Torpedaspis, a New Upper Silurian and Lower Devonian Genus of Cyathaspididae (Ostracodermi) from Arctic Canada

Broad, D.S.; Dineley, DL

doi:10.4095/102368

Cited by 7 publications

(4 citation statements)

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“…With regard to the faunas from the Cape Phillips Formation, this similarity is further emphasised by the presence of a form which Thorsteinsson (1967) considered to be reminiscent of Tesseraspis denisoni (Tarlo, 1964) which is also known from the Beaver River fauna. The latter fauna, as well as those referred to above, also shows some similarity to faunas recorded from strata dated as late Silurian or Siluro-Devonian on Somerset Island and Prince ofWales Island (the Cape Storm and the Douro Formations and the lower member of the Peel Sound Formation; Broad, 1973;Broad & Dineley, 1973;Loeffler & Jones, 1976Miall et al, 1978;Thorsteinsson, 1980;Elliott & Dineley, 1983;Elliott, 1984a, b), and in Western Yukon (the Gossage Formation) and District of Mackenzie (the Delorme Formation; Broad & Lenz, 1972;Dineley & Loeffler, 1976).…”

Section: The Washington Land Ostracoderm Assemblage and Its Relationship To Silurian Faunas From North Western And Arctic Canadasupporting

confidence: 72%

Silurian ostracoderms from Washington Land (North Greenland), with comments on cyathaspid structure, systematics and phyletic position

Bendix-Almgreen¹

1986

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The few detached dermal elements recorded here document a new ostracoderm fauna comprising undeterminable species of one anaspid, two cyathaspids and a heterostracan which might have its closest relatives among the pteraspids. This fauna is derived from marine deposits of ultimate Wenlock or possibly Early Ludlow age at the top of the Lafayette Bugt Formation in its type section, in Washington Land, western North Greenland. It is probably equivalent to one of the undescribed faunas known from the Monograptus testis - M. nilssoni sequence of the Cape Phillips Formation in the Canadian Arctic Archipelago. Comparative material from Norway and Spitsbergen is considered in this study which prompted general comments on cyathaspid squamation, vestigial fin structure, cyathaspid systematics, their phyletic position relative to the pteraspids, system of stability control in swimming, their habitats and diets.

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Section: The Washington Land Ostracoderm Assemblage and Its Relationship To Silurian Faunas From North Western And Arctic Canadasupporting

confidence: 72%

Silurian ostracoderms from Washington Land (North Greenland), with comments on cyathaspid structure, systematics and phyletic position

Bendix-Almgreen¹

1986

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“…Such a hypothesis can only be adequately tested by examining the phylogenetic history of oral dental elements. A number of other stemgnathostome groups also exhibit evidence of dental skeletal elements associated with the mouth, but these appear to be structurally confluent with the dermoskeletal dental elements (e.g., ascending lamina and oral plates of heterostracans, Kiaer [1932], Watson [1954], Broad and Dineley [1973], Purnell [2002]; pre-oral field of osteostracans, Janvier [1985a,b]). At least some thelodonts also possess mineralized dental elements in association with their oral cavity, pharynx, and/or branchial skeleton (van der Brugghen and Janvier, 1993; Donoghue and Smith, 2001).…”

Section: Gnathostome Stem-lineagementioning

confidence: 99%

Origin and early evolution of vertebrate skeletonization

Donoghue

Sansom

2002

Microscopy Res & Technique

200

255

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Data from living and extinct faunas of primitive vertebrates imply very different scenarios for the origin and evolution of the dermal and oral skeletal developmental system. A direct reading of the evolutionary relationships of living primitive vertebrates implies that the dermal scales, teeth, and jaws arose synchronously with a cohort of other characters that could be considered unique to jawed vertebrates: the dermoskeleton is primitively composed of numerous scales, each derived from an individual dental papilla; teeth are primitively patterned such that they are replaced in a classical conveyor-belt system. The paleontological record provides a unique but complementary perspective in that: 1) the organisms in which the skeletal system evolved are extinct and we have no recourse but to fossils if we aim to address this problem; 2) extinct organisms can be classified among, and in the same way as, living relatives; 3) a holistic approach to the incorporation of all data provides a more complete perspective on early vertebrate evolution. This combined approach is of no greater significance than in dealing with the origin of the skeleton and, combined with recent discoveries and new phylogenetic analyses, we have been able to test and reject existing hypotheses for the origin of the skeleton and erect a new model in their place.

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“…The Hall Land vertebrates oceur at almost the same stratigraphieal level as the large and varied vertebrate fauna diseovered in recent years in marine beds of the Peel Sound Formation in the Canadian Aretie Arehipelago (Thorsteinsson, 1958;Thorsteinsson & Tozer, 1963;Broad, 1973;Broad & Dineley, 1973). The general similarity between Palaeozoic strata in North Greenland and Aretic Canada is well known (e.g.…”

Section: Discussionmentioning

confidence: 94%

Early Devonian vertebrates from Hall Land, North Greenland

Bendix-Almgreen¹,

Peel²

1974

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During investigation of collections from North Greenland made by P. R. Dawes and J. H. Allaart, as part of Operation Grant Land 1965-66, one of the authors (J. S. P.) found vertebrate remains in samples which had been subjected to acetic acid digestion. The vertebrate material was subsequently examined by S.E.R.A. who found it to comprise thelodonts, heterostracans and acanthodians (illustrated in Bendix-Almgreen, in press) suggestive of an approximate late Silurian (Pridoli) - Lower Devonian age. This age is in general agreement with the late Silurian - early Devonian date suggested by Berry et al. (this report) for graptolites from stratigraphically slightly lower beds in the same sequenee of strata in western Hall Land. The two age determinations provide the first palaeontological evidence for the presenee of late Silurian (Pridoli) and early Devonian strata in the Franklinian geosynclinal sequence of North Greenland.

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Torpedaspis, a New Upper Silurian and Lower Devonian Genus of Cyathaspididae (Ostracodermi) from Arctic Canada

Cited by 7 publications

References 0 publications

Silurian ostracoderms from Washington Land (North Greenland), with comments on cyathaspid structure, systematics and phyletic position

Silurian ostracoderms from Washington Land (North Greenland), with comments on cyathaspid structure, systematics and phyletic position

Origin and early evolution of vertebrate skeletonization

Early Devonian vertebrates from Hall Land, North Greenland

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