Quality and morphology of outcrop exposure places fundamental constraints on what ichnological observations can be made and the veracity of these observations. Whilst the limits and potential biases are well known and reported for core studies, in the majority of field studies the equivalent biases are typically overlooked. In this paper we present a widely applicable method for recording outcrop characteristics based on their morphology, and how these characteristics may affect observations. We consider the impacts of structural orientation, superficial cover, and outcrop location on outcrop quality. Finally, we present two case studies, from the Tumblagooda Sandstone of Western Australia and the Armorican Sandstone Formation of northwestern France, to highlight the importance of recording outcrop characteristics.

The Horseshoe Canyon Formation has provided a wealth of vertebrate skeletal fossils over the past 100 years of collection. Vertebrate trace fossils such as footprints and trackways, however, have been markedly underrepresented. Trackways can provide a wealth of information regarding behaviour and soft tissues reflective of autopodial anatomy. Discovery of several giant, high-fidelity ichnites in series from the Morrin Member represents the first definitive dinosaur trackway reported from the Horseshoe Canyon Formation. The trackway is composed of three footprint casts in series, alongside 22 associated ichnites. The ichnites were formed in soft sediment molds along a non-uniform walking surface. The deep substrates allowed for the preservation of both the plantar surface and dorsal components of the trackmakers’ feet. Some ichnites show soft tissue morphologies like interdigital webbing, toe pads, and skin impressions. Presence of these features and small kidney-shaped forelimb prints allow referral to Hadrosauropodus langstoni. The preservation of the trackway demonstrates asymmetries useful for comparison of the relief and impression surfaces of prints using both discrete and morphometric characteristics, improving confidence in identifying partial or isolated Hadrosauropodus prints of various modes of formation.

ABSTRACT Previous neoichnological studies with arthropods, especially arachnids, have often conducted experiments with only a small number of trackways produced in a subset of subaerial conditions. Thus, we conducted a comprehensive neoichnological study of scorpions (Hadrurus arizonensis), tarantulas (Grammostola rosea), and crayfish (Procambarus clarkii), under various moisture levels (dry, damp, wet drying, wet saturated, and subaqueous [or wading]) and horizontal, shallow, and steep slope angles. The invertebrates made a total of 473 trackway runs resulting in 489 symmetric trackway segments that were characterized and digitally measured. We analyzed the trackways using trackway parameter trend diagrams and non-metric multidimensional scaling (N-MDS) visualizations to compare trackway morphology among the sand moisture conditions. Results generally show imprints become progressively smaller, with more dotted multifid imprints going from loose to stiff sand. N-MDS showed trackway morphology overlapped among some conditions, including those with disparate water content (e.g. dry and wet saturated sand, or subaqueous and wet drying sand). Additionally, trackways consisted usually of a four-imprint series, though species- and condition-specific exceptions were found. Interestingly, the scorpions rarely dragged their metasomas, while the crayfish always dragged their tail fan except sometimes underwater. Our neoichnological photos and quantitative dataset provide a basis for future comparative ichnological studies.

Because almost all marine trace fossils were produced in underwater settings such as shoreface, offshore, continental shelf, slope, trench, and abyssal plain, investigating their modern analogues in these settings is important. In this discussion, I delve into a range of recent developments in the field of underwater neoichnology, concentrating on both my own contributions and those of fellow researchers. These advancements have been achieved through investigations conducted in various underwater settings, spanning from shallow coastal waters to the depths of the ocean floor. Our research methods have involved SCUBA diving as well as participation in submersible scientific expeditions.

Since their discovery in 1978, the hominin fossil footprints from Laetoli have been the focus, of extensive research on the locomotion, speed, body size, and behavior of the responsible track-makers (nominally Australopithecus afarensis). In this work, we show that careful examination of walking speed and displacement yields valuable information regarding the interaction between individuals, as well as group behavior of the track-maker hominins. First, we calculate statures for the Site G and S hominins using appropriate footprint length/stature ratios, obtaining statures ranging from 1.2 to 1.6 − 1.7 m. This range is somewhat taller than that proposed for Au. afarensis from skeletal remains (roughly 1.1 to 1.6 m), thus suggesting that comparatively large individuals are possibly represented in the Laetoli footprints. We then calculate speeds for the Site G track-makers from a stride length-speed scaling for humans. Stride and step lengths are measured from a digital model using the deepest point on the heel area of the G1 and G3 footprints as reference, and the deepest point on the hallux area for the overprinted G2 footprints. The hominins responsible for the Site G trackways all walked at a very similar mean speed, around 0.8 m s−1, which is faster than the speeds proposed by some previous studies. Detailed step-to-step speed calculations for G1 and G3 hominins show that the walking speed varied substantially (up to a factor of 1.5) over distances of just a few meters, perhaps due to surface conditions or behavioral reasons. The centers of mass of the G1 and G3 hominins traced very similar trajectories along the trackway portion examined. Thus, all Site G track-makers appear to have been moving together: the G1 and G3 hominins walked over the Laetoli ashes together in parallel, following behind the G2 hominin.

The sedimentological and palaeoecological interpretation of early Miocene age shallow marine deposits from one of the most emblematic geological areas of Taiwan – Yehliu peninsula – is not easy to approach in detail, and several contrasting proposals can be found in the literature. The present ichnological study helps to corroborate a delta environment as the most likely palaeoenvironmental setting, and to recognize the different sub-environments and hydrodynamic processes involved. The distal delta front displays the greatest trace fossil diversity, assigned to the Cruziana ichnofacies, including Ophiomorpha, Phycosiphon, Planolites, Rosselia, Schaubcylindrichnus, Scolicia, Thalassinoides and vertical equilibrium adjustment structures. The delta front records predominantly vertical traces attributable to the Skolithos ichnofacies. Amalgamated shell beds (most likely related to storm events) show concentrations of broken bivalve shells. After storm a selective colonization is interpreted, firstly by bioerosive tracemakers during times of decreasing sedimentation rate, followed by a dominance of trophic generalists such as those producing Ophiomorpha during post-storm sedimentation.

In his short joint ventures across the world of vertebrate tracks, Richard Bromley recognized the aeolian sands as unsuitable soft substrates for their preservation. Only after his work in the Balearic Islands, a more systematic study of coastal aeolianites worldwide revealed that these depositional systems could preserve a highly important record of behavioural trace fossils for the evolution of vertebrates, especially in the Pleistocene, including extinct megafauna and the escalation of the Homo. Here we describe coastal aeolianites from the upper Pleistocene of SW Iberia, namely SW Portugal and Gibraltar, with trackways, tracks and trampled surfaces of the last elephants in mainland Europe. Photogrammetric 3 D modelling and analysis of the relevant proboscidean track levels allowed revision of and support for previous ichnotaxonomic identification to Proboscipeda panfamilia and behavioural interpretations of the producer. Smaller and very large trackways and footprints attributed to Palaeoloxodon antiquus are described and discussed according to new and recent, but always rare findings. The seeming progressive and definitive extinction of this species towards southern Iberia, following the same pattern for the replacement of the Neanderthals during the last initial Pleniglacial (until ca. 28 ka), suggests evidence for co-evolution.

A new ichnospecies, Linichnus bromleyi, is described on bone substrate as the result of a very likely predator/scavenger interaction. L. bromleyi consists of a single groove with a non-serrated edge. This new ichnotaxon is compared with L. serratus which was defined as a single elongate serrate-edged groove. L. bromleyi has been identified over the surface of bones of marine mammals (in particular, cetaceans and pinnipeds) from two Pliocene outcrops of Andalusia, southern Spain. The new ichnospecies can be clearly related with a trophic interaction between sharks and marine mammals (mainly whales, dolphins and seals).

The ichnospecies Gastrochaneolites dijugus Kelly and Bromley 1984 and Teredolites longissimus Kelly and Bromley 1984, attributed to the boring activity of gastrochaenoid and pholadid bivalves, are described respectively from the Miocene Vilanova Basin and the Pliocene Almería-Níjar Basin. Miocene and Pliocene traces are preserved as positive casts associated to invertebrate shells and wood fragments, respectively; in both cases, the host substrate (shells and wood) has been lost almost entirely by different taphonomic processes (mainly dissolution). For the first time in the fossil record, the complete ichnogenetic sequence of these two ichnospecies is described and figured.

The lower Maastrichtian deposits of the Mateur-Beja area in northern Tunisia are mainly composed of fine-grained marl and limestone alternations occasionally interbedded by coarse-grained calcarenites and gravel deposits. In the coarse-grained intervals sedimentary structures are indicative of storm-induced high-energy currents in an outer ramp to slope setting and of local reworking by bottom currents in the basin. In deeper environments, fine-grained sediments accumulated mainly while settling from storm-induced suspensions. The lower Maastrichtian deposits contain abundant Zoophycos exhibiting two main morphotypes, skirt-shaped Zoophycos in deposits around storm-wave base and tongue-shaped Zoophycos in somewhat deeper sediments. The types differ in burrow architecture, morphology of lobes, and size of structural elements. These differences are attributed to different behavioral programs modulated by the availability of benthic food that decreased seaward. Storm-affected environments seem to be a prerequisite for these Zoophycos-producers to choose their habitat.