Geochemical investigation of the taphonomy, stratigraphy, and palaeoecology of the mammals from the Ouled Abdoun Basin (Paleocene-Eocene of Morocco)

International audienceWe performed different geochemical analyses of Paleogene terrestrial mammal remains to establish their taphonomy, stratigraphic provenance, and palaeoenvironmental conditions. Rare earth element (REE) results indicate a similar diagenetic history to that of previously investigated marine taxa from these beds. Therefore, the mammal remains were initially deposited in a marine setting, and probably not long after the death of the animals their bodies were washed into the sea. The Ce/Ce* and Pr/Pr* ratios for the mammal fossils were compared with the background dataset from the phosphate mines, which varies with time. This allowed us to characterize the stratigraphic levels bearing the fossils. The provenances of fossils with known origins were confirmed, while remains with unknown origins could be assigned to certain stratigraphic horizons that are compatible with previously proposed phylogenic relationships. Marine diagenesis affected the various skeletal tissues differently, with the largest alteration in the bone and the least or none in the enamel. This is mostly demonstrated by the high F concentration, high Ca/P, and seawater related 87 Sr/ 86 Sr in the bone/dentine samples. Enamel shows the opposite, and retained the most pristine terrestrial values. The δ 18 O PO4 and δ C results from mammal enamel revealed warm (>20°C mean annual temperature-MAT) and dry (<500mm mean annual precipitation) conditions for Paleocene-Eocene period in the region. From the early to mid-Ypresian about +5°C ∆MAT is recorded that might be linked to the Early Eocene Climatic Optimum. Furthermore, the 87 Sr/ 86 Sr ratios derived from shark tooth enameloid fit the global open ocean Sr-isotope record during the latest Paleocene and early Eocene providing further evidence for the age of these phosphate beds in the Ouled Abdoun Basin. However, older marine fossils yielded higher ratios than the global Sr-isotope curve, reflecting an alteration and/or somewhat restricted conditions in the Moroccan coastal basins, possibly triggered by global sea-level changes

Vertebrate footprints from the Kem Kem beds (Morocco): a novel ichnological approach to faunal reconstruction

The first survey of vertebrate fossil tracks and trackways from the well-known Kem Kem beds of southern Morocco is here presented. The aims are to: (1) discuss the diversity of vertebrate trackmakers represented in two trace-yielding units at three localities, and (2) apply the novel data to ongoing debates about vertebrate ecological associations within the Kem Kem. The majority of the tracks we recorded from the Kem Kem are tridactyl theropod footprints; other dinosaurian track records include those of possible ornithopod dinosaurs, extremely rare as body fossils within Kem Kem collections. Traces of swimming turtles are reported, alongside the first tracks of crocodyliforms and possible pterosaurs to be recorded from the Moroccan Cretaceous (both unsurprising given their abundance as body fossil records in this region). Differences between the collected ichnological sample and faunal reconstructions made on the basis of skeletal evidence are discussed; as trace fossils record the same environment in which the trackmaker lived (i.e. not subject to post-mortem transportation), data of this type arguably provide a more precise palaeoecological sample than the heavily re-worked and usually fragmentary body fossils from the Kem Kem