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The depth to which a vertebrate track is indented can provide a wealth of information, being a direct result of the weight, duty factor, and limb kinematics of the animal as well as media ( = substrate or sediment) consistency. In order to recreate the formation of the track and elucidate media consistency at the time of track formation, such factors as animal mass, duty factor, and foot morphology must be taken into consideration. This study uses Finite Element Analysis and physical modeling to demonstrate for the first time that the shape of the foot is an important factor that influences the depth to which the sediment is penetrated. In cohesive sediment, less compact morphology allows more sediment to move vertically upwards at the edges of the foot, dissipating force at the surface, and retarding transmission of load vertically down into the sediment. The reverse of this effect is seen in noncohesive sediment. Foot morphology, therefore, has a direct impact on preservation potential, both of surface tracks and undertracks, that is irrespective of the pressure exerted on the sediment surface by the foot and independent of mass and duty factor.
Science historians separated the scientific origins of ichnology and body fossil paleontology; the birth of body fossil paleontology is attributed to the Renaissance, whereas the beginnings of ichnology are placed in the 19th century. The present study shifts the boundaries of the history of paleontology and provides new information on an obscure chapter of scientific thought: the ichnological studies of Leonardo da Vinci. This report examines the ichnological observations of Leonardo da Vinci by (1) interpreting the Codex Leicester and the ichnosites described therein, and (2) studying the ichnological drawing included in the Codex I. This paper demonstrates the modernity and correctness of the observations and interpretations made by da Vinci, who used trace fossils to complement his hypothesis concerning the relationship of body fossils to the host sediment. The result from new information presented here is the establishment of a line of continuity between the two main branches of paleontology—trace fossils and body fossils—that emerge united by the genius of Leonardo da Vinci, the founding father of ichnology.
Diverse and locally abundant Lowermost Triassic (lower Induan, Griesbachian) trace-fossil assemblages are described and their significance for the location and characteristics of western Pangean environmental refugia are assessed. Trace fossils within the Montney Formation in northwestern Alberta and northeastern British Columbia record the activities of a wide variety of marine invertebrates. Many forms represent the dwelling and feeding traces of allochthonous storm-transported colonizers. Anachronistic forms—more typical of Paleozoic than Mesozoic successions—including Cruziana, Diplichnites, Monomorphichnus, and Trichophycus, are common. Notably these Paleozoic holdovers, as well as Rhizocorallium, Thalassinoides, and Spongeliomorpha, were likely constructed by marine arthropods. Trace fossils are rare in both shallow water (upper shoreface and foreshore) and offshore depositional settings, but are abundant in offshore transition to distal lower shoreface depositional settings. Low diversity and low ichnofabric indices characterize autochthonous infauna in Montney offshore transition settings, whereas high diversity, low ichnofabric indices distinguish allochthonous infauna in the same settings. High diversity and high ichnofabric indices typify distal lower shoreface successions. Several lines of evidence, including diminutive trace fossils and low diversity of resident infauna in proximal-offshore settings, support the hypothesis of shallow marine anoxic to dysoxic conditions in the study area during the Griesbachian. This trace-fossil distribution, and the abundance of allochthonous faunas in the study interval, reflect an infauna whose distribution was limited by both wave-stressed proximal settings and oxygen-stressed distal settings, resulting in colonization of a very narrow habitable zone. High diversity of trace-fossil assemblages in the study interval suggests the presence of shallow marine refugia wherein organisms survived the extinction interval and weathered the adverse conditions that dominated the world's oceans during the lowermost Mesozoic. Mid- to high paleolatitude refugia, such as the Pedigree-Ring-Kahntah area, played a crucial role in both extinction survival as well as post-event recolonization of the world's oceans.
A systematic, semiquantitative measurement of intensity of euendolithic microbioerosion aids in understanding the interactions between microorganisms and basalt glass. These interactions are important because they occur widely in ocean basins and lead to incongruent dissolution of glass. No semiquantitative method currently exists for measuring euendolithic microbioerosion. We modify the ichnofabric index (ii of Droser and Bottjer, 1986) to the microendolithic ichnofabric index (MII), a scale-independent, orientation-independent, semiquantitative classification scheme specifically for euendolithic microborings in volcanic glass, but applicable to any medium. Material used to develop the MII comes from the phase one core, Hawaii Scientific Drilling Project #2 well and ranges in age from ~636 to 413 ka. Microtubular features in the glass are linear or curvilinear, ~0.5–2 µm in diameter, 1 µm to >100 µm long, and originate from the margins of glass fragments found in hyaloclastites and pillow lavas. Standard categories of the ii were modified to address the circumstances of the microborings. Percent disruption of primary fabric is the basis of the MII rather than percent disruption of bedding. Six categories are used ranging from no (MII = 1) to complete disruption (MII = 6). Modification of the ii extends the measuring scale of bioerosion to near the minimum size range for trace fossils. By extension, MII can be used for any traces that penetrate the associated medium, from microbial borings to dinosaur footprints, if the ratio of measurement length to diameter of the traces is ~30 : 1.
The epi- and endobiont communities (EEBCs) found within an exquisitely preserved collection of 48 Manicina areolata specimens from two Pleistocene localities in southeastern Florida, United States, were examined in detail. The EEBCs include a broad taxonomic spectrum of encrusting and boring organisms, but differ markedly between the two localities. Specimens from the Canal locality generally show an equable distribution of EEBCs, with serpulids, spirorbids, and/or chamids numerically dominant and chamids dominating in average area, whereas the Palm Beach Aggregates (PBA) coralla have a much less even distribution of EEBC constituents and lithophagids numerically and spatially dominate virtually all bases. Given the relative proximity of the two localities and inferred distance from the Pleistocene shoreline, it seems unlikely that any of the EEBC components would have been substantially less available in one locality as compared to the other. Therefore, we favor an explanation focused on sedimentologic differences between the two areas. The Canal environment was shelly, carbonate mud, in contrast to the shelly, coarser-grained siliciclastic sediment present at PBA. The substrate at the Canal site was relatively soft, which resulted in corallum basal morphology commencing with a prominent apical cone, whereas the substrate at the PBA site was firmer and this support produced much flatter bases as well as allowing for a substantially greater number of lithophagid bivalves to bore into the coralla.
We report the first record of bite marks on an Upper Triassic dicynodontid bone from Poland. The bone comes from the Upper Triassic (Norian) Woźniki Limestone of Zawiercie, Kraków-Częstochowa Upland, southern Poland. The bone has several longitudinal bite marks on the anterior side of its shaft, as well as a row of small oval pits. The specimen bears, on its posterior side, evidence of additional damage—parts of bone are missing in the proximal- and distal-end areas. The analysis of the longitudinal bite marks and pits indicates that more than one carnivore fed on the dicynodontid carcass. The different types of marks suggest that the specimen was scavenged.