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All post- Cambrian ichnospecies of Psammichnites Torell, 1870 belong to Olivellites Fenton and Fenton, 1937a

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Abstract

The ichnogenus Psammichnites herein restricted to Psammichnites gigas is based on comparison of morphology, feeding behaviour, contrast between the burrows and the host rock, and possible producers. The record of siphonal activity as a “snorkel device” is discussed. The diagnosis of the ichnogenus Olivellites now is amended and includes all the records of Psammichnites in the post-Cambrian. Olivellites is now documented in successions other than the classical tidal flat deposits facies of the Carboniferous of the USA. We propose that the producer of Olivellites was an animal with capacity for displacement to different shallow infaunal levels for different feeding strategies. An interpretation of detritus feeding behavior with sediment displacement (pasichnia) is favoured here. The producer of Olivellites was likely to have been a bivalved mollusc that evolved after the Late Ordovician mass extinction. It was euryhaline and lived in a broad bathymetric range, and is recorded in temperate to glacially related successions. The material of Olivellites implexus from western Argentina is the youngest record of the ichnogenus from Western Gondwana.

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... Mángano et al., 2003;Gaillard and Racheboeuf, 2006;Seilacher, 2007;Sarkar et al., 2009;Bradshaw, 2010 Davies and Shillito, 2018;Shillito and Davies, 2020;Muszer, 2020;Morelle and Denayer, 2020;Bosetti et al., 2021). Recently, Pazos and Gutiérrez (2021) proposed to resurrect Olivellites for all post-Cambrian ichnospecies of Psammichnites, based on specimens from the Carboniferous El Imperial Formation of western Argentina. However, analysis of the types and of additional material of Carboniferous ichnospecies from Gondwana and Laurentia suggests that the overall trace-fossil morphology and infill (i.e. ...
... Other characteristics (e. g. tendency to scribble, cross-section morphology, type of active fill) are used as ichnotaxobases at ichnospecies level, promoting the use of a hierarchical approach in ichnotaxonomy (Bertling et al., 2006;Buatois and Mángano, 2011;Rindsberg, 2018). The absence of a clear internal structure in the type of Psammichnites gigas, as mentioned by Pazos and Gutiérrez (2021), was already explained by Mángano et al. (2002a) as a taphonomic effect of its preservation in quartzite. Moreover, backfill has been confirmed in weathered specimens from the Hardeberga Sandstone (Rohde, 2009) and in other specimens of this ichnospecies elsewhere, clearly indicating a taphonomic control (see above). ...
... In spite of these similarities, the more diverse (i.e. pretzel-like, circling, spiral), predominantly self-overcrossing tracefossil courses, pad-like backfill, and apparent lack of any indication of an axial structure in Parapsammichnites pretzeliformis distinguish it from Psammichnites gigas and other ichnospecies of Psammichnites (contra Pazos and Gutiérrez, 2021). ...
Article
Taphrhelminthopsis was originally introduced for trace fossils with a bilobate lower surface recorded in post-Paleozoic deep-marine deposits but has more recently been reinterpreted convincingly as a preservational variant of Scolicia. However, Taphrhelminthopsis has also been used for Cambrian shallow-marine trace fossils, whose taxonomic affinity remains elusive. This practice was introduced with the erection of Taphrhelminthopsis circularis Crimes et al., 1977, based on specimens from lower Cambrian strata of Asturias, Spain, that have a bilobate morphology with a median furrow and a tendency to form a roughly circular course. Taphrhelminthopsis circularis subsequently has been recorded in many lower Cambrian successions worldwide. No information on toponomy was provided in the original description, which has complicated the reevaluation of this ichnotaxon. Reanalysis of the type specimen and study of additional material at the type locality demonstrate that Taphrhelminthopsis circularis occurs on the tops of sandstone layers, with a convex-upward bilobate structure, representing a preservational and behavioral variant of Psammichnites, in agreement with earlier tentative proposals. The presence in some material of a sinuous axial furrow, which is regarded as diagnostic of Psammichnites gigas, argues for synonymization of Taphrhelminthopsis circularis with that ichnospecies. However, to underscore potentially significant preservational and behavioral variability, we refer to this form as Psammichnites gigas circularis. We also discuss the relationships between Psammichnites and other trace fossils commonly recorded from Cambrian shallow-marine strata under a wide variety of names, including Archaeonassa fossulata, Arcuatichnus wimani, Helminthoida crassa, Helminthoida miocenica, Multilaqueichnus ganluonensis, Multilaqueichnus meishucunensis, Nereites saltensis, Parapsammichnites pretzeliformis, Plagiogmus arcuatus, Sellaulichnus meishucunensis, Taphrhelminthoida dailyi, Taphrhelminthopsis nelsoni, and Taphrhelminthopsis minimus. We recommend reassigning Plagiogmus arcuatus to Psammichnites gigas arcuatus, acknowledging the distinctive “ladder-trail” ornament found on its lower surface but also its overall similarity to Psammichnites gigas, as recognized by previous workers. Additionally we recommend applying the designation Psammichnites gigas gigas to specimens of Psammichnites gigas characterized by high convexity, a straight to sinuous axial ridge or groove, and a straight, sinuous, or curved path, and lacking a “ladder-trail” ornament. Documenting the multiple preservational variants of Cambrian Psammichnites is important to estimate ichnodiversity levels accurately during the Cambrian explosion and to enhance the value of this ichnotaxon for stratigraphic correlation.
... P-83737, however, lacks the small transverse striations on the ribbons usually seen in Psammichnites, though this could be an artifact of preservation (taphonomy). Pazos and Gutiérrez (2023) recently reassigned post-Cambrian Psammichnites to Olivellites, and we follow that reassignment here. ...
... Olivellites is normally found in intertidal and shallow marine settings, was likely made by a mollusc, and most records are early Paleozoic, though Permian records are known (Mángano et al., 2002;Luo et al., 2017;Pazos and Gutiérrez, 2023). This is not only the first Abo record of Olivellites, but also a first record in nonmarine fluvial redbeds. ...
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A recently discovered tracksite in the Abo Formation in the Quebradas region of Socorro County is distinguished by unusually high ichnodiversity and exceptional preservation. This site, NMMNH (New Mexico Museum of Natural History) locality 12617, is north of Tinajas Arroyo in the Cañon de Espinoso Member of the Abo Formation, about 5 meters below the base of the overlying Yeso Group. The fossil-bearing stratum is a 0.7-1.5 m thick interval of thin-bedded, ripple-laminated, very fine sandstone with extensive mudcracks. At locality 12617, many surfaces with trace fossils have microbially induced sedimentary structures (MISS), and microbial mediation of preservation likely caused some of the exceptional ichnofossil preservation at this site. The invertebrate trace (ribbon trail) Olivellites (= Psammichnites) is reported here from the Abo Formation for the first time. Tetrapod ichnogenera from locality 12617 are Amphisauropus, Batrachichnus, Dromopus, Dimetropus, Limnopus and Varanopus. Plant specimens consist of the conifer Walchia, the peltasperm Supaia, and the callipterid Autunia conferta. Walchia and Supaia are typical of the Abo Formation throughout its extent; most Abo fossil plant sites are dominated by conifer remains of several types, but some fewer by Supaia. Mixed assemblages are uncommon. Autunia conferta, of the small-pinnule type, is common only in the upper Abo Formation (Cañon de Espinoso Member). The ichnofaunal composition at NMMNH locality 12617, which is dominated by anamniote, parareptile/eureptile and synapsid tracks, is very different from that of the Erpetopus biochron just above it. This is consistent with data from North America and Europe that identify a substantial change in the composition of footprint ichnoassemblages at the beginning of the Erpetopus biochron (close to the beginning of the Leonardian) due to the diversification of sauropsid reptiles, likely driven by climate changes (drying) across much of Pangea. Indeed, paleoenvironmental changes across the Abo-Yeso transition—regional marine transgression and a trend towards drier climates—are well reflected in the changes in trace fossil and floral composition during the early Leonardian.
... P-83737, however, lacks the small transverse striations on the ribbons usually seen in Psammichnites, though this could be an artifact of preservation (taphonomy). Pazos and Gutiérrez (2023) recently reassigned post-Cambrian Psammichnites to Olivellites, and we follow that reassignment here. ...
... Olivellites is normally found in intertidal and shallow marine settings, was likely made by a mollusc, and most records are early Paleozoic, though Permian records are known (Mángano et al., 2002;Luo et al., 2017;Pazos and Gutiérrez, 2023). This is not only the first Abo record of Olivellites, but also a first record in nonmarine fluvial redbeds. ...
Article
Full-text available
A recently discovered tracksite in the Abo Formation in the Quebradas region of Socorro County is distinguished by unusually high ichnodiversity and exceptional preservation. This site, NMMNH (New Mexico Museum of Natural History) locality 12617, is north of Tinajas Arroyo in the Cañon de Espinoso Member of the Abo Formation, about 5 meters below the base of the overlying Yeso Group. The fossil-bearing stratum is a 0.7-1.5 m thick interval of thin-bedded, ripple-laminated, very fine sandstone with extensive mudcracks. At locality 12617, many surfaces with trace fossils have microbially induced sedimentary structures (MISS), and microbial mediation of preservation likely caused some of the exceptional ichnofossil preservation at this site. The invertebrate trace (ribbon trail) Olivellites (= Psammichnites) is reported here from the Abo Formation for the first time. Tetrapod ichnogenera from locality 12617 are Amphisauropus, Batrachichnus, Dromopus, Dimetropus, Limnopus and Varanopus. Plant specimens consist of the conifer Walchia, the peltasperm Supaia, and the callipterid Autunia conferta. Walchia and Supaia are typical of the Abo Formation throughout its extent; most Abo fossil plant sites are dominated by conifer remains of several types, but some fewer by Supaia. Mixed assemblages are uncommon. Autunia conferta, of the small-pinnule type, is common only in the upper Abo Formation (Cañon de Espinoso Member). The ichnofaunal composition at NMMNH locality 12617, which is dominated by anamniote, parareptile/eureptile and synapsid tracks, is very different from that of the Erpetopus biochron just above it. This is consistent with data from North America and Europe that identify a substantial change in the composition of footprint ichnoassemblages at the beginning of the Erpetopus biochron (close to the beginning of the Leonardian) due to the diversification of sauropsid reptiles, likely driven by climate changes (drying) across much of Pangea. Indeed, paleoenvironmental changes across the Abo-Yeso transition—regional marine transgression and a trend towards drier climates—are well reflected in the changes in trace fossil and floral composition during the early Leonardian.
... The work of Curran and Glumac (2021) importantly identifies that the trace fossil Dactyloidites ottoi is present in the shallowest-marine facies in the Pleistocene of the Bahamas, making this an environment of critical importance for understanding sea-level change. The trace fossils Psammichnites and Olivellites are commonly recognized in shallow-marine deposits; a detailed morphological and palaeobiological review by Pazos and Gutiérrez (2022) has concluded that post-Cambrian examples are all Olivellites and probably result from the activity of a burrowing bivalve. ...
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The ichnology between the marine and non-marine environments is a key field of work concerning the understanding of the variation of environmental parameters from inland to the offshore transition. In order to understand the geological and palaeobiological processes, this special issue attempts to discuss records in shallow marine to transitional environments through the Phanerozoic, including topics such as ichnotaxonomy, ichnofacies analysis, ichnofabric analysis both for records from shallow marine and transitional environments, and neoichnological aspects. The volume includes fourteen papers in total, namely: one contribution is about aspects of neoichnology in rock iguana in coastal settings, nine papers treat various shallow marine paleoenvironments topics, while four contributions address issues about dinosaur tracks in transitional environments.
... The work of Curran and Glumac (2021) importantly identifies that the trace fossil Dactyloidites ottoi is present in the shallowest-marine facies in the Pleistocene of the Bahamas, making this an environment of critical importance for understanding sea-level change. The trace fossils Psammichnites and Olivellites are commonly recognized in shallow-marine deposits; a detailed morphological and palaeobiological review by Pazos and Gutiérrez (2022) has concluded that post-Cambrian examples are all Olivellites and probably result from the activity of a burrowing bivalve. ...
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The ichnology of shallow-marine to transitional environments is a key field of study with respect to understanding the variability of environmental parameters from inshore marginal-marine settings to the offshore transition zone. Over the last decades ichnology has evolved from being a tool to determine bathymetry, becoming the standard palaeoenvironmental methodology by which trace fossils can be used to inform sedimentary facies models. In particular, the analysis of mixed assemblages of invertebrate and vertebrate trace fossils allows detailed palaeoenvironmental and facies analysis. This volume focuses on the ichnological record of shallow-marine to transitional environments through the geological record, in addition to modern ones through neoichnology.
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The trace fossil record implies that large worm-like animals were in place along with the skeletonizing organisms during the initial stage of the Cambrian explosion. Body fossils of large worms, however, have so far not been found. Here, we describe a large, soft-bodied, worm-like organism, Vittatusivermis annularius gen. et sp. nov. from the lowest Cambrian of South China , which is constrained to the Fortunian Age (541-529 Ma) of the Cambrian Period. The elongate body of Vittatusivermis was large enough to have supported organ systems and a fluid skeleton that facilitated peristaltic locomotion, thus allowing for more complex patterns of movement than those of flatworms. Its occurrence on the same bedding surface as trace fossils suggests that Vittatusivermis might have produced epichnial trails and shallow burrows on and within sediments. Therefore, Vittatusivermis is likely to have been one of the long expected producers of trace fossils in the earliest Cambrian.
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An exceptional find of a chiton preserved at the end of its locomotion trace comes from the Culm facies, that is, from a succession of turbidity-controlled dark shales, greywackes and sandstones. The chiton trace is a smooth, rather indistinct, 7-8 mm wide bilobate ridge (convex epirelief), forming an incompletely preserved loop of estimated extent 50 x 80 mm. At its end is preserved a completely articulated chiton Proleptochiton sp., 4.0 mm wide and 11.5 mm long, oriented congruently with the trace. The neighbouring strata provide relatively common ichnofossils, including Chondrites isp., Planolites isp., Dictyodora liebeana (Geinitz) and Diplocraterion isp. The chiton’s trace fossil corresponds to ichnotaxa that have historically been compared to modern gastropod trails. The gastropods are well-known for two different monotaxic locomotion techniques, one for hard substrates such as glass, and another for soft substrates, where the animals move through muscular waves of much higher amplitude than observed on glass. Thereby, adhesion useable for movement on the hard surface is functionally replaced with friction. Loosening of the sediment by rapid movements of foot muscles is the cause of the structure’s convexity, that is, increasing volume. Similar behaviour is documented for the first time in chitons. The studied specimen is the first locomotion trace fossil attributed to polyplacophorans. The find documents the burrowing technique of chitons in deep-marine, turbidity-influenced soft substrate during the Viséan (330 Ma). It demonstrates the similarity of chiton and some gastropod traces in soft substrates, and adds to the lengthening list of animals that were fossilized within their traces.
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The pre-Carboniferous evolution of the San Rafael Block is described in different stages. The first one is referred to the Mesoproterozoic basement derived from a complex plutonic and volcanic protolith of Cerro La Ventana Formation. The signature of this basement indicates a common origin with the present eastern part of Laurentia. The carbonate platform of Cuyania terrane has been drifted away during Early Cambrian to Early Ordovician times. The Ordovician silico-carbonate sequences of the San Rafael Block are unconformably deposited over the basement near the present eastern slope of the Cuyania terrane. Detrital zircon ages show a provenance derived from Mesoproterozoic source. The El Nihuil dolerites with a tholeiitic ocean floor signature considered the southern end of the Famatinian ophiolites were interpreted as a Late Ordovician–Early Silurian extensional event. The collision of Cuyania produced a new west polarity subduction and a magmatic arc, represented by the Devonian Rodeo de la Bordalesa tonalite and the granitoids of the “Agua Escondida Mining District”. The Late Silurian–Early Devonian sequences of La Horqueta and Río Seco de los Castaños formations were deformed during the collision and accretion of the Chilenia terrane against the proto-Andean margin, and recorded an east vergent cleavage developed on the previous deformed rocks. This collision produced the strong angular unconformity between the La Horqueta/Río Seco de los Castaños Formations and the El Imperial Formation (Upper Paleozoic). The new subduction with east polarity characterized the beginning of the Gondwanian cycle. The new magmatic arc was interrupted by the intense Lower Permian deformation of the San Rafael tectonic phase.
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Cisterna, G.A., Sterren, A.F., López Gamundí, O. & Vergel, M.M., March 2017. Carboniferous postglacial faunas in the late Serpukhovian–Bashkirian interval of central-western Argentina. Alcheringa, ISSN 0311-5518. Typical glacial–postglacial sequences associated with the Late Palaeozoic Ice Age (LPIA) are recognized in the Calingasta-Uspallata Basin, central-western Argentina, particularly in the Hoyada Verde and El Paso formations (late Serpukhovian–Bashkirian) at Barreal Hill (San Juan province). Brachiopods and bivalves accompanied by gastropods, conulariids, nautiloids, corals and ostracods constitute the marine assemblages of the El Paso Formation. They are assigned to the Aseptella–Tuberculatella/Rhipidomella–Micraphelia (AT/RM) fauna, characterized by two fossil assemblages: Aseptella–Tuberculatella, identified in the lower fossiliferous interval, and Rhipidomella–Micraphelia in the upper. The development of the different invertebrate assemblages within the El Paso Formation, and their relationship with coeval suite in the Hoyada Verde Formation, can be explained by a complex array of abiotic factors (substrate stability, turbidity, nutrient availability, variation in oxygen levels, poor circulation and salinity variations in the water column) that were directly related to glacial retreat dynamics and coastal configuration. A restricted palaeofjord setting is proposed for the depositional environment of the El Paso Formation in contrast to an exposed open marine coast with a gently sloping shelf for the Hoyada Verde Formation. The study of the postglacial fauna of the El Paso Formation and its relationship with the Levipustula fauna in the Calingasta-Uspallata Basin, help determine the main controls on the distribution of the postglacial faunas in other late Palaeozoic South American basins, such as the Tepuel Genoa Basin in Patagonia and the Tarija Basin in Bolivia. Gabriela A. Cisterna [gabrielacisterna@conicet.gov.ar], CONICET-UNLAR, Av. Dr. Luis M. de la Fuente s/n, La Rioja, 5300, Argentina; Andrea F. Sterren [asterren@unc.edu.ar], CICTERRA (CONICET – Universidad Nacional de Córdoba), Av. Vélez Sarsfield 1611, X5016GCA, Córdoba, Argentina; Oscar López Gamundí [orlg2003@yahoo.com], P1C Consultants 1121 Banks Street, Houston, TX 77006, USA; María del Milagro Vergel [vergelmar@tucbbs.com.ar], CONICET – INSUGEO – Facultad de Ciencias Naturales e Instituo Miguel Lillo (UNT), Miguel Lillo 205, 4000, San Miguel de Tucumán, Argentina.
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The glaciomarine sediments related to the Late Paleozoic Ice Age (LPIA) have an excellent stratigraphic record in Argentina, particularly those associated to the Late Carboniferous glacial episode identified along the southwestern margin of South America: Bolivia (Tarija Basin), west central Argentina (Calingasta-Uspallata Basin) and Patagonia (Tepuel-Genoa basins). The aim of this contribution is mainly a biostratigraphy update of the carboniferous brachiopod faunas that occur in the earliest postglacial interval (late Serpukhovian–Bashkirian) in the west central Argentina (i.e., Levipustula and Aseptella-Tuberculatella/Rhipidomella-Micraphelia faunas) and its regional correlation with those equivalents in the nearby basins. Components of these faunas are recognized from the Bolivia to Argentine Patagonia and their compositional variations appear to be controlled principally by a paleolatitudinal factor. The affinities showed by the postglacial faunas of the Calingasta-Uspallata Basin and the faunal assemblages that integrate the Lanipustula and Tuberculatella biozones in Patagonia differ from the significant contrast proposed by other authors, based on the paleogeographical position of Patagonia in the Late Paleozoic. Paleoecological studies focused on the paleoenvironmental controls related with the glacial dynamic are suggested to understand the complex relationship between these postglacial faunas.
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The El Imperial Formation is the classic unit of the Upper Palaeozoic of the San Rafael Basin. It is one of the best known basins of the central western of Argentina. The unit today is not in complete agreement with the rules of the Código Argentino de Estratigrafía, related to the type section, type area, and formal internal divisions. In this paper several stratigraphic aspects are sorted out, but also the hypostratotype for the Cañon del Atuel section is proposed. Two formal members are defined and characterized. Correlation with the type section is proposed and an analysis of this new stratigraphic schemel is discussed with previous ones. The age and the relevance of the discovery of marine deposits in the uppermost section, and the significance in the evolution of the sedimentary infill is discussed
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Occurrences of Psammichnites are of particular interest not only because of their unique biostratigraphic attributes underlying the oldest Cambrian trilobites in the Montagne Noire (southern France), but also because of their environmental significance. They are compared with other Lower Cambrian Psammichnites found elsewhere, particularly in siliciclastic-dominant platforms of south-western Europe, in which this ichnogenus occurs from late Tommotian to middle Atdabanian (Siberian chart) or late Cordubian to middle Ovetian (Iberian scale) times.
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Diversification patterns and faunistic turnovers of bivalves and brachiopods through the Carboniferous - Early Permian interval in the central western Argentinian basins are analyzed and compared with the global events proposed in former studies. This study reveals a generalized increase of bivalves, at familiar and generic levels, through three time intervals, i.e., Early carboniferous (Tournaisian-Visean), Late Carboniferous (Bashkirian-Kasimovian) and Early Permian (Asselian-Sakmarian), while the brachiopod diversity seems to remain stable from the Late Carboniferous to the Early Permian. The trends recognized in the faunistic diversity appear to be closely related to the palaeoclimatic, palaeogeographic and palaeotectonic evolution at the Southwestern Gondwana margin. Highly stressing environmental changes in the Early Carboniferous, resulting fundamentally from the development of glacial conditions, may account for the lowest faunistic diversity recorded. Particular stress conditions, such as the nutrient availability, temperature and oxygen level, would have mainly affected the brachiopod faunas that evidence the lowest diversity recognized in the interval studied. At the Visean-Serpukovian boundary, the Late Palaeozoic marine record of the Precordillera shows a major break linked to a globally recognized glacial maximum, whereas an important faunistic turnover is mainly identified in the brachiopod faunas at the beginning of the Late Carboniferous. The more stable, less stressing environmental situation developed during the Late Carboniferous-Early Permian postorogenic sedimentation is also reflected by the different faunal assemblages studied. The Late Carboniferous was characterized by postglacial transgressions. During this time local rebound, a continuous increase of the diversity and an important faunal turnover, which mainly affected the brachiopod faunas, were recorded. These faunal trends may be related to the Early Permian climatic amelioration that affected the central western Argentinian basins. The subsequent Permian transgressive events, which produced new areas of potential spreading for the benthic fauna, allowed its increase and diversification, much better reflected by the bivalve assemblages.
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New occurrences of Psammichnites gigas are reported from the Mackenzie Mountains, northwest Canada. A locality in the hanging wall of the Plateau Fault, just below the top of the upper member of the Backbone Ranges Formation, demonstrates that the uppermost part of the unit is Tommotian (latter part of Cambrian Age 2) or possibly earliest Atabanian (earliest Cambrian Age 3) in its previously undated proximal manifestation. Localities in the trilobite-bearing Sekwi Formation confirm that Psammichnites gigas can be at least as young as Atdabanian (early to middle parts of Cambrian Age 3) in Laurentia. A review of reported occurrences suggests Psammichnites gigas, and the related ichnotaxa Plagiogmus arcuatus and Taphrelminthopsis circularis, may be valuable for correlations in western Laurentia if their ichnotaxonomic relationships are clarified.
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This paper characterizes the ichnology and sedimentology of the Lower Paleozoic Parnaíba Basin beds exposed in the Poti River Canyon (Piauí State, NE Brazil) and discusses the paleoenvironmental significance of the ichnofauna. The sedimentary succession represents the Silurian–Devonian infill of the Parnaíba Basin and comprises mouth bar deposits (Ipu Formation) and shoreface deposits (Tianguá and Pimenteira formations). The Silurian ichnofauna is represented by Heimdallia isp. in the topmost beds of the Ipu Formation, and Musculopodus sedentarius, Didymaulichnus lyelli, Didymaulyponomos rowei, Diplocraterion isp., Heimdallia isp., Lockeia siliquaria, Nereites irregularis, Palaeophycus tubularis, and Thalassinoides horizontalis in the Tianguá Formation. The Devonian ichnofauna occurs in the Pimenteira Formation and is represented by Beaconites antarcticus, Bifungites munizi, Bifungites crucifomis, Nereites isp., and Rhizocorallium commune. Horizontal burrows and furrows occupying shallow and middle tiers dominate the ichnofauna, suggesting proximal expressions of the Cruziana ichnofacies. The predominance of sandy, unbioturbated, storm-generated beds in the shoreface deposits indicates a high frequency of storm surges in shallower areas of the shelf, which often inhibited or frequently erased most of the post-event substrate colonization record. Thus, the trace fossil in the analyzed succession represents substrate colonization below the low-tide base and above the storm wave base in shoreface settings. The presence of Musculopodus sedentarius in this assemblage expands the geographic and temporal record of the ichnogenus. The similar composition of the trace fossil assemblage with other Lower Paleozoic ichnofaunas reinforces ichnostratigraphic correlations represented in coeval Gondwanan units.
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The Malvinokaffric Realm is an endemic paleogeographic region that inhabited Gondwanan high latitude seas during Early-Middle Devonian times. The causes for the collapse of this fauna are still debated but seem to be related to a transgressive event during Middle Devonian in the Chaco and Paraná basins in Bolivia and Brazil, which probably generated warmer water currents into the seas bearing Malvinokaffric fauna. This study applies ichnology as a relative proxy to better understand the impact of the main paleobiological events in the collapse of the Malvinokaffric Realm. Eight Devonian ichnoguilds are recognized in this study (Asterosoma, Glossifungites, Macaronichnus, Phycosiphon, Planolites, Skolithos, Teichichnus, and Zoophycos), and their stratigraphic distribution was compared with macrofossil distribution in Paraná Basin. The Pragian to Middle Emsian strata represent the climax of the diversity of body and trace fossils, recording distinct invertebrate life habits; the Asterosoma and Skolithos ichnoguilds predominate in the southern and northwestern borders, respectively, the last representing proximal settings. The “first decline” in Malvinokaffric diversity is diagnosed during the Eifelian, after an extensive regressive event during the late Emsian characterized by the reduction in different life habits, mostly suspension-and detritus-feeding. Trace fossils represent the Planolites ichnoguild principally, and the Eifelian strata are virtually absent on the northwest edge close to the paleo-basin flanks. The Givetian interval is characterized by the most expressive flooding event (Káčak event) that connected several Gondwanic basins, allowing the presence of extra-Malvinokaffric taxa in the Paraná Basin. Trace fossils are represented chiefly by the Phycosiphon ichnoguild in the Eifelian–Givetian boundary in the southern edge, and Planolites, Asterosoma, and Skolithos ichnoguilds in the upper strata. Finally, the Frasnian strata were diagnosed only to the northwestern edge of the basin, presenting a very low macrofossil diversity (e.g., lingulids and Australocoelia), and a low-ichnodiversity progradational trend from Phycosiphon to Skolithos ichnoguild. The identified paleoenvironmental changes evidences that the Early Devonian shallow seas (Jaguariaíva Member) were impacted by a gradual increase in freshwater input towards the Middle Devonian.
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The Río Seco de los Castaños Formation (San Rafael Block) holds one of the few middle Palaeozoic (Silurian−Devonian) records worldwide of a Nereites-Dictyodora dominated ichnofauna with sedimentological features such as oscillatory and combined-flow deposits. This record is associated with microbial mats in fine-grained intervals between turbidite-like deposits documented above the storm wave base. In this work, a detailed sedimentological study permitted to divide the unit into two informal sections separated by an erosional unconformity attributed to a sea level fall. Prograding turbidite-like sand-grained deposits document gravitational turbulent flows. The tectonostratigraphic framework allowed to disregard a submarine fan, whereas the unconformity does not support an autocyclic deltaic evolution. Palaeocurrents and palaeoslope indicators to the SW suggest a high source area to the NE, that contrasts with the well-established E-W trend of most of the units of similar age in the Cuyania terrane. Deposition was probably deflected by subaqueous highs with the development of mini-basins most likely structurally controlled. The ichnological analysis allowed to recognise ichnotaxa and intergradation cases between ichnospecies previously unknown for the unit, adding to the most diverse record of Dictyodora and Nereites in central-western Gondwana. Chondrites intricatus, Chondrites targionii, Chondrites? Dictyodora zimmermanni, and specimens resembling Dictyodora liebeana are recorded for the first time. Nereites missouriensis is documented in intergradation with Nereites jacksoni, whereas Dictyodora scotica is recognised in intergradation with Dictyodora atuelica and Dictyodora tenuis. A decrease in ichnodiversity throughout the section could be related to variation in environmental parameters between the lower and upper sections. The ichnofacies assignment is discussed in terms of ethological categories and ichnodiversity. Some of the defined ichnoassemblages are assignable to a non-standard record of the Nereites Ichnofacies, and one in particular to the Nereites Ichnosubfacies, while another shows some characteristics coincident with the Zoophycos Ichnofacies. A transitional case between ichnofacies for the ichnological content of the unit as a whole, as previously reported in other units, cannot be disregarded.
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The southwestern margin of South America offers a complete record of the Late Paleozoic Ice Age (LPAI) that affected the Gondwana supercontinent. The tripartite division of LPIA glacial episodes has been refined with the help of new radiometric dates and biostratigraphic (flora and fauna) zonations in recent years to five shorter-lived discrete events: 1. Latest Devonian-earliest Tournaisian, 2. Tournaisian, 3. Visean, 4. Serpukhovian – Early Bashkirian, 5. late Pennsylvanian-earliest Permian. The glacial events 1, 2 and 3, and 4 are capped by postglacial transgressive deposits with marine fauna. The unbalanced preservation potential of the glacial deposits, skewed toward the glaciomarine sediments, provides an uneven stratigraphic record with few cases of continental glacial sedimentation, confined to the Serpukhovian – Early Bashkirian event, and numerous examples of glacial sedimentation in marine environments. Glacial sedimentation in marine settings has been grouped in two main facies associations: a valley-glacier-retreat (fjord) facies association and a submarine-retreat (glaciomarine apron) facies association in open-marine areas. Transitional facies, correspondent to those formed by the flooding of valleys during postglacial transgressions, are widely distributed along the Protoprecordillera, where paleofjord successions are well exposed particularly in western Paganzo Basin and mapped in subsurface in the Tarija basin. A general paleofjord model includes (from base to top) the following stages: (i) Incision of paleovalley and deposition of subglacial diamictites in ice contact deltas, (ii) Early Transgressive stage characterized by resedimentation of subglacial material by subaqueous sediment gravity flows and slumps in proglacial settings, (iii) Maximum flooding (late transgressive stage) dominated by black shales or laminated mudstones related to a marine incursion that flooded valleys; normal marine or brackish conditions may dominate this stage and (iv) Highstand: progradation of a fluvial-deltaic system including in some cases Gilbert-type deltas. In glaciomarine apron environments, the basal facies includes massive clast-supported conglomerates, with few striated and polished clasts, followed by fining-upward successions including thinly bedded diamictites with ice-rafted debris (IRD) and locally contorted sandstone masses in diamictite beds, indicative of mass-emplacement mechanisms. The presence of inter- and intratill pavements suggests glacial advance/retreat fluctuations along the basin margins. Deglaciation sequences, reflecting deposition mainly during the retreat of ice sheets, ice caps and alpine glaciers and successive deglaciation, can be used as operational tools for the analysis of glacial successions in SW Gondwana. They are characterized as rather simple upward-thinning successions in open marine settings as exemplified in most of the Calingasta-Uspallata Basin, Sauce Grande (Ventana Foldbelt, VFB) and central portions of the Paraná and Karoo basins. In more proximal areas (i.e. paleofjords) this vertical trend is commonly punctuated with deltaic wedges fed by nearby provenance areas. The late Paleozoic glacial-related successions of southwestern Gondwana exhibit a common tripartite motif, equivalent to second-order sequences with estimated durations of 10–80 Myr. The lower section corresponds to glacial and glacially-influenced diamictites; the middle interval is initiated with postglacial transgressions. The lower and middle intervals correspond to the deglaciation sequence as described and identified in several basins of Gondwana. Finally, the upper term includes coastal progradation, followed in some places by continentalization, accompanied in many sectors by increasing aridization. Examples of second-order sequences can be identified in the thick late Paleozoic successions of the Paraná and Karoo basins and in the VFB. Thinner second order sequences can be identified in the Calingasta-Uspallata, Rio Blanco, Paganzo and San Rafael basins. In the Paganzo and San Rafael basins the middle interval is also punctuated by short lived marine ingressions. The basal sequence boundary is commonly an abrasion surface (glacial erosion surface, GES) developed on bedrock. Deglaciation sequences are assigned to third order sequences made up of, when present, of a thin lowstand system tract (LST) of subglacial deposits followed upward by thick glaciomarine and glacially influenced sediments. These facies are part of a thick transgressive systems tract (TST) that culminates with marine shales that reflect interglacial or postglacial conditions during ice retreat. Thus, the deglaciation sequences are proposed to be third order sequences made up of LST-TST or exclusively TST.
Article
New and previous fossil remains and resulting biostratigraphy of the El Imperial Formation at Arroyo del Imperial, Quebrada de La Horqueta, and Cañón del Atuel key sections are analyzed, while the faunal relationships among them are clarified. Two diachronnous faunas, the pTS and TSAIII associations, relatives to the Tivertonia- Streptorhynchus assemblage are recognized and constrained to early late Bashkirian and Moscovian ages, respectively. These age assignments are supported by statistical analyses and available palynological and radiometric dating. Previous mentions of brachiopods from Arroyo del Imperial and Quebrada de La Horqueta are elucidated with the identification of Buxtonia cf. riojanae (Leanza), Streptorhynchus inaequiornatus Leanza, Spiriferellina? sp., Septosyringothyris (Precosyringothyris) aff. jaguelensis Lech, Septosyringothyris (Precosyringothyris) cf. feruglioi (Amos), Saltospirifer guevarai Cisterna and Archbold and Pericospira sp. A new marine fauna from the upper part of the Cañón del Atuel section (Cabecera del Cañón Member) is reported. It includes the brachiopods Argentiella cf. A. stappenbecki Archbold, Cisterna and Sterren, Oehlertella annae (Feruglio), Orbiculoidea saltensis Reed, Calytrixia piersoni Taboada, Coolkilella aredesi Taboada, Costatumulus sp. and Septosyringothyris? sp. A bio-chronostratigraphic correlation scheme, including key lithostratigraphic units and biozones of central-western Argentina is updated.
Article
Dictyodora has been generally considered an ichnogenus with a restricted temporal range from the Cambrian to the Mississippian. Until now, there have been no reports of Dictyodora after the Mississippian. Here we report on well-preserved and abundant Dictyodora from deep-sea sediments of the Lopingian Maomaolong Formation in West Qinling, central China, which is hitherto the youngest occurrence of Dictyodora and extends the stratigraphic range of Dictyodora to the Late Permian. Two ichnospecies of Dictyodora are distinguished: D. zimmermanni and D. cf. scotica. Unlike the small-sized Dictyodora in the pre-Pennsylvanian, the three-dimensional morphology of Dictyodora studied here shows larger amplitudes and longer limbs with clearly inclined walls and basal burrows, which are interpreted to have been made by a soft-bodied worm-like organism with a snorkel-like organ as similarly documented in previous studies. Detailed systematic ichnological features and SEM and EDS results indicate that Dictyodora here is not simply a respiration structure made during the locomotion of the trace maker, but resulted from active filling by the trace maker. Dictyodora is probably not a good indicator of the deep-marine environment in the Paleozoic. From our dataset, Dictyodora originated from the shallow-marine environment in the early Cambrian, then migrated into the deep sea in the Ordovician and the marginal-marine setting in the Wenlock, and was finally restricted to the deep-marine environment in the Carboniferous and Permian. Both Psammichnites and Dictyodora are structures made by organisms with snorkel-like organs, and both were eliminated during the end-Permian mass extinction.
Article
Ichnofossils from the type locality of the Famennian are here described and figured for the first time. The siliciclastic supratidal alluvial to proximal subtidal deposits of S Belgium yield a diverse ichnofauna composed of Arenicolites ispp. (two morphotypes), Chondrites intricatus, Diplocraterion isp., Dolopichnus gulosus, Gordia marina, Helminthopsis isp., Lockeia cordata, L. siliquaria, Palaeophycus tubularis, P. sulcatus, Planolites isp., Protovirgularia obliterata, P. cf. rugosa, P. isp. and Psammichnites implexus. As a whole, these 16 ichnospecies and 11 ichno-genera form the typical assemblage of the Cruziana ichnofacies where Palaeophycus is largely dominant. However, the Belgian Famennian displays a large range of lithofacies corresponding to various environments in which distinct ichnofossil assemblages are identified. Arenicolites isp. collected from sabkha-type primary dolomite indicates the probable colon-isation of hypersaline environment by Arenicolites tracemakers as early as the Late Devonian. The type material of Crossochorda marioni Dewalque, 1881 is revised and attributed to Protovirgularia obliterata and P. cf. rugosa.
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The El Imperial Formation (San Rafael Basin) shows a complete record of the late Carboniferous - early Permian stratigraphy in western basins of Argentina. The sedimentological and stratigraphic analysis in the type locality allowed recognizing eight facies associations. Facies association A includes diamictites and conglomerates related to the Late Paleozoic glacial event, facies B composed of shales and fine-grained sandstones, was formed during the postglacial transgression while facies C represents sandy littoral bars, that pass upward to shales and mudstones of the facies association D. The conglomerates and sandstones of the facies association E entirely correspond to fluvial sedimentation, followed by a new transgressive event represented in fine-grained sandstones and shales of the facies F. The last transgression is recorded in shales, mudstones and very fine-grained sandstones belonging to the facies G, which are covered by sandstones and conglomerates corresponding to multi-channel fluvial systems. From these facies associations, 33 palynofloras divided into three palynological associations were obtained. The palynological assemblages that characterized the basal section contain abundant trilete spores and monosaccate pollen grains, with a progressive increase of taeniate pollen towards the top of the unit. The presence of scolecodonts characterizes palynofloras from transitional to marine environments. The composition of the palynofloras allows correlations with the current biostratigraphic scheme of the center-west of Argentina. The presence of the Biozone Raistrickia densa- Convolutispora muriornata in the lower and middle part of the El Imperial Formation, together with Pakhapites fusus-Vittatina subsaccata Biozone in the upper part, allows us to refer the palynofloras to the late Serpukhovian/early Cisuralian.
Article
Macaronichnus segregatis degiberti, a relatively large ichnosubspecies of Macaronichnus segregatis, is an almost straight to gently curved, cylindrical, fossilized burrow, oriented horizontal to oblique to the bedding plane. It is interpreted as a pascichnial trace fossil formed through selective sand feeding and excretion of a free-living polychaete, such as a relatively large travisiid (formerly classified as opheliid or scalibregmatid) polychaete Travisia. While the other ichnosubspecies, i.e., M. s. segregatis, M. s. lineiformins, M. s. meandriformis, and M. s. spiriformis, are commonly 2–5 mm in diameter and occur exclusively in foreshore deposits, M. s. degiberti attains a diameter of up to 15 mm and shows wide environmental distribution, ranging from tidal channels, tidal sand bars, tidal sandridges, tidal flats, upper to lower shorefaces, bioturbated sandy shelves, shelf storm-sheets, to shelf sand ridges. The core of M. s. degiberti, consisting mainly of light mineral-rich sand grains, is composed of alternating lamellae of light mineral-rich and heavy mineral-rich sands, arranged oblique to the bedding plane. On the other hand, the mantle, composed mainly of heavy mineral-rich sands, has a smooth outline, or evenly spaced lobes flanked on both sides. The morphology of the mantle lobes and core lamellae suggests repeated pulses of sediment probing and excreting behaviour of the tracemaker. Two or more burrows of this ichnosubspecies tend to occur adjacently, sometimes intertwining. As Travisia develops directly, lacking any planktic larval stages, aggregations of the burrows can be interpreted to reflect the burrowers’ interindividual exploratory behaviour with the aim of copulation. Travisia, also known as a “stink worm” secretes volatile chemical substances that might act as sex pheromones to attract other individuals for reproduction within the substrate. Therefore, a new category of ethological classification of trace fossils “sequorichnia” (sequor, follow; and ichnia, traces), for exploration of other individuals, is proposed here. This is the first record of interindividual exploratory behaviour of infaunae.
Article
True substrates are defined as sedimentary bedding planes that demonstrably existed at the sediment-water or sediment-air interface at the time of deposition, as evidenced by features such as ripple marks or trace fossils. Here we describe true substrates from the Silurian Tumblagooda Sandstone of Western Australia, which have been identified by the presence of the surficial trace fossil Psammichnites. The examples are unexpected because they have developed along erosional internal bounding surfaces within a succession of cross-bedded sandstones. However, their seemingly counterintuitive preservation can be explained with reference to recent advances in our understanding of the time-incomplete sedimentary-stratigraphic record (SSR). The preservation of true substrates seems to be an inevitable and ordinary result of deposition in environments where sedimentary stasis and spatial variability play important roles. We show that the true substrates developed during high-frequency allogenic disturbance of migrating bedforms, forcing a redistribution of the loci of sedimentation within an estuarine setting, and subsequently permitting an interval of sedimentary stasis during which the erosional bounding surfaces could be colonized. These observations provide physical evidence that supports recent contentions of how sedimentary stasis and the interplay of allogenic and autogenic processes impart a traditionally underestimated complexity to the chronostratigraphic record of geological outcrop.
Article
The Permian-Triassic sedimentary succession of the southern Sydney Basin in southeastern Australia contains a wealth of well-preserved trace fossils that are important for systematic ichnological, palaeoecological, and palaeoenvironmental interpretations. In this study, a new ichnofossil assemblage comprising Macaronichnus, Palaeophycus, Psammichnites, Protovirgularia, Rosselia, and Teichichnus is documented from the tide-influenced shoreface deposit of the Middle Permian Jamberoo Sandstone Member of the Broughton Formation. Two distinct ichnofabrics are recognized: i) the Psammichnites ichnofabric characteristic of the upper–middle shoreface deposit; and ii) the crowded Rosselia ichnofabric (CRI) representing the lower shoreface. The Psammichnites-dominated ichnofabric is interpreted to have resulted from opportunistic behaviours of unknown trace makers, whereas the CRI is interpreted to represent possible strategic behaviours of stress-tolerant polychaetes (e.g., terebellid, spionid, and cirratulid polychaetes) in a distal shoreface with high sedimentation rate. Thus, the Psammichnites–crowded Rosselia ichnofabric succession can be considered to represent a response to an environmental shift from proximal to distal shoreface. As such, this study highlights the utility of these two ichnofabrics as stressed environmental indicators.
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The San Rafael Block as part of the Cuyania terrane, lies eastwards of the present-day Andean Cordillera in Mendoza province and it develops south of the Nazca flat-slab subduction zone. It is a geographical region constituted by a set of rather convex elevation oriented NW–SE from Sierra de las Peñas to Cerro Nevado as the eastern Neogene volcanic arc and ending at the transitional zone known as the La Escondida mining district; as a geological province was also cited as ‘Sierra Pintada’. The knowledge about this geological region started on 1891 and was continued during the twentieth century with intense regional mapping projects carried out by different Argentine institutions through which the geological background was founded. This book is dedicated to the tectonic evolution of the pre-Carboniferous units and was organized by chronological stages, in order to know the implications in the proto-Andean SW Gondwana margin, as follows: The Mesoproterozoic basement of Laurentian affinity; tectonic extension, passive margin and Cuyania terrane collisional event during the Lower Paleozoic; Silurian-Lower Devonian orogenic sedimentation, Chanic compressional phase during the Chilenia terrane accretion in the Upper Devonian-Lower Carboniferous and finally the tectonic evolution synthesis. An updated geological map compilation is also subdivided in three regions: Sierra de las Peñas, Sierra Pintada-Cerro Nevado and La Escondida transitional zone.
Chapter
The San Rafael block is a pre-Andean geological entity situated in central-western Mendoza Province, Argentina. It is part of the Cuyania composite terrane. In this terrane it is important to consider the units exposed at the ‘pre-Carboniferous’ outcrops because they record geological events before the accretion to Gondwana. One of which is the siliciclastic La Horqueta Formation of an uncertain Lower-Middle Paleozoic sedimentary age. It is characterized by asymmetric, open to similar folds, with southeast vergence. KI values obtained from the La Horqueta Formation in its type area vary from 0.24 to 0.33 Δ°2θ, indicating very low-grade (high anchizonal) to low-grade (epizonal) metamorphic conditions, that increase slightly from south to north. The white mica b-parameter measured (9.016 ± 0.007 Å) suggest an intermediate pressure regime. Whole rock Rb-Sr isochronic ages were obtained on metapelites from the key outcrops in the La Horqueta area (379 ± 15 Ma, MSWD: 1.4) and in the Los Gateados area (371 ± 62 Ma, MSWD: 3.7), indicating that metamorphism and deformation occurred during the Devonian Chanic Orogenic phase, probably related to Chilenia terrane collision. U-Pb LA-MC-ICPMS detrital zircon ages patterns suggest that the La Horqueta Formation received a dominant sedimentary input from Mesoproterozoic sources, minor contributions from cratonic environments of Paleoproterozoic and Neoarchean ages, and finally a younger input from Pampean and Famatinian orogenic belts. U-Pb detrital zircon ages indicate a maximum sedimentation age close to the Silurian-Devonian limit for the La Horqueta Formation.
Article
A recently discovered trace fossil assemblage of late Westphalian D age from the province of Palencia, northwest Spain, is described and interpeted. The trace fossils occur in a sequence of laminated shales and siltstones indicating a low-energy, quiet water environment. Body fossils are not associated with trace fossils. At least six ichnogenera have been recognised, including Kouphichnium, Monomorphichnus, Arborichnus n. ichnogen. Petalichnus, ?Olivellites, and Scolicia. The assemblage represents traces left by vagrant benthos such as xiphosurids, gastropods, and possibly eurypterids; they are interpreted as dominantly walking, swimming-grazing, and crawling tracks.-Authors
Article
During the late Palaeozoic ice age (LPIA), ice-proximal marine regional communities record contrasting responses to climate change compared to ice-distal communities. However, there is still much to be understood in distal regions in order to fully understand the palaeobiological consequences of the LPIA. Here, were analyse brachiopod and bivalve environmental preferences along the bathymetric gradient during a major glacial event and the subsequent non-glacial interval in western Argentina. Median environmental breadths did not change with the reassembly of communities during the non-glacial interval. Moreover, bivalves and brachiopod immigrants show similar environmental breadths although they tend to have immigrated from different palaeogeographical regions. These patterns reinforce the idea that the worldwide marine fauna was probably culled of stenotopic taxa during the LPIA. On the other hand, analysis of the preferred depths of survivors and immigrants sheds light on the substantial modification of the bathymetric diversity gradient. Among different possible explanations, the immigration of taxa with affinities for deep environments is the only one supported. In addition, results underscore the observation that the higher turnover in the offshore environment was probably driven by immigration rather than extinction. Finally, stability in environmental preferences at a regional scale is not mirrored by stability in survivors’ individual preferences, because survivors’ preferred depth is not correlated during the glacial and non-glacial intervals. Moreover, the amount of change in survivors preferred depth is not related to their environmental breadth, nor to their occupancy. These patterns suggest: (1) instability in realized niches; and (2) individual responses of survivor genera.
Article
The Lower Pennsylvanian (Morrowan/Atokan) portion of the Fountain Formation in the Manitou Springs, Colorado, area commonly has been interpreted as a subaerial alluvial fan. However, approximately 12 marine-nonmarine cycles, each represented by a discrete progradational sequence, have been recognized within the lower third of the Fountain Formation in this area. Two diverse trace-fossil assemblages within the Fountain Formation are restricted to the marine portions of the section, or to those portions within 1 m below marine-deposited strata. Trace-fossil composition changes along a roughly south-to-north, nearshore-to-offshore gradient, generally reflecting increased influence and duration of normal-marine sedimentation. Ichnotaxa present and their distributions within marine strata in the lower part of the Fountain Formation suggest that they belong to the Curvolithus ichnoassemblage, which has been shown to indicate high sedimentation rates in relatively nearshore shelf settings. The Curvolithus ichnoassemblage can be subdivided into Macaronichnus-dominated and Curvolithus-dominated parts. Macaronichnus-dominated portions of the Fountain Formation indicate generally higher wave-energy sedimentation as compared with Curvolithus-dominated portions. -from Authors