Terminal Cambrian and lowest Ordovician succession of Mexican West Gondwana: biotas and sequence stratigraphy of the Tiñu Formation

Landing, Ed; Westrop, Stephen R.; Keppie, J. Duncan

doi:10.1017/s0016756807003585

Cited by 87 publications

(100 citation statements)

References 58 publications

(123 reference statements)

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“…Only three such occurrences of orthoceroids are known, and one of these is ambiguous. Slemmestadoceras attavus (Brøgger, 1882) occurs with an as yet undescribed Ellesmeroceras Foerste, 1921 in the middle Tremadocian Bjørksholmen Formation in Norway (Kraeger 2008), and the middle Tremadocian collection from the Rio Salinas Member, Tiµu Formation of Oaxaca State, Mexico, which is dominated by Rioceras and as yet undescribed eothinoceratids (Flower 1968;Landing et al 2007). Wilson (1954) (Thoral, 1935), Bactroceras mourguesi (Thoral, 1935), and Rioceras estivali (Thoral, 1935) (Fortey & Owens 1987).…”

Section: Synopsis -Faunal Composition and Depositional Settingmentioning

confidence: 99%

Review and palaeoecological analysis of the late Tremadocian - early Floian (Early Ordovician) cephalopod fauna of the Montagne Noire, France

Kröger¹,

Evans

2011

Fossil Record

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HS‐26, the mouse homologue of HS‐40, is the major regulatory element of the mouse α‐globin gene locus. Like HS‐40, HS‐26 is located within an intron of a house‐keeping gene; comparison of the nucleotide sequences of HS‐26 and HS‐40 reveals conservation of the sequences and positions of several DNA binding motifs in the 5′ regions of both elements (3 GATA, 2 NFE‐2, and 1 CACCC sites) and the absence in HS‐26 of three CACCC sites and one GATA site that are present in the 3′ region of HS‐40, suggesting that the two elements might not be identical. We report here that when HS‐26 is linked to a 1.5 kb Psti human α‐globin gene fragment, it has a weak enhancer activity in induced MEL cells and in transgenic embryos, and it does not have any detectable activity in adult transgenic mice. This suggests that HS‐26 does not have Locus Control Region (LCR) activity but can act as an enhancer during the embryonic life when integrated at a permissive locus. To further test the importance of HS‐26 at its natural locus, we have generated embryonic stem cells and chimeric animals in which 350 bp containing HS‐26 have been replaced by a neomycin resistance gene by homologous recombination. The sizes of the chimeras' red cells were then estimated by measuring forward scattering on a FacsScan apparatus in hypotonic conditions. This revealed that a fraction of the chimeric animals' red cells were smaller than normal mouse red cells and were very similar to cells from mice heterozygous for α‐thalassemia. Density gradient analysis also suggested the presence of thalassemic cells. These results indicated that despite its lack of LCR activity, HS‐26 is important for the regulation of the mouse α‐globin gene locus. Am. J. Hematol. 54:30–39, 1997 © 1997 Wiley‐Liss, Inc.

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Section: Synopsis -Faunal Composition and Depositional Settingmentioning

confidence: 99%

Review and palaeoecological analysis of the late Tremadocian - early Floian (Early Ordovician) cephalopod fauna of the Montagne Noire, France

Kröger¹,

Evans

2011

Fossil Record

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“…Landing et al (1978) showed that Cordylodus proavus appears in the Westergaardia Subzone of the middle Acerocare Zone of Avalonian New Brunswick, and this puts an upper bracket on the correlation of the Eoconodontus Zone in the Avalonian and Baltic trilobite successions. The underlying upper Peltura Zones yield Proconodontus serratus¸a chararacteristic form of the Eoconodontus Zone, along with Cordylodus andresi in the Peltura scarabaeoides Zone of Sweden (Szaniawski & Bengtson 1998).…”

Section: Global Correlation Of the Eoconodontus Notchpeakensis Zonementioning

confidence: 99%

“…The lowest specimens of Eoconodontus notchpeakensis occur in platform and upper slope facies of the lower Tiñu Formation in Mexican West Gondwana above the Cordylodus andresi FAD (Landing et al 2007a). Although definition of a biostratigraphically significant E. notchpeakensis FAD can be readily done in the lower Tiñu Formation, the FAD is from a part of the section with provincial (Gondwanan) species of geographically widespread trilobite genera.…”

Section: Global Correlation Of the Eoconodontus Notchpeakensis Zonementioning

confidence: 99%

The Lawsonian Stage - the Eoconodontus notchpeakensis FAD and HERB carbon isotope excursion define a globally correlatable terminal Cambrian stage

Landing¹,

Westrop²,

Adrain³

2011

Bull. Geosci.

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The best definition for the base of the terminal Cambrian (Stage 10) is the conodont Eoconodontus notchpeakensis FAD ± onset of the HERB carbon isotope excursion. These horizons allow precise intercontinental correlations in deep marine to peritidal facies. The agnostoid Lotagnostus americanus (Billings, 1860) FAD has been suggested as a Stage 10 base, but restudy of types and typotypes shows that the species occurs only in Late Cambrian (Sunwaptan) debris flow boulders in Quebec (Westrop et al., this volume). Non-Quebec reports of "L. americanus" are an amalgum of small samples of often poorly documented specimens with effaced–highly furrowed cephala and pygidia and with or without a highly trisected pygidial posteroaxis. Many of these occurrences have local species names, but no evidence suggests that they record intraspecific variation of a globally distributed taxon. They are not synonyms of L. americanus. Lotagnostus, largely a dysoxic form, does not allow precise correlation into oxygenated platform facies. Another proposal used the conodont Cordylodus andresi FAD as a Stage 10 base, but other work shows this FAD is diachronous. An unrealistic approach to L. americanus’ systematics and the correlation uncertainty of C. andresi are overcome by defining a Stage 10 base at the globally recognizable E. notchpeakensis FAD, with the C. andresi FAD a useful proxy on cool-water continents. The "Lawsonian Stage", named for Lawson Cove in western Utah, has a basal GSSP at the E. notchpeakensis FAD and replaces informal Stage 10. The Lawsonian, ~150 m-thick in western Utah, underlies the basal Ordovician Iapetognathus Zone

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“…The earliest sedimentary Paleozoic unit is the Tiñú Formation, composed of limestone and shale strata. This unit is divided in a Lower Member of limestone with abundant trilobites, linguliform brachiopods and other invertebrates from the Furongian (late Cambrian) (Robison & Pantoja-Alor, 1968;Landing et al, 2007;Streng et al, 2011), and an Upper Member of shale that records graptolites from the Lower Ordovician (Tremadocian) (Pantoja-Alor, 1970;Sour-Tovar & Buitrón-Sánchez, 1987;Sour-Tovar, 1990).…”

Section: Geological Settingmentioning

confidence: 99%

Carboniferous brachiopods (Productida and Orthotetida) from Santiago Ixtaltepec, Oaxaca, Southern Mexico

Torres-Martínez¹,

Sour-Tovar²,

González-Mora³

et al. 2018

Rev. bras. paleontol.

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-Ten species of Carboniferous brachiopods of the orders Productida and Orthotetida are described. The material occurs in Santiago Ixtaltepec, considered as one of the most important regions where Paleozoic rocks of Mexico are exposed. Ozora sp., Tolmatchoffia keokuk and Marginatia sp. were found in rocks from the Santiago Formation (APS-1), meanwhile the other taxa were collected in different strata from the Ixtaltepec Formation (API-2, API-5, API-6 and API-7). The record of the genera Ozora and Marginatia and the species Tolmatchoffia keokuk corroborate the Tournaisian-Visean age for the Lower Member of the Santiago Formation. The presence of Productus concinnus at API-2 level of the Ixtaltepec Formation places it in at least Visean age. Antiquatonia sp., Orthotetes mixteca, Derbyia sp. and ?Schuchertella sp. were found in previously dated Pennsylvanian strata . The fossil associations and the lithology allowed to relate each level where brachiopods were found with an intertidal, subtidal or peri-reef paleoenvironment. The presence of typical taxa from the Tournaisian of the Mid-Continent (United States) in the Santiago Ixtaltepec region suggests that there was a marine connection that joined both areas at least since the Early Mississippian. The occurrence of Productus concinnus in the Ixtaltepec Formation (API-2) confirms that Europe and Santiago Ixtaltepec region were linked during the Middle Mississippian. Antiquatonia, Orthotetes, Derbyia and Schuchertella are considered as cosmopolite genera whose presence in localities from the Mid-Continent is very common. Keywords

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Terminal Cambrian and lowest Ordovician succession of Mexican West Gondwana: biotas and sequence stratigraphy of the Tiñu Formation

Cited by 87 publications

References 58 publications

Review and palaeoecological analysis of the late Tremadocian - early Floian (Early Ordovician) cephalopod fauna of the Montagne Noire, France

Review and palaeoecological analysis of the late Tremadocian - early Floian (Early Ordovician) cephalopod fauna of the Montagne Noire, France

The Lawsonian Stage - the Eoconodontus notchpeakensis FAD and HERB carbon isotope excursion define a globally correlatable terminal Cambrian stage

Carboniferous brachiopods (Productida and Orthotetida) from Santiago Ixtaltepec, Oaxaca, Southern Mexico

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