Melanins in Fossil Animals: Is It Possible to Infer Life History Traits from the Coloration of Extinct Species?

Paleo-colour scientists have recently made the transition from describing melanin-based colouration in fossil specimens to inferring life-history traits of the species involved. Two such cases correspond to counter-shaded dinosaurs: dark-coloured due to melanins dorsally, and light-coloured ventrally. We believe that colour reconstruction of fossils based on the shape of preserved microstructures—the majority of paleo-colour studies involve melanin granules—is not without risks. In addition, animals with contrasting dorso-ventral colouration may be under different selection pressures beyond the need for camouflage, including, for instance, visual communication or ultraviolet (UV) protection. Melanin production is costly, and animals may invest less in areas of the integument where pigments are less needed. In addition, melanocytes exposed to UV radiation produce more melanin than unexposed melanocytes. Pigment economization may thus explain the colour pattern of some counter-shaded animals, including extinct species. Even in well-studied extant species, their diversity of hues and patterns is far from being understood; inferring colours and their functions in species only known from one or few specimens from the fossil record should be exerted with special prudence.Peer reviewe

Undrowning a lost world - The Marine Isotope Stage 3 landscape of Gibraltar

The Rock of Gibraltar, at the south-western extreme of the Iberian Peninsula and 21. km from the North African coast, is a 6-km long limestone peninsula which was inhabited by Neanderthals from MIS 5e until the end of MIS 3. A total of 8 sites, either with Neanderthal fossils or their Mousterian lithic technology, have been discovered on the Rock. Two, Gorham's and Vanguard Caves, are the subject of ongoing research. These caves are currently at sea level, but during MIS 3 faced an emerged coastal shelf with the shoreline as far as 5. km away at times. They hold a unique archive of fauna and flora, in the form of fossils, charcoal and pollen, helping environmental reconstruction of now-submerged shelf landscapes. In addition, geological and geomorphological features - a 300-metre dune complex, elevated aeolian deposits, raised beaches, scree, speleothems - complement the biotic picture.The work is further complemented by a study of the ecology of the species recorded at the site, using present-day observations. The species composition in this fossil record closely matches the present day fauna and vegetation of the Doñana National Park, SW Spain: a mosaic of pine groves, coastal dunes, shrubland and seasonal wetlands and currently the richest reserve in terms of biodiversity in the Iberian Peninsula, located only 100. km to the northwest from Gibraltar.All this information permits, for the first time, the quantification of the vegetation structure of the ancient coastal plain and the modelling of the spatio-temporal dynamics of the MIS 3 coastal shelf off GibraltarPeer reviewe