Arab-Madagascan brachiopod dispersal along the North-Gondwana paleomargin towards the Western Tethys Ocean during the Early Toarcian (Jurassic)

Abstract

Multiple approaches, mainly focused on assessing the depositional environments, paleotemperature, chronostratigraphical and paleobiogeographical data, morphometrical analyses and the study of the internal structure of spiriferinide brachiopods assigned to the genus Calyptoria, have revealed that this brachiopod fauna migrated from their Arab-Madagascan homeland along the North-Gondwana paleomargin into the peri-Iberian epicontinental platform system, in the same well-known spreading episode suffered by the Arab-Madagascan Bouleiceras ammonite fauna over the worldwide-distributed early Toarcian platforms. This brachiopod fauna has been so far overlooked as potential Arab-Madagascan immigrant fauna, as it was integrated together with diverse assemblages well-established in the peri-Iberian basins. Dispersal of Calyptoria stock was conditioned by the interplay of several factors, such as the tectonic framework, the development of epicontinental seas on both Tethyan margins, the early Toarcian transgression, the prevailing ocean current pattern, and their limited ability for dispersal. The revised chronostratigraphical framework of this dispersal episode reveals the coincidence with the thermal maximum recorded prior to the Early Toarcian Mass Extinction Event (ETMEE) in the westernmost Tethys Ocean. The concurrence of these factors played a significant role in the Calyptoria spreading, showing an inter-tropical distribution between 0º and 30º in both hemispheres. The taxonomical updating performed in the light of the current systematic trends support

Bouleiceras (Hildoceratidae, Ammonitina) from the lower Toarcian (Jurassic) of the Iberian Range (Spain): Taxonomy, stratigraphic distribution and insights on its dispersal

“…Martínez (2017b) postulated that other genera of the same subfamily (Paroniceras, Frechiella and Oxyparoniceras) have been influenced in their geographical distribution more by latitudinal constraints (temperature) than by bathymetry or other factors. Furthermore, the distribution of Bouleiceras shows a notable parallelism with that of the contemporaneous brachiopod Calyptoria (Cooper 1989), that has been interpreted by Baeza-Carratalá et al (2018) as controlled mainly by temperature. Paleotemperature increased globally in the late Tenuicostatum and the Eaely Serpentinum zones by 7 8C (Bailey et al, 2003;McElwain et al, 2005;Gó mez et al, 2008;Goy, 2011, Ruebsam et al, 2019), reaching in wide areas values similar to the equatorial conditions of the Arabian region.…”

“…The area of origin and the dispersal routes of Bouleiceras remain unclear, but their distribution seems to follow high temperature conditions and would have been favored by high sea levels. Damborenea, 2002 andBaeza-Carratalá et al, 2018). The main ocean currents assumed for this time are indicated (after Arias, 2006aArias, , 2008.…”

“…11. A. Paleogeographic map of the world in the early Toarcian, showing the position of the basins where Bouleiceras has been recorded (modified afterDamborenea, 2002 andBaeza-Carratalá et al, 2018). The main ocean currents assumed for this time are indicated (afterArias, 2006aArias, , 2008.…”

Análisis de elementos traza en braquiópodos del Jurásico Inferior del Paleomargen Sud-Ibérico (SE de España). Correlación con las señales bióticas e implicaciones ambientales en torno al Evento de Extinción Masiva del Toarciense inferior

“…Thus, Lobothyris arcta is recorded prior to the Jenkyns Event in the Emaciatum-Polymorphum zones (García Joral et al, 2011, Baeza-Carratalá, 2013 together with several spiriferinid (Calyptoria vulgata) and athyridide representatives (the so-called Koninckinid fauna; Fig. 6), which became extinct in the earliest Serpentinum Zone as an effect of the Jenkyns Event (Ager, 1987;Vörös, 2002;Comas-Rengifo et al, 2006;Baeza-Carratalá et al, 2015, 2018aVörös et al, 2016Vörös et al, , 2019. After this event, Soaresirhynchia bouchardi led the repopulation interval in many Western Tethyan basins (Fig.…”

“…The evolution of the Early Jurassic depositional environments and ecological conditions in the South-Iberian Palaeomargin are well understood, evolving from shallow carbonate platforms to an epioceanic swell/graben system with changing environmental conditions and ecospaces for the marine communities (Braga et al, 1981;Rodríguez-Tovar & Uchman, 2011;Sandoval et al, 2012;Reolid et al, , 2015. Amidst these communities, the brachiopod fauna is widely documented in the South-Iberian Palaeomargin (Baeza-Carratalá, 2011Baeza-Carratalá et al, 2014, 2016a, 2016b, 2018a and shows fluctuations in which cor-relate with the major environmental perturbation events. In particular, the biotic crisis related to the Jenkyns Event represented the most important brachiopod faunal turnover during the Mesozoic and the Cenozoic worldwide (Hallam, 1996;Vörös, 2002;Ruban, 2004Ruban, , 2009García Joral et al, 2011; Bae- Ruebsam et al (2020, continuous line).…”