The biostratigraphical and palaeogeographical framework of the earliest diversification of tetrapods (Late Devonian)

Abstract

The earliest diversification of tetrapods is dated as Late Devonian based on 10 localities worldwide that have yielded bone remains. At least 18 different species are known from these localities. Their ages span the 'middle'-late Frasnian to latest Famennian time interval, with three localities in the Frasnian, one at the F/F transition (though this one is not securely dated) and six in the Famennian. These localities encompass a wide variety of environments, from true marine conditions of the nearshore neritic province, to fluvial or lacustrine conditions. However, it does not seem possible to characterize a freshwater assemblage in the Upper Old Red Sandstone based upon vertebrates. Most of the tetrapod-bearing localities (8 of 10) were situated in the eastern part of Laurussia (¼Euramerica), one in North China and one in eastern Gondwana (Australia), on a pre-Pangean configuration of the Earth, when most oceanic domains, except Palaeotethys and Panthalassa, had closed.

Revision of the early tetrapod Obruchevichthys Vorobyeva, 1977 from the Frasnian (Upper Devonian) of the North-western East European Platform

“…Pan der's collection, and being so, it should have possibly originated from the Novgorod Region of Russia, from which some of Pander's specimens came. This assumption became cited later by subsequent authors (for example, Blieck et al, 2007) who suggested that one of the "possible" localities was an area exposing the Upper Frasnian deposits along the Lovat' River.…”

Early seed plants from Western Gondwana: Paleobiogeographical and ecological implications based on Tournaisian (Lower Carboniferous) records from Argentina

“…The second is more focused on the paleobiogeographic information and places the two continents already in close proximity during the Devonian (Benedetto, 1984;McKerrow et al, 2000;Cocks and Torsvik, 2004, 2006. The contrast between these two reconstructions has been noted many times and the question has been addressed using several fossil groups, namely miospores (Streel et al, 1990), plants (Meyer-Berthaud et al, 1997), fishes (Ahlberg et al, 2001), and early tetrapods (Blieck et al, 2007). All these groups are characterized by continental life habit and their biogeographic analyses gave similar results.…”

Sequences, stratigraphy and scenarios: what can we say about the fossil record of the earliest tetrapods?

“…Classic Euramerican deposits known to yield early digited tetrapods and close relatives-including the Upper Old Red Sandstone of Scotland, the Catskill Formation of the USA, the Escuminac Formation of Canada and various strata of the Baltic states and Russia [32]-have been collected since the mid-late nineteenth century [33]. Many important recent discoveries have come from Australia and Asia, but understanding of the record in these regions is still maturing.…”

“…The Zachełmie tracks were made by a taxon of unclear phylogenetic position, and, despite their great age, we regard their implications for the environmental context of the emergence of digit-bearing tetrapods as similarly ambiguous. Skeletal remains of Devonian digited tetrapods and their closest relatives derive from a diverse range of marine and continental facies ( [32], table 1), and current uncertainties about the interrelationships and anatomy of some of these taxa means that the precise environmental context(s) for the origin of digits remains unclear. As a parallel example, we Timing tetrapod origins M. Friedman & M. D. Brazeau 437 point to the broad set of inferred habitats for some of the earliest cetaceans [36], and note that it is possible that important steps in the evolution of digits similarly occurred in a series of distinct settings.…”