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Hendra, Australia

Articulated specimens of jawed fishes, and assemblages of disarticulated elements that can be assigned to a single biological species, are extremely rare from pre-Devonian deposits. The acanthodian species Ischnacanthus? scheii Spjeldnaes is based on a monospecific assemblage, comprising fin spines, dentigerous jaw bone fragments and scales, from the ?Siluro-Devonian boundary beds of the Devon Island Formation in central west Ellesmere Island, Canadian Arctic Archipelago, Nunavut. A new examination of the type material, in particular by scanning electron microscopy and thin sectioning of scales, shows that the species is a porosiform poracanthodid that is now assigned to Radioporacanthodes scheii comb. nov. Scales of the same species are also recognized from the upper Pridoli of Cornwallis Island and the ?Pridoli or Lochkovian of north Greenland. Source

Newman M.J.,Vine Lodge | Burrow C.J.,Ancient Environments | den-Blaauwen J.L.,University of Amsterdam | Davidson R.G.,35 Millside Road
Geodiversitas | Year: 2014

The five species of genus Euthacanthus Powrie, 1864 are reduced to two species on morphological and stratigraphical evidence. Euthacanthus macnicoli Powrie, 1864 and Euthacanthus grandis Powrie, 1870 are here synonymised in the type species E. macnicoli Powrie, 1864. In a previous article, Euthacanthus gracilis Powrie, 1870 and Euthacanthus elegans Powrie, 1870 were combined in the species E. gracilis, and the fifth species, Euthacanthus curtus Powrie, 1870, was reassigned to Uraniacanthus curtus (Powrie, 1870). In this work, we give an in-depth study of the full range of morphological and histological structure of scales over the body of E. macnicoli, as well as of fin spine structure. Our study reveals new features of E. macnicoli, including a large ornamented dorsal sclerotic bone, ornament on the branchiostegal plates, a separate series of gular rays, calcified cartilage forming the jaws, and a postbranchial protruding spinose plate rather than the flat prepectoral plate previously described. © Publications Scientifiques du Muséum national d’Histoire naturelle, Paris. Source

Turner S.,Ancient Environments
Geoheritage | Year: 2013

Geology and landscape profoundly influence society, civilization and cultural diversity on our planet. The subtle relationships between peoples have changed irrevocably since our species began its journey in the Ice Age. The last 10,000 years have been a boom time: we planted crops, domesticated animals and built cities; population burgeoned; and in most places, the link to the land was lost. Important geological places (geosites) help us to rekindle and remember our place. Our geoheritage, now with the added designation of 'Geoparks', needs to reflect this intimate relationship: by helping people refind their roots and learning from early and indigenous people through their experiences to answer modern challenges, such as surviving climate change. The Geopark concept has brought economic revitalization to many rural regions, assisting local communities and indigenous populations, and added a new tool for geoconservation. In particular, women are being empowered to pursue new lines of work and to get involved in the Geopark process. Examples from Australian, Chinese, European and Iranian Geoparks show how the Global Geopark Network is supporting UNESCO ideals for women in the twenty-first century. This trend is important because women are traditionally the primary educators of children and they bring different perspectives to understanding geoheritage and to the Geopark process. © 2013 The European Association for Conservation of the Geological Heritage. Source

Newman M.J.,Vine Lodge | Davidson R.G.,35 Millside Road | Den Blaauwen J.L.,University of Amsterdam | Burrow C.J.,Ancient Environments
Geodiversitas | Year: 2012

The acanthodian originally described as Euthacanthus curtus Powrie, 1870 from the Early Devonian (Lochkovian) of Scotland was tentatively reassigned to Diplacanthus Agassiz, 1844 later in the nineteenth century, although doubt was cast on this revision. In 1976 Paton suggested that specimens comparable with the single type could belong to Uraniacanthus Miles, 1973, based on similarities with the type species U. spinosus Miles, 1973 from the Lochkovian of England. Hanke et al. (2001) noted that the Canadian Lochkovian species Gladiobranchus probaton Bernacsek & Dineley, 1977 was also very similar to U. spinosus. Our investigations indicate that all three species belong to the genus Uraniacanthus (which has priority over Gladiobranchus Bernacsek & Dineley, 1977) in the family Gladiobranchidae Bernacsek & Dineley, 1977, order Diplacanthiformes Berg, 1940 (revised). This identification supports a biogeographical connection between the Canadian, Scottish and English Early Devonian based on the common presence of the genus Uraniacanthus, as well as other acanthodian genera, including Ischnacanthus Powrie, 1864. Uraniacanthus could also be represented by isolated scales in coeval deposits in the Baltic. © Publications Scientifiques du Muséum national d'Histoire naturelle, Paris. Source

Long J.A.,Flinders University | Long J.A.,Australian National University | Burrow C.J.,Ancient Environments | Ginter M.,University of Warsaw | And 5 more authors.
PLoS ONE | Year: 2015

Background: Living gnathostomes (jawed vertebrates) comprise two divisions, Chondrichthyes (cartilaginous fishes, including euchondrichthyans with prismatic calcified cartilage, and extinct stem chondrichthyans) and Osteichthyes (bony fishes including tetrapods). Most of the early chondrichthyan ('shark') record is based upon isolated teeth, spines, and scales, with the oldest articulated sharks that exhibit major diagnostic characters of the group - prismatic calcified cartilage and pelvic claspers in males - being from the latest Devonian, c. 360 Mya. This paucity of information about early chondrichthyan anatomy is mainly due to their lack of endoskeletal bone and consequent low preservation potential. Methodology/Principal Findings: Here we present new data from the first well-preserved chondrichthyan fossil from the early Late Devonian (ca. 380-384 Mya) Gogo Formation Lägerstatte of Western Australia. The specimen is the first Devonian shark body fossil to be acid-prepared, revealing the endoskeletal elements as three-dimensional undistorted units: Meckel's cartilages, nasal, ceratohyal, basibranchial and possible epibranchial cartilages, plus left and right scapulocoracoids, as well as teeth and scales. This unique specimen is assigned to Gogoselachus lynnbeazleyae n. gen. n. sp. Conclusions/Significance The Meckel's cartilages show a jaw articulation surface dominated by an expansive cotylus, and a small mandibular knob, an unusual condition for chondrichthyans. The scapulocoracoid of the new specimen shows evidence of two pectoral fin basal articulation facets, differing from the standard condition for early gnathostomes which have either one or three articulations. The tooth structure is intermediate between the 'primitive' ctenacanthiform and symmoriiform condition, and more derived forms with a euselachian-type base. Of special interest is the highly distinctive type of calcified cartilage forming the endoskeleton, comprising multiple layers of nonprismatic subpolygonal tesserae separated by a cellular matrix, interpreted as a trnsitional step toward the tessellated prismatic calcified cartilage that is recognized as the main diagnostic character of the chondrichthyans. © 2015 Long et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

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