scholarly journals Vertebrate fauna genesis in the Middle Paleozoic Podolian paleobasin

2020 ◽  
pp. 195-208
Author(s):  
Victor Voichyshyn
Keyword(s):  
Shallow Water ◽  
Sharp Increase ◽  
Evolutionary Development ◽  
Ecological Niches ◽  
Early Devonian ◽  
Vertebrate Fauna ◽  
High Ranking ◽  
Middle Paleozoic ◽  
Local Endemic

The formation of the Early Devonian ichthyofauna occurred under the combined influence of historical, paleogeographic and paleoecological factors. A consequence of evolutionary development at the beginning of the Devonian period arose a number of high-ranking taxa of sea vertebrates, which actively colonized the shallow water basins of new continent Laurussia. For representatives of local endemic faunas there was an opportunity to expand their habitats. There were exchanges of migrants between neighboring regional faunas. All this was accompanied by the evolution of ecosystems, the formation and development of new ecological niches. Early Devonian for most groups of vertebrates was marked by a sharp increase in the number of taxonomic units. The formation of Podillya regional ichthyofauna illustrates these trends of global biotic changes in that time.

Paleogeographie devonienne et mineralisations ferrugineuses de Dielette (Manche) et plombo-zinciferes de Surtainville (Manche)

1964 ◽  
Vol S7-VI (1) ◽  
pp. 121-126 ◽  
Author(s):  
Marie Jose Pavillon
Keyword(s):  
Shallow Water ◽  
Early Devonian ◽  
Lead Zinc ◽  
Caledonian Orogeny

Abstract Marine clastic formations of Cambrian, Ordovician, and Silurian age in the Flamanville area of northwestern France were folded during the Caledonian orogeny into a series of broad anticlinal and synclinal folds with the tops of the anticlines emergent and undergoing erosion by early Devonian time. The earlier Devonian formations were formed by deposition of the detritus in the adjacent synclinal troughs. Later deposits formed after renewed subsidence show facies differences between the marine shallow-water areas of the anticlinal crests, the deeper water of the flanks, and the deepest water of the synclinal troughs. Ferruginous oolite beds occur in marine sandy shales in the northern part of the area, and veinlets of lead-zinc mineralization occur in the southern part. The minerals probably were deposited in the original sediments, and later metamorphosed by intrusion of the Flamanville granite whose contact-metamorphic effects are prominent. The iron mineralization probably was deposited in marine shallows, and the lead-zinc minerals in adjoining belts.

The Reproductive Biology of the Deep-Sea Asteroid Bathybiaster Vexillifer

1982 ◽  
Vol 62 (1) ◽  
pp. 57-69 ◽  
Author(s):  
P. A. Tyler ◽  
S. L. Pain ◽  
J. D. Gage
Keyword(s):  
Shallow Water ◽  
Reproductive Biology ◽  
Deep Sea ◽  
Reproductive Strategies ◽  
Ecological Niches ◽  
Physico Chemical ◽  
Males And Females ◽  
Planktotrophic Larvae ◽  
Shallow Water Species ◽  
Water Species

INTRODUCTIONThe reproductive biology of asteroids from a wide variety of ecological niches has been examined (Farmanfarmaian et al. 1958; Cognetti & Delavault, i962;Pearse, 1965; Chia, 1968; Crump, 1971; Jangoux & Vloebergh, 1973; Worley, Franz & Hendler, 1977; Barker, 1979; Shick, Taylor & Lamb, 1981). Most of the species within this class appear to show some degree of seasonal reproductive synchrony with very few species showing aseasonal reproduction (Shick et al. 1981). Although the seasonally reproducing asteroids show a wide variety of reproductive strategies, from planktotrophic larvae to direct development, they all occur in relatively shallow water and are thus subject to the seasonal fluctuations of the physico-chemical environment. Only two shallow-water species, Ctenodiscus crispatus (Shick et al. 1981) and Patiriella exigua (Lawson-Kerr & Anderson, 1978), have aseasonal reproduction in both males and females. However, the deep sea is the only major environment in the world's ocean for which we have no data for the reproductive cycle of asteroids.

Shallow water mud-mounds of the Early Devonian Buchan Group, East Gippsland, Australia

2012 ◽  
Vol 281 ◽  
pp. 208-221 ◽  
Author(s):  
A.-M.P. Tosolini ◽  
M.W. Wallace ◽  
S.J. Gallagher
Keyword(s):  
Shallow Water ◽  
Early Devonian ◽  
Mud Mounds

Silurian orogenesis in the western Penobscot Bay region, Maine

1995 ◽  
Vol 32 (11) ◽  
pp. 1845-1858 ◽  
Author(s):  
David P. West Jr ◽  
Charles V. Guidotti ◽  
Daniel R. Lux
Keyword(s):  
New England ◽  
Regional Metamorphism ◽  
Thrust Fault ◽  
Low Grade ◽  
Early Devonian ◽  
Middle Paleozoic ◽  
Thermal Signature ◽  
Structural Levels ◽  
Stratigraphic Boundary ◽  
Penobscot Bay

New 40Ar/39Ar mineral ages from rocks collected west of Penobscot Bay, Maine, indicate this region was regionally deformed, metamorphosed to amphibolite facies conditions, and intruded by plutons in Silurian times rather than in the Devonian as previously assumed. Disturbed hornblende age spectra, along with the presence of some Devonian felsic plutons and extensive retrograde metamorphic textures do suggest, however, that these rocks were subsequently affected by low-grade Devonian thermal events. In sharp contrast, rocks west of the Sennebec Pond thrust fault, a major tectono-stratigraphic boundary in this region, lack a significant Silurian tectono-thermal signature, and instead record the effects of intense Devonian deformation and high-grade regional metamorphism. The data suggest the two regions experienced very different pre-Devonian histories and were most likely juxtaposed by the Sennebec Pond thrust fault in latest Silurian to Early Devonian time. Rocks now exposed east of the Sennebec Pond fault probably occupied much higher structural levels during Devonian orogenesis and were not subjected to the same intense Devonian deformation and metamorphism as those rocks now found to the west of this structure. The Silurian tectonism now recognized in this region bears striking resemblance to events of similar age recorded along the northwest margin of the Avalon composite terrane throughout much of Atlantic Canada. This greatly extends the zone of Silurian orogenesis in the northern Appalachians and requires that previous models of New England middle Paleozoic tectonism be significantly revised.

Early Devonian conodonts from a limestone horizon in the Caballos Novaculite, Marathon Uplift, west Texas

1995 ◽  
Vol 69 (6) ◽  
pp. 1112-1122
Author(s):  
James E. Barrick ◽  
Paula J. Noble
Keyword(s):  
North America ◽  
Shallow Water ◽  
North American ◽  
Early Devonian ◽  
West Texas ◽  
Close Proximity ◽  
Northwestern Margin ◽  
Carbonate Material ◽  
Water Carbonate ◽  
Shallow Water Carbonate

Early Devonian (Lochkovian; eurekaensis Zone) conodonts occur in discontinuous limestone beds in the Caballos Novaculite at five localities in the northwestern half of the Marathon uplift, west Texas. Similar conodont faunas at all five localities indicate that the limestone beds lie at one biostratigraphic horizon within the Caballos. The upper novaculite member directly overlies the limestone horizon at one locality, giving the upper novaculite a maximum age of Lochkovian. The limestone beds are dominantly skeletal calcarenites that represent shallow-water carbonate material transported into a deeper water setting by gravity processes. Restriction of the limestones to the northwestern margin of the uplift and provenance of reworked clasts and redeposited Ordovician and Silurian conodonts suggest a North American shelf source and are evidence of the close proximity of some strata exposed in the Marathon uplift to North America in the Early Devonian. Icriodus gravesi n. sp. is described from the limestone fauna.

Bringing planktonic crinoids back to the bottom: Reassessment of the functional role of scyphocrinoid loboliths

Paleobiology ◽  
2019 ◽  
Vol 46 (1) ◽  
pp. 104-122
Author(s):  
Przemysław Gorzelak ◽  
Dorota Kołbuk ◽  
Mariusz A. Salamon ◽  
Magdalena Łukowiak ◽  
William I. Ausich ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Distal Portion ◽  
Unconsolidated Sediments ◽  
Ecological Niches ◽  
Filter Feeder ◽  
Recumbent Posture ◽  
Distal Side ◽  
Middle Paleozoic ◽  
Long Stem ◽  
Gas Leaks

AbstractLiving crinoids are exclusively passive suspension feeders and benthic as adults. However, in the past they adapted to a broad range of ecological niches. For instance, the stratigraphically important middle Paleozoic scyphocrinoids are hypothesized to have been planktonic, employing their inferred gas-filled globular, chambered structure at the distal end of the stem, the so-called lobolith, as a buoyancy device with the crinoid calyx suspended below it. Here, we evaluate this hypothesis using evidence from skeletal micromorphology and theoretical biomechanical modeling. Lobolith walls are typically composed of ossicles, which are exclusively composed of constructional labyrinthic stereom. In plates from the distal side of the lobolith, this stereom extends into microperforate stereom layer, forming wavy ridges and spines. No microscale adaptations for preventing gas leaks and/or ingress of water (such as internal and external imperforate stereom layers) are known. Furthermore, theoretical calculations suggest that the scyphocrinoid tow-net mode of feeding would have resulted in small relative velocities between the towed filter and the ambient water, thus making it an ineffective passive filter feeder. We suggest that the lobolith of these crinoids acted as a modified holdfast rather than as a floating buoy. Its globular shape and distally positioned microspines served as adaptations for living in unconsolidated sediments, analogous to iceberg- and snowshoe-like strategies used by some mollusks and brachiopods. Like modern isocrinids, scyphocrinoids could have maintained an upright feeding posture by extending the distal portion of the stalk along the bottom. In this recumbent posture, the distal part of the stalk with the lobolith might have functioned as a drag anchor. As a consequence of the ~3-m-long stem, even with this posture, the benthic scyphocrinoids could have risen to the highest epifaunal tier in the Paleozoic.

scholarly journals The role of environment in the diversity and evolutionary turnover rates of the Foraminiferida

1992 ◽  
Vol 6 ◽  
pp. 278-278 ◽  
Author(s):  
S.W. Starratt
Keyword(s):  
Shallow Water ◽  
Sea Level ◽  
Deep Water ◽  
Taxonomic Diversity ◽  
Late Paleozoic ◽  
Ecological Niches ◽  
Time Interval ◽  
Turnover Rates ◽  
Extinction Event

Taxonomic databases are important tools in the study of faunal diversity and evolution. The usefulness of the inferences drawn from these databases is diminished when the role of environment is not considered. Analysis of the foraminiferal database at the genus and family levels is used to demonstrate the effect of water depth on presumed changes in taxonomic diversity and evolutionary turnover rates.This paleoenvironmental effect is particularly noticeable when foraminiferal faunas of the late Paleozoic and the Mesozoic and Cenozoic intervals are compared. The late Paleozoic fauna is dominated by the Fusulinina and shallow-water (0–200 m) Textularuna. Standing diversity fluctuates greatly, and evolutionary turnover is high. This reflects short-term fluctuations in sea level which led to the rapid formation and destruction of narrow ecological niches. Evolutionary turnover appears to be related to reef growth during this time. This trend may also reflect an increased number of k-selected specialists which serve as proxy indicators for a slow-circulating oligotrophic ocean system. Shallow-water taxa may also be predisposed to extinction due to their reliance on symbiotic algae. The extinction event at the end of the Permian resulted in the loss of almost 70% of the standing generic diversity. This included the complete loss of the Fusulinina as well as a number of shallow-water textularids. Cohort survivorship curves are steep and taxon ages short during this time.The diversity increase over the past 245 million years has largely been due to the addition of deep-water (200-10,000 m) taxa. This was particularly true during the Late Cretaceous and early Eocene, and may reflect the relatively high eustatic sea level during those intervals. The relationship between reef development and evolutionary turnover rates is less clear during this time interval. Although the extinction event that marked the end of the Cretaceous resulted in a greater loss in absolute taxonomic diversity than occurred at the end of the Permian, the relative loss in generic diversity was only about 21% due to the large number of deep-water taxa. When the entire fauna is considered, cohort survivorship curves are less steep and taxon ages are longer than in the late Paleozoic, but when only the shallow-water taxa are considered, the results are similar to those for the late Paleozoic.

scholarly journals The Rockalliidae, a new family of Cainozoic Cytheracean Ostracoda

1982 ◽  
Vol 1 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Robin Whatley ◽  
Henning Uffenorde ◽  
Christopher Harlow ◽  
Sian Downing ◽  
Karin Kesler
Keyword(s):  
New Species ◽  
Shallow Water ◽  
Evolutionary Development ◽  
New Family

Abstract. The Rockalliadae, a new family of Cytheracean Ostracoda, is erected based on Rockallia Whatley, Frame & Whittaker, 1978 and an undescribed genus from the Tertiary of Argentinian Patagonia. Rockallia, hitherto monotypic, is augmented by the description herein of five new species: R. eocenica, R. vscripta and R. inceptiocelata from the Eocene, Neogene and Quaternary of the S.W. Pacific respectively and R. woutersi and R. sp. from the Oligocene and Miocene of N.W. Europe. The older species seem to have lived in relatively shallow water while the younger species are exclusively bathyal and abyssal. The genus is rediagnosed and its origins, evolutionary development and dispersal are discussed.

The green algaChaetocladus(Dasycladales)

1997 ◽  
Vol 71 (5) ◽  
pp. 940-949 ◽  
Author(s):  
Steven T. LoDuca
Keyword(s):  
New York ◽  
New Species ◽  
Green Alga ◽  
Early Diagenesis ◽  
Early Paleozoic ◽  
Comprehensive Investigation ◽  
Early Devonian ◽  
Middle Ordovician ◽  
Incertae Sedis ◽  
Middle Paleozoic

Two species of the enigmatic algaChaetocladus, C. ruedemanni(new species) andC. dubius(previously regarded as a graptolite incertae sedis), are described from the Silurian Lockport Group of New York and Ontario, Canada, respectively. A comprehensive investigation reveals that these and otherChaetocladustaxa occur in distinctive Konservat-Lagerstätten in association with other thallophytic algae, annelid worms, and lightly sclerotized arthropods. The sedimentology, taphonomy, and biotic composition ofChaetocladus-bearing deposits indicate that this alga thrived in shallow, stagnant, occasionally storm-agitated marine environments. In these settings, preservation of thallophytic algae and associated soft-bodied animals apparently was facilitated by a combination of obrution, anoxia, and early diagenesis of the burial muds.The morphology ofChaetocladuscorresponds to that characteristic of the green alga order Dasycladales, and it is herein referred to this long-ranging taxon as a representative of a new subtribe (Chaetocladinae, new subtribe) within the tribe Salpingoporelleae (emended herein), family Triploporellaceae (emended herein). This euspondyl, endosporate genus extends the range of the euspondyl dasyclads significantly, from the Early Devonian back to the Middle Ordovician, and bridges an evolutionary gap between early Paleozoic aspondyl, endosporate forms and middle Paleozoic euspondyl, cladosporate forms.

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