Orthid Brachiopods from the Middle Ordovician of the Central Iberian Zone, Spain

Abstract

The present study of a large collection of orthid brachiopods from Middle Ordovician (middle Darriwilian) strata of Spanish regions of the Central Iberian Zone of the Iberian Massif, as well as the type collection of Portuguese species from the same Zone, revealed the occurrence of five genera of the family Orthidae, two of them new, and to which most of the seven previously reported species of Orthis from the same areas can be assigned. Besides the two new genera and species Almadenorthis auriculata Reyes−Abril and Villas gen. et sp. nov., and Gutiorthis incurvata Reyes−Abril and Villas gen. et sp. nov., three further new species are erected: Paralenorthis estenaensis Reyes−Abril and Villas sp. nov., Paralenorthis lolae Reyes−Abril and Villas sp. nov., and Sivorthis calatravaensis Reyes−Abril and Villas sp. nov. Paralenorthis alata and Orthambonites sp. are also identified in the same beds. Orthis noctilio is ascribed to the genus Sivorthis, and the species Orthis lusitanica and Orthis miniensis are restricted to only their type specimens. Orthis duriensis is poorly described and illustrated, its type material missing, and actually it may belong to Sivorthis noctilio. These brachiopod taxa invaded the cold waters of the Afro−South European Gondwanan margin from lower latitudes, coincident with the mid Darriwilian transgression, as they belonged to a family that diversified in temperate and tropical seas during the early Mid Ordovician.

A Gondwanan perspective on the Ordovician Radiation constrains its temporal duration and suggests first wave of speciation, fuelled by Cambrian clades

“…; Reyes‐Abril et al . ). This transgression facilitated a facies and habitat change, which coincided with a demise in the linguliformeans, and an influx of several new brachiopod groups not previously recorded from the Mediterranean region.…”

“…These include the orthids, and to a lesser extent ranorthids, linoporellids, rafinesquinids, draboviids and cremnorthids (Reyes‐Abril et al . ). However, as seen in Figure , the orthoid arrival into the cold waters of high‐latitude Gondwana was brief as this group became scarce and less diverse in the upper Darriwilian assemblages (upper Oretanian).…”

“…This was also noted by Reyes‐Abril et al . () who found the linguliformeans to be replaced by orthoids, as well as by newcomers such as the rafinesquinines. Our data support these findings with a rapid diversification within orthoids and dalmanelloids, as well as the first occurrences of strophomenoids and plectambonitoids in the region (Fig.…”

“…The middle Darriwillian diversity pulse peaks in the black shales of the Navas de Estena Formation and equivalent units (see Guti errez-Marco et al 1984 for equivalent unit names). This facies change from the arenaceous facies to a deeper siliciclastic facies during the D. artus graptolite Zone is linked to the globally occurring mid-Darriwilian transgression known as the Basal Llanvirn Drowning Event (Nielsen 2004;Haq & Schutter 2008;Rasmussen et al 2009;Reyes-Abril et al 2010). This transgression facilitated a facies and habitat change, which coincided with a demise in the linguliformeans, and an influx of several new brachiopod groups not previously recorded from the Mediterranean region.…”

Evolution of trilobite enrolment during the Great Ordovician Biodiversification Event: insights from kinematic modelling

“…haematite). They came from the lower part of the Navas de Estena Formation in the Mounts of Toledo area of Central Spain, involving the classic localities of the Acebr on stream (south of Las Ventas con Peña Aguilera, province of Toledo), and Valderuelo site (east of Navas de Estena, province of Ciudad Real): for more details concerning the localities see Reyes-Abril et al (2010). Both localities are approximately coeval and are of early Oretanian age (=early Darriwilian 2 according to the global Ordovician scale, see .…”