Ammonite diversity and its palaeobiogeographical structure during the early Pliensbachian (Jurassic) in the western Tethys and adjacent areas

Biogeography of Triassic Ammonoids

“…As these analyses often compare intervals with different duration, sampling intensity, paleoenvironments or geographic scales, their results may not be directly comparable, if not intrinsically biased. However, some of these biases can be controlled, if not at least partly ruled out, using for instance traditional sample-based rarefaction curves (Foote 1992;Dommergues et al 2009) in order to compare the taxonomic diversity estimates at comparable levels of sampling effort. Other potential bias such as the unequal duration of time bins, from which diversity counts are obtained, can be circumvented by the use of Unitary Association Zones.…”

“…McGowan 2005; Brayard et al 2006Brayard et al , 2007bBrayard et al , 2009cDommergues et al 2009;Dera et al 2011;. Basic extraction of the biogeographical signal as the inter-locality compositional similarity is often (if not automatically) done by classical hierarchical cluster analysis (hCA) and nonmetric multidimensional scaling (NMDS), applied to different specific time slices (sub-zones to stages).…”

Ammonite paleobiogeography during the Pliensbachian–Toarcian crisis (Early Jurassic) reflecting paleoclimate, eustasy, and extinctions

“…On this topic, numerous studies have depicted modifications of paleobiogeographical patterns at the end of the Early Jurassic, associated with prominent changes in species distribution. For instance, a strong faunal provincialism was first empirically and then analytically evidenced in the NW Tethyan realm during the Pliensbachian, with a noticeable contrast between the Euro-Boreal and Mediterranean ammonites (Meister and Stampfli, 2000;Dommergues et al, 2009), ostracods Whatley, 2005, 2009), belemnites (Doyle, 1994), bivalves (Hallam, 1977;Liu et al, 1998), brachiopods (Vörös, 1977(Vörös, , 1980Manceñido, 2002;Vörös, 2005), and dinoflagellates (Bucefalo Palliani and Riding, 2003). Conversely, a dislocation of this paleobiogeographical pattern was suggested for the Early Toarcian, related to the extinction of endemic taxa at the onset of the biotic crisis (Aberhan and Fürsich, 1997; and northward expansions of Mediterranean faunas (Macchioni and Cecca, 2002;Cecca and Macchioni, 2004).…”

Early Jurassic (Pliensbachian) brachiopod biogeography in the western Tethys: The Euro-Boreal and Mediterranean faunal provinces revised

“…Recently, 52 comprehensive, numerical studies on the Euro-Boreal and Mediterranean ammonoid 53 palaeobiogeography were also presented (Dommergues et al, 2009;Dera et al, 2011). The 54 middle Early Jurassic (Pliensbachian) appeared as suitable to demonstrate the provinciality of 55 the Tethyan marine fossil groups because then, at first time in the Mesozoic, the "Boreal" vs. 56 Tethyan" differentiation reached the realm level (Westermann, 2000b).…”