Lingulate brachiopods from the Lampazar Formation (late Cambrian) of the Cordillera Oriental of northwestern Argentina

Abstract

The Angosto de Lampazar, a classic locality for the study of lower Paleozoic successions in the Cordillera Oriental, NW Argentina, has yielded a late Cambrian relatively diverse, lingulate brachiopod fauna. Sandy lenses with calcareous cement from the uppermost levels of the Lampazar Formation have yielded abundant remains of articulate and phosphatic brachiopods. Among the latter, the new speciesEurytreta harringtoniMergl and Herrera,Lingulella?melonicaMergl and Herrera,Libecoviella lenticularisMergl and Herrera, andSchizambon cardonalisMergl and Herrera, as well as the new genus and speciesSaltaia lampazarensisMergl and Herrera are formally introduced. Trilobites and conodonts from the same horizons characterize theCordylodus proavusZone, allowing a correlation with Stage 10 of the Furongian Series. Although the information on lingulate brachiopods from theC.proavusZone is scarce across the world, the composition of the studied association displays a relationship with coeval and slightly younger faunas of Utah and Kazakhstan. The Argentine brachiopods, the first described from the late Cambrian Proto-Andean margin of Gondwana, are more closely related to temperate Laurentian faunas than to those from the high latitude North African margin of Gondwana.

Linguliform brachiopods across a Cambrian–Ordovician (Furongian, Early Ordovician) biomere boundary: the Sunwaptan–Skullrockian North American Stage boundary in the Wilberns and Tanyard formations of central Texas

“…One possibility is Kazakhstan, where another Eurytreta species occurs in Sunwaptan-equivalent strata in the Malyi Karatau Range (Holmer et al, 2001). Another older occurrence of species of Eurytreta is in the Cordillera Oriental of Argentina, on the margin of Gondwana (Mergl et al, 2015).…”

“…Although the species of Schizambon documented in Texas are apparently endemic to Laurentia, the oldest reported occurrences of the genus are from Gondwana terranes in strata coeval with the Laurentian Cambrian upper Steptoean Stage (Shergold et al, 1976; Henderson et al, 1992; González-Gómez, 2005) or Sunwaptan Stage (Mergl et al, 2015). Schizambon has its lowest appearance in lower Skullrockian strata in the Great Basin (Popov et al, 2002), the same stratigraphic level as in Texas, suggesting migration of species of the genus from Gondwana to Laurentia during or after the Sunwaptan–Skullrockian faunal turnover.…”

Broeggeria Walcott and other upper Cambrian and Tremadocian linguloid brachiopods from NW Argentina

“…Lingulella hesperia (Williams and Curry, ), from the Floian of Ireland, clearly differs in its much more elongate shell outline. Recently, Mergl et al () described a minute obolid from Furongian beds of NW Argentina (but see comments on the age by Muñoz and Benedetto, ) referred to as Lingullela ? melonica Mergl and Herrera.…”

“…In addition to the smaller size (up to 5 mm long), this species clearly differs from our specimens in its ovate shell outline and the almost smooth exterior with radial ribbon‐like striations superimposed to concentric growth fila. According to Mergl et al (), L .? melonica is more comparable in size and outline with the North American Lingulella similis (Walcott, ), of late Cambrian age (Robson and Pratt, ).…”

“…12-15), which was removed from the linguloideans and reassigned to the rostroconchian mollusc Tolmachovia (Gutiérrez Marco and Aceñolaza, 1991). Knowledge of lower Paleozoic linguliforms from the Central Andean Basin recently increased with the faunas published by Benedetto and Muñoz (2015) and Mergl et al (2015).…”