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This study adopts a new approach describing palaeohydrology and palaeoclimates based on the interpretation of stable oxygen isotopes (δ18 O p) recorded in fossil crocodilian teeth. They represent an archive of prime interest for tracking freshwater palaeoenvironmental change, applicable to many palaeontological localities in the world: crocodilian teeth are abundant in continental basins and have been widely distributed since their diversification during the Mesozoic; the enamel phosphate is resistant to diagenesis and retains its original isotopic composition over geological timescales; and their δ18 O p mainly relies on that of the crocodilian's home waterbody (δ18 O w), which in turn reflects waterbody types, regional climate, and evaporation conditions. This study presents the first application of this theoretical interpretative model to the Shungura Formation (Lower Omo Valley, Ethiopia), a key witness of the important environmental change in eastern Africa during the Plio-Pleistocene that impacted the evolution of regional faunas, including humans. In this complex and variable environmental context, the δ18 O p of coexisting crocodilians allows for the fingerprinting of the diversity of aquatic environments they had access to at a local scale. This study sheds light on two important results: the δ18 O p of crocodilian teeth (1) indicates stable aquatic environments in the northern Turkana Depression from 2.97 to ca. 2.57 Ma but a decline in local waterbodies diversity after 2.32 Ma, suggesting increasing aridity, and (2) shows, like previous geochemical studies on palaeosols and bivalves in the area, a significant increase in δ18 O w from 2.97 to ca. 1.14 Ma, likely due to the shifting air stream convergence zones between the West African and Indian Summer Monsoons and/or reduced rainfall over the Ethiopian Highlands. [ABSTRACT FROM AUTHOR]

Otophysan fish are identified as a natural group and have been studied as such since the first half of the 19th century. This very speciose group largely dominates the vertebrate diversity of inland waters today. In the 1980’s passionate debates concerned the otophysan radiation and notably their primary habitat: are they primitively freshwaters or marine animals? To answer we need to better understand the phylogenetic relationships including those of the fossils and thus we need to enhance our knowledge on key bony structures such as the Weberian Apparatus. In this context we propose a CT scan approach, for a specimen of †Chanoides macropoma. In the last years, palaeontology benefited from the developments of phase contrast X-ray microtomography. We expect great advances to investigate the Weberian apparatus and its evolution in Otophysan fishes.

This study adopts a new approach describing paleohydrology and paleoclimates based on the interpretation of stable oxygen isotopes (δ18Op) recorded in fossil crocodilian teeth. They represent an archive of prime interest for tracking freshwater paleoenvironmental change, applicable for many paleontological localities in the world: crocodilian teeth are abundant in continental basins and widely distributed since their diversification during the Mesozoic; the enamel phosphate is resistant to diagenesis and retains its original isotopic composition over geological timescales; their δ18Op mainly relies on that of the crocodilian's home water body (δ18Ow), which in turn reflects water body types, regional climate, and evaporation conditions. This study presents the first application of this interpretative model to the Shungura Formation (Lower Omo Valley, Ethiopia), a key witness of the important environmental changes in eastern Africa during the Plio-Pleistocene that impacted the evolution of regional faunas, including humans. In this complex and variable environmental context, the δ18Op of coexisting crocodilians allows for fingerprinting the diversity of aquatic environments they had access to at a local scale. Like previous geochemical studies performed on paleosols and bivalves in this area, our data indicate a marked increase in δ18Ow between 2.97 Ma and ca. 1.14 Ma, probably resulting from the joint effect of the migration of the air streams convergence zones between the West African and Indian Summer Monsoons and of the decrease in rainfall amounts above the Ethiopian Highlands. Contrary to some conclusions based on terrestrial proxies, the δ18Op of crocodilian teeth does highlight any major change affecting aquatic environments, rather pointing to stability of these environments between 2.97 Ma and ca. 2.57 Ma. By contrast, the diversity of aquatic environments accessible to crocodilians seems to be restricted in most analysed stratigraphical units after ca. 2.32 Ma, a feature that may reflect more arid conditions in the Turkana Depression. [ABSTRACT FROM AUTHOR]

The family Latidae is considered to have originated in marine waters of the Tethys, and the fossil record of this group indicates a widespread occurrence of latid fishes in the past. In the Mediterranean–Paratethyan basins, the genus Lates is represented by a number of fossil species, the youngest of which have been reported from Miocene deposits of Italy and Ukraine. Here we report on Lates fossils recovered from Late Miocene (Pontian) deposits of the Shkodova Gora locality of Ukraine, with a description of a new species †Lates odessanus sp. nov. The new species bears distinct morphological traits, especially on its maxilla, premaxilla, and parasphenoid, not found in other spatiotemporally close relatives. The fossil record shows that much of the latid species diversity was lost after the Late Miocene, and the newly described species, †L. odessanus, appears to be the last known extinct representative of this group in low salinity deposits of the Mediterranean–Paratethyan basins. The only extant Lates species in the Mediterranean, L. niloticus, has survived in estuarine environments of the southern shore. [ABSTRACT FROM AUTHOR]

Author(s): Michel Brunet (corresponding author) [1]; Franck Guy [1, 2]; David Pilbeam [2]; Hassane Taisso Mackaye [3]; Andossa Likius [1, 3]; Djimdoumalbaye Ahounta [4]; Alain Beauvilain [4]; Cécile Blondel [1]; [...]

Author(s): Patrick Vignaud (corresponding author) [1]; Philippe Duringer [2]; Hassane Taïsso Mackaye [3]; Andossa Likius [1, 3]; Cécile Blondel [1]; Jean-Renaud Boisserie [1]; Louis de Bonis [1]; Véra Eisenmann [4]; [...]

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