Trace and soft body fossils from the Pedroche Formation (Ovetian, Lower Cambrian of the Sierra de Córdoba, S Spain) and their relation to the Pedroche event

Geobios (Impact Factor: 1.19). 07/2006; 39(4):443-468. DOI: 10.1016/j.geobios.2005.04.004

ABSTRACT The low Lower Cambrian rocks from the Sierra de Córdoba contain one of the best successions in Europe, which consists of well exposed mixed facies with abundant fossil assemblages showing long stratigraphical ranges throughout the Pedroche Formation. These assemblages include diverse Ovetian archaeocyaths, trilobites, small shelly fossils, calcimicrobes, trace fossils and stromatolites. Trace fossils are still poorly known, and thus they are the main objective of this work. Ichnological data are obtained from the Arroyo de Pedroche 1, Arroyo de Pedroche 2 and Puente de Hierro sections. Trace fossils include the ichnogenera Bergaueria, aff. Bilinichnus, Cochlichnus, aff. Cosmorhaphe?, Cylindrichnus, Dactyloidites, Dimorphichnus, Diplichnites, Monocraterion, Palaeophycus, aff. Phycodes, Planolites, Psammichnites, Rusophycus, Skolithos, Torrowangea and Treptichnus, as well as faecal pellets, meniscate trace fossils and others. They are abundant in shales and sandstones, and indicate important changes in the benthic conditions with respect to the underlying Torreárboles Formation. Changes in fossil assemblages within Member I of the Pedroche Formation indicate palaeoecological disruptions, which led to the disappearance of numerous archaeocyath species and the decrease of stromatolite biodiversity. This was followed by dominance of trilobite and brachiopod assemblages, accompanied by trace fossils of the Psammichnites ichnosp. A ichnoassociation. This biotic turnover (Pedroche event) occurred at the lower part of the archaeocyath Zone III, within the Bigotina bivallata biozone. The diagnoses of the ichnospecies Cochlichnus anguineus and Dactyloidites cabanasi are emended.

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    ABSTRACT: The Early Permian Robledo Mountains Formation of the Robledo Mountains in Doña Ana County, southern New Mexico contains a diverse and abundant nonmarine trace fossil assemblage. Invertebrate and vertebrate trace fossils both occur in abundance and formed in an upper intertidal flat setting, a long way inshore and essentially under nonmarine conditions. Eighteen invertebrate ichnogenera, including 16 established ichnospecies, one reassigned ichnospecies and two new ichnospecies are described and illustrated, together with nine trace fossils described in open nomenclature. Previously described vertebrate ichnogenera and ichnospecies are reviewed and illustrated, together with the description of one new ichnospecies, totalling ten ichnogenera and 13 ichnospecies. The ichnotaxonomy of Lithographus hieroglyphicus and Stiaria intermedia is also revised in light of the material from the Robledo Mountains Formation of the Robledo Mountains and comparative Early Permian material from the Early Permian Standenbühl Formation of the Saar-Nahe Basin near Frankfurt in Germany, the Hornburg, Oberhof, Rotterode and Eisenach Formations from the Thüringer Forest in Germany, the Coconino Sandstone Formation of Arizona, and the Shalem Colony Formation of the Robledo Mountains. The invertebrate trace fossils from the Robledo Mountains Formation of the Robledo Mountains are dominated by arthropod trackways (Dendroidichnites irregulare, Diplichnites isp., Diplopodichnus biformis, Kouphichnium? isp., Lithographus hieroglyphicus, Octopodichnus cf. didactylus, Palmichnium macdonaldi, P. palmatum, P. pottsae and Stiaria intermedia), including several enigmatic arthropod trackways, as well as intergrading arthropod trackways (Diplichnites isp. × Diplopodichnus biformis, Diplopodichnus biformis × Dendroidichnites irregulare and cf. Lithographus × Diplopodichnus biformis), arthropod resting traces (cf. Lockeia, Rotterodichnium major, Selenichnites belosis nov. isp. Tonganoxichnus apacheensis nov. comb., and T. buildexensis), arthropod locomotory jumping traces (T. robledoensis), combined arthropod trackways and locomotory jumping traces (Stiaria intermedia × T. robledoensis), and arthropod grazing/raking traces (Stiallia pilosa and Striatichnium biflabellis nov. isp.). Invertebrate feeding traces (Treptichnus bifurcus) and grazing trails (Cochlichnus anguineus and looping trails) are present but rare. Trace fossils similar to the typically deep marine graphoglyptids are also present (cf. Spirorhaphe azteca), as well as horizontal helical-shaped burrows (Augerinoichnus helicoidalis) that may also have affinities with graphoglyptids. Further trace fossils described under open nomenclature include horizontal burrows and various enigmatic invertebrate trace fossils. The vertebrate trace fossils are dominated by tetrapod trackways (Batrachichnus salamandroides, Batrachichnus aff. salamandroides, Dimetropus nicolasi, D. leisneranius, Dromopus lacertoides, cf. Erpetopus, Limopus vagus, Gilmoreichnus hermitanus and Hyloidichnus bifurcatus), whilst tetrapod swimming trackways (Lunichnium rotterodium, Serpentichnus robledoensis and S. sigmoidalis nov. isp.) and fish swimming trails (Undichna bina, U. britannica and Undichna? unisulca) are also present. The trace fossil assemblage can be considered as an example of the Scoyenia ichnofacies, although the presence of rare elements of the Mermia ichnofacies indicates that there are pre- and syn-desiccation suites of trace fossils. Cluster analysis of trace fossil distributions across nonmarine depositional settings from the Early Permian of the southwest USA reveals patterns consistent with previous models, based on qualitative observations, of the distribution of vertebrate trace fossils and their palaeoenvironmental implications. Comparisons of analyses conducted using the vertebrate, invertebrate and all trace fossils from the assemblages reveals that, for assemblages covering a limited temporal and palaeogeographic scope, vertebrate trace fossils allow greater potential for identifying trace fossil associations that enable discrimination amongst different depositional settings than invertebrate trace fossils alone, whereas a holistic approach, utilising all available trace fossil data, allows the greatest number of trace fossil associations, which correspond to different depositional settings, to be identified.
    Special Papers in Palaeontology 01/2009; 82:5-107. · 1.77 Impact Factor
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    ABSTRACT: A Lockeia-Protovirgularia ichnofauna representing the Cruziana ichnofacies is reported from a calcareous sandstone horizon of the Callovian Bada Bagh Member, Jaisalmer Formation, Rajasthan. The ichnoassemblage is characterized by Lockeia cunctator, L. siliquaria, Protovirgularia ?bidirectionalis, P. rugosa, Ptychoplasma vagans along with Palaeophycus tubularis, P. striatus, Heliophycus isp. and ?Lophoctenium isp. Use of numerical analysis yielding length to width ratio, slopes and coefficient of determination helps in confirming identification of ichnospecies of Lockeia. Fine morphological details of Lockeia and Protovirgularia, especially sharp and closely spaced chevrons of Protovirgularia, indicate that the substrate in which they were emplaced was stiff, resistant, dewatered and better consolidated. Therefore, it construes that this ichnoassemblage belonging to the classical Cruziana ichnofacies occurs in stiff softground and not a typical softground. Though the ichnofacies of this calcareous sandstone bed indicates low-medium energy condition under subtidal environment of deposition, underlying strata containing Arenicolites, Skolithos and Curvolithus of Skolithos ichnofacies indicate intertidal sandy shore environment with high energy conditions. Thus, it is concluded that this area was undergoing continuous, gradual deepening. However, the percentage of Thalassinoides, Ophiomorpha and Phycodes in the overlying bed is quite high suggesting an increase in the energy conditions resulting from a probable shallowing.
    Journal of Earth System Science 10/2013; 122(5):1359-1371. · 0.70 Impact Factor
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    ABSTRACT: Stelloglyphus llicoensis isp. nov. is a large radial, discoidal to ellipsoidal trace fossil with a central shaft and single to bifurcating branches radiating from different levels. A 30 m thick measured section of the Ranquil Formation at Punta Litre contains an associated trace fossil assemblage including Zoophycos, Chondrites, Phycosiphon, Nereites missouriensis, Lockeiasiliquaria, Psammichnites(?), Parataenidium,Ophiomorpha, and Rhizocorallium, some of which reworked the Stelloglyphus traces. The sedimentology, together with micro- and macrofossils and the associated trace fossil assemblage, suggest that the succession was deposited in an outer continental shelf to slope environment in subtropical to tropical waters.
    Revista Geologica de Chile 07/2008; 35(2):307-319. · 0.56 Impact Factor


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