“…1.1), but is also known from an isolated outcrop at Sierra de Las Minitas, in La Rioja Province (Fig. 1.2), in the northernmost part of the basin (Rustán et al, 2011a). Figure 1 Location of Lower Devonian fossil localities (black stars) in the Precordillera Basin, Argentina: ( 1 ) detail of the outcrops at Sierra de las Minitas, La Rioja Province; ( 2 ) detail of the outcrops in San Juan Province.…”
Section: Stratigraphy and Geological Settingmentioning
confidence: 95%
“…With a long history of paleontological investigation, the rich records of the Argentine Precordillera have provided the best source of information on Devonian marine faunas from Argentina (e.g., Vaccari et al, 1994; García-López and Fernández-Martínez, 1995; Herrera, 1995a, b; Sánchez et al, 1995; Herrera et al, 1998; Rustán and Vaccari, 2010, 2012; Rustán et al, 2011a, b; Carrera et al, 2013; Salas et al, 2013; Carrera and Rustán, 2016). However, in spite of this extensive paleontological record, no cephalopods other than the wastebasket genus Orthoceras have been reported from this basin to date (Thomas, 1905; Keidel, 1921; García, 1945; Leidhold and Wetten, 1947).…”
Abstract.-Devonian bactritids are described for the first time from South America. They come from siliciclastic rocks of the Talacasto Formation in the Precordillera Basin, west-central Argentina. The host strata span the Lochkovian-Emsian and contain other non-ammonoid cephalopods as well, thus refuting the alleged virtual absence of cephalopods in circumpolar Devonian basins from southwestern Gondwana (the Malvinokaffric Realm). We report Bactrites gracilis and Devonobactrites? sp., whose wide distribution contrasts with the endemic paleobiogeographic signature of some other taxonomic groups in these basins. Furthermore, new Lochkovian and Pragian records of Bactrites sp. provide new insights into the earliest bactritid records worldwide.
“…1.1), but is also known from an isolated outcrop at Sierra de Las Minitas, in La Rioja Province (Fig. 1.2), in the northernmost part of the basin (Rustán et al, 2011a). Figure 1 Location of Lower Devonian fossil localities (black stars) in the Precordillera Basin, Argentina: ( 1 ) detail of the outcrops at Sierra de las Minitas, La Rioja Province; ( 2 ) detail of the outcrops in San Juan Province.…”
Section: Stratigraphy and Geological Settingmentioning
confidence: 95%
“…With a long history of paleontological investigation, the rich records of the Argentine Precordillera have provided the best source of information on Devonian marine faunas from Argentina (e.g., Vaccari et al, 1994; García-López and Fernández-Martínez, 1995; Herrera, 1995a, b; Sánchez et al, 1995; Herrera et al, 1998; Rustán and Vaccari, 2010, 2012; Rustán et al, 2011a, b; Carrera et al, 2013; Salas et al, 2013; Carrera and Rustán, 2016). However, in spite of this extensive paleontological record, no cephalopods other than the wastebasket genus Orthoceras have been reported from this basin to date (Thomas, 1905; Keidel, 1921; García, 1945; Leidhold and Wetten, 1947).…”
Abstract.-Devonian bactritids are described for the first time from South America. They come from siliciclastic rocks of the Talacasto Formation in the Precordillera Basin, west-central Argentina. The host strata span the Lochkovian-Emsian and contain other non-ammonoid cephalopods as well, thus refuting the alleged virtual absence of cephalopods in circumpolar Devonian basins from southwestern Gondwana (the Malvinokaffric Realm). We report Bactrites gracilis and Devonobactrites? sp., whose wide distribution contrasts with the endemic paleobiogeographic signature of some other taxonomic groups in these basins. Furthermore, new Lochkovian and Pragian records of Bactrites sp. provide new insights into the earliest bactritid records worldwide.
“…It includes carbonate‐rich bioturbated nodules with an associated fauna consisting of trilobites, corals, sponges, bivalves, nautiloids, conulariids, and brachiopods (Rustán et al . ).…”
The distribution and diversity of marine palynomorphs, such as acritarchs and chlorophytes, and terrestrial palynomorphs, such as miospores, are controlled mainly by palaeoenvironmental and palaeogeographical conditions. Recently, global patterns of organic-walled phytoplankton were illustrated for the Late Silurian to earliest Devonian based on data from different stratigraphic sections and palaeocontinents. Here, we analyze the Silurian and the Early Devonian diversity in the Argentinean Precordillera, Central Andean, and Chacoparanense basins. The evolution of the diversity is evaluated in a well-constrained biostratigraphic framework, bearing in mind local palaeoenvironmental conditions and changes within each basin. Taking into account recently published and unpublished data from well-dated sections, the biodiversity of Silurian phytoplankton seemingly increases upwards, reaching its maximum peak during the Ludlovian. However, palynomorphs are rarely recorded in Wenlockian strata, and the supposed Pridolian layers are not confidently well constrained. The first record of trilete spores in Argentina is Ludlovian, approximately 30 million years after their first appearance in the Late Ordovician. Palynomorph diversity increases in the Early Devonian, with a higher diversity of miospores than that of the marine phytoplankton. We interpret possible discrepancies in biodiversity trends of organic-walled phytoplankton between Argentina and other regions, as related to the quantitatively and qualitatively disparity of data, as well as the lack of rigorous biostratigraphic and palaeoenvironmental assessments of the Argentinean basins.
“…sp. (Rustán 2011, 2016) were recorded from siliciclastic outcrops of the Lower Devonian Talacasto Formation in the central Precordillera Basin. Fossils come from Lochkovian to Pragian lower muddy intervals (see García Muro et al, 2018), preserved in nodules.…”
Section: Geological Settingsmentioning
confidence: 99%
“…As a result of preliminary revisions of this genus from the Lower Devonian of Argentina (Rustán, 2011, 2016), we revisit and test this proposal, focusing on Malvinokaffric records. Hence, a profound revision of some poorly defined taxa appeared necessary to better understand biostratigraphic, phylogenetic, and paleobiogeographic patterns of dalmanitids in the middle Paleozoic of Southwestern Gondwana and particularly from South America.…”
The dalmanitid trilobite Kasachstania Maksimova, 1972, previously reported from the Lower Devonian of Kazakhstan and North America (USA) and the upper Silurian–Lower Devonian of South America (Bolivia and Argentina), is revised. Kasachstania kasachstanica (Balashova in Maksimova,1968) and K. septicostata (Maksimova, 1968) are regarded as junior synonyms of the type species K. saryarkensis (Maksimova, 1960), all from the Lower Devonian of the type locality in central Kazakhstan (northern Balkhash). On the basis of a new diagnosis, K. ulrichi ulrichi (Delo, 1940) from the Emsian of the United States, K. ulrichi asiatica (Maksimova, 1968), K. pristina (Maksimova, 1968), and K. alperovichi Pour et al., 2019, from the Lower Devonian of Kazakhstan, K. andii (Kozłowski, 1923) from the upper Silurian–Lower Devonian of Bolivia, and K. gerardoi Edgecombe and Ramsköld, 1994, from the upper Silurian–Lower Devonian of Bolivia and Argentina are excluded from Kasachstania. This genus, represented only by K. saryarkensis and K. kiikbaica (Maksimova, 1968), is restricted to the Lower Devonian of central Kazakhstan, corresponding to the Balkhash–Mongolo–Okhotsk province in the paleobiogeographic context of the Old World Realm, instead of being nearly cosmopolitan as previously considered. In addition, we provide some remarks about Saryarkella Maksimova, 1978b, a monospecific dalmanitid genus largely overlooked although valid from the Emsian of the same area in central Kazakhstan.
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