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A trace fossil, also ichnofossil, is a fossil record of biological activity but not the preserved remains of the plant or animal itself. Trace fossils contrast with body fossils, which are the fossilized remains of parts of organisms' bodies, usually altered by later chemical activity or mineralization. Ichnology is the study of such trace fossils and is the work of ichnologists.
The golden-mantled ground squirrel is a ground squirrel native to western North America. It is distributed in British Columbia and Alberta through the western United States to California, Arizona, and New Mexico.
The internal structure of Earth, structure of the solid Earth, or simply structure of Earth refers to concentric spherical layers subdividing the Solid earth, i.e., excluding Earth's atmosphere and hydrosphere. It consists of an outer silicate solid crust, a highly viscous asthenosphere and solid mantle, a liquid outer core whose flow generates the Earth's magnetic field, and a solid inner core.
An ichnotaxon is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. Ichnotaxa comes from the Greek ίχνος, ichnos meaning track and ταξις, taxis meaning ordering.
Trace fossils are classified in various ways for different purposes. Traces can be classified taxonomically, ethologically, and toponomically, that is, according to their relationship to the surrounding sedimentary layers. Except in the rare cases where the original maker of a trace fossil can be identified with confidence, phylogenetic classification of trace fossils is an unreasonable proposition.
Zoophycos is a somewhat cosmopolitan ichnogenus thought to be produced by moving and feeding polychaete worms.
Having a mean density of 3,346.4 kg/m3, the Moon is a differentiated body, being composed of a geochemically distinct crust, mantle, and planetary core. This structure is believed to have resulted from the fractional crystallization of a magma ocean shortly after its formation about 4.5 billion years ago. The energy required to melt the outer portion of the Moon is commonly attributed to a giant impact event that is postulated to have formed the Earth-Moon system, and the subsequent reaccretion of material in Earth orbit. Crystallization of this magma ocean would have given rise to a mafic mantle and a plagioclase-rich crust.
Paleodictyon is a trace fossil, usually interpreted to be a burrow, which appears in the geologic marine record beginning in the Precambrian/Early Cambrian and in modern ocean environments. Paleodictyon were first described by Giuseppe Meneghini in 1850.
Skolithos is a common trace fossil ichnogenus that is, or was originally, an approximately vertical cylindrical burrow. It is produced by a variety of organisms in shallow marine environments globally and appear as lineated features in sedimentary rocks.
Rhizocorallium is an ichnogenus type of burrow, the inclination of which is typically within 10° of the bedding planes of the sediment. These burrows can be very large, over a meter long in sediments that show good preservation, e.g. Jurassic rocks of the Yorkshire Coast, but the width is usually only up to 2 cm, restricted by the size of the organisms producing it. It is thought that they represent fodinichnia as the animal scoured the sediment for food.
Diplocraterion is an ichnogenus describing vertical U-shaped burrows having a spreite between the two limbs of the U. The spreite of an individual Diplocraterion trace can be either protrusive or retrusive. Some ichnospecies have both types. The presence/absence of funnel-shaped openings should not be used as an ichnotaxobase due to the high probability that the upper portions of the trace may have been eroded away. Observation of the orientation of Diplocraterion in the field is frequently used to determine the way up of rock strata at outcrop.
Pteraichnus is an ichnogenus that has been attributed to pterosaurs. It has been found in, among other units, the Lower Jurassic Aztec Sandstone and Lake Ezequiel Ramos Mexia in the Candeleros Formation.
Planolites is an ichnogenus found throughout the Phanerozoic that is made during the feeding process of worm-like animals. The traces are generally small, 1–5 mm (0.039–0.197 in), unlined, and rarely branched, with fill that differs from the host rock.
Scoyenia is an ichnogenus found in paleozoic-mesozoic strata in North America. It appears to be the preserved remains of animal burrows.
Fugichnia is an ichnogenus of trace fossil characterized as "escape burrows" that are formed as a result of organisms' attempts to escape burial in sudden high-sedimentation events like turbidity currents. The burrows are often marked with chevron patterns showing the upward direction the organisms were tunneling.
Teredolites is an ichnogenus of trace fossil, characterized by borings in substrates such as wood or amber.
Nereites is a genus of trace fossil. Modern tracemakers of incipient Nereites include worm-like organisms, horseshoe crabs and hermit crabs. Traditionally, two models have been proposed for Nereites:
- in the ‘worm model’, Nereites is a feeding burrow produced by wormlike organisms, probing and backfilling laterally
- in the ‘arthropod model’, the characteristic lobes are pressure-release structures made by arthropod legs. According to this interpretation, Nereites is a locomotion trail
Spreite, meaning leaf-blade in German is a stacked, curved, layered structure that is characteristic of certain trace fossils. They are formed by invertebrate organisms tunneling back and forth through sediment in search of food. The organism moves perpendicularly just enough at the start of each back-and-forth pass so that it avoids reworking a previously tunneled area, thereby ensuring that it only makes feeding passes through fresh, unworked sediment.
Aviadactyla is a Mesozoic bird ichnogenus. It is similar to the ichnogenus Aquatilavipes, but in this ichnogenus the toeprints fuse farther from the body and have a "stick-like" character.
Solecurtus strigilatus, also known as the rosy razor clam, is a species of saltwater clam, a marine bivalve mollusc in the family Solecurtidae. This mollusc is a suspension feeder and can burrow with great rapidity to escape predators. It is an unusual bivalve in that its shell valves are too small to contain all the soft tissue, and the animal is unable to retreat into its shell.
References
- ↑ "KU Ichnology". ichnology.ku.edu. Retrieved 2019-05-28.
- ↑ "The ichnogenus Beaconites and its distinction from Ancorichnus and Taenidium | The Palaeontological Association". www.palass.org. Retrieved 2019-05-28.
- ↑ "Ancorichnus". fossiilid.info. Retrieved 2019-05-28.
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