Invertebrate Trace Fossils Research Articles

An ichnotaxonomic assessment of the Cretaceous Dakota Group, Front Range, Colorado, USA, and its comparison to other Western interior seaway deposits

The Aptian-Cenomanian Dakota Group along the Colorado Front Range is known for its dinosaur tracks; however, it also contains extensive invertebrate marine and continental trace fossils. The Dakota Group in Colorado is subdivided into the Lytle, Plainview, Glencairn (Cañon City), Skull Creek Shale (Denver, Fort Collins), and Muddy formations. Thirty-two invertebrate ichnogenera and 34 ichnospecies were identified: Archaeonassa, Arenicolites, Asterosoma, Asthenopodichnium, Aulichnites, Chondrites, Cochlichnus, Conichnus, Cruziana, Cylindrichnus, Diplocraterion, Gyrolithes, Lockeia, Macaronichnus, Margaritichnus, Naktodemasis, Ophiomorpha, Palaeophycus, Planolites, Protovirgularia, Rhizocorallium, Rosselia, Rusophycus, Schaubcylindrichnus, Scolicia, Skolithos, Taenidium, Teichichnus, Teredolites, Thalassinoides, Treptichnus, and Zoophycos. Six tetrapod ichnogenera and three ichnospecies were identified: Caririchnium, Dromaeosauripus, Hatcherichnus, Ostendichnus, Magnoavipes, and Tetrapodosaurus. Three tetrapod ichnogenera Chelonipus, Ignotornis, and Mehliella have been reported at other sites in the Dakota Group, but none were found at our study sites. Rhizohaloes are reported in the Muddy Formation. Three vertebrate ichnogenera and two ichnospecies were previously described elsewhere by other workers. The Dakota Group trace fossils comprise eight ichnocoenoses–Caririchnium, Diplocraterion, Lockeia, Naktodemasis, Rhizohalo, Scolicia, Skolithos-Teichichnus, and Zoophycos–representing dwelling, deposit- and filter-feeding, and locomotion behaviors of plants, invertebrates, and tetrapods. Twelve previously unreported ichnogenera were identified: Archaeonassa, Asthenopodichnium, Conichnus, Cylindrichnus, Gyrolithes, Macaronichnus, Naktodemasis, Protovirgularia, Rusophycus, Taenidium, Treptichnus, and Zoophycos. This study is the first systematic ichnotaxonomic assessment of the invertebrate trace fossils of the Dakota Group along the Colorado Front Range, which has the highest reported ichnodiversity when compared to other Western Interior Seaway deposits.

AVIAN FORAGING ON AN INTERTIDAL MUDFLAT SUCCESSION IN THE EOCENE TANJUNG FORMATION, ASEM ASEM BASIN, SOUTH KALIMANTAN, INDONESIAN BORNEO

Abstract Moderately diverse trace fossil assemblages occur in the Eocene Tambak Member of the Tanjung Formation, in the Asem Asem Basin on the southern coast of South Kalimantan. These assemblages are fundamental for establishing depositional models and paleoecological reconstructions for southern Kalimantan during the Eocene and contribute substantially to the otherwise poorly documented fossil record of birds in Island Southeast Asia. Extensive forest cover has precluded previous ichnological analyses in the study area. The traces discussed herein were discovered in newly exposed outcrops in the basal part of the Wahana Baratama coal mine, on the Kalimantan coast of the Java Sea. The Tambak assemblage includes both vertebrate and invertebrate trace fossils. Invertebrate traces observed in this study include Arenicolites, Cylindrichnus, Diplocraterion, Palaeophycus, Planolites, Psilonichnus, Siphonichnus, Skolithos, Thalassinoides, Taenidium, and Trichichnus. Vertebrate-derived trace fossils include nine avian footprint ichnogenera (Aquatilavipes, Archaeornithipus, Ardeipeda, Aviadactyla, cf. Avipeda, cf. Fuscinapeda, cf. Ludicharadripodiscus, and two unnamed forms). A variety of shallow, circular to cylindrical pits and horizontal, singular to paired horizontal grooves preserved in concave epirelief are interpreted as avian feeding and foraging traces. These traces likely represent the activities of small to medium-sized shorebirds and waterbirds like those of living sandpipers, plovers, cranes, egrets, and herons. The pits and grooves are interpreted as foraging traces and occur interspersed with both avian trackways and invertebrate traces. The trace fossils occur preferentially in heterolithic successions with lenticular to flaser bedding, herringbone ripple stratification, and common reactivation surfaces, indicating that the study interval was deposited in a tidally influenced setting. Avian trackways, desiccation cracks, and common rooting indicate that the succession was prone to both subaqueous inundation and periodic subaerial exposure. We infer that the Tambak mixed vertebrate-invertebrate trace fossil association occurred on channel-margin intertidal flats in a tide-influenced estuarine setting. The occurrence of a moderately diverse avian footprint and foraging trace assemblage in the Tambak Member of the Tanjung Formation illustrates that shorebirds and waterbirds have been using wetlands in what is now Kalimantan for their food resources since at least the late Eocene.

Life in an Artinskian (Cisuralian) Permian megacaldera: Benthic palaeoecology in the shadow of the Bolzano Supervolcano (Athesian Volcanic District, Italy)

Volcanic processes create peculiar types of terrestrial and freshwater ecosystems but, surprisingly, very little is known about the infaunal palaeoecology of continental volcanic ecosystems such as caldera lakes and streams. Here, we report an invertebrate trace fossil association from the largest and best-exposed Permian (Cisuralian) supervolcano in Europe, the Bolzano Supervolcano. The fossil association is dominated by abundant trace fossils that are unusually straight, i.e., their curvature is zero along the entire preserved length. The trace fossils are attributed to Planolites and Palaeophycus and they form a bioturbated texture (ichnofabric) with a characteristically high bioturbation intensity (percent bioturbated>90%). U-shaped (Arenicolites) and concentrically-lined (Cylindrichnus) burrows are minor components of the ichnofabric. The characteristics of the trace fossil association suggest substrate colonization by r-strategic organisms during periods of minor volcanic activity. In these periods of stasis, the volcanic rocks were eroded by seasonal streams, which provided suitable softground substrates for the infauna. Insects are regarded as the most plausible tracemakers of the straight burrows. Similar ichnofabrics are found in other continental volcanoclastic sites, suggesting that ichnofabrics dominated by straight burrows may represent an ichnological proxy of brief windows for colonization in volcanically influenced freshwater environments. Generative artificial intelligence has been used to graphically reconstitute the tiering pattern and the palaeoenvironment. As such, this study provides the first application of AI to the graphic representation of a bioturbated palaeoenvironment.

Reviewing the Palaeontological and Palaeoenvironmental Heritage of the Monti Pisani Massif (Italy): A Compelling History of Animals, Plants and Climates through Three Geological Eras

The Monti Pisani massif (Tuscany, central Italy) is an isolated mountain relief known for its rich geodiversity, including a remarkable palaeontological heritage from the Palaeozoic, Mesozoic and Cenozoic eras. The Palaeozoic record consists of exquisitely preserved plant remains and rarer invertebrates of Permo-Carboniferous age, which testify to extensive rainforests and large swamps that thrived in an alluvial system under a humid, (sub)tropical climate. In addition to invertebrate shells, invertebrate trace fossils and microbial structures, the Mesozoic record features a diverse Middle Triassic tetrapod ichnoassemblage consisting of tracks of lepidosauromorphs, archosaurs (among which are the earliest dinosauromorph fossils of Italy) and nonmammalian therapsids. These vertebrates lived in a subsiding costal setting that stretched across an expanding rift valley under a subarid climate. The Cenozoic record features abundant fossils of terrestrial vertebrates (including spectacular members of the mammalian megafauna) from karst deposits, testifying to the manifold inhabitants of the massif during the glacial and interglacial phases of the Late Pleistocene. Overall, this long-lasting fossil record remarkably demonstrates how much the Earth’s environments have been changing through the Phanerozoic. The outstanding palaeontological heritage of the Monti Pisani area is in need of specific efforts of conservation and valorisation, especially with respect to the many palaeontological sites that punctuate the massif.

Ichnological analysis and depositional setting of late Miocene marginal marine deposits from the Tafna Basin (northwestern Algeria)

Abstract The late Miocene marginal marine deposits of the Sikkak area (Tafna Basin, northwestern Algeria) encompass moderately diversified invertebrate trace fossils preserved mainly as epichnia. The present study documents for the very first time the trace fossils occurring in this area, where 16 ichnotaxa, dominated by post-depositional domichnial, repichnial and fodinichnial components, are reported: ? Bifurculapes isp., Diplocraterion isp., Helminthoidichnites isp., ? Kouphichnium isp., ? Megagrapton irregulare , Ophiomorpha annulata, Ophiomorpha cf. nodosa , Oravaichnium isp., Palaeophycus isp., Planolites cf. beverleyensis , Planolites montanus , Ptychoplasma isp., Skolithos isp., S. linearis , Thalassinoides isp. and T. suevicus . The main producers of the studied trace fossils are arthropods (crustaceans, limulids, insects), annelids (polychaetes, phoronids) and bivalves. These traces are commonly associated with sedimentary structures that are caused by hydrodynamics, suggesting high-energy conditions and opportunistic colonization within a marginal marine environment (i.e. backshore to foreshore), and corresponding to the Skolithos ichnofacies. The crustacean trace ? Bifurculapes and the limulid trackways Kouphichnium are reported herein for the first time in Algeria. Sedimentological data suggest an imbricated sandstone channel within a marginal marine setting and subaerial exposures indicated by mud-cracks. The foraminiferal assemblage, dominated by shallow marine species, therefore suggests a Tortonian age for these deposits.

Invertebrate trace fossils from Paleogene fluvial strata in Western Washington, USA

Fluvial strata in the Paleogene Chuckanut Formation contain a wealth of trace fossils that include both vertebrate and invertebrate ichnofossils. Vertebrate traces have received careful scrutiny, but invertebrate traces have not previously been described. Trace fossils occur in two sediment types. Mudstones deposited in subaqueous environments include highly bioturbated layers that are dominated by horizontal meniscate burrows. Siltstone and fine-grained sandstone beds primarily contain vermiform trails on bedding surfaces, with sparse vertical traces. Some of these sandy beds also contain vertebrate tracks. Chuckanut Formation beds commonly show rapid facies changes in sediments that were deposited along a meandering river during a time of semitropical climate. Transitions from subaqueous to subaerial conditions may have been related to changing water levels caused by variations in seasonal precipitation or episodic flood events. Other possible factors include ponds created by abandonment of channels, overbank sediment s deposited by floods, and breaching of levees to form crevasse splay deposits. Trace fossil assemblages show local variations in the diverse depositional environments of the Chuckanut Formation. Many of the ichnofossil suites clearly represent Scoyenia Ichnofacies, but some occurrences may involve overprinting of Scoyenia and Mermia ichnofacies.

Non-marine invertebrate trace fossils from the Tertiary Calatayud-Teruel basin, NE Spain

Relatively diverse trace fossils made by insects, other arthropods and oligochaete worms occur in the Miocene lacustrine and marginal lacustrine deposits of the Calatayud-Teruel basin (NE Spain). They include the ichnospecies Celliforma isp., Celliforma? isp. A and B, Celliforma? aff. habari, Rosellichnus cf. arabicus, Spongeliomorpha isp., Labyrintichnus terrerensis n. igen. et isp., Taenidium barreti, Beaconites filiformis n. isp. and Polykladichnus aragonensis n. isp. Their taxonomic and ethologic interpretations and cross-cutting relationships permit to envisage new lines of evidence for reconstructing transitions from dry-ground terrestrial to moist-ground and subaqueous environments, related to episodic floodings in lacustrine ponds. These environmental transitions (related to external controls) are characterized by benthic community replacements, evinced by vertical successions of Termitichnus, Scoyenia and Mermia-like ichnofacies.

Ichnology and sedimentology of the Coniacian non-marine Frontier Formation, western Centennial Mountains, southwestern Montana, USA

ABSTRACT The Coniacian non-marine portion of the Frontier Formation in southwestern Montana has been primarily studied stratigraphically, whereas its trace fossil record and relative sedimentological significance have remained overlooked so far. We present the first description of a trace fossil assemblage reported from Frontier Formation deposits exposed in the western Centennial Mountains, Beaverhead County, Montana. Three main lithofacies groups with distinctive trace fossil assemblages have been recognised at the locality of Price Creek: (1) coarse-grained, thin and laterally extensive cross-bedded sandstone channel bodies characterised by rare vertical, passively filled burrows; (2) fine-grained overbank sandstones and siltstones, with abundant horizontal, meniscated, and unwalled burrows, sinusoidal trails, vertical burrows, and dinosaur tracks, and (3) fining-upward, planar cross-bedded silty sandstones, associated with carbonaceous plant material and bone fragments. The trace fossil assemblage is ascribed to the pre-desiccation suit of the Scoyenia ichnofacies. The occurrence of theropod, ornithopod, and thyreophoran dinosaur tracks, and invertebrate trace fossils suggests considerable diversity of terrestrial and aquatic fauna. Tracks described here represent the first dinosaurian record reported from Coniacian deposits in Montana and one of the few fossil records reported from non-marine Coniacian deposits in North America.

First occurrence of sauropod and theropod footprints in the pre‐Campanian deposits of the Nubian Sandstone, south Eastern Desert, Egypt

Dinosaur footprints occur in the Upper Cretaceous strata known as the Nubian Sandstone Formation in the south Eastern Desert, Egypt. The Nubian Sandstone unit is subdivided into three informal members: A lower member is marked by reddish‐brown, trough cross‐bedded, coarse‐ to medium‐grained sandstone interbedded with thin beds of varicolored mudstone, reflecting deposition in a braided fluvial system, a middle member is characterized by reddish‐white to yellow, planar cross‐bedded, medium‐grained sandstone with ferruginous siltstone intercalations, interpreted as meandering fluvial deposits, and an upper member consists of repeated coarsening‐upward cycles of rippled siltstone to fine‐ to medium‐grained sandstone and planar cross‐bedded, yellowish‐white sandstone, containing many vertebrate footprints and invertebrate trace fossils, reflecting deposition in a coastal to deltaic environment. Sixteen dinosaur footprints are recorded at the base of the upper member of the Nubian Sandstone, on inclined surfaces of rippled, fine‐grained sandstones. Twelve are overlapping each other and belong to distinct individuals of dinosaurs, the other four are distributed on a younger bedding surface. Twelve footprints are from more than one sauropod dinosaur, while three of the isolated footprints belong to a theropod dinosaur. The footprints described are semiplantigrade and digitigrade. This discovery is the second record of tetrapod footprints in Egypt and the first record of tetrapod footprints in the Eastern Desert.

The Lower Cretaceous “Continental Intercalaire” around Tidikelt (Central Sahara, Algeria): Sedimentology, palaeontology and ichnology

The Lower Cretaceous strata are exposed over a large surface in the northern part of the Ahnet basin. They consist of transgressive, horizontal formations overlying the folded Palaeozoic formations by angular unconformity across the Tidikelt region. The present study addresses the respective lithostratigraphical units of the “Continental Intercalaire” succession and their subsequent palaeo-environment in the Tidikelt area using a trace fossil analysis combined with sedimentological and palaeontologic data. The lithological and sedimentological features of the study sections recognised eleven sub-units organised within four lithological units: the Lower Clay Unit of Barremian-Neocomian age consisting of three Sub-units (Akablie Sandstone, Sidi Mahmoud Clays and Pebbly Sands); the Quartzite Sandstones Unit referred to a Late Barremian-Early Aptian age; the Middle Clay-Sandstone Unit consisting of a thick deposit of Early Aptian-Albian age, divided into five Sub-units (Tit Sandstones, In Salah Sand-Clay, In Salah Sandstone, Foum El Bouib Sandstone, and Sandstone-Clay); and the Upper Clay Unit comprising the Oued Taleh Sand and the El-Golea Clays Sub-units. Vertebrate remains all evidence a Late Albian-Early Cenomanian age for the top part of the Continental Intercalary. Ichnologic data analysis documents lower diversity of the invertebrate trace fossils: only ten ichnotaxa are recorded so far and grouped in five ichnoassemblages. Fuvial-lacustrine ichnoassemblage represents a continental ichnofacies of a fluvial-lacustrine environment: Mermia, Scoyenia and Skolithos ichnofacies. Fluvial Ichnoassemblage of the Quartzite Sandstone Unit is represented by insect trace fossils typical of the Coprinisphaera ichnofacies. Fluvio-marginal ichnoassemblage corresponds to a tidal-influenced, fluvial deposit transgressive on Unit B, represented by Skolithos and Psilonichnus ichnofacies. Lower shoreface ichnoassemblage shows the upper part of Unit C, documented by horizontal trace fossils such as Thalassinoides and vertical root traces, all supporting a lower shoreface environment in a semi-arid climate interlined by well-oxygenated episode with nutrient-rich conditions and vegetation dominance. Near to shoreface ichnoassemblage coincides with the upper unit D of coastal deposits with fluvial-tidal influence at the base (Oued Taleh Sands) associated with Scoyenia and Skolithos trace fossils and lagoon deposit of the El-Golea Clays Sub-units.

Non-marine invertebrate trace fossils from the Tertiary Calatayud- Teruel Basin, NE Spain. Reply

We thank the comments of Dr Calzada. We think that this kind of discussions is very healthy to the Paleontology and it would be necessary to do it more frequently, so that thanks again for your example. It is true that some of the descriptions of ichnofossils in our work need further discussion and comments, but when we analysed several poorly-preserved specimens (such as the so-called Spongeliomorpha isp.) we preferred to make a quick introduction and describe them in open nomenclature. It was beyond the scope of our paper to make a revision of the ichnogenus with this kind of material, but we hope that Calzada's comments and our reply will improve some ideas concerning the ichnogenus Spongeliomorpha.

Palliedaphichnium gondwanicumnew ichnogenus new ichnospecies, a millipede trace fossil from paleosols of the upper Permian Gondwana sequence of India

AbstractThe new invertebrate trace fossil from paleosols of the Bijori Formation,Palliedaphichnium gondwanicumnew ichnogenus new ichnospecies, which belongs to an upper Permian Gondwana sequence of India, makes a significant contribution to the meager records of invertebrate trace fossils from Permian and Indian paleosols. This trace fossil attributed to Diplopoda and composed of tunnels and chambers filled with pellets is also an important addition to the scarce record of Permian millipedes. The abundance of plant remains in the same paleosol indicates that these millipedes probably fed on leaf litter as other fossil and extant representatives. Chambers and abundant pellets in burrows indicate adverse conditions on the surface, at least seasonally. This finding contributes to the emerging scenario of invertebrate ichnofaunas from paleosols and points to a successive dominance of millipedes during the Paleozoic, crayfishes and earthworms in the Mesozoic, and insects in the Cenozoic.UUID:http://zoobank.org/4378c739-9bd1-4382-b084-e2176045e209

Experimental rain prints and gas escape structures as a framework for interpreting circular imprints in shales of the Pottsville Formation (Pennsylvanian, Alabama)

AbstractCoal‐bearing, fine‐grained clastic rocks of the Pennsylvanian Pottsville Formation contain well‐preserved vertebrate and invertebrate trace fossils and disarticulated plant fossils. These fossil‐bearing rocks also contain small, circular imprints that resemble raindrop impressions but have also been interpreted as structures formed by gas bubble escape from wet sediment. Because rain prints are associated with arid, subaerially exposed depositional conditions and gas escape structures with water‐saturated, organic rich sediments, the interpretation of the circular structures profoundly impacts the palaeoenvironmental reconstruction and interpretation of the life habits of the trace‐makers. In this project, rain prints and gas escape structures were produced to compare these two hypotheses regarding mode of formation and to gain insight into interpretations of similar circular pits in the geological record. The results indicate that gas escape structures form most readily in fine‐grained sediment under water‐saturated conditions, in contrast to rain prints, which form most readily in unsaturated sand. A comparison with experimental structures suggests that the Pottsville shales preserve gas escape structures, not raindrop impressions, suggesting that the environment was rarely desiccated. Because rain prints and gas escape structures are superficially similar, genetic interpretations should not be based on these similarities, but rather on the differences observed between them. Reexamination of circular pits in the sedimentary rock record might require adjustment of environmental interpretations.

The Silurian inception of inland desert ecosystems: trace fossil evidence from the Mereenie Sandstone, Northern Territory, Australia

The Silurian was an interval of profound change in terrestrial ecosystems as the earliest non-marine animal communities began to become established on the continents. Whilst much is known about the transition of pioneering animals from shallow-marine to coastal and alluvial habitats, evidence for animal activity in contemporaneous aeolian strata is rare. Here, we present trace fossil evidence that closes this knowledge gap, indicating that Silurian desert environments, dominated by aeolian processes, were occupied by resident invertebrate communities. The evidence comes from the Mereenie Sandstone, Northern Territory, Australia, which is demonstrated to have been deposited in a wet inland aeolian system, typified by small crescentic sand dunes and extensive interdune flats. The invertebrate trace fossil associations from the Mereenie Sandstone ( Arenicolites isp., ‘burrow entrance with radial feeding traces', Didymaulichnus lyelli, Diplichnites gouldi, Helminthopsis isp., Laevicyclus isp., Palaeophycus isp., Polarichnus garnierensis , Skolithos isp.) are restricted to damp interdune deposits, whereas dune strata are barren. The ichnofauna are described and compared to those from other Palaeozoic aeolian systems, in order to re-evaluate the timing of the early stages of arthropod terrestrialization.

Dinosaur taphonomy of the Jurassic Shishugou Formation (Northern Junggar Basin, NW China) – insights from bioerosional trace fossils on bone

Bioerosional trace fossils can offer invaluable insights into taphonomic processes, ecosystem dynamics and environmental conditions that are not obtainable by other lines of evidence. Here, we describe the first invertebrate trace fossils on dinosaur bone from the Upper Jurassic Shishugou Formation of the northeastern Junggar Basin. The traces occur as spherical holes in the bone, closely resembling boreholes attributed to either indeterminate insects or dermestid beetles and thus they are here likewise ascribed to feeding and/or pupation by necrophagous insects. Such bioerosional trace fossils have several taphonomical and palaeoecological implications for they are only inflicted on subaerially exposed tissues and preferentially when carcasses are desiccated. We, therefore, conclude that the dinosaur carcass was exposed for at least several weeks under a semi-arid and seasonal climate before it was buried by sediment. This supports the general palaeoclimatological and paleoenvironmental reconstructions for the Shishugou Formation from sedimentological data. Moreover, this is the first evidence for invertebrate–vertebrate interactions from the Late Jurassic of Asia, offering a novel glimpse into the diverse biotic relationships of this ancient Jurassic ecosystem.

A trace fossil made by a walking crayfish or crayfish-like arthropod from the Lower Jurassic Moenave Formation of southwestern Utah, USA.

New invertebrate trace fossils from the Lower Jurassic Moenave Formation at the St. George Dinosaur Discovery Site at Johnson Farm (SGDS) continue to expand the ichnofauna at the site. A previously unstudied arthropod locomotory trace, SGDS 1290, comprises two widely spaced, thick, gently undulating paramedial impressions flanked externally by small, tapered to elongate tracks with a staggered to alternating arrangement. The specimen is not a variant of any existing ichnospecies, but bears a striking resemblance to modern, experimentally generated crayfish walking traces, suggesting a crayfish or crayfish-like maker for the fossil. Because of its uniqueness, we place it in a new ichnospecies, Siskemia eurypyge. It is the first fossil crayfish or crayfish-like locomotion trace ever recorded.

New record of Late Cretaceous vertebrate tracks from the Yacoraite Formation (Juella, Quebrada de Humahuaca, northwestern Argentina): aerial drone survey, preservation and sedimentary context

The Yacoraite Formation is a worldwide known unit due to the diversity and abundance of vertebrate ichnological record. The complex tectono-sedimentary evolution related to the Andean Cycle generated high dip angles of bedding and, consequently, large tracksites are not easily accessible, making hard the ichnological analysis. Here, we describe a new tracksite named “La Banderita”, near Juella town (Quebrada de Humahuaca, Jujuy, Argentina), where abundant vertebrate and invertebrate trace fossils have been identified on different high slope surfaces. A small, portable unmanned aerial vehicle (UAV) equipped with a digital camera was employed to overcome difficulties in studying traces. After the aerial survey, digital photogrammetry was applied to get 3D models of the trampled surfaces (about 7700 m2) and to obtain track distribution maps (more than 100 tracks). As a complement, a detailed 3D model of an easily accessible small area was also made (about 315 m2). Trace fossils were preserved within three facies intervals from subtidal/lower intertidal (Intervals I-II) to intertidal (Interval III) settings. In this last interval, quadrupedal (probably sauropod), bipedal (theropod) and undetermined tracks, differently preserved as undertracks, true tracks and natural casts, are identified. These three modes are product of narrow preservational windows, which have prevented weathering destruction process after original trampling. Ichnological and sedimentological data are coherent with those of other localities from the Yacoraite Formation, and suggest that dinosaurs moved along peritidal settings. This contribution highlights the use of aerial drone survey and 3D photogrammetric models, which besides traditional ichnological and sedimentological techniques, allowed a detailed reconstruction of track formation and preservation, contextualizing the trampled surfaces in their palaeoenvironmental setting.

The Upper Jurassic Faïdja Formation (Northwestern Algeria): Sedimentology, biostratigraphy and ichnology

The Faïdja Formation displays mixed siliciclastic-carbonate deposits distributed in three members, which are organised from bottom to top as follows: the Clayey Sandstone Faïdja Member; the Clayey Limestone Bel Aoura Member and the Sandy Claystone Douaouda Member. Sedimentological data indicate the evolution of a subsiding marine environment from the shelf edge to the lower shoreface, sporadically dominated by storms. New age based on recently collected ammonite fauna allowed us to update the age of the Faïdja Formation as Early-Late Kimmeridgian. Ichnological analysis reveals the occurrence of abundant and diverse invertebrate trace fossils, grouped in four ichnoassociations. Ichnoassociation -A- coincides with the lowermost part of the Clayey Sandstone Faïdja Member; it is distinguished by a combination of pre-graphoglyptids and post-depositional traces, ascribed to the distal Cruziana ichnofacies transitional to the Nereites ichnofacies, which indicates a lower offshore zone to shelf edge environment characterised by a low-oxygenated period (anoxic event), frequent storm events and nutrient frequency. Ichnoassociation -B- occupies the middle and upper parts of the Clayey Sandstone Faïdja Member, it is characterised by an abundance of post-depositional traces, corresponding to the archetypal Cruziana ichnofacies that indicates a lower to transitional offshore environment with short phases of low hydrodynamic energy. Ichnoassociation -C- corresponds to the Clayey Limestone Bel Aoura Member that coincides with a drastic facial change and depositional conditions; this association documents a proximal Cruziana ichnofacies, and indicates an upper to transitional offshore zone as a depositional environment. Finally, ichnoassociation -D- coincides with the Sandy Claystone Douaouda Member; it is ascribed to the proximal Cruziana ichnofacies, indicating a lower shoreface environment. The combined sedimentological and ichnological data indicates a relatively subsiding platform with shallowing upwards corresponding to distal, archetypal and proximal Cruziana ichnofacies, respectively.

First evidence of rooting lycopsids preserved as imprints and trace fossils from the Silves Sandstone (Upper Triassic, eastern Algarve, South Portugal)

Rooting lycopsids, preserved as imprints on the Upper Triassic Silves Sandstone in the Eastern Algarve region (South Portugal), are recorded for the first time in this area. The Silves Sandstone is composed of the characteristic dark red sandstone and conglomerates of this formation and contains all the studied imprints. These have a quadrate or pseudohexagonal outline corresponding to the departure of roots placed in four to six roughly symmetrical points around the stem bases. Two generations of plants are observed, including the imprints of seedings. Palaeoenvironmental conditions for the lower unit have been interpreted as a shallow lagoon or stationary bodies of water in a swap-like environment subjected to sporadic current activity. This would have uprooted stems and ripped off the leaves. The upper unit would correspond to a fluvial environment with the establishment of an inundated floodplain with periodic subaerial exposure; this is where root imprints, shallow vertebrate (Rhynchosauroides isp.) and invertebrate trace fossils (Cochlichnus anguineus, Vagorinchus cf. anyao, Palaeophycus tubularis, Taenidium isp., Scoicia isp.), tetrapod footprints and raindrop imprints were recorded. Lycopsids maw have colonized these marshy areas in between wet (occasional flash floods) and drier episodes. Uprooting of the stems was probably caused by sudden and strong mass flow produced during intervals of heavy rain

Invertebrate borings from the Eocene of Seven Rivers, parish of St. James, western Jamaica

The fossil biota of the Eocene Yellow Limestone Group of Jamaica is diverse in vertebrates and, particularly, invertebrates. However, its invertebrate trace fossils remain understudied. Herein, we document the borings of the Seven Rivers vertebrate site in western Jamaica. This is in the Litchfield Formation, high in the Lutetian (about mid-Middle Eocene). The suite of borings identified from this site comprises Apectoichnus longissimus (Kelly and Bromley); Entobia isp.; Oichnus simplex Bromley; and Oichnus paraboloides Bromley. Substrates infested by Entobia isp. include both molluscs and sirenian ribs. Oichnus ispp. occur only in bivalves and are mainly non-penetrative, which may be a taphonomic artifact. Tubes of the common A. longissimus are preserved free from any woody substrates, which have presumably rotted away; however, one specimen has a dark, carbonaceous external film and others have carbonized wood inclusions. The occurrence of A. longissimus in the Jamaican rock record coincides with periods of sub-aerial exposure.