The ichnospecies Trisulcus laqueatus is an epichnial trail that is constructed of three grooves separated by two ridges. It exhibits significant amounts of extramorphological variation because the maker was moving through wet sediment. Thus, most details of the maker are obscured. Nonetheless, there is evidence of it having been made by arthropods, including the sharply-angled turns in one example, the division of the lateral grooves into separate imprints in some locations along the length of the trail, and comparison to modern trails produced by Cydnidae (burrower bugs).

ABSTRACT Dinosaur tracks have been illustrated since they were first found. The earliest illustrations depicted dinosaur tracks as the work of mythical beings. With the advent of scientific inquiry into dinosaur tracks in the nineteenth century, natural explanations were sought for the fossil tracks. Illustrations of the period were relatively realistic but were influenced by then-current beliefs and were constrained by the artists’ skills and by what scientists considered salient. In the mid-nineteenth century, the first photographs were used for the scientific study of fossil tracks. Photography eliminated some limitations of artistic talent and showed complete specimens, not just aspects that were deemed salient. The ability to compare and name similar tracks from disparate authors and places became easier. Advances in photography, laser scanning, optical scanning and lidar, and the ability to manipulate images with computers, have enabled the modern synthesis of illustrating dinosaur tracks, which combines many types of images. With each advance and the adoption of newer technologies, the older methods have not been retired. Rather, we have continued to see new uses for old methods and an integration of illustrative styles. For Patrick. Your friendship and your vision will be so deeply missed.

The ichnogenus Grammepus, which is inferred to have been made by a winged (pterygote) insect, was differentiated from other ichnotaxa because its largest tracks were nearly continuous, forming two furrows. Otherwise, it strongly resembles the ichnogenus Lithographus. Examination of both ichnogenera indicate that the largest tracks in Lithographus can be very close together, that some specimens of Grammepus lack furrow-like tracks, and that the type specimen of the type species Grammepus erismatus has separate tracks in some places, and furrow-like ones in others. Given the lack of a feature that can consistently differentiate Lithographus and Grammepus , the latter is synonymized with the former. Experiments with the modern cricket Acheta domesticus in sediment of different saturation levels indicate that a single pterygote producer could produce both “Grammepus-” and Lithographus -like morphologies, with the former being formed in wet, soft sediment wherein the legs drag, and the latter being formed in firmer, drier sediment wherein the legs do not drag .

Three trackways attributable to the ichnospecies Bifurculapes laqueatus Hitchcock, 1858 found in Lower Jurassic rocks of the Newark Supergroup in northeastern North America are preserved in association with current lineations. Each trackway takes turns so that parts of the trackway parallel the current lineations. This parallelism is interpreted as evidence that the trackmakers were entrained in flowing water and had to change course due to the current. If this interpretation is correct, then morphological differences between B. laqueatus and terrestrial insect trackways could be explained by the trackmaker moving subaqueously. Further, B. laqueatus would constitute only the second insect trackway from this region to be recognized as being made subaqueously. From an ecological standpoint, the aquatic insects that made B. laqueatus were probably near the base of the local food chain, the apex predators of which were piscivorous theropod dinosaurs.

THe ichnogenus Conopsoides, established in the Nineteenth Century, was differentiated from other ichnogenera by the presence of mounds of sediment associated with the tracks, but this characteristic is now considered an invalid ichnotaxobase by some invertebrate ichnologists. Consequently, Conopsoides has been compared to other ichnogenera in the Hitchcock collection in order to determine if other characteristics could be used to differentiate it. As a result, the morphologies exhibited by Conopsoides are seen in two other ichnogenera, Acanthichnus and Bifurculapes. Specifically, the morphologies seen in the type species, Conopsoides larvalis, are observed in Acanthichnus cursorius and Acanthichnus saltatorius, and therefore different specimens of Conopsoides larvalis are considered to belong to these two ichnospecies. Similarly, the morphology observed in Conopsoides curtus is observed in Bifurculapes laqueatus, so the former ichnospecies is considered a junior subjective synonym of the latter.

The ichnospecies Lunulipes obscurus is reevaluated and a new diagnosis provided. All samples from Early Jurassic lacustrine deposits of the Deerfield Basin in Massachusetts, USA that were previously determined to bear Lunulipes or Lunulipes-like traces were examined. This reevaluation revealed that the ichnospecies is restricted only to two slabs. The morphology of Lunulipes obscurus suggests that its arthropod maker beat a single pair of legs synchronously. This type of locomotion is used by aquatic insects such as backswimmers (Notonectidae), water boatmen (Corixidae), and predaceous diving beetles (Dytiscidae). Neoichnological experiments with these three taxa indicate that water boatmen produce trackways that are the most similar to the fossil, and hence we conclude that a water boatman or an unknown insect that employed a similar method of swimming produced the Early Jurassic traces. These trackways provide the first tentative evidence of water boatmen in the Deerfield Basin, and, if correctly identified, represent the first trace fossils of this aquatic insect group anywhere.

The ichnogenera Camurichnus and Hamipes have been reevaluated based on examination of their type specimens, and their geographic and stratigraphic ranges determined based on a review of the literature. The characteristics used to distinguish Camurichnus (originally erected as Sagittarius) and its included ichnospecies alternans, have been observed in Bifurculapes laqueatus and therefore Camurichnus alternans is considered a junior subjective synonym of B. laqueatus herein. Hamipes is a distinct ichnogenus that can be differentiated from similar ichnotaxa by the number, shape, and arrangement of the tracks. Cretaceous trackways from Spain that were attributed to Hamipes belong to Bifurculapes. Additionally, the species H. molassicus is moved to the ichnogenus Conopsoides. Since the only other occurrence of Hamipes was the type specimen, the ichnogenus is again known only from the Early Jurassic of Massachusetts, U.S.A. The ichnotaxonomic reassignment, however, extends the geographic and stratigraphic range of Bifurculapes to the Cretaceous of Europe.

The collection and dissemination of vertebrate ichnological data is struggling to keep up with techniques that are becoming commonplace in the wider palaeontological field. A standard protocol is required to ensure that data is recorded, presented and archived in a manner that will be useful both to contemporary researchers, and to future generations. Primarily, our aim is to make the 3D capture of ichnological data standard practice, and to provide guidance on how such 3D data can be communicated effectively (both via the literature and other means) and archived openly and in perpetuity. We recommend capture of 3D data, and the presentation of said data in the form of photographs, false-colour images, and interpretive drawings. Raw data (3D models of traces) should always be provided in a form usable by other researchers (i.e. in an open format). If adopted by the field as a whole, the result will be a more robust and uniform literature, supplemented by unparalleled availability of datasets for future workers.

A large open-pit quarry in Plainville, Massachusetts, has yielded fourteen invertebrate ichnotaxa from the Pennsylvanian Rhode Island Formation of the Narragansett Basin. These traces include Cochlichnus anguineus , Diplichnites cuithensis, Diplichnites gouldi, Diplopodichnus biformis, Gordia carickensis, Helminthoidichites tenuis, Lockeia isp., Mitchellichnus cf. ferrydenensis, Planolites montanus, Siskemia elegans, Stiallia pilosa, Stiaria intermedia, Tonganoxichnus buildexensis and Narragansettichnus fortunatus new ichnogenus and ichnospecies. Specimens were collected from talus and the depositional environment has been inferred from sedimentary structures. The sediment - ology of the slabs on which the traces were preserved indicates that the rocks represent lake-margin and shallowlacustrine sedimentary facies. Distinct ichnofacies occur in the different sedimentary environments. The lake-margin traces belong to the Scoyenia ichnofacies and include traces of apterygote insects, arthropleurid myriapods, bivalved arthropods and vermiform animals in association with tracks of temnospondyl amphibians and diapsid reptiles. The lacustrine traces include arthropod trackways, fish trails and a newly named body imprint possibly produced by an aquatic mayfly larva. These shallow lacustrine traces are attributed to the Mermia ichnofacies.

Edward Hitchcock was one of the most influential 19th century ichnologists. In a career that lasted nearly three decades, he established 31 invertebrate ichnogenera for Early Jurassic traces from the Hartford and Deerfield Basins of Connecticut and Massachusetts, some of which are in widespread use today. Upon re-examining some of Hitchcock's specimens, we have identified a number of fossils that are similar to the well-known ichnogenus Treptichnus. Modern ichnologists generally interpret non-marine occurrences of these burrows as the traces of larval insects. In some instances, Hitchcock ascribed his fossils to the activities of annelids or larval insects, and his descriptions of their mode of formation are similar to those presented in much more recent works. However, he also interpreted some treptichnids as algal/plant fossils. We suspect that his varied interpretations reflect differences in morphology and preservation among specimens. Hitchcock worked in the 19th century, a time known as the "Age of Fucoids", and his comments also reflect the prevailing uncertainty on trace fossil origins.

The type specimens of the ichnospecies Haplotichnus indianensis and Treptichnus bifurcus were compared under low-angle light. H. indianensis was found to exhibit segments with projections, which are morphological characteristics of T. bifurcus. Consequently, H. indianensis is reinterpreted here as a shallow, subsurface burrow and is considered to be a subjective junior synonym of T. bifurcus. Traces assigned to H. indianensis, other than the type, should be reassigned to other ichnotaxa. Looping surface trails, for example, should be called Gordia isp.

Characters differentiating the arthropod trackway Bifurculapes from the similar ichnogenera Lithographus and Copeza include the position, arrangement and orientation of the tracks within the series. Of the five species of Bifurculapes originally described, only Bifurculapes laqueatus and Bifurculapes scolopendroideus are recognized herein; the other three ichnospecies are considered to be nomina dubia or junior subjective synonyms of Bifurculapes laqueatus. Two new specimens, recovered from the Early Jurassic East Berlin Formation of the Hartford Basin in Holyoke, Massachusetts, represent only the second unequivocal occurrence of the ichnogenus outside of the Deerfield Basin. Bifurculapes is currently known only from the Early Jurassic.

Eubrontes giganteus is a common ichnospecies of large dinosaur track in the Early Jurassic rocks of the Hartford and Deerfield basins in Connecticut and Massachusetts, USA. It has been proposed that the trackmaker was gregarious based on parallel trackways at a site in Massachusetts known as Dinosaur Footprint Reservation (DFR). The gregariousness hypothesis is not without its problems, however, since parallelism can be caused by barriers that direct animal travel. We tested the gregariousness hypothesis by examining the orientations of trackways at five sites representing permanent and ephemeral lacustrine environments. Parallelism is only prominent in permanent lacustrine rocks at DFR, where trackways show a bimodal orientation distribution that approximates the paleoshoreline. By contrast, parallel trackways are uncommon in ephemeral lacustrine facies, even at sites with large numbers of trackways, and those that do occur exhibit differences in morphology, suggesting that they were made at different times. Overall, the evidence presented herein suggests that parallelism seen in Hartford Basin Eubrontes giganteus is better explained as a response to the lake acting as a physical barrier rather than to gregariousness. Consequently, these parallel trackways should not be used as evidence to support the hypothesis that the trackmaker was a basal sauropodomorph unless other evidence can substantiate the gregariousness hypothesis.

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