Ichnos

There are varying approaches toward evaluating fossil and modern arthropod and pathogen herbivory on land plants. Historically, traditional metrics have been used in numerous studies as well as a recent metric designed to measure herbivory at a fine-grained scale. Application of these methods are designed to address major ecological and evolutionary questions in the fossil record of plants and their interactions with insects, mites, and pathogens. Ten germane questions are provided and discussed for addressing major events in the fossil record that have altered the trajectory of herbivory in space and time. These events deserve further exploration for understanding the ecological dynamics of plant hosts and their herbivorous arthropods and pathogens. A special emphasis is placed on exploring the least understood event: the relationships between Oligocene and Neogene grassland hosts and their non-vertebrate herbivores.

New large felid footprints from the Monte Hermoso site (Late Pleistocene) located in the Pehuen Co-Monte Hermoso Nature Reserve (Buenos Aires Province, Argentina) are described and compared to Felipeda cf. bottjeri. The discovery consists of a trackway of five footprints associated with sloth footprints. Although the preservation quality of the trackway is moderate, diagnostic features - such as the tetradactyl configuration, subrounded digital pads arranged in an arc, and a subrounded metapodial pad with a flat to slightly concave anterior margin - support its assignment to Felipeda, comparable to Felipeda bottjeri. It would therefore be the only record of this ichnospecies for South America. Comparisons indicate that the Monte Hermoso footprints differ from those of a Late Pleistocene big felid from Argentina recognized as Felipeda miramarensis in the morphology of the metapodial pad and in the marked differences in size between the manus and pes prints observed in the latter. The occurrence of F. biancoi which exhibit distinct morphological characteristics compared to the analysed specimen in stratigraphically equivalent layers at the nearby Pehuen Co site indicates the presence of two distinct morphotypes of Felipeda in deposits of comparable age. The associated large sloth footprints assigned to cf. Mylodontidichnum isp. suggest coexistence of large felids and ground sloths. The footprint-bearing level, located in the middle member of the Agua Blanca Sequence (Late Pleistocene), which is consistent with other megafauna ichnological assemblages from the Pehuen Co site (dated between 28.5 and 12.0 ka). Morphometric and ichnological comparisons with modern and fossil felid footprints point to a large pantherine cat-possibly Panthera onca mesembrina as the most probable trackmaker, whereas Smilodon fatalis appears a less likely candidate. These findings expand the ichnological and paleoecological record of Late Pleistocene large felids in the Pampas region and reinforce the significance of the Monte Hermoso-Pehuen Co Natural Reserve sites.

A unique tracksite in Korea is known as the only example of dinosaur tracks preserved as impressions in an intrusive igneous sill. This bold claim was based on the premise that the sill intruded into lithified rock, molding pre-existing footprints. Here, we present new field and petrographic evidence that challenges this long-held hypothesis. Our analysis indicates that the structures are more consistent with geological potholes than with dinosaur tracks, given their irregular trackway pattern and lack of anatomical features. The premise of a post-lithification intrusion is called into question by a convergence of evidence for syn-sedimentary emplacement into wet, unconsolidated mud, including: (1) the re-identification of supposed 'breccia' as peperite, (2) thermal alteration of the host mudstone, and (3) the presence of fluid escape structures in the overlying sediment. We conclude that the Deokmyeong-ri structures likely represent pseudofossils formed by a combination of shallow magmatic intrusion and subsequent intertidal erosion. This re-evaluation corrects the ichnological record and serves as a critical cautionary tale, underscoring the necessity of integrating detailed geological analysis with morphological observation to distinguish genuine biological traces from their sophisticated geological mimics.

The marine middle-upper Permian exposed in southern Tunisia represents a typical example of a mixed siliciclastic-carbonate shelf system. These deposits contain a diverse assemblage of trace fossils - 21 ichnogenera in total - representing the highest known diversity in marine Permian worldwide. The ichnofossils are typical of the Cruziana ichnofacies, with its possible variants. In the thinly bedded fine-grained sandstones of the offshore-transition environment, the presence of ?Nereites, Protovirgularia, and Psammichnites, and other horizontal traces represent the archetypal to distal variants of the Cruziana ichnofacies. Lower shoreface sandstones are characterized by trace fossils such as Archaeonassa, Palaeophycus, Parataenidium, and Siphonichnus, while the upper shoreface and foreshore sandstones yield a more diverse suite, including ?Ancorichnus, Cruziana, ?Diplocraterion, Halopoa, ?Helminthopsis, Palaeophycus, Parataenidium, Psammichnites, Planolites, and Siphonichnus. Atypically, these collectively reflect signals of the proximal to archetypal Cruziana ichnofacies, where the Skolithos ichnofacies should already be present. This is explained by less energetic conditions related to possible morphological protection and the influence of tides. Of particular significance is the identification of Cruziana for the first time in the same stratigraphic unit where the only known Tunisian specimen of the trilobite Pseudophillipsia sumatrensis (Roemer) group has been found - likely the trace maker. Inter-reef tidal channel sandstones also preserve ichnofossils such as Planolites, Phycodes, Parataenidium, Protovirgularia, and?Gyrophyllites, which are attributed to the archetypal Cruziana ichnofacies.

The Homestead Site at Garita Creek is an Upper Triassic locality within the Garita Creek Formation of east-central New Mexico of Revueltian (Norian) age. In addition to abundant bones, scales, and teeth, thousands of coprolites make up a significant portion of the rich collection. Like the bones themselves, coprolites provide insight into the disparity of the assemblage, as coprolite morphologies are important indicators of paleoecological relationships. We examined a subset of 600 microcoprolites from the Homestead Site, finding that 316 (53%) preserve fossil inclusions, often ganoid scales, in either external (73%) or cross-sectional (27%) view, 22 (4%) bear abiotic inclusions, and 262 (44%) bear no visible inclusions. Most inclusions are visible externally, indicating that most coprolites do not require 'digital dissection' to determine whether inclusions are present. We identify four coprolite morphotypes: striated, cylindrical, spiral, and scroll, and those deemed nondiagnostic (too fragmentary and/or featureless). Of the 316 fossil-bearing coprolites, 22 (7%) are striated, 133 (42%) are cylindrical, 139 (44%) are spiral, 2 (1%) are scroll, and 20 (6%) are nondiagnostic. There is a well-defined ichnotaxonomy associated with Triassic coprolites. Striated coprolites align with the concept of Alococopros, and are interpreted to represent diapsid or temnospondyl perpetrators. Spiral coprolites align with the concept of Heteropolacopros and Saurocopros, and scroll coprolites align with the concept of Tikicopros, all of which are thought to represent spiral-valved chondrichthyan and/or sarcopterygian perpetrators. Within the context of the Homestead Site, coelacanths and lungfish are the only known taxa to have reached sufficient size to perpetrate the spiral coprolites. Cylindrical coprolites align with the concept of Eucoprus and within the context of the Homestead Site were likely perpetrated by actinopterygians. Our survey supports the hypothesis of the Homestead Site representing a diverse assemblage of fish and tetrapods interacting in a complex aquatic ecosystem.

In the last decade, ichnological analysis has been revealed as a tool in the characterization of bottom current processes and products (contourites). Evolution of large contourite deposits (drifts) is determined by several control factors one of them being changes in paleoenvironmental (ecological and depositional) conditions, affecting sedimentological and ichnological features at several orders of magnitude. Miocene deep-marine deposits in Cyprus allow for an interpretation of the influence of bottom currents on sedimentation. This contribution presents ichnological research focused on ichnofabric analysis, based on the investigation of a section near Spitali (Pakhna Formation). The palaeoenvironmental changes during the evolution of a Miocene contourite drift are discussed. The carbonate succession can be divided into 4 units (A-D). The study focuses on the lower and middle parts (A-C) consisting dominantly by decimetre- to meter-thick bigradational sequences of bioclastic contourites, interbedded hemipelagic/pelagic deposits, turbidites, and reworked turbidites, and a few debrites. The lower part (A) of the succession is dominated by sandy bi-gradational contourite sequences, while the middle part (B and C) comprises predominantly mud-rich contourites forming thinner, bi-gradational sequences. The sedimentary stacking pattern records the long-term upslope migration of the drift. Significant variations in ichnological properties are observed through A to C units, as revealed in the registered ichnofabrics, and three main ichnofabrics have been differentiated. The lower part of it (A) displays the vertical traces ichnofabric, characterized by an absence/scarcity of discrete traces (ii 1-2) and dominant vertical structures showing scarce cross-cutting relationships. Unit B is differentiated by the Zoophycos ichnofabric, dominated by Zoophycos, showing the highest abundance of traces (ii 3-5), with vertical and horizontal structures (i.e. Palaeophycus, Planolites, and Thalassinoides), and cross-cutting relationships. The Unit C shows the vertical-horizontal traces ichnofabric, with low/moderate (ii 2-3) vertical and horizontal traces (i.e. Planolites and Thalassinoides) but an absence of Zoophycos. These variations in ichnofabrics are interpreted as reflecting changes in environmental conditions on the drifts through time, in terms of oxygenation, hydrodynamic energy, sedimentation rates, and food availability, from a proximal/shallower, more energetic setting, followed by a short-lived shift to a distal/deeper environment, and a subsequent return to proximal/shallower conditions.

In this study, 252 bromalite specimens from the paleontological collection of the Benem & eacute;rita Escuela Normal de Coahuila were examined. These specimens were collected in the Cerro del Pueblo Formation (Upper Campanian) in the state of Coahuila, Mexico, and analyzed to obtain paleoecological and, for the first time, taphonomic data. A total of 18 morphotypes were classified and assigned to various potential producers, including teleosts, basal actinopterygians, elasmobranchs, crocodilians, testudines, amphibians, reptiles, theropod dinosaurs, and possibly other groups of omnivorous vertebrates. A multivariate analysis supported relationship between morphotypes and their associated potential producers. Additionally, some specimens present macroscopic and microscopic inclusions, such as bone remains and plant fragments, suggesting that these could represent predator-prey and herbivore-plant interactions. In contrast, traces of bioerosion in some specimens suggest coprophagy. The oxidized/reduced colorations, fragmentation, and biostratinomic alterations in the specimens indicate that they were likely deposited in floodplain environments. Furthermore, the ichnogenera Alococopros isp., Eucopros isp., and Struocopros isp. were identified within the collection, thus representing the first coprolite ichnotaxonomic records for northern Mexico from the Late Cretaceous. The biotic interactions inferred from the inclusions in the bromalites, their associated potential producers, and their distinct taphonomic histories suggest the presence of a diverse fauna that inhabited the various types of terrestrial and transitional environments within the Cerro del Pueblo Formation at the end of the Cretaceous.

The Cretaceous rocks of Iran contain significant oyster-bearing horizons that contribute to expanding the dataset on bivalve paleontology in the region. Herein, Oscillopha dichotoma (Bayle, 1849), colonized by sclerobionts from the Pol-e-Dokhtar section, the informal Lopha Limestone Member of the Gurpi Formation (Zagros Basin, SW Iran) of Campanian age is recorded. This is also a documented occurrence of Oscillopha dichotoma- Pycnodonte vesicularis Zone from the Lopha Limestone Member, a local biozone in North Africa and the Middle East. Additionally, the first records of sclerobionts, including Entobia cretacea Portlock, 1843, Entobia cateniformis Bromley and D'Alessandro, 1983, Oichnus simplex Bromley, 1981, Gastrochaenolites lapidicus Kelly & Bromley, 1984, Maeandropolydora isp., Maeandropolydora sulcans Voigt, 1965, Talpina ramosa von Hagenow, 1840, Rogerella pattei Saint-Seine, 1954, Trypanites isp., and Glomerula serpentina Goldfuss, 1831 associated with encrusting bryozoans and oysters are identified. These traces suggest a well-oxygenated nearshore setting with warm waters and low rates of sedimentation.

We describe and discuss invertebrate trace fossils originating from a limited, less than 2 m-thick sequence of sandstone beds from the Emsian Klerf Formation of the Olkenbach Syncline (SE Eifel) in Germany. The trace fossil suites are characterized by vertical and horizontal dwelling or feeding burrows or trails with relatively simple constructions and show a low to moderate ichnodiversity (about 15 ichnotaxa), although some ichnotaxa are abundant. The following ichnogenera are recorded: ?Arenicolites (and possibly Skolithos), Conichnus, Gyrochorte, Helminthopsis, Lockeia, Nereites, Palaeophycus, Planolites, Psammichnites, Ptychoplasma, Rosselia, and Spirophyton. Lockeia alfbachensis isp. nov. is proposed for a resting trace probably produced by bivalves. The overall geological and sedimentological context, the presence of adjacent mudstones with non-fully marine biota, low amount of bioturbation, and a sporadically heterogeneous distribution of the trace fossils suggest a stressed environmental setting, possibly induced by reduced salinity and/or subjected to episodic erosion and deposition. We propose a marginal-marine, deltaic setting, probably a distal tidal flat, as sedimentary environment for the trace fossil-bearing bedset under consideration.urn:lsid:zoobank.org:pub:49D0E07E-622F-4DDF-AD30-C7C8DE67B8EE

This study presents the first ichnological analysis of the Upper Devonian Imperial Formation in the Mackenzie Mountains (Northwest Territories, Canada), a siliciclastic succession deposited during the Ellesmerian orogeny. By integrating sedimentological and ichnological data from four measured sections, seven sedimentary facies were grouped into four facies associations that record a transition from wave-dominated delta front and storm-dominated lower shoreface deposits to storm-influenced prodelta, and ultimately to slope. Nineteen ichnotaxa were identified, with the highest ichnodiversity and bioturbation intensities occurring in wave-dominated shallow-marine and ramp settings. The trace-fossil assemblages in these settings reflect a typical Cruziana Ichnofacies and comprise tiered communities dominated by deposit- and detritus-feeders. In contrast, turbidite deposits of deeper slope settings contain sparse, diminutive trace fossils, reflecting rapid sedimentation rates and high hydraulic energy conditions. In contrast to the underlying Canol Formation, which was deposited under anoxic conditions, the Imperial Formation reflects more oxygenated conditions, as indicated by the higher diversity of trace-fossil assemblages. These ichnological patterns are interpreted as responses to evolving depositional environments and benthic food availability during foreland basin development. This work contributes a rare data point for Devonian shallow to deep-marine ichnology in western North America and enhances our understanding of post-Frasnian-Famennian recovery faunas in clastic foreland basin settings.

Fundalutum tielongtanensis isp. nov. represents the first record of anomuran microcoprolites from Upper Cretaceous shallow-marine carbonates of the Tibetan Plateau. It occurs in great abundance in ooidal grainstones of the Tielongtan Group bearing no other microfossils and assigned to an inner platform depositional setting. An early-middle Campanian age is assumed based on the presence of the orbitolinid Calveziconus lecalvezae Caus & Cornella below and above the microcoprolite-bearing samples. Fundalutum tielongtanensis represents the third ichnospecies of Fundalutum Senowbari-Daryan & Kuss all recorded from the middle-late Cretaceous interval. Besides minor differences in size, the three ichnospecies differ above all by the arrangement of the canals notably their orientation and position with respect to the symmetry plane.

Ichnofabrics have been categorized as simple (i.e. resulting from the activity of a single community at a given moment, therefore representing a single bioturbation or bioerosion event) and composite (i.e. produced by the replacement of successive communities or by the upward migration of a tiered community). The latter is further divided into autocomposite (i.e. comprising a single ichnocoenosis and produced by gradual upward relocation of a tiered community), heterocomposite (i.e. comprising more than one ichnocoenosis formed in response to short- to long-term environmental perturbations within a depositional system), and ultracomposite (i.e. resulting from the overprinting of ichnocoenoses that are markedly temporally disjunct and result from bioturbation in more than one depositional system). In this study, we document a specific type of simple ichnofabric referred to as unconformity-bound simple ichnofabrics. This type is illustrated by the Precambrian basement of the Orinoco Oil Belt hosting bioturbation structures produced in continental environments during the Miocene. A well core penetrating into the top of the Precambrian basement shows meniscate backfilled trace fossils assigned to Taenidium that are present in a quartz micaceous schist that has been weathered to sand and clay. Bioturbation is interpreted to have occurred during the Miocene on a regolith formed on top of the Precambrian basement. This ichnofabric is similar to ultracomposite ichnofabrics in involving significant temporal disjunction. However, it is distinguished from the latter by representing a single bioturbation event, therefore being a simple ichnofabric despite the temporal disjunction between colonization (Miocene) and the host rock (Precambrian). Failure to recognize the temporal disjunction involved may result in wrong claims regarding the age of evolutionary events in the stratigraphic record.

Burrowing animals produce either traces having distinct outlines and characteristic geometry allowing an ichnotaxonomic classification or biodeformational structures, which disturb pre-existing structures considerably by layer-bending, disruption or homogenization. Since biodeformational structures represent structural phenomena, it is proposed to use '-textura' (pl. '-texturae') as a post-modifier. Two major groups of biodeformational structures are distinguished according to size: (1) sub-macroscopic 'cryptotexturae' with three informal subtypes [i.st. in the following], and (2) macroscopic 'deformitexturae', which are subdivided by structural criteria.(1) Cryptotexturae blur to homogenize the sediment(a) cryptotextura i.st. mixta exists in surface mixed-layer sediments and oxygenated shallow-marine arenitic deposits containing nutritional organic matter, (b) cryptotextura i.st. rubra occurs in oceanic red beds (ORB) that accumulated at low rates under oxygenated conditions and were limited in benthic food resulting - over the long term - in a miniaturization of fauna, and (c) cryptotextura i.st. atra is present in 'black mud' formed under oxygen-deficient conditions with small fauna living near-surface.(2) Deformitexturae. (a) Navitexturae with fluidal and soft-sediment deformations occur in soupy substrate wherein burrowing animals need to swim. (b) Turbiditexturae show irregular deformation structures with sharp boundaries resulting from a strong consistency contrast between burrow fill and host sediment. (c) Miscitexturae represent eddy-like disturbances with indistinct boundaries (also 'mottling') in sandy to muddy sediment through that animals burrow 'unspecifically'. (d) 'Cribritexturae' (biostratifications) represent a millimeter- to centimeter-thick, but internally poorly organized enrichment of coarser material below heavily bioturbated finer sediment. (e) 'Fugitexturae' represent vertically stacked, U- to V-shaped to funnel-like deformations formed by animals rapidly responding to deposition or erosion. (f) Equilibritexturae exhibit concave and/or convex stacked laminae or layers extending vertically for millimetres to centimetres, while animals responded to moderately paced deposition or erosion.(1) Cryptotexturae blur to homogenize the sediment(a) cryptotextura i.st. mixta exists in surface mixed-layer sediments and oxygenated shallow-marine arenitic deposits containing nutritional organic matter, (b) cryptotextura i.st. rubra occurs in oceanic red beds (ORB) that accumulated at low rates under oxygenated conditions and were limited in benthic food resulting - over the long term - in a miniaturization of fauna, and (c) cryptotextura i.st. atra is present in 'black mud' formed under oxygen-deficient conditions with small fauna living near-surface.(2) Deformitexturae. (a) Navitexturae with fluidal and soft-sediment deformations occur in soupy substrate wherein burrowing animals need to swim. (b) Turbiditexturae show irregular deformation structures with sharp boundaries resulting from a strong consistency contrast between burrow fill and host sediment. (c) Miscitexturae represent eddy-like disturbances with indistinct boundaries (also 'mottling') in sandy to muddy sediment through that animals burrow 'unspecifically'. (d) 'Cribritexturae' (biostratifications) represent a millimeter- to centimeter-thick, but internally poorly organized enrichment of coarser material below heavily bioturbated finer sediment. (e) 'Fugitexturae' represent vertically stacked, U- to V-shaped to funnel-like deformations formed by animals rapidly responding to deposition or erosion. (f) Equilibritexturae exhibit concave and/or convex stacked laminae or layers extending vertically for millimetres to centimetres, while animals responded to moderately paced deposition or erosion.

The early Cretaceous dinosaur fauna of Mongolia is poorly known, in contrast to the extensively documented Upper Cretaceous record. Here we describe recently excavated dinosaur trackways from the historic Saijrakh locality from the Barremian-Aptian Shinekhudag Formation. The ichnoassemblage includes multiple trackways of large sauropods and theropods preserved on a single bedding plane. The sauropod trackways are wide-gauge and exhibit a unique mosaic of features: the manus prints have a distinct pollex impression (a plesiomorphic trait), but also possesses posterior lobes suggestive of derived soft-tissue pads. The pes prints are characterized by straight, anteriorly directed digits I-IV. The combination of primitive and derived characters is most consistent with a basal titanosauriform trackmaker, providing new insights into sauropod locomotor evolution. Associated theropod tracks are large, broad (as wide as its length), and functionally tridactyl, with wide interdigital angles (>60 degrees). The theropod tracks confirm the presence of large predators in this ecosystem. Beyond individual morphologies, the high density of trackways, with frequent overprinting, indicates that the site represents a zone of repeated transit or a high-traffic corridor. The parallel sauropod trackways may further infer that these large-bodied herbivores followed optimal pathways to minimize locomotor costs as modern elephants do.