Swimming Traces Research Articles

New fossil sea turtle trackway morphotypes from the Pleistocene of South Africa highlight role of ichnology in turtle paleobiology

AbstractMore than 130 late Pleistocene trackway sites from the coastal eolianites and beach deposits of the Cape south coast, South Africa, have previously mostly yielded tracks of large mammals and birds. However, two sites east of Still Bay, and a third near Garden Route National Park, yield distinctive trackways of hatchling sea turtles, made during the short posthatching (postemergence) interval when the trackmakers headed for the sea. One assemblage of approximately parallel trackways indicates smaller loggerhead turtle hatchlings, with alternating gaits, and contrasts with a wider trackway indicating a leatherback turtle hatchling. These are the world's first reports of fossil traces that document this brief “run-for the-sea” phenomenon. They help delineate late Pleistocene sea turtle breeding ranges and indicate climatic conditions along the Cape south coast. Ichnotaxonomically defined swim tracks of large adult sea turtles are known from a few Mesozoic sites. Likewise, walking and swim traces of terrestrial freshwater turtles are also known from the Mesozoic and Cenozoic. However, as no ichnotaxonomy exists for these diagnostic hatchling trails, we assign the trackways of the inferred loggerheads to the new ichnotaxonAustralochelichnus agulhasiiichnogen. et ichnosp. nov., and the inferred leatherback trackway toMarinerichnus latusichnogen. et ichnosp. nov.

New discoveries of vertebrate remains from the Triassic of Riba de Santiuste, Guadalajara (Spain)

The palaeontological sites of Riba de Santiuste and Sienes (Riba de Santiuste area) are located in the province of Guadalajara, Spain. They include a stratigraphic interval in Muschelkalk facies belonging to the “Cuesta del Castillo Sandstones” Formation and “Royuela Dolostones, Marls and Mudstones” Formation. These sites include numerous fossil plants, direct vertebrate remains, and vertebrate swim traces. The vertebrate remains correspond to a multitude of anatomical elements of Sauropterygia (Nothosauroidea, Placodontia) and possible Archosauria (Rauisuchia) remains. The fossil material attributed to nothosaurs includes teeth, coracoids, a thoracic vertebra, some isolated vertebral centra, humerus, rib fragments, and some dorsal and caudal vertebrae. The remains attributed to placodonts correspond to fragments of skull, quadrate, teeth and osteoderms. Other undetermined sauropterygian remains, such as ulnas, fragments of long bones, fragments of ribs, and articular facets of ribs have been also recovered. Additionally, a fragment of mandible and an intervertebral disk of indeterminate reptiles whose size could be compatible with archosaurs are also described. These bones are exceptionally well-preserved because the fossilization processes have preserved the microstructure of the tissues. The sites also show vertebrate traces, with parallel scratch impressions interpreted as swim traces. The relative stratigraphic position and the palaeontological content of these sites suggest a Ladinian age (Middle Triassic). The interpretation of the sedimentary facies here described also suggests that the sites could correspond to detrital-carbonate mixed deposits of coastal intertidal to supratidal environments.

The fish swimming trace Undichna unisulca from the Silurian of Sweden: probably the oldest vertebrate locomotion trace fossil

The fish swimming trace <i>Undichna unisulca</i> from the Silurian of Sweden: probably the oldest vertebrate locomotion trace fossil

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.

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.

A diverse trackway-dominated marine ichnoassemblage from the Lower Triassic in the northern Paleotethys: Ichnology and implications for biotic recovery

We document a diverse ichnoassemblage from marine interbeds of the Lower Triassic terrestrial succession in the Houzhougongmiao (HZGM) section of Shaanxi Province, northwestern China. Integrated biostratigraphic data (bivalve, palynology and conchostracan) reveals that the ichnofossil-bearing marine beds are Griesbachian (Induan, Early Triassic) in age. The marine interbeds are interpreted to be the result of the earliest Triassic transgression of the Paleotethys Ocean northward onto the southern margin of the North China Craton. The HZGM ichnoassemblage includes 17 ichnospecies in 16 ichnogenera and is dominated by shallow-tier Asteriacites and Biformites produced by ophiuroids, the scratch marks or trackways Dimorphichnus, Diplichnites, and Monomorphichnus produced by arthropods, and a rare occurrence of the fish swimming trace Undichna. Of these, the hook-shaped imprints Biformites, representing the moving arm impressions of ophiuroids, are reported for the first time from the Lower Triassic. These trace-makers are interpreted to have lived in a low energy, semi-restricted, shallow embayment environment. Although possessing relatively high ichnodiversity, the HZGM ichnoassemblage differs clearly from other coeval diverse ichnocoenoses in the lack of complex burrow forms (i.e. Thalassinoides, Diplocraterion, or Rhizocorallium) and a mixed layer, and in having abundant shallow tiers. In addition, high ichnodiversity may occur at both high and low latitudes during the Griesbachian (or Induan). Accordingly, the resting trace or trackway-dominated ichnoassemblage from the HZGM section may represent the initial recovery of the trace-maker ecosystem after the Permian-Triassic mass extinction. Trace-makers such as arthropods and ophiuroids were perhaps opportunistic organisms that proliferated in marginal marine settings when other biota were still suffering post-extinction biotic depletion and environmental stresses.

Diverse Middle Triassic Tetrapod Footprint Assemblage from the Muschelkalk of Germany

ABSTRACTWe describe a Middle Triassic tetrapod footprint assemblage from the Muschelkalk along the margin of the Germanic Basin. Twelve excavated footprint levels yielded the ichnogenera Synaptichnium, Isochirotherium, Chirotherium, Atreipus-Grallator, Rotodactylus, Gwyneddichnium, Rhynchosauroides, Procolophonichnium, therapsid footprints similar to Dicynodontipus, an undetermined chirotheriid with exceptionally large manus imprints and tetrapod swim traces. Track makers of the Muschelkalk assemblages were archosauromorphs and crown-group archosaurs and synapsids. The absence of mudcracks and the high diversity of tetrapods suggest a paleoenvironment with long-term availability of water and food resources.

Effects of Aluminium on Long-Term Memory in Rats and on SIRT1 Mediating the Transcription of CREB-Dependent Gene in Hippocampus.

Epidemiological investigations have shown that aluminium (Al) is an important neurotoxicant which can be absorbed by organisms via various routes. Previous studies have confirmed that exposure to Al could cause neurodegenerative diseases, decline CREB phosphorylation and then down-regulate the transcription and protein expression of its target genes including BDNF. However, recent studies revealed that CREB activation alone was far from enough to activate the expression of long-term memory (LTM)-related genes; there might be other regulatory factors involved in this process. Several studies showed that TORC1 might be involved in regulating the transcription of downstream target genes as well. Also, TORC1 could be mediated by SIRT1 during the formation of LTM. However, the role of CREB regulating system in Al-induced LTM impairment was still not utterly elucidated till now. This study was designed to establish the rat model of subchronic Al exposure to observe the neuroethology, regulatory factor levels and molecularbiologicalalterations in hippocampal cells. The results showed that, with the increasing AlCl3 dose, blood Al content increased gradually; morphology of the hippocampus and neuronal ultrastructure were aberrant; in the Morris water maze test, the escape latency and distance travelled became longer, swimming traces turned more complicated in the place navigation test; intracellular Ca2+ , cAMP levels declined significantly in AlCl3 -treated rats, followed by abated nuclear translocation of TORC1 and decreased SIRT1, TORC1 and pCREB levels. These results indicate that SIRT1 and TORC1 might play an important mediating role in Al-induced LTM impairment.

An archosauromorph dominated ichnoassemblage in fluvial settings from the late Early Triassic of the Catalan Pyrenees (NE Iberian Peninsula).

The vertebrate recovery after the end-Permian mass extinction can be approached through the ichnological record, which is much more abundant than body fossils. The late Olenekian (Early Triassic) tetrapod ichnoassemblage of the Catalan Pyrenean Basin is the most complete and diverse of this age from Western Tethys. This extensional basin, composed of several depocenters, was formed in the latest phases of the Variscan orogeny (Pangea breakup) and was infilled by braided and meandering fluvial systems of the red-beds Buntsandstein facies. Abundant and diverse tetrapod ichnites are recorded in these facies, including Prorotodactylus mesaxonichnus isp. nov. (tracks possibly produced by euparkeriids), cf. Rotodactylus, at least two large chirotheriid morphotypes (archosauriform trackmakers), Rhynchosauroides cf. schochardti, two other undetermined Rhynchosauroides forms, an undetermined Morphotype A (archosauromorph trackmakers) and two types of Characichnos isp. (swimming traces, here associated to archosauromorph trackmakers). The Pyrenean ichnoassemblage suggests a relatively homogeneous ichnofaunal composition through the late Early Triassic of Central Pangea, characterized by the presence of Prorotodactylus and Rotodactylus. Small archosauromorph tracks dominate and present a wide distribution through the different fluviatile facies of the Triassic Pyrenean Basin, with large archosaurian footprints being present in a lesser degree. Archosauromorphs radiated and diversified through the Triassic vertebrate recovery, which ultimately lead to the archosaur and dinosaur dominance of the Mesozoic.

Traces of Floating Archosaurs: An Interpretation of the Enigmatic Trace Fossils from the Triassic of the Tabular Cover of Southern Spain

abstractTwenty-six enigmatic footprints composed of three elongated parallel depressions (two lateral ones and a shorter central one located forward with respect to the others) are described from Middle Triassic red beds of the Tabular Cover in southern Spain. The purpose of this work is the interpretation of these enigmatic tracks. The footprints range from 28 to 48 cm in length and 23 to 44 cm in width. Limestones on top of the footprint-bearing sandstone contain invertebrate traces such as Planolites, Thalassinoides, and Rhizocorallium, and bivalves (Pleuromya, Trigonodus, and Unionites), typical of marine and brackish environments. They indicate that these footprints developed in a coastal or nearly coastal environment. Whereas the enigmatic trace fossils correspond to tridactyl footprints, the digital marks are parallel and do not show any divarication as in typical walking footprints of archosauria. These traces were left when the trackmaker was swimming in a waterbody deep enough for floating only occasionally touching the ground with the digit tips. The tracks formed as a result of the backward sweeping of the tips when the digits came in contact with the bottom while the animal was buoyed by water. They differ from typical swim traces of other archosaurs (such as theropods) that show three longitudinal scratches because in studied tracks the axial digit (III) of the bipedal tridactyl archosaur sinks in the sediment and gives a short and deep scratch. The other digit scratches (from digits II and IV) would correspond to the upper surface of the toes. The studied tracks correspond to Characichnos ichnofacies (swimming tracks composed by parallel scratch marks) and they were made by a bipedal tridactil archosaur or some functionally tridactyl, chirothere tracemaker.

Palaeoenvironmental reconstruction and early Permian ichnoassemblage from the NE Iberian Peninsula (Pyrenean Basin)

AbstractRecent finds of tetrapod ichnites in the red-bed and volcaniclastic succession of the Iberian Pyrenean Basin permits an assessment of the faunal diversity and palaeoenvironment of a late early Permian setting. The tetrapod ichnoassemblage is inferred with the aid of photogrammetry and constituted byBatrachichnus salamandroides,Limnopusisp., cf.Amphisauropus(these three ichnotaxa present associated swimming traces, assigned toCharacichnos), cf.Ichniotherium,Dromopusisp., cf.Varanopus,Hyloidichnusisp. andDimetropus leisnerianus. These ichnotaxa suggest the presence of temnospondyls, seymouriamorphs, diadectomorphs, araeoscelids, captorhinids and synapsid pelycosaurs as potential trackmakers. These faunas correlate to the late early Permian. Two ichnoassociations correspond to two different palaeoenvironments that were permanently or occasionally aquatic (meandering fluvial systems and unconfined runoff surfaces, respectively). Ichnotaxa in the fluvial system is more diverse and abundant than in the runoff surfaces system. The Iberian Pyrenean ichnoassemblage reveals the faunistic connection and similarities among nearing basins (Spain, southern France and Morocco) differing from the Central European basins (i.e. German Tambach Formation). Based on the palaeogeography and the climate models of the early Permian, we suggest the correlation of ichnofaunal composition with different palaeoclimate biomes. This results in a diffuse boundary of Gondwana–Laurasia land masses, indicating no geographic barriers but a possible climate control on the faunal distribution. Further studies, integrating data from distant tracksites, should refine these biome boundaries.

A tetrapod footprint assemblage with possible swim traces from the Jurassic–Cretaceous boundary, Anning Formation, Konglongshan, Yunnan, China

A small tetrapod footprint assemblage from the Anning Formation (Upper Jurassic–Lower Cretaceous) at Konglongshan Town, Yunnan Province, China, contains possible swim traces attributable to theropod dinosaurs based on their tridactyl and mesaxonic pes morphology. Morphotypes are tentatively assigned to the ichnogenera Characichnos and Wintonopus, a third one is similar to Hatcherichnus. Due to the inherent variability observed in tetrapod swim tracks, the names are used here informally describing footprints that reflect a distinct trackmaker behavior rather than anatomically accurate images of the pes anatomy. Variation of the imprint shape is obviously due to extramorphological effects and does not indicate taxonomic diversity of trackmakers. Elongate, slender impressions associated with these tracks are discussed here as possible tail traces. Trackmakers were possibly buoyant and active swimming individuals touching and scratching the bottom of deeper waterbodies with the distal ends of their digits. The orientation of the traces perpendicular to preserved ripples suggest cross-current movement and activities.

Real-Time Analysis of Chemotactic Motion of &lt;i&gt;Euglena&lt;/i&gt; Cells Confined in a Microchip Toxicity Sensor

We developed the real-time analysis of chemotactic motion of microbial cells (Euglena gracilis), for on-chip cytotoxicity sensing for environmental chemical substances. TheEuglenacells were confined in a closed-type micro-aquarium in a PDMS microchip, and their movements were taken by a CMOS video camera. When 1.5%-H2O2was introduced into a microchannel running aside of the micro-aquarium, the H2O2molecules permeated into the micro-aquarium by diffusion through porous PDMS wall, and the cells fell into continuous rotation instead of single step turning and/or straightforward swimming. Such an abnormal swimming behavior is the result of metabolic disturbing effects evoked by radical oxygen species released from H2O2. In order to sensing the metabolic disturbing effects, we achieved real-time categorization of the swimming traces into straightforward swimming or continuous rotation; firstly the swimming traces in the video image were sectioned into squares, and then the aspect ratio and filling factor for each square were calculated. High aspect ratio or small filling factor corresponded to straightforward swimming, whereas low aspect ratio and high filling factor to continuous rotation. This motion analysis enables to measure the metabolic disturbing effects on swimmingEuglenacells quantitatively, which is important to detect unidentified toxic substances in environments.

Application of vertebrate trace fossils to palaeoenvironmental analysis

This is a review of the main uses of vertebrate trace fossils, ichnofabrics and ichnofacies in the palaeoenvironmental analysis of sedimentary sequences. The article accounts for the significant developments produced in the last three decades, including the application of the ichnofacies concept to vertebrate trace fossils. Recognition of footprints in cross-sectional view and their distinction from inorganic structures and burrow fills, is first discussed. The response of different substrates, showing contrasting water content and imprinted by different animals or devices, is compared in terms of the morphology of the resultant footprint. Trackways with sand crescents are typical of aeolian cross-strata and are absent in associated flat-lying to low-angle deposits. Thick packages of highly bioturbated sandy dune and interdune sediments have been interpreted as reflecting periods of increased rainfall. Neoichnological observations in modern lake basins suggest that distinct zones can be recognized in the margins of fossil ponds and lakes, including onshore, shoreline and shallow subaqueous zones. Abundant flamingo-like footprints and flamingo nest mounds are good indicators of alkaline and/or saline lake waters. Hippopotamus trails are found closely associated with modern and fossil freshwater wetlands. Dinosaur and pterosaur swim traces from lacustrine and fluvial deposits can be used to estimate water depth. Turtle, crocodile, amphibian, hippopotamus and fish swim traces allow one to infer a subaqueous substrate. Certain modern intertidal fish feeding traces are oriented with the predominant tidal current and can be used as palaeocurrent indicators. The preferential orientation of tetrapod trackways in lacustrine and fluvial deposits is analyzed. Vertebrate trace fossils can help to infer discharge variability in fluvial channels. The descriptions of vertebrate ichnofabrics are commonly limited to heavily bioturbated beds due to trampling by vertebrates, and to a few examples of ichnofabrics with discrete trace fossils. The nature and implications of the recognized vertebrate ichnofacies are still being debated and have a limited utility in palaeoenvironmental analysis. The distinction of a potential vertebrate burrow ichnofacies in carbonate-bearing palaeosols is proposed to represent well-drained soils, developed under arid or semiarid climate.

Ichnology and Depositional Environment of the Cambrian Nagaur Sandstone (Nagaur Group) Along the Dulmera Section, Bikaner-Nagaur Basin, Rajasthan

The Lower Cambrian Nagaur Sandstone (Marwar Supergroup) has yielded trace fossils Treptichnus, Cruziana, serially repeated Rusophycus, Diplichnites, Monomorphichnus, Bergaueria, arthropod swimming traces and leap frogging marks of Cruziana ichnofacies. This ichnofossils assemblage is dominantly preserved in fine to medium grained red sandstone beds of the Mohra Member (Nagaur Sandstone). The presence of graded rip-up clasts, current ripples, dune cross-stratification with mud drapes and tidal bundles indicates a subtidal paleoenvironment for the deposition of Nagaur Sandstone Formation, which is corroborated by the Cruziana ichnofacies trace fossil assemblage.

Crocodile swim tracks from the latest Cretaceous of Europe

Recently discovered evidence of tracks in the continental beds of the Late Cretaceous Tremp Formation in the southern Pyrenees (NE Iberian Peninsula) has been identified as scratch marks made by buoyant crocodiles. The tracks are preserved in two distinct environments and substrates (marly limestones originating in a littoral mud flat and fine-grained sandstones deposited in fluvial settings). Most of the crocodylian traces are ascribed to ichnogenus Characichnos, whereas a single plantigrade pes track is assigned to ichnogenus cf. Crocodylopodus. The crocodylian swim traces (Characichnos ichnofacies) found in the early and late Maastrichtian co-occur with Brontopodus ichnofacies attributable to terrestrial tetrapods (titanosaur sauropods, cf. Brontopodus ichnogenus; and hadrosaurid ornithopods, Hadrosauropodus ichnogenus). Analysis of the tracks allows the interpretation of palaeoenvironmental settings and track production. Thus, in lagoonal environments, swim tracks of crocodylians were produced during the rise of the water level in successive tide cycles; in fluvial settings, the swim traces of crocodylians were produced within the channel at the low-water stage. To date, there are no reports of Late Cretaceous crocodylian tracks in Europe, and the studied evidence represents the first and youngest track record of the group in the latest part of the Cretaceous (C29r) in this continent and probably in the world.

3A1-K04 電場による原生生物の行動制御に関する研究 : 垂直面方向に対するゾウリムシの行動制御特性について(バイオミメティクス・バイオメカトロニクス)

We have been investigating how to use microorganisms for bio-micromachines. We succeeded to rotate φ0.5mm micro impeller by motion controlled Paramecium. The paramecium was controlled by the weak electrical field by applying their negative galvano-taxis. We also succeeded to attach an operation tool on a Paramecium and the tool installed Paramecium could transport an object more efficiently. In our previous paper, we improved Paramecium's motion control accuracy by using large distance electrode pool. The average control deviation was within 0.15mm. In this paper, we investigated the motion control property of Paramecium in the vertical plane to prepare the real 3 dimensional motion control. First, we developed a motion control pool for the vertical set up. Basically the controllability of Paramecium in the vertical plane is not so different to the controllability in the horizontal plane. We can control paramecium very stably for over 100 laps along the star-shaped target route by using this newly made experimental pool. The controllability was improved with the progression of making a circuit. It may relate to the dropping of the swimming speed. The swimming trace showed the peculiarity that related to the vertical movements. The swimming speed of the downward direction is higher than that of the upward direction. We tried to adjust the motion control algorism to decrease the average control deviation by using the features of the trace shape.

Reevaluation of the Lark Quarry dinosaur Tracksite (late Albian–Cenomanian Winton Formation, central-western Queensland, Australia): no longer a stampede?

ABSTRACT The Lark Quarry dinosaur tracksite has previously been recognized as recording the stampede of a mixed herd of dozens of small theropod and ornithopod dinosaurs. A reexamination of trackway material reveals that the small theropod-type tracks, previously assigned to the ichnotaxon Skartopus, can co-occur within individual trackways of the ornithopod-type tracks assigned to Wintonopus. Moreover, in singular deep tracks where the overall surface outline resembles Skartopus, the base of the track can also resemble Wintonopus. Whereas the Wintonopus holotype may reflect the pedal anatomy of a short-toed or subunguligrade ornithopod trackmaker, the elongate ‘toe’ impressions typically associated with Skartopus (including the holotype) primarily provide information on digit movement through the sediment and, in many instances, may represent swim traces. The morphological differences between the two ichnotaxa are therefore not taxonomically significant and we formally propose that Skartopus australis should be considered a junior synonym of Wintonopus latomorum. Longitudinal depth profiles through tracks indicate that many are swim traces. The sedimentology and lithology of Lark Quarry further indicates the site represents a time-averaged assemblage formed in a fluvial-dominated floodplain under variable subaqueous conditions, with the parallel orientation of the numerous trackways formed by trackmakers under the influence of downstream current flow. This indicates that the fluvial environment may have been a preferred route for hydrophilic bipedal dinosaurs. We thus do not consider the Lark Quarry dinosaur tracksite to represent a ‘stampede.’ Instead, the tracksite may represent part of a riverine setting, where the water was shallow, in which small dinosaurs swam and/or waded. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

First record of Lower Triassic Undichna spp. fish swimming traces from Emei, Sichuan Province, China

We discuss traces from the ichnospecies Undichna unisulca recorded from the Triassic that are reported for the first time in this paper. These fossils are also some of the oldest vertebrate ichnites discovered in China to date. The fish swimming traces (Undichna unisulca) described originate from the Lower Triassic. These traces were found in the Jialingjiang Formation and are located at a gorge ∼7.5 km from Emei, Sichuan Province, China. The ichnospecies Undichna unisulca consists of a regular sinusoidal wave. The wavelengths and amplitudes are quite constant between each specimen ranging between 28–32 mm and 9–12 mm, respectively. The fish swimming traces and distribution within the same bed are preserved as hypichnial ridges at the undersurface.

The Fish Swimming Trace Undichna from the Mississippian Mauch Chunk Formation, Eastern Pennsylvania

Undichna, the swimming trace of fish, was recovered from the middle member of the Mauch Chunk Formation in eastern Pennsylvania in strata of Late Mississippian (Visean) age. These traces represent the only evidence of fish known from the Mauch Chunk Formation and the Carboniferous of Eastern Pennsylvania. The Mauch Chunk Formation in the study area is characterized by an ephemeral fluvial depositional environment that yields a diverse invertebrate ichnoassemblage of the Scoyenia ichnofacies and a tetrapod footprint assemblage dominated by the tracks of temnospondyl amphibians. The Undichna specimens are preserved on fine-grained, mudstone-draped, rippled sandstone. Two specimens, assigned to U. Britannica, consist of pairs of well-defined, narrowly incised, sinusoidal wave traces that are out-of-phase. Two specimens, assigned to U. quina, consist of two pairs of in-phase sinusoidal waves intersected by an additional single wave with a greater amplitude. Two specimens, each composed of a single wave, are assigned to U. unisulca. The slabs of rock with the Undichna traces also preserve tetrapod undertracks assigned to Batrachichnus, Matthewichnus, and Hylopus. This trace fossil association indicates the presence of small fish, some with caudal and/or anal fins and some with pectoral, pelvic, and anal and/or caudal fins, that touched the sediment during periods of intermittent flooding of subaerial surfaces walked upon by early tetrapods. Examples of Undichna from Mississippian or older deposits, especially from a fluvial paleoenvironment, are rare; few have been reported from the Devonian and the Lower Carboniferous.