| Titre | The Psammichnites-Taphrhelminthopsis conundrum: implications for calibrating the Cambrian explosion |
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| Auteur | Mángano, M G; Buatois, L A; MacNaughton, R B ; Jensen, S; Gougeon, R; Marcos, A; Meek, D; Piñuela, L; García-Ramos, J C |
| Source | Earth-Science Reviews vol. 227, 103971, 2022 p. 1-20, https://doi.org/10.1016/j.earscirev.2022.103971 |
| Image |  |
| Année | 2022 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20210382 |
| Éditeur | Elsevier |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1016/j.earscirev.2022.103971 |
| Media | papier; numérique; en ligne |
| Formats | pdf; html |
| Région | Asturias |
| Lat/Long OENS | -6.1833 -6.1667 43.5667 43.5500 |
| Sujets | paléontologie systématique; taxonomie; évolution; empreintes fossiles; ichnofossiles; ichnologie; milieux marins; géologie du substratum rocheux; lithologie; roches sédimentaires; grès; morphologie des
fossiles; paléogéographie; paléontologie; Sciences et technologie; Nature et environnement; Phanérozoïque; Paléozoïque; Cambrien |
| Illustrations | tableaux; cartes de localisation; cartes géolscientiques généralisées; photographies |
| Programme | GEM-GéoNord : La géocartographie de l'énergie et des minéraux Coordination du programme GEM |
| Diffusé | 2022 03 05 |
| Résumé | (disponible en anglais seulement)
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. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Ce manuscrit rapporte un nouveau type de terrier animal fossilisé de la période cambrienne de l'histoire de la Terre. Ce type de terrier a reçu
le nom scientifique Taphrhelminthopsis circularis. Le rapport est basé en partie sur une visite de certains des auteurs sur le site en Espagne où ce type de terrier a été documenté pour la première fois dans les années 1970. Il est également basé sur
une revue d'exemples publiés précédemment. L'étude montre que ce terrier est une variante d'un autre type nommé de terrier fossile, appelé Psammichnites gigas. Ces types de terriers ne se trouvent que dans les roches d'âge cambrien et sont donc
utiles pour déterminer l'âge des strates rocheuses. Cela comprend les strates du nord-ouest du Canada qui sont étudiées pendant GEM-GeoNorth. |
| GEOSCAN ID | 329157 |
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