Geologisk Museum

Copenhagen, Denmark

Geologisk Museum

Copenhagen, Denmark
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Topper T.P.,Geologisk Museum | Harper D.A.T.,Geologisk Museum | Harper D.A.T.,Durham University | Brock G.A.,Macquarie University
Journal of Systematic Palaeontology | Year: 2013

The relationship of many Cambrian rhynchonelliform brachiopods is poorly understood, with many genera displaying a combination of morphological features that are taxonomically confusing. The study of middle Cambrian-early Tremadocian brachiopods is critical because this interval is sandwiched directly between the two largest radiation phases in the early Palaeozoic and provides raw data for deciphering the events leading up to the explosion of brachiopod genera in the Ordovician. Here we present a parsimony analysis of a wide selection of Cambrian and Ordovician brachiopod genera with a particular focus on the evolution and phylogeny of Billingsellida. The billingselloids were widespread by the late Cambrian and the group was originally thought to represent the ancestral stock of many Ordovician brachiopod lineages. The phylogenetic analyses portray the polytoechioids as derived billingselloids separate from the clitambonitoids that form a sister group. The Gondwanan brachiopod Roanella is interpreted as ancestral to the clitambonitoids within the Billingsellida and is reassigned to Clitambonitoidea within a new monogeneric family, Roanellidae nov. Antigonambonites displays no obvious relationship with the clitambonitoids and should be formally transferred to the polytoechioids. The monogeneric family Chaniellidae exhibits characters reminiscent of members of the polytoechioids and is transferred to the superfamily Polytoechioidea. The recently reappraised clitambonitoid Arctohedra is interpreted as a basal member of the entire order Billingsellida. © 2013 Natural History Museum.

Topper T.P.,Geologisk Museum | Harper D.A.T.,Durham University | Ahlberg P.,Lund University
GFF | Year: 2013

The acrotretide Acrotreta socialis von Seebach, 1865 has suffered a long and tumultuous history since its original description from the middle Cambrian (Guzhangian Stage) Andrarum Limestone of Bornholm, Denmark. Uncertainties regarding key morphological characters have resulted in numerous revisions and redescriptions of the species with much of the taxonomic shuffling occurring before the mid-20th century. A major problem with the early documentation of acrotretide brachiopods is that many species were described in the days before the advent of the Scanning Electron Microscope (SEM), resulting in dubious interpretations of significant morphological characteristics, like the position of the pedicle foramen and the internal morphology of both valves. A detailed revision of Acrotreta species resulted in the proposal that the genus is restricted solely to the Ordovician with the Bornholm acrotretide species subsequently left floating in taxonomic limbo. Recent taxonomic suggestions have been provisional, awaiting morphological information based on type or topotype material. The examination of topotype material in addition to supplementary material collected from southern Sweden has elucidated many of the previous ambiguous morphological characteristics of the species confirming that the original description was based on more than one brachiopod species. The new morphological information acquired here has resulted in the erection of a new acrotretid genus, Clupeafumosus gen. nov., to accommodate the material previously described as Acrotreta socialis. Co-occurring with Clupeafumosus socialis in southern Sweden is another new acrotretide brachiopod, Monophthalma andersoni sp. nov., which is additionally described. © 2013 Copyright Geologiska Föreningen.

Topper T.P.,Geologisk Museum | Skovsted C.B.,Swedish Museum of Natural History | Harper D.A.T.,Geologisk Museum | Harper D.A.T.,Durham University | Ahlberg P.,Lund University
Journal of Paleontology | Year: 2013

A small assemblage of shelly fossils, dominated by the brachiopod Treptotreta jucunda and the bradoriid arthropod Mongolitubulus aspermachaera new species is described from a Furongian limestone of Västergötland, south-central Sweden. Mongolitubulus aspermachaera is represented in the assemblage by individual valves and numerous, ornamented spines. Valves and spines share identical ornament and microstructure leaving no doubt that the isolated spines were once attached to the bradoriid valves. Mongolitubulus aspermachaera adds to the increasing list of spinose Cambrian bradoriid arthropods, and Mongolitubulidae new family is erected here to incorporate the genera Mongolitubulus, Tubuterium and Spinospitella. Mongolitubulus aspermachaera represents the youngest member of the new family and supplements the biodiversity of bradoriids in the Furongian, an interval when bradoriid diversity is considered to be very much on the decline. The brachiopod Treptotreta jucunda described predominantly from the 'middle' to 'late' Cambrian of Australia is here documented for the first time from outside Gondwana, dramatically extending the biogeographical range of the species. Other elements of the faunal assemblage include typical Baltic Furongian representatives, such as the trilobite Parabolina, the agnostoid Agnostus and the phosphatocopids Hesslandona and Vestrogothia. © 2013 The Paleontological Society.

Topper T.P.,Uppsala University | Holmer L.E.,University of Glasgow | Skovsted C.B.,Swedish Museum of Natural History | Brock G.A.,Macquarie University | And 4 more authors.
Acta Palaeontologica Polonica | Year: 2013

The morphology and organophosphatic shell structure of the paterinate brachiopod Askepasma is documented using new and previously collected specimens from the lower Cambrian of South Australia. Lack of adequately preserved material has seen the majority of paterinate specimens previously reported from South Australia referred to the genus Askepasma and treated under open nomenclature. Large collections of paterinates from the lower Cambrian Wilkawillina, Ajax, and Wirrapowie limestones in the Arrowie Basin, South Australia have prompted redescription of the type species Askepasma toddense and the erection of a new species, Askepasma saproconcha sp. nov. Askepasma saproconcha sp. nov. currently represents the oldest known brachiopod from the lower Cambrian successions in South Australia with a FAD in pre-trilobitic (Terreneuvian, Cambrian Stage 2, lower Atdabanian) strata in the basal part of the Wilkawillina and Wirrapowie limestones. Askepasma toddense predominantly occurs in Abadiella huoi Zone equivalent strata (Unnamed Cambrian Series 2, Stage 3, middle-upper Atdabanian) in the upper part of the lower Wilkawillina, Wirrapowie, and Ajax limestones. The shell microstructure of Askepasma suggests a proximal stem group position within the Brachiopoda and similarities with tommotiid taxa provides further evidence that the ancestry of crown group brachiopods is firmly entrenched within the Tommotiida. Copyright © 2012.

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