Kimberella instance of fossil taxon
Kimberella is an extinct genus of bilaterian known only from rocks of the Ediacaran period. The slug-like organism fed by scratching the microbial surface on which it dwelt in a manner similar to the gastropods, although its affinity with this group is contentious.Specimens were first found in Australia's Ediacara Hills, but recent research has concentrated on the numerous finds near the White Sea in Russia, which cover an interval of time from 555 to 558 million years ago. As with many fossils from this time, its evolutionary relationships to other organisms are hotly debated. Paleontologists initially classified Kimberella as a type of Cubozoan, but, since 1997, features of its anatomy and its association with scratch marks resembling those made by a radula have been interpreted as signs that it may have been a mollusc. Although some paleontologists dispute its classification as a mollusc, it is generally accepted as being at least a bilaterian.The classification of Kimberella is important for the scientific understanding of the Cambrian explosion; if it was a mollusc, or at least a protostome, this would mean that the two dominant Nephrozoan lineages would have diverged significantly before 555 million years ago, and if it was at least bilaterian, its age would indicate that animals were diversifying well before the start of the Cambrian.Occurrence
Kimberella has been found in the Ediacara Hills of South Australia, in the Ust’ Pinega Formation in the White Sea region of Russia and the Kushk Series of central Iran. The White Sea fossils are often associated with the Ediacaran "animals" Tribrachidium and Dickinsonia, meandering trace fossil trails, possibly made by Kimberella; and algae. Beds in the White Sea succession have been dated to 555.3 ± 0.3 million years ago and 558 million years ago by radiometric dating, using uranium-lead ratios in zircons found in volcanic ash layers that are sandwiched between layers that contain Kimberella fossils. Kimberella fossils are also known from beds both older and younger than this precisely dated range. The fossils from the Ediacara Hills have not been dated precisely.Ecology
Kimberella dwelt in shallow waters (up to tens of meters in depth), sharing the calm, well-oxygenated sea floor with photosynthetic organisms and microbial mats. Assemblages bearing Kimberella often also bear fossils of Andiva, Yorgia, Dickinsonia, Tribrachidium and Charniodiscus, suggesting that it lived alongside these organisms.Kimberella probably grazed on microbial mats, but a selective predatory habit cannot be ruled out. Fossilized gut content seems to confirm it was grazing on bentic bacteria and algae, the latter having gone through their own ecological "big bang" 650 million years ago in the marine ecosystem, providing a more nutrient rich diet for early animals. Fedonkin reckons that as it ate, it moved "backwards"; the trail thus created was destroyed by the subsequent grazing activity. Conversely, Gehling et al. claim that it moved 'forwards'.  Fans of grooves are often found radiating from the "head" end of the organism; these indicate that the organism stayed in one place, and raked the surface of the microbial mat towards it by extension of its head, which bore two "teeth". Gehling et al. reconstruct Kimberella as having a long neck that operated like the arm of a digger, rotating about an axis perpendicular to the sea floor in order to produce the sweep of the fan, and rotating towards and away from the animal to scrape food from the substrate to the mouth. In one community Kimberella has been shown to be avoiding its grazing traces, demonstrating complex sensory behaviour.The lack of evidence of asexual reproduction suggests that the organisms reproduced sexually. Budding or fission has never been observed.The waters in which Kimberella dwelt were occasionally disturbed by sandy currents, caused when sediments were whipped up by storms or meltwater discharge, and washed over the creatures. In response to this stress, the organisms appear to have retracted their soft parts into their shells; apparently they could not move fast enough to outrun the currents. Some organisms survived the current, and attempted to burrow out of the sand that had been deposited above them; some unsuccessful attempts can be seen where juveniles were fossilised at the end of a burrow a few centimetres long.
type of example of manifestation of representation of