and compared with summary data from the 64 Morrison Formation tracksites currently known. [ABSTRACT FROM AUTHOR]

Literature concerning dinosaur footprints or trackways exhibiting abnormal gait or morphology reflecting pathology (ichnopathology) is rare. We report on a number of Jurassic and Cretaceous occurrences of theropod footprints from western North America with unusual morphologies interpreted herein as examples of inferred pathologies, orichnopathologies. The majority of ichnopathologies are primarily manifested in the digit impressions and include examples of swelling, extreme curvature, dislocation or fracture, and amputation. A number of occurrences are single tracks onex situblocks with substantial deformation (inferred dislocation or fracture), or absence of a single digit impression. Two occurrences are fromin situnatural mould trackways, one of which is a lengthy trackway of a presumed allosauroid with no noticeable deformation of the digits or feet but with strong inward rotation of the left footprint toward the midline and a pronounced, waddling limp. The other is a tyrannosaurid trackway consisting of three footprints (one right, two left) with the two left prints exhibiting repetitive ichnopathology of a partially missing Digit II impression. [ABSTRACT FROM AUTHOR]

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-gaugeBrontopodustrackways suggesting a tentative assignment to cf.Brontopodus. The discovery enlarges the distribution and diversity ofBrontopodus-like trackways and their producers in the Cretaceous Sichuan Basin. [ABSTRACT FROM AUTHOR]

Fluvial palaeochannels of coastal plain sediments of the Lower Jurassic Sose Bugt Member of the Rønne Formation exposed in the coastal cliffs at Sose Bugt, Bornholm, contain abundant dinosaur or other large vertebrate tracks in the form of deformation structures exposed in vertical section. The tracks are represented by steep-walled, flat-to-concave-bottomed depressions, with a raised ridge at each side. The tracks are filled with laminated sediments, draping the contours of the bottom of the depression. Underprints, stacked concave deformations beneath the prints, are present beneath each track. Contemporary Upper Triassic - Lower Jurassic strata from southern Sweden and Poland contain a diverse track fauna, supporting our interpretation. This is the earliest evidence of dinosaur activity in Denmark. [ABSTRACT FROM AUTHOR]

We describe an extensive ichnofossil assemblage from the likely Cenomanian-age ‘lower’ and ‘upper’ units of the ‘Kem Kem beds’ in southeastern Morocco. In the lower unit, trace fossils include narrow vertical burrows in cross-bedded sandstones and borings in dinosaur bone, with the latter identified as the insect ichnotaxon Cubiculum ornatus. In the upper unit, several horizons preserve abundant footprints from theropod dinosaurs. Sauropod and ornithischian footprints are much rarer, similar to the record for fossil bone and teeth in the Kem Kem assemblage. The upper unit also preserves a variety of invertebrate traces including Conichnus (the resting trace of a sea-anemone), Scolicia (a gastropod trace), Beaconites (a probable annelid burrow), and subvertical burrows likely created by crabs for residence and detrital feeding on a tidal flat. The ichnofossil assemblage from the Upper Cretaceous Kem Kem beds contributes evidence for a transition from predominantly terrestrial to marine deposition. Body fossil and ichnofossil records together provide a detailed view of faunal diversity and local conditions within a fluvial and deltaic depositional setting on the northwestern coast of Africa toward the end of the Cretaceous. [ABSTRACT FROM AUTHOR]

In modern terrestrial ecosystems, the population size of large predators is low, and a similar pattern has usually been assumed for dinosaurs. However, fossil finds of monospecific, large theropod accumulations suggest that population dynamics were more complex. Here, we report two Early Cretaceous tracksites dominated by large theropod footprints, in Querulpa Chico (Peru) and Chacarilla (Chile). The two sites correspond to distinct depositional environments--tidal basin/delta (Querulpa Chico) and meandering river (Chacarilla)--with both subject to extensive arid or semiarid palaeoclimatic conditions. Although most trackways show no preferred orientation, a clear relationship between two trackmakers is observed in one instance. This observation, coupled with the high abundance of trackways belonging to distinct large theropods, and the exclusion of tracks of other animals, suggests some degree of grouping behaviour. The presence of freshwater sources in a dry climate and perhaps social behaviour such as pair bonding may have promoted interactions between large carnivores. Further, the occurrence of these two tracksites confirms that large theropod dinosaurs, possibly spinosaurids and/or carcharodontosaurids, existed on the western margin of Gondwana as early as the earliest Cretaceous. [ABSTRACT FROM AUTHOR]

Abstract: The John Martin Reservoir tracksites from the Dakota Group of Bent County, in southeastern Colorado form part of the mid Cretaceous Dinosaur Freeway characterized by abundant ornithopod footprints (Caririchnium). Over 350 tracks (331 Caririchnium, 1 Magnoavipes, 22 crocodiles, and a few pterosaurs) were discovered at 10 new tracksites. All tracks were found as natural casts, including Caririchnium trackways that were still in-situ, parallel and regularly spaced, suggesting gregarious behavior. Most crocodile tracks are swimming tracks that consist of three or four scratch marks also with parallel orientations in many cases. A few pterosaur tracks consist of pes footprints and scratch marks suggesting swimming or floating activity in shallow water. This is the first pterosaur evidence from the Dakota Group. The Caririchnium size structure from John Martin Reservoir is consistent with the size structure tendency of the whole Dinosaur Freeway, which shows larger track size in the north. This tendency could be interpreted as evidence for more than one ornithopod species spread out across the Dinosaur Freeway. The alternative, that there was one ornithopod species that migrated north and south seasonally is less likely. The John Martin paleoecosystem is interpreted from the track evidence as a well-vegetated coastal plain environment with many ornithopods and a few theropods on land, crocodiles in the water, and pterosaurs in the skies and on the water. [Copyright &y& Elsevier]

We report the first occurrence of the trackway of a quadrupedal ornithopod from the Jindong Formation (Late Aptian) of Korea. Although trackways of ornithopods are abundant in the Cretaceous of Korea, especially in the Jindong Formation, trackways of a quadrupedal trackmaker have never been reported from Korea. Moreover, the manus shows an unusual morphology with three subcircular indentations arranged in an unusual, elongate arc unlike any seen in other ornithopod ichnospecies. The specimen is clearly different from all other known Korean ornithopod footprints and is herein named as Caririchnium kyoungsookimi. To date, Caririchnium is one of only two ichnogenus names applied with confidence to Lower Cretaceous ornithopod tracks from Asia. [ABSTRACT FROM AUTHOR]

Bird tracks are abundant and ubiquitous in many Cretaceous formations in Korea. To date, in order of discovery and description, the following six ichnogenera have been reported: Koreanaornis, Jindongornipes, Uhangrichnus, Hwangsanipes, Ignotornis, Goseongornipes and ?Aquatilavipes. As more bird tracks are discovered it has become possible to amend descriptions of existing ichnotaxa to better understand track morphology (and ichnotaxonomic relationships), trackway patterns and associated feeding traces and gain further insight into the behavior and ecology. We review and re-evaluate the most important bird tracksites in Korea, with special reference to sites not previously fully or adequately described in accessible English language journals. We pay special attention to material from the Uhangri Dinosaur Museum, Haenam area, and the Gyeongsangnamdo Institute of Science Education, Gajin area, presenting revised descriptions, illustrations and information on Uhangrichnus and Goseongornipes. [ABSTRACT FROM AUTHOR]

New sauropod tracks are described herein as Brontopodus pentadactylus ichnosp. nov. from the Early Cretaceous Haman Formation of Jinju area, Korea. B. pentadactylus is characterized by a medium gauged trackway with wide pentadactyl manus tracks revealing hitherto unreported morphology. Thus, B. pentadactylus provides new insight into the morphology of the fleshed-out manus of sauropods showing that, unlike most semi-circular manus tracks that lack discrete digit traces, some indicate trackmakers with clearly differentiated, well-defined, and very wide manus digits. Manus tracks sometimes appear as tridactyl impressions that appear outwardly rotated at right angles to the midline of the trackway. This track morphology appears to reflect greater weight distribution on the outer, postero-lateral part of the manus. The pes is elongate, pentadactyl, outwardly rotated, and typical of Brontopodus. The manus pes heteropody ratio is about 1:2. These sauropod tracks are associated with thousands of bird footprints in a lakeshore paleoenvironment. [ABSTRACT FROM AUTHOR]

New didactyl dinosaur tracks from the fine-grained sandstone of the Early Cretaceous Jinju Formation, Namhae area, Korea, are herein described as Dromaeosauripus jinjuensis ichnosp. nov. A trackway about 4.3 m long is composed of 12 consecutive didactyl traces. The tracks average about 9.3 cm long and 6.8 cm wide. Pace, stride, and pace angulation are 40 cm, 80 cm, and 175°, respectively. D. jinjuensis is a small didactyl track characterized by slender digit impressions, very narrow divarication angle between digits III and IV, digit III slightly longer than IV, and sharp claw impressions. D. jinjuensis measurements differ significantly from D. hamanensis in length (only 60% of the latter), width (81%), length/width ratio (0.72), and digit thickness (55%). The didactyl tracks are tentatively interpreted to be formed by a small dromaeosaurid walking bipedally on a lake margin. D. jinjuensis represents the oldest theropod dinosaur tracks described in the Cretaceous of Korea and the second ichnospecies of Dromaeosauripus. It suggests more diversity and wider stratigraphic and paleogeographic distribution of dromaeosaurids. The track morphology may also indicate a more digitigrade gait. [ABSTRACT FROM AUTHOR]

More than 2,500 well-preserved bird tracks associated with theropod and sauropod tracks are recorded from a dense assemblage in lacustrine deposits of the Early Cretaceous Haman Formation of the Gajin area, Jinju, Korea. These tracks are preserved in the recently constructed Fossil Heritage Hall at the Gyeongsangnamdo Institute of Science Education. Bird tracks are attributed to Ignotornis gajinensis ichnosp. nov., Koreanaornis hamanensis, Goseongornipes markjonesi, and ?Aquatilavipes. Like G. markjonesi, I. gajinensis is a semi-palmate bird track, similar to Hwangsanipes (ichnofamily Ignotornidae) with a postero medially directed hallux and characterized by interdigital angles between digits II and III larger than III and IV. However, Hwangsanipes is a larger morphotype than Ignotornis with a more pronounced semipalmate web. I. gajinensis has associated arcuate to semi-circular, double-grooved, or paired impressions resulting from spoonbill-like feeding behavior. Similar rare but more linear traces occur in one Ignotornis specimen from the Cretaceous of Colorado. The Gajin site represents a record of the world's most-dense assemblage of bird tracks (up to ∼600 per m2) at a single locality and provides striking evidence of the diversity of avian ichnotaxa during the Cretaceous. The Gajin tracksite provides new insight into the morphology of four of the eight ichnogenera known from the Cretaceous of Korea. The Goseongornipes sample is the largest and best-preserved available. In the case of Ignotornis, feeding traces shed new light on behavior and paleoecology of the trackmakers, which appear to have been remarkably convergent with modern shore birds. [ABSTRACT FROM AUTHOR]

New dinosaur tracksites are described from the Bajocian-Bathonian Bemaraha Formation of western Madagascar. Two track-bearing surfaces can be followed over a distance of at least 4 km, suggesting the existence of a hitherto unrecognized megatracksite. The track assemblage is theropod dominated, but sauropod tracks also occur at one site. Qualitative and quantitative analysis of the abundant theropod track material suggests that most, if not all, theropod footprints are attributable to a single trackmaker and are referred to Kayentapus isp. Although this ichnogenus, originally described from the Lower Jurassic of North America, has never been recorded from Gondwana nor from the Middle Jurassic, track morphology strongly suggests this attribution. Palaeogeographical, sedimentological and ichnological data suggest that the dinosaur tracks formed in an intertidal to supratidal setting where the coastline influenced the preferred walking direction of the animals. [ABSTRACT FROM AUTHOR]

Abundant and diverse dinosaur footprints have been discovered recently on bedding surfaces of the Lower Cretaceous Patuxent Formation of Maryland and Virginia. Found along with those ichnofossils is a fossil preserved partially as natural casts and partially as natural molds of a baby nodosaurid ankylosaur so small as to justit'y interpreting it as a hatchling. Despite the rather unusual type of preservation, the find is properly termed a body fossil and not an ichnite, per Se, because it records not the action of an organism, but the body form and bone structure (including partial articulation) of a dinosaur. We here name it Propanoplosaurus marylandicus and provide a description of its diagnostic characteristics, Although actual skeletal remains referable to P. marylandicus have not been found in the Patuxent Formation, other nodosaurids recognized from skeletal remains are known from both the Lower and Upper Cretaceous strata of the Western Interior of North America and Europe. P. marylandicus represents the only diagnostic nodosaurid from the Early Cretaceous of the eastern U.S.A., provides information on growth patterns among nodosaurids, and is the first direct evidence of a dinosaur hatchling and, deductively, nesting, on the entire eastern seaboard. [ABSTRACT FROM AUTHOR]

Mateus, O. & Milàn, J. 2009: A diverse Upper Jurassic dinosaur ichnofauna from central-west Portugal. Lethaia, Vol. 43, pp. 245–257. A newly discovered dinosaur track-assemblage from the Upper Jurassic Lourinhã Formation (Lusitanian Basin, central-west Portugal), comprises medium- to large-sized sauropod tracks with well-preserved impressions of soft tissue anatomy, stegosaur tracks and tracks from medium- to large-sized theropods. The 400-m-thick Lourinhã Formation consists of mostly aluvial sediments, deposited during the early rifting of the Atlantic Ocean in the Kimmeridgian and Tithonian. The stratigraphic succession shows several shifts between flood-plain mud and fluvial sands that favour preservation and fossilization of tracks. The studied track-assemblage is found preserved as natural casts on the underside of a thin bivalve-rich carbonate bed near the Tithonian–Kimmeridgian boundary. The diversity of the tracks from the new track assemblage is compared with similar faunas from the Upper Jurassic of Asturias, Spain and the Middle Jurassic Yorkshire Coast of England. The Portuguese record of Upper Jurassic dinosaur body fossils show close similarity to the track fauna from the Lourinhã Formation. □ Dinosaur tracks, Lusitanian Basin, Portugal, skin impressions, Upper Jurassic. [ABSTRACT FROM AUTHOR]

Background: Fossil tracks made by non-avian theropod dinosaurs commonly reflect the habitual bipedal stance retained in living birds. Only rarely-captured behaviors, such as crouching, might create impressions made by the hands. Such tracks provide valuable information concerning the often poorly understood functional morphology of the early theropod forelimb. Methodology/Principal Findings: Here we describe a well-preserved theropod trackway in a Lower Jurassic (~198 millionyear- old) lacustrine beach sandstone in the Whitmore Point Member of the Moenave Formation in southwestern Utah. The trackway consists of prints of typical morphology, intermittent tail drags and, unusually, traces made by the animal resting on the substrate in a posture very similar to modern birds. The resting trace includes symmetrical pes impressions and welldefined impressions made by both hands, the tail, and the ischial callosity. Conclusions/Significance: The manus impressions corroborate that early theropods, like later birds, held their palms facing medially, in contrast to manus prints previously attributed to theropods that have forward-pointing digits. Both the symmetrical resting posture and the medially-facing palms therefore evolved by the Early Jurassic, much earlier in the theropod lineage than previously recognized, and may characterize all theropods. [ABSTRACT FROM AUTHOR]

Abstract: New dinosaur tracks have been found near Bisceglie (Bari, Apulia), on loose blocks ascribed to the Corato Member (late Bedoulian to early Gargasian) of the Calcare di Bari Fm. The material consists of isolated footprints as well as of short trackways of quadrupedal and bipedal dinosaurs. The new tracksite has yielded a quite differentiated dinosaur ichnocoenosis, including theropod, sauropod, thyreophoran and ornithopod footprints. The discovery of early Aptian dinosaur footprints in the limestone of the carbonate platform of southern Italy gives new insights on dinosaur distribution, and new palaeontological constraints for the palaeogeographic reconstruction of the Mediterranean Tethys during the Cretaceous. The analysis of this and others ichnosites of the periadriatic carbonate platforms, gives evidence of repeated emersions and of widespread land-vertebrates dwelling. The characteristics of the associations suggest that the trackmakers did not constitute a real coevolved association but the occasional co-occurrence of taxa after migration. The results emphasize the need of both structural and environmental continuity and walking ways between a southern continent and the periadriatic carbonate platforms during the Early Cretaceous. [Copyright &y& Elsevier]

Abstract: A track from the Late Cretaceous previously described as being generated by a semi-palmate bird was studied with the aid of high resolution laser scanning. Substrate conditions at the time of track formation were diagnosed (fine-grained, soft, waterlogged sediment) and used to constrain a finite element track simulator. The indentation of a non-webbed virtual tridactyl foot in such conditions created a resultant track with features analogous to ‘webbing’ between digits. This ‘webbing’ was a function of sediment deformation and subsequent failure in 3D, specific to rheology. Variation of substrate conditions and interdigital angle was incrementally stepped. Apparent webbing impressions were clearly developed only within a limited range of sediment conditions and pedal geometry. The implications of this work are that descriptions of ‘webbed’ tracks should account for the possibility that webbing was indirectly formed through sediment failure and not necessarily the direct impression of a webbed foot. Additionally, dating the earliest occurrence of webbed feet in the fossil record, and potentially extending phylogenetic ranges, should be treated with caution when based upon evidence from tracks. [Copyright &y& Elsevier]

Azhdarchid pterosaurs were among the most widespread and successful of pterosaur clades, but their paleoecology remains controversial. Morphological features common to all azhdarchids include a long, shallow rostrum; elongate, cylindrical cervical vertebrae that formed a long and unusually inflexible neck; and proportionally short wings with an abbreviated fourth phalanx. While azhdarchids have been imagined as vulture-like scavengers, sediment probers, swimmers, waders, aerial predators, or stork-like generalists, most recent authors have regarded them as skim-feeders, trawling their lower jaws through water during flight and seizing aquatic prey from the water's surface. Although apparently widely accepted, the skim-feeding model lacks critical support from anatomy and functional morphology. Azhdarchids lack the many cranial specialisations exhibited by extant skim-feeding birds, most notably the laterally compressed lower jaw and shock absorbing apparatus required for this feeding style. Well-preserved azhdarchid skulls are rare, but their rostra and lower jaws appear to have been sub-triangular in cross-section, and thus dissimilar to those of skim-feeders and sediment probers. Taphonomic data indicates that azhdarchids predominately inhabited inland settings, and azhdarchid morphology indicates that they were poorly suited for all proposed lifestyles bar wading and terrestrial foraging. However, azhdarchid footprints show that their feet were relatively small, padded and slender, and thus not well suited for wading. We argue that azhdarchids were stork- or ground hornbill-like generalists, foraging in diverse environments for small animals and carrion. Proficient terrestrial abilities and a relatively inflexible neck are in agreement with this interpretation. [ABSTRACT FROM AUTHOR]

A dinosaur trackway in the Middle Jurassic eolian Entrada Sandstone of southern Utah, U.S.A., exposes three undertracks that we have modeled as isolated tectonic regimes showing the development of fold-thrust ramp systems induced by the dinosaur's feet. The faulted and folded sequence is comparable to crustal-scale tectonics associated with plate tectonics and foreland fold-thrust belts. A structural analysis of the dinosaur tracks shows the timing and direction of the forces exercised on the substrate by the animal's foot during the stride. Based on the structural analysis, we establish a scenario for foot movements and weight distribution in the feet. During the end of the weightbearing phase of the stride, the weight of the animal was transferred to the front of the digits, creating a rotated disk below the foot that was bounded by an extensional fault at the front and a thrust ramp toward the back. As the body accelerated, the foot was forced backward. The rotated disk was forced backward along a detachment fault that was bounded by lateral ramps. The interramp segment matches the width of the dinosaur's foot, which created an imbricate fan thrust system that extended to the far end of the undertrack. The total length of the tectonic disturbance created by the dinosaur is up to three times that of the original footprint. Early, near-surface cementation gave the substrate the rheological properties necessary for development of the observed structures. [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]

Abstract: Highly distinctive, well-preserved, three-toed dinosaur footprints with bilobed heel impressions from the Cretaceous of Thailand are assigned to the new ichnotaxon Siamopodus khaoyaiensis. The tracks, which represent small- to medium-sized gracile theropods, are unlike any previously known from Thailand or elsewhere. By contrast other robust, small- to medium-sized theropod tracks with bulbous heel impressions are reported from a new locality and shown to be similar to Lower Cretaceous tracks from elsewhere in Asia. When added to previously reported robust, large theropod tracks, the Cretaceous track record in Thailand appears dominated by a significant diversity of theropod track types that differ from one locality to the next. Thus, the track record is in general agreement with the skeletal record of theropods in Thailand. The occurrence of footprints with bilobed heel impressions is reviewed briefly. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

This article focuses on the discovery of dinosaur footprints from four different site. Eighty-eight tracks of large theropods were found, all apparently of the same ichnogenus. Forty-three of the theropod footprints are of identical age to that of the sauropod tracks. The other 43 are marginally older, but of particular interest because among them five track ways are identified. There are a number of instances of overprinting of tracks and the overall signs and implications are of group theropod behavior, possibly connected with predation.

Sauropod footprints in the Uhangri Formation (Cretaceous) of Korea exhibit an unusual pattern of morphology, with the interior of each print partitioned into a series of pockets by conspicuous radial crests. The crests are evidently extramorphological features and have been interpreted as upwellings of sediment extruded through the floor of the footprint following its fracture by impact of the trackmaker's foot. That explanation entails some inconsistencies, and an alternative explanation is proposed here. The alternative explanation envisages delamination of a superficial sheet of sediment that was lifted into a canopy, which subsequently collapsed in radiating folds. The superficial sheet of sediment might have been lifted by either or both of two mechanisms—by adhering to the underside of the trackmaker's foot or by being forced upward into a blister-like dome by the backflow of water previously displaced by impact of the trackmaker's foot. These alternative explanations draw attention to minor morphological features that were previously unexplained. [ABSTRACT FROM AUTHOR]

Archosaur tracks are described that have been found in 1999 in a single track bed in the Dethfurth-Formation of the Middle Bunter (Lower Triassic) near Wolfhagen (Central Germany). The taxonomic evaluation of these tracks requires the erection of the new genus and species Protochirotherium wolfhagense ichnogen. n. ichosp. n. Apart from this a rearrangement of groups of chirotheroid tracks is proposed due to the digital proportions. [ABSTRACT FROM AUTHOR]

Dinosaur tracks were first reported from the coal-bearing clastic sequences of the Ross River Block in 1999 by members of a University of Alaska Museum field party, and track sites were confirmed by a joint Alaska-Yukon team in 2000. This fault-bounded sedimentary block is 3 kilometers west of Ross River, in the Yukon Territory. The discovery was followed by two years of field mapping and collection. This research has resulted in the documentation of 251 individual tracks at two separate but stratigraphically related sites, as well as a short (four-footprint) trackway at one of the sites. Six ichnogenera were identified. Ornithomimipus, Amblydactylus, and Gypsichnites were recognized at one site. At a stratigraphically higher site, four ichnogenera were documented including Tetrapodosaurus, Irenesauripus, Amblydactylus, and Columbosauripus. This ichno-assemblage is compared with those of Aptian to Cenomanian age from Alberta, British Columbia, and Alaska. The discovery of unequivocal dinosaur evidence in a small structural inlier in the Tintina Trench that was previously assumed to be Eocene in age resulted in a restudy of the palynology and biostratigraphy of this coal-bearing sequence and the recent assignment of a middle Albian to early Cenomanian age to the upper part of the dinosaur-bearing interval. [ABSTRACT FROM AUTHOR]

At least 22 tridactyl dinosaur tracks, poorly preserved in various degrees of expression, have recently been found at an exposure in the Dakota Formation (Lower Cretaceous, Albian) in Jefferson County, Nebraska. These tracks generally have broad, blunt digits and a broad posterior margin. The largest of the tracks measures 57 cm in length and 58 cm in width. All of the tracks lie within a stratigraphic horizon of 40 cm or less, but they do not form a single trackway. We interpret the trackmakers to have been ornithopods. The Jefferson County tracks are in a well-cemented sandstone with oscillation ripples, at a stratigraphic level between two well-established sequence boundaries. Channel forms and lateral accretion units are common in the stratigraphic interval enclosing the tracks, and the site is interpreted as a bar or sand flat in a tidally influenced river. The Jefferson County tracks are only the second known occurrence of large Mesozoic tetrapod tracks east of the Rocky Mountain Front-High Plains Margin, including the Black Hills of South Dakota, west of the Atlantic Coastal Plain, and north of the Gulf Coastal Plain. Further, this paper is the first documentation of in situdinosaur fossils from the Nebraska-Iowa area. [ABSTRACT FROM AUTHOR]

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 180m 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 northeasterly 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. [ABSTRACT FROM AUTHOR]

The fossil record of vertebrate tracks in Mexico is taxonomically rich and geographically diverse, and ranges in age from Middle Jurassic to Pleistocene and possibly Holocene. Middle Jurassic saurischian dinosaur tracks from Oaxaca represent the oldest record of vertebrate tracks in Mexico. Tracks attributed to Late Jurassic theropods and ornithopods are known from Michoacán. Theropod tracks of supposed Jurassic age are known from Durango. Lower Cretaceous Saurischian and ornithopod tracks are known from southern Puebla. Central Mexico has yielded Late Cretaceous hadrosaurid and sauropod tracks (Puebla), and tracks belonging to Theropoda and Ornithopoda (El Aguaje, Michoacan). In Coahuila several tracksites occur within the Cerro del Pueblo Formation and include tracks of mesoreptiles, pterosaurs, small to large theropods, bipedal and quadrupedal ornithopods, birds and possibly a mammal. A tracksite in the Olmos Formation includes tracks of turtles, crocodilians, medium-sized theropods, small ornithopods, and birds. Bird tracks of supposed Eocene age are known from Sinaloa. Two important Pleistocene ichnofaunas occur in the states of Puebla (Tepexi de Rodríguez) and Jalisco (San Juan de los Lagos), and include tracks of camelids, artiodactyls, small ungulates, elephants, large felids and birds. Pleistocene human tracks occur in Coahuila and Jalisco. Mexico's track record provides important insights into vertebrate diversity, paleoecology, and paleoenvironments. Given the rate of new discoveries since 1998, there is no doubt that new sites await to be found. [ABSTRACT FROM AUTHOR]

The enigmatic ichnogenus Selenichnus (Hitchcock, 1858) from the Lower Jurassic of Massachusetts and Utah may represent poorly preserved, extramorphological examples of Batrachopus . Selenichnus trackways from the St. George area (Utah) are virtually indistinguishable from the type material described by Hitchcock (1858) and Lull (1953) from Massachusetts. However, Selenichnus type specimens from Massachusetts, as well as the material from Utah, suggest a relationship with Batrachopus: The former track morphology appears to transform into the latter as preservational conditions change. The size and gait indicated by the two ichnogenera are similar. The suggested relationship between the two ichnogenera does not alter the fact that there are distinct differences in the morphology of the type specimens. Thus, pending discovery of more material, formal synonymy of the two ichnogenera is not formally proposed. [ABSTRACT FROM AUTHOR]

Public lands in the Rocky Mountain West are home to an abundance of vertebrate paleontological resources. These fossils typically are found in badlands terrain and at some distance from convenient transportation. These and other factors often make conventional surveying and mapping techniques time-consuming and problematic. Even obtaining quality images, at useful scales with limited distortions, can be difficult. In order to preserve the value of these unique paleontological resources, an integrated approach to close-range photogrammetry and high-accuracy ground-control surveying was developed in northern Wyoming for the documentation of tracks at the Red Gulch Dinosaur Tracksite. At this site, several methods for taking high-resolution, lowdistortion photographs of localities were investigated. These methods included using tripods of various heights, remote-controlled airplanes, and an Aerial Camera Blimp System. In addition, the use of a variety of ground-control collection methods, including high accuracy GPS and Light Detection and Ranging, have also been investigated. These various field data collection methods were successfully integrated using soft copy photogrammetry to produce digital terrain models, which can represent the surface to a precision of 1 cm or less. The three-dimensional data were brought into GIS software where they are displayed, combined with photographs, and rotated for viewing from different perspectives. As a result of the success of these technologies in Wyoming, studies of other dinosaur tracksites in Colorado, Utah, and Wyoming (as well as bonebeds) have utilized these methods. The information gained from these sites is aiding in our understanding of community dynamics and preservational history of dinosaur populations in the Rocky Mountain West. [ABSTRACT FROM AUTHOR]

An introduction to the journal is presented in which the editor discusses the natural history of dinosaurs.

Presents research which described Late Triassic therapod trackways from East Greenland. Use of dinosaur footprints as biostratigraphic markers; Studied trackways providing three-dimensional records of foot movement; Prints compared with those of ground-dwelling birds.