Search

The ichnospecies Gastrochaneolites dijugus Kelly and Bromley 1984 and Teredolites longissimus Kelly and Bromley 1984, attributed to the boring activity of gastrochaenoid and pholadid bivalves, are described respectively from the Miocene Vilanova Basin and the Pliocene Almería-Níjar Basin. Miocene and Pliocene traces are preserved as positive casts associated to invertebrate shells and wood fragments, respectively; in both cases, the host substrate (shells and wood) has been lost almost entirely by different taphonomic processes (mainly dissolution). For the first time in the fossil record, the complete ichnogenetic sequence of these two ichnospecies is described and figured. [ABSTRACT FROM AUTHOR]

A new ichnotaxon, Lepeichnus giberti igen. nov. isp. nov., is described from sandy silts and sands of the upper Miocene (Tortonian–Messinian) of the Guadalquivir Basin (Lepe, Huelva, SW Spain). It is a complex bioturbation structure consisting of two vertical shafts interconnected by a horizontal C-shaped gallery, which in turn exhibits a hook-shaped branch. L. giberti is interpreted as probably produced by a crustacean that could have combined dwelling, deposit feeding and farming strategies in a shallow-marine environment. Its architectural similarities with modern upogebiid burrows suggest the record of a new burrowing behavior, not yet known today, for this group of mud shrimps. The large number of studied specimens and their exceptional degree of preservation allow proposing the new concept of ‘ichnogeny’, as a tool to describe the origin and development of a modern or fossil boring or burrowing trace. [ABSTRACT FROM AUTHOR]

Abstract: Clavate borings found in the tympanic bulla of a Miocene cetacean from El Camp de Tarragona Basin constitute the first evidence of the ichnogenus Gastrochaenolites in bones of an autochthonous cetacean carcass. Previous records of similar trace fossils on marine bones were described from transported or reworked remains. Based on their morphology and ichnotaxonomy, the borings are assigned to the activity of pholadid bivalves, which would have colonized the skeletal carcass on the sea floor after removal of covering soft tissues. Sedimentological and paleontological data indicate a low-energy depositional setting with low sedimentation rate, which would have provided the temporal window for bivalve colonization. This new finding contributes to widen our knowledge of bioerosion in marine vertebrate skeletons. [Copyright &y& Elsevier]

Abstract: A new finding of a marine mammal is documented from the middle Miocene of El Camp basin in Tarragona (NE Spain). The incomplete and disarticulated bone remains belong to the skeleton of a juvenile cetacean. These remains appear deposited above a transgression surface and included within a glauconitic calcisiltite layer. This unit constitutes the beginning of a shallowing-upwards sequence and was deposited under low-energy conditions and low sedimentation rates in a middle-outer platform setting. This context was responsible for the long exposure of the remains and, consequently, an extension of the biostratinomic stage. These conditions favored the natural decomposition and disarticulation of the carcass, allowing the action of different types of scavenging organisms. The interpretation of the paleoenvironmental setting is based in the combination of different datasets: taphonomic data of the bone remains, paleoecologic and taphonomic information provided by the fauna associated to the bones, and ichnologic and sedimentologic interpretation of the sediments where the fossils are included. Combination of such different proxies enables a very good characterization of the paleoenvironmental context of the studied fossils. [Copyright &y& Elsevier]