Invertebrate Trace Research Articles

Polyonyx-like tracks from Middle-?Upper Jurassic red beds of Morocco: Implications for sauropod communities on southern margins of tethys

A new dinosaur tracksite is reported from continental red beds of the Jurassic (Late Bathonian-?Callovian) Isli Formation along the northern flank of the Aït Ali ou Ikkou Syncline of the Imilchil area, Central High Atlas, Morocco. The succession was deposited in a fluvio-lacustrine environment, and contains at least fourteen track-bearing levels. The diverse dinosaur-dominated ichnofauna includes the footprints of crocodylomorphs, pterosaurs, theropods, sauropods and ornithischians, together with numerous invertebrate traces. Here, we focus on a long sauropod trackway, which comprises nine consecutive manus-pes sets preserved as concave epireliefs. The low heteropody and asymmetry of manus prints with a large digit I (pollex) impression oriented medially, and a large triangular claw trace, which is posteriorly oriented, are characteristic of the ichnogenus Polyonyx. Different from typical Polyonyx is the narrow gauge pattern compared to the wide gauge observed in the type trackway from Portugal. Additional material from Morocco, similar to Polyonyx, comprises the trackway of a very small (?juvenile) individual found close to the main trackway, as well as a short trackway from a different locality in the Isli Formation. Our data from the Moroccan High Atlas indicates the presence of basal eusauropods in the Middle Jurassic-Early Cretaceous interval in the northwestern part of Gondwana for the first time, and suggests they inhabited a lacustrine paleoenvironment.

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.

Two previously unrecorded xiphosurid trace fossils, Selenichnites rossendalensis and Crescentichnus tesiltus , from the Middle Jurassic of Yorkshire, UK

The invertebrate trace fossils Selenichnites rossendalensis and Crescentichnus tesiltus are recorded and described from the Middle Jurassic Gristhorpe Member of the Cloughton Formation of the Cleveland Basin. This is the first record of these ichnospecies from the basin and now completes the occurrence of these and other traces assumed to have been made by limulids from all three non-marine formations of the Ravenscar Group.

Pleistocene fauna of the Cape south coast revealed through ichnology at two localities

East of Still Bay on the Cape south coast of South Africa lies a rugged, remote stretch of sea cliffs that expose Late Pleistocene aeolianites. A zone of dense concentration of fossil tracks occurs within this area. Two large rocks, which we call Roberts Rock and Megafauna Rock, were identified ~400 metres apart. These rocks contained a variety of trackways, individual tracks, burrow traces and invertebrate trace fossils on multiple bedding planes. Both rocks were found ex situ, but their context could be determined. Roberts Rock has subsequently slid into the ocean, and Megafauna Rock lies at the base of a coastal cliff. Probable trackmakers include elephant, long-horned buffalo, giant Cape horse, rhinoceros, medium and small artiodactyls, golden mole, birds and invertebrates. Dating studies at an adjacent site, which is comparable to the stratigraphy described here, indicate that both rocks were most likely deposited in Marine Isotope Stage 5e (~128–116 ka). Analysis and description of these tracksites confirms the potential of ichnology to complement the skeletal fossil record and to enhance the understanding of Pleistocene life in southern Africa. The ephemeral nature of such tracksites makes repeated visits to this coastline desirable, both to monitor the fate of known sites and to search for newly exposed trace fossil surfaces.
 Significance:
 
 Roberts Rock and Megafauna Rock are two remarkable fossil tracksites on the Cape south coast, which contain tracks of four members of the Late Pleistocene megafauna. They provide a glimpse of Pleistocene dune life and suggest an area teeming with large mammals.
 These tracks were made on dune surfaces near an interface between the grassland of the Palaeo-Agulhas Plain and the inland Fynbos–Strandveld–Renosterveld. Faunal assemblages from both vegetation zones might therefore be recorded.
 The trace fossil record and body fossil record both have inherent biases, but have the potential to independently provide complementary information on palaeofaunal composition.
 The two rocks have provided the first South African records of fossil elephant tracks (as first described by Dave Roberts and colleagues in 2008), the first rhinoceros track and the first extinct giant Cape horse track, and track evidence of the extinct long-horned buffalo.
 Roberts Rock has slumped into the ocean, and it provides an example of the fate of many exposed tracksites. Conversely, new sites frequently become exposed. This scenario stresses the need for regular ichnological surveys along this track-rich coastline to monitor existing sites and to search for new sites.

Taenidium barretti Bradshaw, 1981 na Formação Malhada Vermelha (Cretáceo Inferior), Bacia de Malhada Vermelha, Ceará, Brasil

The invertebrate trace fossil record in the Malhada Vermelha Basin, although recognized, is quite sparse and poor from the Systematic Ichnology approach. Field researches carried out in this basin found the presence of these structures which are studied and taxonomically identified in the current work. The absence of wall lining and the presence of a meniscate backfill characteristic of Taenidium barretti allowed assigning this ichnospecies to the analyzed samples. These traces are ascribed here as the result of bioturbation activity in moist sediments exposed to subaerial conditions in paleoenvironmental features of a hot climate.

Invertebrate trace fossils from the Alveley Member, Salop Formation (Pennsylvanian, Carboniferous), Shropshire, UK

The late Carboniferous–early Permian was a period of major environmental change, with the rainforests that covered the equatorial zone during the Carboniferous disappearing due to increasing aridification. This environmental transition had significant impacts on the terrestrial biota, including a major extinction event among plant and vertebrate groups. A rich and unique ichnofauna from the Alveley Member (Moscovian: Westphalian D) of the Salop Formation at Alveley in Shropshire (England) has yielded important insights into late Carboniferous terrestrial communities. However, research to date has focused entirely on the vertebrate footprints. Abundant invertebrate ichnofossils also occur at Alveley, typically on the rippled upper surfaces of beds assigned to a floodplain facies that preserve the vertebrate tracks in hyporelief on their base. We provide the first detailed examination of the invertebrate ichnofauna from Alveley, identifying six ichnospecies within five ichnogenera (Diplichnites, Gordia, Paleohelcura, Palmichnium, Protichnites), including a new species of the common arthropod ichnogenus Diplichnites. This moderately diverse invertebrate ichnofauna is dominated by arthropod repichnia. There is no evidence of infaunal bioturbation and the single example of Gordia indicates limited sediment grazing activity. The Alveley ichnofauna is typical of Euramerican continental ichnoassemblages from the very latest Carboniferous, and indicates a moderate diversity of arthropods (crustaceans, arachnids and chelicerates) living alongside the marginal freshwater to terrestrial assemblage of temnospondyl amphibians, and basal synapsid, diadectomorph and captorhinomorph amniotes.

Unusual archosaur trackway and associated tetrapod ichnofauna from Irohalene member (Timezgadiouine formation, late Triassic, Carnian) of the Argana Basin, Western High Atlas, Morocco

ABSTRACT An archosaur trackway consisting of 10 successive pes imprints has been recovered from the Late Triassic Irohalene Member of the Timezgadiouine Formation (Argana Basin, Morocco). Footprints are tetradactyl-pentadactyl, and show an elongated ‘heel’, probably enclosing the trace of digit V. The trackway lacks a manus impression, which could be due to bipedal progression of the trackmaker or be a preservational phenomenon. It is assigned to cf. Parachirotherium isp. based on similarities with the ichnogenus that has been described from the same stratigraphic unit. Other footprints of this assemblage are assigned to the ichnotaxa Grallator-Eubrontes (dinosauromorphs/crocodilian-stem archosaurs), Brachychirotherium isp. (crocodilian-stem archosaurs), Rhynchosauroides isp. (lepidosauromorphs/archosauromorphs), and indeterminate ichnotaxa. Associated with the footprints are numerous invertebrate traces such as Scoyenia gracilis. The ichnofauna of the Irohalene Member supports a cosmopolitan distribution of pentadactyl but functionally tridactyl chirotheres (Parachirotherium) and grallatorids across the Ladinian-Carnian boundary. Similar assemblages are known from the Germanic Basin and from Eastern North America. Furthermore, it documents the occurrence of very large Eubrontes trackmakers in the early Carnian. The depositional environment of the lower part of the Irohalene Member is interpreted as wet red beds of a flood basin transitional to a distal braid plain.

An ichnofossil assemblage from the fluvial deposits of the Upper Pliocene–Pleistocene Pinjor Formation (Siwalik Group), northwestern Himalayas, India: Palaeoenvironmental implications

Continental (fluvial) strata of the Pinjor Formation (Siwalik Group), northwestern Himalayas, India, contain an invertebrate trace fossil assemblage containing Planolites beverleyensis, Palaeophycus isp., Scoyenia gracilis, Taenidium barretti and other undifferentiated traces. The traces are found in an \(\sim \)26 m thick interval of alternating pinkish red siltstone, which is intercalated with mudstone, and thickly-bedded buff and greenish coloured sandstone. These sediments are interpreted as the deposits of floodplains and channel-bars of fluvial environments and low-energy overbank floodplain deposits. The trace fossils studied here are the first well documented ichnofossil assemblage from the vast, late Cenozoic Siwalik depositional system. They are not only of palaeoenvironmental significance, but they add to the growing ichnofossil database in facies of fluvial origin and should be an impetus to further ichnological studies of the Siwalik Group.

Trace fossils on dinosaur bones reveal ecosystem dynamics along the coast of eastern North America during the latest Cretaceous.

Direct evidence of paleoecological processes is often rare when the fossil record is poor, as in the case of the Cretaceous of eastern North America. Here, I describe a femur and partial tibia shaft assignable to theropods from two Late Cretaceous sites in New Jersey. The former, identifiable as the femur of a large ornithomimosaur, bears several scores interpreted as shark feeding traces. The tibia shaft has punctures and flaked bone from the bites of mid-sized crocodyliforms, the first documented occurrence of crocodyliform traces on dinosaur bone from the Maastrichtian of the Atlantic Coastal Plain. The surface of the partial tibia is also littered with indentations interpreted as the traces of invertebrates, revealing a microcosm of biological interaction on the coastal seafloor of the Cretaceous Atlantic Ocean. Massive crocodyliforms, such as Deinosuchus rugosus and the slightly smaller Deltasuchus motherali, maintained the role of terrestrial vertebrate taphonomic process drivers in eastern North America during the Cretaceous. The report of crocodyliform bite marks on the ornithomimosaur tibia shaft in this manuscript reinforces the importance of the role of crocodyliforms in the modification of terrestrial vertebrate remains during the Cretaceous in North America. The preserved invertebrate traces add to the sparse record of the presence of barnacles and other marine invertebrates on dinosaur bone, and the evidence of shark feeding on the ornithomimosaur femur support the “bloat-and-float” model of terrestrial vertebrate fossil deposition in marine deposits from the Cretaceous of eastern North America.

Crocodylomorph, turtle and mammal tracks in dinosaur-dominated Middle–?Upper Jurassic and mid-Cretaceous ichnoassemblages of Morocco

We report tetrapod traces from two stratigraphic intervals in Morocco, and discuss their palaeoecological implications. In the first interval, crocodylomorph footprints assigned to Crocodylopodus meijidei are described from Middle–?Upper Jurassic continental fluvial red beds of the Isli Formation in the Imilchil region, Central High Atlas, Morocco. These traces are associated with a diverse dinosaur-dominated ichnofauna, including the footprints of theropods, ornithischians, sauropods and pterosaurs, together with numerous invertebrate traces. In the second interval, we report crocodylomorph swim traces assigned to Hatcherichnus isp., turtle trackways assigned to Emydhipus isp. and isolated mammal footprints in the mid-Cretaceous Midelt Formation, in the High Moulouya region, Morocco. These traces are, also, associated with a diverse dinosaur-dominated ichnofauna including theropods and ornithopods as well as pterosaurs and abundant invertebrate traces. Together with plant remains, conchostracans and fishes, findings indicate a diverse community populating a fluvial-brackish environment.

Trace Fossils from the Late Pleistocene Marginal Marine Deposits of Jeju Island, Korea: Implications for the Psilonichnus and Skolithos Ichnofacies

Moderately diverse, but very abundant trace fossils are found from the Late Pleistocene deposits of Jeju Island, Korea. Vertical I-, Y- and U-shaped domichnia of annelids or decapods are, over 2500, extremely abundant, 3D network domichnia of callianassids are, over 200, very abundant, and small sinuous trails of nematode repichnia are, over 50, abundant in number. Horizontal trails attributable to polychaete or worm-like animals are, less than 50, common, but horizontal spreiten burrows, fish traces and crab trackways are, less than 10, rare in occurrence. Of these trace fossils, Taenidium barretti, Undichna britannica and Undichna unisulca represent the first record from the Pleistocene in Asia. Psilonichnus upsilon is the second record in Asia. Crab trackways probably produced by underwater punting gait of sideway walking crabs may represent the first record in the world. In addition, diverse and very abundant footprints of more than 500 hominids, more than 200 birds and more than 1000 mammals are closely associated with these invertebrate trace fossils. Trace fossil assemblage integrated with sedimentary facies is interpreted to have been formed in the marginal marine foreshore to backshore environment corresponding to the Psilonichnus and Skolithos ichnofacies.

First report on swimming trace fossils of fish from the Upper Permian and Lower Triassic of the Dolomites (Italy)

In the Upper Permian continental to marginal-marine succession of the Southern Alps (Dolomites, north Italy), the ichnological record consists of diverse vertebrate footprints and non-diverse invertebrate trace fossils, mainly occurring in the “Bletterbach ichnoassociation” of the Val Gardena Sandstone Formation. After the Permian-Triassic Boundary event, vertebrate ichnoassociations are scarce until the Middle Triassic (Anisian), whereas the uppermost Permian–Lower Triassic Werfen Formation preserves a rich invertebrate trace-fossil record. To date, fish body and trace fossils ( Undichna ) are very rare in the pre- and post-extinction deposits of the Dolomites; only Undichna gosiutensis Gibert, 2001 was identified in the “Voltago Conglomerate” (Middle Anisian), whereas some unidentified fossil fish casts were found in the Permian Val Gardena Sandstone and some fish remains in the overlying Werfen Formation. Recently, for the first time, fish trails have been discovered in the Val Gardena Sandstone (Lopingian) and in the Werfen Formation (Campil member, Early Triassic, Smithian). Val Gardena Sandstone yielded Undichna cf. quina Trewin, 2000 and U. bina Anderson, 1976 and these represent the oldest fish trails found in the Southern Alps so far. Conversely, the specimens found in the Werfen Formation can be assigned to Undichna cf. britannica Higgs, 1988. They represent the oldest Mesozoic record of fish trace fossils in northern Italy and one of the few records of Undichna from marine environments. These trace fossils are consistent with the fossil association found in the two formations and reflect fish swimming activity in different environments: in very shallow, calm, brackish distal-floodplain to marginal-marine environments in the Late Permian, in association with abundant and diverse tetrapod tracks, and non-diverse invertebrate trace fossils, and in inter- to subtidal calm, shallow, marine environments in the Early Triassic, together with abundant, but not diverse invertebrate trace fossils.

Invertebrate ichnofossils and rhizoliths associated with rhizomorphs from the Marília Formation (Echaporã Member), Bauru Group, Upper Cretaceous, Brazil

The Marília Formation (Bauru Group, Upper Cretaceous, Brazil) has furnished a large array of vertebrate fossils. However, its ichnological and botanical contents are poorly explored to date. Here we report findings of invertebrate trace fossils (Beaconites isp., Skolithos isp., and Taenidium barretti), rhizoliths associated with rhizomorphs with preserved hyphae, and fossil roots from the Echaporã Member, Marília Formation, São Paulo State, Brazil. The association of trace fossils suggest they can be regarded to the Scoyenia Ichnofacies. The rhizoliths indicate that at least two types of herbaceous/arbustive plants inhabited the area, one of them living in the vadose zone and the other one with roots closer to the water table, under arid/semiarid conditions. Sedimentological analyses suggest the studied outcrop comprises fluvial deposits, with predominance of sand bars that underwent different and relatively long periods of subaerial exposure.

Vertebrate and Invertebrate Trace Fossils in the Late Pennsylvanian (Carboniferous) Fluvio-Lacustrine San Giorgio Basin (South-West Sardinia): Remarks on the Oldest Continental Ichnoassociation of Italy

ABSTRACTA new study of the ichnotaxonomy and palaeoecology of the Late Pennsylvanian San Giorgio Basin's trace fossils was carried out. The tetrapod tracks were attributed to Batrachichnus salamandroides and to indet. tracks with a possible small temnospondyl and/or lepospondyl affinity. The invertebrate trace fossils include locomotion traces (Diplichnites isp.), grazing traces (Cochlichnus anguineus), and feeding structures (Treptichnus bifurcus, Treptichnus isp.). The trace fossils were evaluated by means of ichnofacies, highlighting a transitional Scoyenia-Mermia ichnofacies, typical of Carboniferous freshwater settings. The trace fossil co-occurrence and taphonomy was utilized to give a new interpretation of the fossil-bearing lithofacies, which are dolomitic mudstones-fine sandstones expression of marginal lacustrine environments repeatedly subject to flooding (three different ichnoassociations highlight different bathymetry/emersion). This is the oldest continental ichnoassociation of Italy, and its moderately high diversity and complexity suggest further study of this important Carboniferous trace fossil locality.

Lithostratigraphy of the Pietermaritzburg Formation (Ecca Group, Karoo Supergroup), South Africa

Abstract The Lower Permian Pietermaritzburg Formation is a mudrock-dominated, upward-coarsening stratigraphic unit in the lower Ecca Group (Karoo Supergroup) in the northeastern part of the main Karoo Basin of South Africa. The formation extends over most of the KwaZulu-Natal Province, and due to its lithology and the local climate, it is usually poorly exposed; hence the description is mainly based on borehole records. From a measured thickness of about 430 m south of the type area around Pietermaritzburg, the formation thins progressively northwards and pinches out against the Dwyka Group and pre-Karoo basement north of latitude 26° 30' S. This Lower Permian formation is considered a stratigraphic equivalent of the Prince Albert Formation in the southern part of the main Karoo Basin. The Pietermaritzburg Formation only preserves scattered, fragmentary plant fossil and invertebrate trace fossils, which are diagnostic of marine conditions (e.g. Helminthopsis). Based on its sedimentary facies characteristics and ichnofossil assemblages, the unit was probably deposited under low energy conditions on a northerly shallowing marine shelf that initially experienced deepening (during a major Artinskian transgression) and then shallowing in the early Kungurian.

Invertebrate trace fossils from the Pennsylvanian Rhode Island Formation of Massachusetts, USA

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.

The invertebrate trace fossil Labyrintichnus in the Late Triassic red beds of the Argana Basin (Western High Atlas Mountains, Morocco)

Labyrintichnus terrerensis Uchman and Álvaro, 2000, a cylindrical, intrastratal, passively filled trace fossil composed of irregular nets and branched galleries, so far known from Miocene marginal lacustrine clastic sediments, was found in Carnian alluvial-plain sediments of the Argana Basin, Morocco. This is the oldest occurrence of this rarely reported trace fossil. Associated tetrapod footprints and invertebrate trace fossils (Diplopodichnus, Scoyenia, Spongeliomorpha, Taenidium, cf. Helminthoidichnites, and others) point to the Scoyenia ichnofacies typical of inundated and desiccating sediments. Co-occurring current-ripples, mudcracks and raindrop imprints confirm this interpretation. The trace fossils reflect changing consistency from softground (cf. Helminthoidichnites; Diplopodichnus) to firm ground (e.g., Spongeliomorpha). Beside beetles and their larvae, fly larvae are considered as possible tracemakers of shallow Labyrintichnus terrerensis on the basis of similarities to recent burrows.

SHORT-TERM EVOLUTION OF PRIMARY SEDIMENTARY SURFACE TEXTURES (MICROBIAL, ABIOTIC, ICHNOLOGICAL) ON A DRY STREAM BED: MODERN OBSERVATIONS AND ANCIENT IMPLICATIONS

A wide variety of sub-ripple-scale sedimentary surface textures are known from bedding planes in the sedimentary rock record. Many of these textures were traditionally ascribed an abiotic origin (e.g., due to rain drop impact, adhesion, etc.), but in recent decades the role of microbial mats and biofilms in sculpting and mediating some forms has become increasingly recognized. Microbial sedimentary textures are now well-described and understood from modern tidal environments and biological soil crusts, but descriptions from fluvial settings are less common, despite their known occurrence in ancient alluvium. This paper reports a suite of primary sedimentary surface textures which were observed forming in discrete bodies of standing water in the lower reaches of the ephemeral Murchison River, Western Australia. Microbial sedimentary signatures included bubble impressions (burst and intact) and roll-ups, in addition to reduced horizons. Many of these features exhibited rapid temporal evolution of their morphology in the dry days following an interval of heavy rain. Significantly, these microbial features were witnessed in close spatial proximity to other abiotic and biotic sedimentary surface textures including raindrop impressions, adhesion marks, desiccation cracks, and vertebrate and invertebrate traces. Such proximity of abiotic and microbial sedimentary surface textures is rarely reported from bedding planes in the rock record, but these modern observations emphasize the fact that, particularly in non-marine environments, such structures should not be expected to be mutually exclusive. An appreciation of the fact that primary sedimentary surface textures such as these develop during intervals of stasis in a sedimentation system is crucial to our understanding of their significance and diversity in the rock record.

Middle to late Cambrian shallow marine trace fossils from the Imfout Syncline (Western Meseta, Morocco): Palaeoecological and palaeoenvironmental significance in NW-Gondwana

The present research provides the first evidence of invertebrate activity assigned to the ichnogenus Selenichnites occurring together with moderately diverse ichnofossils from the middle to late Cambrian of the Moroccan Meseta. The invertebrate traces occur in sandstone strata of the El Hank Formation within the Imfout Syncline, in the northern part of the Rehamna Massif (Coastal Block, western Moroccan Meseta). Bedding surfaces from the top of the El Hank Formation near the Imfout Dam show diverse forms of current ripples and distincts crescentic ichnofossils in concave epirelief scattered on the surface. In this section, the traces provide evidence of the ethology of an organism inhabiting the relatively shallow waters of the area during this time. Selenichnites co-occurs with the ichnogenera Arenicolites, Diplocraterion, Lingulichnus, Monocraterion, Skolithos and unidentified burrows, and the ichnoassemblage is referred to the Skolithos ichnofacies.These traces can be referred to arthropods (e.g. polychaete worms and amphipod crustaceans), lingulid brachiopods, annelids and/or phoronids. The Imfout Selenichnites represents the first occurrence of this ichnogenus from the Cambrian of the Moroccan Meseta, and the second from the Cambrian deposits of Morocco. The potential tracemakers are still questionable, but were most likely xiphosurans, trilobites, euthycarcinoids or crustaceans. If so, the Imfout traces could be among the oldest pieces of evidence for the presence of horseshoe crabs during the Cambrian.The combination of sedimentological and ichnological data indicates that the El Hank Formation was deposited in a sublittoral soft ground environment next to a sandy shore. It was originally part of an early Palaeozoic shallow marine epicontinental platform in west-central Morocco. In addition to the equivalent Cambrian deposits from the Anti-Atlas, the El Hank Formation constituted a part of the northern Gondwana platform domain during the transgression coming from the Rheic Ocean onto the West African Craton margin.

New dinosaur track occurrences from the Upper Jurassic Salt Wash Member (Morrison Formation) of southeastern Utah: Implications for thyreophoran trackmaker distribution and diversity

Recent construction at the Moab Giants dinosaur museum property ~10miles (~16km) north of Moab, in Grand County, Utah in 2014–2015 revealed a number of moderately well preserved dinosaur tracks from the Upper Jurassic, Salt Wash Member of the Morrison Formation. The best specimens were preserved as natural casts on the underside of massive sandstone beds, many containing dense assemblages of invertebrate traces. Here we describe several tridactyl theropod tracks, an ornithischian manus attributable to ichnogenus Stegopodus and an ornithischian pes track attributed to ichnogenus Deltapodus. Variably preserved Deltapodus have now been reported from the Tidwell, Salt Wash and Brushy Basin members of the Morrison Formation from Garfield, Grand and San Juan counties respectively, suggesting a wide distribution in space and time. The Salt Wash specimen is considered to be the most representative of Deltapodus morphologies reported from large samples in other regions, notably in Spain, Portugal western China and North Africa. Differences between Stegopodus and Deltapodus are reviewed. Deltapodus is reported from Europe and Asia as well as North America, in the Middle Jurassic through Late Cretaceous, and is often represented by abundant trackways. Stegopodus is presently reported from the Jurassic where it occurs in the Late Jurassic of North America as isolated tracks, and, with some debate, as trackways and isolated tracks from Europe. A middle Jurassic occurrence from Morocco is also reported.