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Abstract(s)
In the last years, 14 Pleistocene vertebrate ichnological sites in Portugal and five sites in Southwest Spain (3) and Gibraltar (2) were found and described under this thesis project. The first ichnological record of vertebrates in the Cenozoic of Portugal includes large footprints of the red deer Cervus elaphus found in Pessegueiro islet. An ichnotaxonomic review of the Quaternary sites worldwide allowed the description of five new ichnogenera and respective ichnospecies, corresponding to mammals Leporidichnites malhaoi (European rabbit), Suidichnus galani (Iberian wild boar) and Bovinichnus uripeda (aurochs), as well as birds Corvidichnus odemirensis (Western jackdaw) and Buboichnus vicentinus (Eagle owl), in addition to the first occurrence of proboscideans trackways (Palaeoloxodon antiquus) in mainland Europe. Tracks and trackways of wolf, fox, Iberian lynx, goose, seagull and other coastal birds were also described in coastal paleoenvironments dating from the Middle to Upper Pleistocene coastal paleoenvironments (MIS6, MIS5d, MISb and MIS3). Seven track-bearing levels with footprints were dated using Optically-Stimulated Luminescence (OSL) within the scope of the present work (five of them in Portugal), therefore contributing for improving the knowledge about the sequence stratigraphy of the Pleistocene successions. It is worth highlighting the description of the Matalascañas Trampled Surface (Huelva, SW Spain). This surface contains abundant and well-preserved physical and biogenic sedimentary structures, despite its almost instantaneous exposure and degradaon under wave and tidal erosion over the “El Asperillo” cliff. OSL dating of the “Trampled Surface of Matalascañas” allows atiributing their human footprints and trackways to Neanderthals. Human footprints were described from four other sites, all new, two of them in Portugal. A review of ichnological sites with hominin footprints identified 115 occurrences around the world, with footprints atributable to Neanderthals being rare. The five new Iberian sites correspond to more than half of the ichnological occurrences now known for this species. The occasionally presence of certain species in coastal environments, and the association of footprints of different species, allowed the development of interpretaons such as a seasonal (the Matalascañas seasonal lake as a maternity/nursery for the European forest elephant, or the partitioning of food resources demonstrated by the morphometric variation of aurochs footprints) and evolutionary paleoecology (the large size of Sus scrofa scrofa inferred by the tracks, translating possible predation pressure at the end of the Middle Pleistocene), as well as trophic inferences (the Neanderthal presence in interaction with megafauna known as being part of its food diet). The presence of Neanderthal trackways and footprints associated with Mode 3 and Expedited Mode 1 lithic tools, together with ichnological records of megafauna, including P.antiquus, favors the hypothesis that the Matalascañas coastal lake may have been a seasonal habitat for the Neanderthals. Neanderthals may have intentionally hunted/procuring deer and aurochs, or more accessible food targets, such as newborn elephants and females weakened during childbirth, opportunistically eliminating stillbirths and females died in unsuccessful births. The short-range provenance of the lithic materials found, as well as their expeditious nature, do not indicate setlement, but rather of a transit site for Neanderthals. A new predation/feeding structure is described, with the orientation and concentration of multiple eagle owl tracks, along with two converging shorebird tracks, defining a possible snapshot of active capture and manipulation of prey. The rarity of raptor and passerine behaviors in the fossil record gives special significance to this study with compelling evidence of their presence, along with Charadriiformes (including Laridae), shorebirds and possibly coots, which lived or raided in search of food in Pleistocene coastal habitats. Body fossils and ichnofossils of bees were found in four interdune paleosols in southwestern Portugal. Dense ichnoassociations developed on omission surfaces were formed in carbonate paleosols during the climate deterioration that occurred at the end of the Sub-Boreal interval in the Iberian Peninsula, around 2.9 ka ago. The bee cells identified as Palmiraichnus are traditionally atributed to the Andrenidae and Stenotridae families, while the present work expands the possible producers of this ichnogenus to the Eucera complex (Apidae). This is possible because, for the first time, Palmiraichnus castellanosi is described with the exceptional joint preservation of the bee that developed its life cycle until adulthood. These are the first bee ichnofossils described in the Quaternary fossil record of Europe mainland and the first worldwide record that includes the full preservation of the cocoon with its inhabitant.
The Quaternary ichnological sites found in coastal areas from the Quaternary of the southwestern Iberian Peninsula have heritage value, despite their preservation in rocks that are poorly consolidated and subject to active erosion, posing a strong challenge to their “in situ” conservation. An analysis of a wide range of examples of geoheritage valorization of sites with vertebrate tracks on the various continents is presented, demonstrating that the investment made in their conservation has boosted an increasing number of tourist projects based on the valorization of this geological heritage and favors the socio-economic development of regions where they are included, especially when integrated into thematic routes and geoparks.
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Keywords
Vertebrate tracks Neanderthal footprint invertebrate burrows coastal deposits Pleistocene Holocene trilhos de vertebrados pegadas de Neandertais icnofósseis de invertebrados depósitos costeiros Pleistocénico Holocénico