Twenty years and 7,500 fossils reveal what blurs Earth's marine fossil record
In productive marine environments, a square meter (10.8 square feet) of seafloor can be perforated by hundreds to thousands of isolated and interconnected tunnels through which crawl and writhe a cornucopia of clams, shrimp, sea stars, sand dollars, snails, worms and other animals.
Twenty years of research involving 7,500 fossils from various oceanic environments has revealed that the rate of sediment accumulation plays a crucial role in determining the temporal resolution of paleontological data. The study, published in the Proceedings of the National Academy of Sciences, focused on the extent to which burrowing animals mix up sediment and fossils, a phenomenon known as time averaging.
Time averaging occurs when fossils of different ages are preserved together within a single sediment layer, making it challenging to determine the exact age of the fossils. This issue has long puzzled paleontologists as it affects the types of questions that can be asked about past communities and their evolution.
The research team, comprising scientists from Australia, Austria, the Bahamas, Brazil, Italy, Germany, Slovakia, and the United States, analyzed the fossils using radiocarbon dating and amino-acid racemization techniques. Radiometric dating relies on the predictable rate of radioactive decay of isotopes such as carbon-14, which has a half-life of approximately 5,730 years. Amino-acid racemization, on the other hand, examines the ratios of different forms of amino acids that change over time.
The study found that faster sediment accumulation results in less time averaging, as remains from multiple generations of organisms are less likely to accumulate and be preserved together. The researchers were able to estimate sedimentation rates from the environmental context, allowing them to determine the temporal resolution of fossil assemblages based on sedimentation rates.
Prior to this study, the influence of sediment accumulation on time averaging had not been thoroughly investigated due to the high cost and difficulty of obtaining precise data. However, the collaborative efforts of multiple research groups over a 20-year period enabled the collection and analysis of a vast dataset, shedding light on the factors that govern the temporal resolution of paleontological data.
Written by urgent.news from Phys.org's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
