The Detroit River Group is Middle Devonian: Discussion on "Early Devonian age of the Detroit River Group, inferred from Arctic stromatoporoids"

1995 ◽  
Vol 32 (7) ◽  
pp. 1070-1073 ◽  
Author(s):  
Gilbert Klapper ◽  
William A. Oliver , Jr.
Keyword(s):  
Middle Devonian ◽  
Early Devonian ◽  
Detroit River ◽  
Devonian Age

New insights into the origins and radiation of the mid-Palaeozoic Gondwanan stem tetrapods

2018 ◽  
Vol 109 (1-2) ◽  
pp. 139-155 ◽  
Author(s):  
John A. LONG ◽  
Alice M. CLEMENT ◽  
Brian CHOO
Keyword(s):  
Middle Devonian ◽  
Late Devonian ◽  
Early Devonian ◽  
Biogeographic History ◽  
History Of ◽  
Scan Data ◽  
Devonian Age ◽  
High Degree ◽  
Phylogenetic Models

ABSTRACTThe earliest tetrapodomorph fishes appear in Chinese deposits of Early Devonian age, and by the Middle Devonian they were widespread globally. Evidence for the earliest digitated tetrapods comes from largely uncontested Middle Devonian trackways and Late Devonian body fossils. The East Gondwana Provence (Australasia, Antarctica) fills vital gaps in the phylogenetic and biogeographic history of the tetrapods, with the Gondwanan clade Canowindididae exhibiting a high degree of endemism within the early part of the stem tetrapod radiation. New anatomical details of Koharalepis, from the Middle Devonian Aztec Siltstone of Antarctica, are elucidated from synchrotron scan data. These include the position of the orbit, the condition of the hyomandibular, the shape of the palate and arrangement of the vomerine fangs. Biogeographical and phylogenetic models of stem tetrapod origins and radiations are discussed.

scholarly journals The Mandalovoo–Gurvansayhan terranes in the southern Gobi of Mongolia: new insights from the Bayankhoshuu Ruins section

2021 ◽  
Author(s):  
A. Munkhjargal ◽  
P. Königshof ◽  
J. A. Waters ◽  
S. K. Carmichael ◽  
S. Gonchigdorj ◽  
...  
Keyword(s):  
Middle Devonian ◽  
Facies Analysis ◽  
Volcanic Rocks ◽  
Late Devonian ◽  
Basaltic Lava ◽  
Sedimentary Sequence ◽  
Early Devonian ◽  
Subaerial Exposure ◽  
Arc Setting ◽  
Devonian Age

AbstractThe Bayankhoshuu Ruins section in southern Mongolia is characterized by strongly thrusted and folded sequences. Overall, three sections ranging from Ordovician to Carboniferous rocks were studied. Facies analysis combined with stratigraphic data provide improved lithostratigraphic descriptions of Palaeozoic successions in the Mushgai region. The overall marine sedimentary sequence is punctuated by volcanic rocks–basaltic lava of Silurian and Middle Devonian age and volcaniclastic bentonite and tuff in the Middle to Late Devonian and Mississippian suggesting an island arc setting. The Minjin Member of the Botuulkhudag Formation (Middle Devonian to Late Devonian) is primarily composed of thick basaltic and subaerial volcanic rocks with minor silicified siltstone and chert inclusions. Thicker successions of limestone occur in the Ordovician/Silurian, Early Devonian, and the Mississippian. The macrofauna is scarce, except distinct limestone horizons where different fossil groups were recognized. Microfossils, such as radiolarians and conodonts, are scarce and generally poorly preserved. However, based on the re-study of collections from earlier publications and new conodont data, a more detailed biostratigraphic record of the Khoyormod, Botuulkhudag, and Arynshand formations of the Bayankhoshuu Ruins section can be developed. For instance, the Arynshand Formation likely ranges from the late Bispathodus ultimus conodont biozone to the Scaliognathus anchoralis–Doliognathus latus conodont biozone. A tectonic breccia occurs in the early Mississippian and is overlain by a red shale of remarkable thickness at the top of this formation which points to subaerial exposure in the early Mississippian (near the Tournaisian/Visean transition). Due to strong tectonic overprint and/or facies, some unconformities/hiatuses occur. Most strata are intensively folded and faulted, ranging from centimeter to meter scale. Overall, deposition likely occurred on either the Mandalovoo or Gurvansayhan Terrane.

New chonostrophiid brachiopods from the Famennian (Late Devonian) of the Santanghu Basin, Xinjiang, northwest China

2002 ◽  
Vol 76 (2) ◽  
pp. 229-238
Author(s):  
Zhong-Qiang Chen ◽  
Neil W. Archbold
Keyword(s):  
Middle Devonian ◽  
New Genus ◽  
Early Carboniferous ◽  
Northwest China ◽  
Late Devonian ◽  
New Genera ◽  
New Genus And Species ◽  
Early Devonian ◽  
Median Septum ◽  
Devonian Age

Two new genera of the Chonostrophiidae are proposed herein to accommodate the resupinate shells from the Famennian sediments of the Late Devonian in the Santanghu Basin of the Balikun area, Xinjiang Province, northwestern China. Santanghuia santanghuensis new genus and species is distinguishable from other chonostrophiids by the possession of a pair of long dorsal anderidia and absence of a dorsal median septum. Balikunochonetes liaoi new genus and species is distinct because of the presence of a pair of anderidia with secondary anderidia, and a dorsal median septum. Santanghuia new genus is considered to be phylogenetically related to Chonostrophia of late Early to Middle Devonian age, while Balikunochonetes has possibly given rise to Chonostrophiella of Early Devonian age and is a likely ancestor of Tulcumbella of Early Carboniferous age.

Early Devonian age of the Detroit River Group, inferred from Arctic stromatoporoids

1993 ◽  
Vol 30 (12) ◽  
pp. 2465-2474 ◽  
Author(s):  
Eric C. Prosh ◽  
Colin W. Stearn
Keyword(s):  
United States ◽  
Close Relationships ◽  
Species Level ◽  
Ellesmere Island ◽  
The Arctic ◽  
Early Devonian ◽  
Detroit River ◽  
Devonian Age ◽  
First Time ◽  
Group Species

The Detroit River Group of southwestern Ontario and the adjacent United States has traditionally been considered mostly or entirely Middle Devonian in age. Detroit River Group faunas are, however, highly endemic and difficult to correlate to the chronostratigraphic standard; widely accepted conodont-based ages are similarly constrained by endemism and rely heavily upon inferential correlations. Recent evidence from the Blue Fiord Formation of southwestern Ellesmere Island suggests an Emsian (late Early Devonian) age for the full Detroit River Group, based upon shared stromatoporoid species. Four Detroit River Group species, Stromatoporella perannulata Galloway and St. Jean, Stictostroma mamilliferum Galloway and St. Jean, Habrostroma proxilaminata (Fagerstrom), and Parallelopora campbelli Galloway and St. Jean, are recognized for the first time in the Arctic. In addition, Blue Fiord Formation (and younger) species of Trupetostroma and Pseudoactinodictyon demonstrate close relationships to Detroit River Group species. Together, the stromatoporoid evidence and the available conodont data imply a serotinus age for the Amherstburg Formation and a serotinus to patulus age for the Lucas Formation. This is the first direct species-level correlation of a Detroit River Group "endemic" to a globally dateable level and the first regional application of stromatoporoid biostratigraphy in North America.

scholarly journals Palynological indications for Silurian – earliest Devonian age strata in the Netherlands

2021 ◽  
Vol 100 ◽  
Author(s):  
Alexander J.P. Houben ◽  
Geert-Jan Vis
Keyword(s):  
The Netherlands ◽  
Core Material ◽  
Late Devonian ◽  
Time Interval ◽  
The South ◽  
Early Devonian ◽  
The North ◽  
Depositional Settings ◽  
Palynological Study ◽  
Devonian Age

Abstract Knowledge of the stratigraphic development of pre-Carboniferous strata in the subsurface of the Netherlands is very limited, leaving the lithostratigraphic nomenclature for this time interval informal. In two wells from the southwestern Netherlands, Silurian strata have repeatedly been reported, suggesting that these are the oldest ever recovered in the Netherlands. The hypothesised presence of Silurian-aged strata has not been tested by biostratigraphic analysis. A similar lack of biostratigraphic control applies to the overlying Devonian succession. We present the results of a palynological study of core material from wells KTG-01 and S05-01. Relatively low-diversity and poorly preserved miospore associations were recorded. These, nonetheless, provide new insights into the regional stratigraphic development of the pre-Carboniferous of the SW Netherlands. The lower two cores from well KTG-01 are of a late Silurian (Ludlow–Pridoli Epoch) to earliest Devonian (Lochkovian) age, confirming that these are the oldest sedimentary strata ever recovered in the Netherlands. The results from the upper cored section from the pre-Carboniferous succession in well KTG-01 and the cored sections from the pre-Carboniferous succession in well S05-01 are more ambiguous. This inferred Devonian succession is, in the current informal lithostratigraphy of the Netherlands, assigned to the Banjaard group and its subordinate Bollen Claystone formation, of presumed Frasnian (i.e. early Late Devonian) age. Age-indicative Middle to Late Devonian palynomorphs were, however, not recorded, and the overall character of the poorly preserved palynological associations in wells KTG-01 and S05-01 may also suggest an Early Devonian age. In terms of lithofacies, however, the cores in well S05-01 can be correlated to the upper Frasnian – lower Famennian Falisolle Formation in the Campine Basin in Belgium. Hence, it remains plausible that an unconformity separates Silurian to Lower Devonian strata from Upper Devonian (Frasnian–Famennian) strata in the SW Netherlands. In general, the abundance of miospore associations points to the presence of a vegetated hinterland and a relatively proximal yet relatively deep marine setting during late Silurian and Early Devonian times. This differs markedly from the open marine depositional settings reported from the Brabant Massif area to the south in present-day Belgium, suggesting a sediment source to the north. The episodic presence of reworked (marine) acritarchs of Ordovician age suggests the influx of sedimentary material from uplifted elements on the present-day Brabant Massif to the south, possibly in relation to the activation of a Brabant Arch system.

Two new Devonian spine-bearing pleurotomariacean gastropod genera from Alaska

1989 ◽  
Vol 63 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Robert B. Blodgett ◽  
David M. Rohr
Keyword(s):  
Middle Devonian ◽  
New Genera ◽  
Early Devonian ◽  
Old World ◽  
West Central ◽  
Cool Temperate ◽  
Warm Temperate

Two new spine-bearing gastropods, Chlupacispira spinosa n. gen. and sp. and Spinulrichospira cheeneetnukensis n. gen. and sp., are described from the late Early Devonian (Emsian) and early Middle Devonian (Eifelian), respectively, of west-central Alaska. These represent the earliest reported spiny pleurotomariacean gastropods. Otherwise, spinose pleurotomariaceans are known from strata no older than Carboniferous age. Spinulrichospira cheeneetnukensis n. gen. and sp. appears to represent a more highly ornamented derivative of Ulrichospira Donald. Both new genera are part of the more highly ornamented fauna which occurred in warm equatorial waters of the Old World Realm during the Early and Middle Devonian, in contrast to more weakly ornamented shells of the Eastern Americas Realm and even more weakly ornamented (almost totally “plain”) shells of the Malvinokaffric Realm. The latter two realms are thought to represent subtropical to warm temperate and cool temperate to cool polar conditions, respectively.

Adaptive function and phylogenetic significance of novel skeletal features of a new Devonian microconchid tubeworm (Tentaculita) from Wyoming, USA

2021 ◽  
pp. 1-15
Author(s):  
Michał Zatoń ◽  
Mingxi Hu ◽  
Mercedes di Pasquo ◽  
Paul M. Myrow
Keyword(s):  
Middle Devonian ◽  
New Genus ◽  
Adaptive Strategy ◽  
Phylogenetic Significance ◽  
New Genus And Species ◽  
Adaptive Function ◽  
Faunal Assemblage ◽  
Early Devonian ◽  
Narrow Channels ◽  
Algal Thalli

Abstract A new genus and species of microconchid tubeworm, Aculeiconchus sandbergi n. gen. n. sp., is described from the Givetian (Devonian) Maywood Formation of Cottonwood Canyon, Wyoming, USA. It possesses unique hollow spines of various lengths on the tube underside, a position previously undocumented for these fossils. Like some cyclostome bryozoans possessing basal tubular extensions, the basal spines of Aculeiconchus n. gen. were presumably also used for fixation to flexible substrata, e.g., algal thalli, which is a previously undocumented adaptive strategy in microconchids. Together with other skeletal features, such basal spines could suggest that ‘lophophorate’ microconchids, unlike the other tentaculitoids, might be phylogenetically not as distant from bryozoans as previously thought. The Maywood Formation, which contains a few-millimeters thick, monospecific shell accumulation of the microconchids described herein, records deposition in an estuarine brackish setting within narrow channels that were cut into underlying strata. The microconchids were opportunistic taxa that repeatedly colonized these salinity-stressed estuarine channels, leading to a series of adaptive innovations, including colonization of plant stems during the Early Devonian (Beartooth Butte Formation) and possibly flexible, soft-algal substrata during the Middle Devonian (Maywood Formation, this study). Tectonic quiescence during the Early and Middle Devonian indicates that erosion and subsequent deposition of the Maywood and the underlying Beartooth Butte Formation channels were responses to major eustatic events. Over a span of nearly 30 Myr, channels were cut successively during lowstand conditions and a distinctive faunal assemblage with microconchids tracked marine transgressions into the channels. UUID: http://zoobank.org/394c8b32-d5e7-411e-8e56-6fb9f55bbb8a

scholarly journals Graptolite dynamics in Silurian and Devonian time

1987 ◽  
Vol 35 ◽  
pp. 149-159
Author(s):  
T. N. Koren'
Keyword(s):  
Environmental Factors ◽  
Sea Level ◽  
Comparative Studies ◽  
Climate Changes ◽  
Environmental Changes ◽  
Time Intervals ◽  
Early Devonian ◽  
Carbonate Sedimentation ◽  
Reference Sections ◽  
Devonian Age

On the basis of biostratigraphic data known at present some preliminary attempts are made to evaluate graptolite dynamics, that is changes in graptolite diversity in time and space within pelagic fades of Si­lurian and Early Devonian age. For the comparative studies of diversity fluctuations versus some major environmental changes a standard graptolite zonation is used. Several critical and more or less well stu­died stratigraphical intervals are chosen; among them the Ordovician/Silurian, Sheinwoodian/Gorstian and Gorstian/Ludfordian boundary beds. For each level the most complete reference sections are analy­zed. Special attention is given to the graptolite extinction, specification and radiation events within these time intervals. They might have been partly connected with or influenced by the environmental factors as a result of eustatic sea-level and climate changes, alteration of anoxic conditions, migration of carbonate sedimentation in pelagic direction, and other globally detectable events. The graptolite evolution during the time of monograptid existence can be subdivided into three phases using the comparison of the ampli­tude of the extinction-origination events and repeatability of the synphasic cycles.

Deformation associated with gypsum karst in the Salt River Escarpment, northeastern Alberta

1984 ◽  
Vol 21 (8) ◽  
pp. 949-959 ◽  
Author(s):  
Po C. Tsui ◽  
David M. Cruden
Keyword(s):  
Groundwater Flow ◽  
Northwest Territories ◽  
Middle Devonian ◽  
Normal Faults ◽  
Gypsum Karst ◽  
Salt River ◽  
Fort Smith ◽  
Devonian Age ◽  
Northeastern Alberta ◽  
Subsurface Cavities

An escarpment formed by the carbonate Keg River and evaporitic Chinchaga formations of Middle Devonian age extends southwards from the Slave River 30 km west of Fort Smith, Northwest Territories. Newly described folds in the bedrock are due to hydration of the anhydrite to gypsum in the Chinchaga Formation underlying the escarpment. Local groundwater flow has also dissolved subsurface cavities in the Chinchaga Formation. As these openings grew, the carbonates of the Keg River Formation subsided along stepped normal faults. Depressions within the fault blocks occurred where subsidence was concentrated along joints.

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