The Paleontological Context. Ichnology

Abstract

Except for some previous records, the first attempts for the study of the lying tracks on sediments started at the beginning of the nineteenth century, as well as the efforts for creating a suitable terminology. Its installation as a scientific discipline began at the end of the nineteenth century. By middle twentieth century, a modern and organized scheme for the classification of ichnofossils and their location in ichnofacies was proposed. Firstly, the only recognized ichnofacies corresponded to marine environments and were defined by bathymetric levels and particular ichnofossils. Immediately, ichnofacies corresponding to transition environments from those marine to continental were identified. In 1985, the ichnological nomenclature became part of the International Code of Zoological Nomenclature. During the 1970s and 1980s, there were papers describing ichnites of continental origin, events that quickly led to the organization of the formal reconnaissance of environments carrying continental tracks, giving rise to successive ichnofacies. Apart from the paleosurfaces, the ichnological content is rich and quite varied in paleosols and so are the tracks of insect nests, solitary or in groups in these paleosols. Keywords Ichnology • Continental ichnofacies • Ichnites in paleosols Scheme of Continental IchnofaciesAlthough inert in themselves, the constructions made by a living organism contain a true flow of information about the needs and intentions of its builder (Lovelock 1979).Leaving aside some reference to coprolites toward the end of the seventeenth century, the beginnings of ichnology go back to the beginning of the nineteenth century with the description of vertebrate footprints and traces from marine rocks; additional tasks slowly developed and Ichnology attained status of scientific discipline in the last decades of the nineteenth century (Osgood 1975). The term Ichnology was proposed by Buckland in 1836, during the study of invertebrate trace fossils which were interpreted as belonging to algae ("fucoides") until Nathorst (1881), using the Uniformitarism Principle, proved their zoological origin.

Early Cretaceous lepidosaur (sphenodontian?) burrows

“…Fecal pellets are yellowish and rounded to elliptical, with an average diameter of 0.87 ± 0.05 mm. Edaphichnium lumbricatum has been reported typically in the Cenozoic 55 – 58 , although also occur in Late Jurassic and Late Cretaceous paleosols 59 – 61 . Arthropod domiciles are represented by subvertical burrows with massive fill and rounded end (ichnospecies Skolithos linearis ) that occur profusely in the uppermost part of the Los Chivos paleosol, locally with high density (up to 290 burrows/m 2 ) (Fig.…”