Untangling a Darriwilian (Middle Ordovician) palaeoecological event in Baltoscandia: conodont faunal changes across the ‘Täljsten’ interval

2009 ◽  
Vol 100 (04) ◽  
pp. 353-370 ◽  
Author(s):  
Johanna I. S. Mellgren ◽  
Mats E. Eriksson
Keyword(s):  
High Resolution ◽  
Close Correlation ◽  
Environmental Indicators ◽  
Lower Half ◽  
Thick Section ◽  
Zone Boundary ◽  
Middle Ordovician ◽  
Abundance Patterns ◽  
Low Diversity

ABSTRACTConodont faunal dynamics and high-resolution biostratigraphy in the lithologically and faunally anomalous ‘Täljsten’ succession, which spans the DarriwilianLenodus variabilis–Yangtzeplacognathus crassusZone boundary, were investigated in a 2·5 m-thick section on Mt Kinnekulle that includes an interval yielding fossil meteorites and extraterrestrial chromite. The previous interpretation that this interval reflects a regression is consistent with the occurrence and abundance patterns of some conodont taxa. The disappearance of e.g.,Periodon, suggests that the regression began prior to the deposition of the grey ‘Täljsten’. The transition from red to grey limestone coincides with a conspicuous faunal re-arrangement. The lower half of the ‘Täljsten’ reflects a gradual shallowing favourable for some taxa, such asLenodus, and the immigration ofMicrozarkodinacf.ozarkodellaandHistiodella holodentata. In the middle of the ‘Täljsten’ interval, coinciding with the appearance of abundant cystoids, conditions became less hospitable for conodonts, resulting in a low diversity and low abundance fauna, which occurs to the top of the interval. The overlying red limestone, apparently deposited during a deepening event, marks a return to pre-‘Täljsten’ conditions with a re-organised fauna. The close correlation between the lithologic shifts and conodont faunal changes demonstrates the usefulness of conodonts as environmental indicators.

Telephinaand Other Trilobites from the Pratt Ferry Beds, Ordovician of Alabama, U.S.A.

2014 ◽  
Vol 88 (3) ◽  
pp. 545-555 ◽  
Author(s):  
Frederick C. Shaw
Keyword(s):  
North America ◽  
North American ◽  
Original Description ◽  
Eastern North America ◽  
Zone Boundary ◽  
Middle Ordovician ◽  
Conodont Zone ◽  
Stratigraphic Range ◽  
Single Locality

The Pratt Ferry beds are a three meter thick bioclastic carbonate unit containing thePygodus serrus–P. anserinusconodont zone boundary and lying just below theNemagraptus gracilisgraptolite zone at a single locality in Alabama.TelephinaMarek at Pratt Ferry and other eastern North American localities is represented by at least six species. These are judged widespread and in part conspecific with Scandinavian or Asian forms of similar age. Most of the fifteen Appalachian telephinid species proposed by Ulrich (1930) are reviewed and some synonymized.BevanopsisCooper is present, extending its stratigraphic range viaB. buttsi(Cooper). The original description ofCeraurinella buttsiCooper is augmented. Other recorded but poorly represented genera includeAmpyxina,Arthrorhachis,Calyptaulax,Hibbertia,Lonchodomas,Mesotaphraspis,Porterfieldia, andSphaerexochus. The entire faunule represents a mixture of ‘inshore’ and ‘offshore’ or planktonic faunal elements rarely seen elsewhere in the latest Middle Ordovician (Darriwilian) of eastern North America.

Early radiation of echinoderms

1997 ◽  
Vol 3 ◽  
pp. 205-224 ◽  
Author(s):  
James Sprinkle ◽  
Thomas E. Guensburg
Keyword(s):  
Mass Extinction ◽  
Fossil Record ◽  
Early Paleozoic ◽  
Soft Substrate ◽  
Middle Cambrian ◽  
Middle Ordovician ◽  
Late Cambrian ◽  
Low Diversity ◽  
Early Radiation ◽  
Ways Of Life

Echinoderms underwent a major two-part radiation that produced all of the major groups found in the fossil record between the Early Cambrian and the Middle Ordovician. A small initial radiation in the Early and Middle Cambrian produced about nine classes containing low-diversity members of the Cambrian Evolutionary Fauna. These were characterized by primitive morphology, simple ambulacral feeding structures, and the early development of a multiplated stalk or stem for attachment to skeletal fragments on a soft substrate. Several groups became extinct at the end of the Middle Cambrian, leaving the Late Cambrian as a gap of very low diversity in the fossil record of echinoderms with only four classes preserved and very few occurrences of complete specimens, mostly associated with early hardgrounds. The survivors from this interval re-expanded in the Early Ordovician and were joined by many newly evolved groups to produce a much larger radiation of more advanced, diverse, and successful echinoderms representing the Paleozoic Evolutionary Fauna on both hard and soft substrates. At least 17 classes were present by the Middle Ordovician, the all-time high point for echinoderm class diversity, and nearly all of the major ways-of-life (except for deep infaunal burrowing) had been developed. With the rise to dominance of crinoids, many less successful or archaic groups did not survive the Middle Ordovician, and echinoderm class diversity dropped further because of the mass extinction at the end of the Ordovician. This weeding-out process of other less-successful echinoderm groups continued throughout the rest of the Paleozoic, and only five classes of echinoderms have survived to the Recent from this early Paleozoic radiation.

Middle Ordovician (Whiterockian) trilobites from the Sunblood Formation, District of Mackenzie, Canada

1991 ◽  
Vol 65 (5) ◽  
pp. 801-824 ◽  
Author(s):  
James V. Tremblay ◽  
Stephen R. Westrop
Keyword(s):  
New Species ◽  
North America ◽  
The South ◽  
Middle Ordovician ◽  
Low Diversity ◽  
Shallow Subtidal ◽  
Three New Species

In the South Nahanni River area of the District of Mackenzie, the Middle Ordovician Sunblood Formation comprises mainly limestones and dolostones of intertidal and shallow-subtidal origin, as indicated by the presence of desiccation polygons, fenestral fabric, and oncolites. Faunas of well-preserved, silicified trilobites from a low-diversity, nearshore, Bathyurus-dominated biofacies are compositionally distinct from faunas in correlative strata around North America that represent different shelf to upperslope biofacies. A temporal biostratigraphy applicable to nearshore biofacies through much of the Whiterockian Series consists of five zones, in ascending order: Bathyurus mackenziensis, B. sunbloodensis, B. margareti, B. nevadensis, and B. granulosus. Twenty-six species are assigned to 18 genera, of which Ludvigsenella is new. Three new species of Bathyurus are B. mackenziensis, B. sunbloodensis, and B. margareti.

Integrated chitinozoan, conodont, and graptolite biostratigraphy from the upper part of the Cape Cormorant Formation (Middle Ordovician), western Newfoundland

2001 ◽  
Vol 38 (3) ◽  
pp. 387-409 ◽  
Author(s):  
Roberto Albani ◽  
Gabriella Bagnoli ◽  
Jörg Maletz ◽  
Svend Stouge
Keyword(s):  
Early Stage ◽  
Foreland Basin ◽  
Black Shales ◽  
Head Group ◽  
Middle Ordovician ◽  
Head Groups ◽  
Taconic Orogeny ◽  
Low Diversity ◽  
Conodont Fauna ◽  
Abundance And Diversity

The Cape Cormorant Formation of the Table Head Group exposed on the Port au Port Peninsula, western Newfoundland, is composed of dark-brown to black shales with interbeds of thin calcareous silty and sandy distal turbidites. Distinctive carbonate conglomerates and breccias derived from the foundering shelf are occasionally found in the formation. The sediments accumulated in the foreland basin formed during the early stage of the Taconic orogeny. The faunas from the upper part of the Cape Cormorant Formation include graptolites, conodonts, and chitinozoans. The graptolites are well preserved, but are of low diversity and are referred to the Darriwil Pterograptus elegans Zone. Conodonts recorded from the distal turbidites are rare and fragmented. The faunas include taxa that are known from the St. George and Table Head groups. The conodont fauna is tentatively assigned to the Histiodella kristinae Phylozone and to the younger, unzoned interval. The chitinozoans are well preserved and the yield is high. The fauna is assigned to the Cyathochitina jenkinsi Zone and to an undefined interval. The abundance and diversity of the chitinozoan assemblages display a cyclic pattern, which is related to changes of the oceanic watermass in the foreland basin. The new chitinozoan species Belonechitina nevillensis n. sp., Belonechitina uniformipunctata n. sp., and Cyathochitina cormorani n. sp. are described.

High resolution trilobite stratigraphy of the Lower–Middle Ordovician Öland Series of Baltoscandia

2012 ◽  
Vol 150 (3) ◽  
pp. 509-518 ◽  
Author(s):  
HELJE PÄRNASTE ◽  
JAN BERGSTRÖM ◽  
ZHOU ZHIYI
Keyword(s):  
High Resolution ◽  
Horizontal Distribution ◽  
Middle Ordovician ◽  
Bituminous Shale ◽  
Vertical And Horizontal Distribution

AbstractThe first ever list of the regional Öland Series (Tremadocian to mid Darriwilian) trilobites and agnostids from the whole of Baltoscandia is compiled. The study includes revision of systematics as well as vertical and horizontal distribution. This is necessary because of the uneven state of knowledge, some faunas having being studied recently, others not for more than a century. Three successive faunal types are recognized: the Olenid Fauna surviving from the Cambrian in black bituminous shale facies, the immigratingCeratopygeFauna, and the stabilized Asaphid Fauna. The latter fauna collapsed in the middle of Darriwilian and gave way to a set of new post-Ölandian faunas.

Initial diversification of macroboring ichnofossils and exploitation of the macroboring niche in the lower Paleozoic

Paleobiology ◽  
1978 ◽  
Vol 4 (2) ◽  
pp. 163-170 ◽  
Author(s):  
David R. Kobluk ◽  
Noel P. James ◽  
S. George Pemberton
Keyword(s):  
Lower Cambrian ◽  
High Stress ◽  
Lower Paleozoic ◽  
Middle Ordovician ◽  
Rapid Speciation ◽  
Low Diversity ◽  
Stress Environment ◽  
Boring Organisms

The traces of macroboring organisms are known throughout the Phanerozoic, with diversification and exploitation of the macroboring niche paralleling variations in the development of skeletal metazoa. The oldest macroboring biota is an abundant yet low diversity fauna in hardgrounds and reefs of Lower Cambrian age. Following the extinction of archaeocyathids at the end of the Lower Cambrian (and thus the demise of skeletal reefs until the Middle Ordovician), boring organisms appear to be restricted to submarine hardgrounds. With the development of skeletal reefs in the Middle Ordovician the macroboring fauna shows a rapid speciation and a dramatic increase in diversity. This same pattern occurs again in the Devonian. This record appears to represent refuge of the fauna in low stress, hardground environments when skeletal reefs were not present and radiation in the high stress environment of the reef when large skeletal metazoa were abundant and diverse.

Sign in / Sign up

Export Citation Format

Share Document