Journal Article•
Two new conodont species from Middle-Upper Devonian boundary beds of Indiana and New York
TL;DR: Palmatolepis? disparalvea n.sp. as discussed by the authors differs from all species included within Palmatilepis Ulrich and Bassler by possessing a large basal cavity of unusual shape.
Abstract: Two new species of platform conodonts were obtained from beds near the Middle-Upper Devonian boundary in Indiana and New York. Palmatolepis? disparalvea n.sp., differs from all species included within Palmatolepis Ulrich and Bassler by possessing a large basal cavity of unusual shape. Polygnathus alveoliposticus, n. sp., is distinguished by its posterior basal cavity and general lack of a free blade. The thin conodont-rich limestone at the base of the New Albany Shale (Devonian-Mississippian) of southern Indiana yielded the majority of specimens. The conodont fauna of the basal New Albany falls within the Schmidtognathus hermanni-Polygnathus cristatus Zone, a problematical interval between Middle and Upper Devonian.
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TL;DR: The Devonian System of Euramerica contains at least 14 transgressive-regressive (T-R) cycles of eustatic origin this paper, which are separated into three groups (or depophases) and from Carboniferous cycles by three prominent regressions.
Abstract: The Devonian System of Euramerica contains at least 14 transgressive-regressive (T-R) cycles of eustatic origin. These are separated into three groups (or depophases) and from Carboniferous cycles by three prominent regressions. Twelve post-Lochkovian T-R cycles are recognized, and they commonly appear to result from abrupt deepening events followed by prolonged upward shallowing. Deepening events in the western United States (especially Nevada), western Canada, New York, Belgium, and Germany have been dated in the standard conodont zonation and are demonstrably simultaneous in several or all five regions. This synchroneity indicates control by eustatic sea-level fluctuations rather than by local or regional epeirogeny. Facies shifts in shelf sedimentary successions are more reliable indicators of the timing of sea-level fluctuations than are strandline shifts in the cratonic interior, because the latter are more influenced by local epeirogeny. Strandline shifts are most useful in estimating the relative magnitude for sea-level fluctuations.
Devonian facies progressions and the three prominent regressions are of a duration and an order of magnitude that could have been caused by episodes of growth and decay of Devonian oceanic ridge systems. The described T-R cycles could have formed in response to mid-plate thermal uplift and submarine volcanism. The latter process may have been a control on small-scale (1–5 m thick), upward-shallowing cycles within the major T-R cycles. Continental glaciation could have been a factor in sea-level fluctuations only in the Famennian and could not have been responsible for the Devonian facies progressions or the numerous T-R cycles.
The Frasnian extinctions were apparently cumulative rather than due to a single calamity. Two rapid sea-level rises occurred just before, and one at, the Frasnian-Famennian boundary. It is probable that this series of deepening events reduced the size of shallow-shelf habitats, caused repeated anoxic conditions in basinal areas, and drowned the reef ecosystems that had sustained the immensely diverse Devonian benthos.
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TL;DR: In a series of comparisons limited to three species each, all 13 species separate into isolated clusters that are completely congruent with the a priori groups based, with two exceptions, on multielement taxonomy.
Abstract: Multielement taxonomy and shape analysis have led to substantial revisions in the taxonomic concepts of 13 Frasnian species of Palmatolepis, which previously have been based largely on visual discrimination of the Pa elements. Septimembrate apparatuses have been recognized in three species and diagnostic Pb elements are associated with the Pa elements of eight others. The multielement reconstructions thus derived provide the a priori classification that is tested by the canonical variate analysis of the outlines of the Pa elements. The outlines are digitized from a TV image and quantified by calculating mean tangent angles within a specified number of intervals between landmarks. The mean tangent angles for each interval are the variables used in the canonical variate analysis. In a series of comparisons limited to three species each, all 13 species separate into isolated clusters that are completely congruent with the a priori groups based, with two exceptions, on multielement taxonomy. Thus, shape analysis provides a rigorous separation of closely similar species that have been difficult to distinguish by visual discrimination of the Pa elements. Shape analysis is treated herein as an integral part of the systematic descriptions. Newly described species are P. bohemica, P. boogaardi, P. luscarensis, and P. muelleri. The new taxonomic concepts lead to significant revisions in the biostratigraphic ranges of a number of species of Palmatolepis involved in the zonation and graphic correlation of the Frasnian Stage.
65 citations
01 Feb 1970
TL;DR: In this paper, two parallel but disparate conodont sequences are presented, which are presumed to represent different environments: one, the Palmatolepis sequence of the standard zonation is present in the uppermost beds of the Sadler Limestone at Sadler Ridge, the Gogo Formation and much but not all of the Virgin Hills Formation, and presumably represents an inter-reef faunal succession.
Abstract: Ninety species of conodont are recorded from rocks of Frasnian age in the Bugle Gap area in the Canning Basin of Western Australia: 56 of these species are reported for the first time from the Canning Basin. One new subspecies is described. Two parallel but disparate conodont sequences are present, which are presumed to represent different environments: one, the Palmatolepis sequence of the standard zonation is present in the uppermost beds of the Sadler Limestone at Sadler Ridge, the Gogo Formation, and much but not all of the Virgin Hills Formation, and presumably represents an inter‐reef faunal succession; the other consists of a sequence of Icriodus assemblages which is present in the Sadler Limestone and a part of the Virgin Hills Formation at Lawford Range. An Icriodus zonation is proposed for this sequence. No conodonts were recovered from many samples of the Pillara Limestone (back‐reef facies) in the Bugle Gap area. Conodont data presented here suggest that the Gogo Formation in this are...
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TL;DR: In this paper, the Frasnian palmatolepid conodonts are described in open nomenclature, and the holotype of Palmatolepis regularis Cooper is reillustrated.
Abstract: The Chattanooga Shale of the southern Appalachian Basin contains a diverse conodont fauna of the high Givetian, Frasnian, and Famennian. The predominantly fine-grained strata were deposited in an offshore setting where depositional packages are separated by unconformities. Conodonts allow regional and global correlation of these strata, recognition of the Frasnian-Famennian boundary, and narrow biostratigraphic constraint of two Frasnian ash beds, MN Zone 8 for the Belpre Ash and upper MN Zone 13 for the Center Hill Ash. Three new Frasnian palmatolepid conodonts are described in open nomenclature, and the holotype of Palmatolepis regularis Cooper is reillustrated.
44 citations
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...disparalvea (Orr and Klapper, 1968) indicative of the high Givetian disparilis Zone (Fig....
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1,612 citations
TL;DR: In this paper, a great variety of forms which I have collected within the last two years from several different formations in North America are described, and they will at least add something to our previous knowledge, and thus assist in reaching a decision on the subject.
Abstract: Soon after the publication by Dr. Pander, in 1856, of his wellknown monograph, in which he announced the discovery, in the lowest fossiliferous rocks of Russia, of small ‘teeth” named Conodonts, and referred by him to fishes, several discussions arose as to the character of these minute bodies, and various opinions were expressed as to their near relations, without, however, any satisfactory conclusion being arrived at. Since that date Conodonts have been found in several other places; and in this communication I propose to describe a great variety of forms which I have collected within the last two years from several different formations in North America. Though my specimens may not suffice to determine the true position of the organisms to which they were attached, they will at least add something to our previous knowledge, and thus assist in reaching a decision on the subject. The next account, after Dr. Pander9s, of the discovery of Conodonts is by Dr. J. Harley, in an article on the Ludlow bone-bed and its crustacean remains. Only two of the specimens described by this gentleman have any resemblance to the Conodonts of Pander; but a comparison of these with other very differently formed bodies in the same beds led him to express the opinion that all the forms were of crustacean origin, and that Conodonts were probably only spines similar to those attached to the margins of the carapace of Limulus and the caudal segment of Squilla. He therefore included all together under the provisional genus Astacoderma .
159 citations
01 Jan 1926
144 citations
Journal Article•
TL;DR: All late Devonian conodonts available from sedimentary facies of the Lennard Shelf, Canning basin, Western Australia, are described in this paper, where the maximum abundance of conodons is found in direct association with ammonoids in the inter-reef facies represented by the Gogo formation.
Abstract: All late Devonian conodonts available from sedimentary facies of the Lennard Shelf, Canning basin, Western Australia, are described The maximum abundance of conodonts is found in direct association with ammonoids in the inter-reef facies represented by the Gogo formation, and in the fore-reef and inter-reef facies of the Virgin Hills formation Associations of certain conodont and ammonoid taxa are identical with those in the classic antipodal Rhenish Schiefergebirge of Germany Distribution patterns show that the conodont and ammonoid zones are geologically homochronous on a mondial basis Playfordia ngen (conodont) and Ancyrodella rotundiloba alata nsubsp are described
78 citations