{"id":599466,"date":"2026-08-20T19:42:11","date_gmt":"2026-08-20T19:42:11","guid":{"rendered":"https:\/\/www.newsbeep.com\/ie\/599466\/"},"modified":"2026-08-20T19:42:11","modified_gmt":"2026-08-20T19:42:11","slug":"paleontologists-spent-20-years-carbon-dating-thousands-of-marine-fossils-then-used-them-to-decode-a-process-fundamental-to-earths-history","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ie\/599466\/","title":{"rendered":"Paleontologists spent 20 years carbon-dating thousands of marine fossils, then used them to decode a process fundamental to Earth\u2019s history"},"content":{"rendered":"

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Scientists carbon-dated more than 7,500 marine fossils from ocean beds around the world and used that data to determine which environmental factors are most responsible for mixing together fossils from different time periods in the same stratum.<\/p>\n

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Credit: Florida Museum photo by Kristen Grace<\/p>\n

Paleontologists spent 20 years carbon-dating thousands of marine fossils, then used them to decode a process fundamental to Earth\u2019s history<\/p>\n

Key points<\/p>\n

\tOver the course of 20 years, an international team of scientists collected and carbon-dated more than 7,500 marine fossils from ocean beds around the world.
\n\tScientists used the dataset to determine which of several environmental factors contributes most to time averaging, a phenomenon in which organisms that lived in different time periods are mixed and preserved together in the same fossil bed.
\n\tThe results indicate that sedimentation is more important than other factors, such as the number of burrowing animals in a given area or the durability of fossils.
\n\tThe study, published<\/a> in the journal PNAS, establishes guidelines regarding the types of research questions paleontologists can investigate using fossil samples.<\/p>\n

GAINESVILLE, Fla. — In productive marine environments, a square meter 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. All that excavation mixes up the sediment, along with any shells and other skeletal remains that happen to be there. This temporal smearing is a problem for paleontologists, because when that piece of seafloor is buried and becomes part of the fossil record, it\u2019s difficult and expensive to figure out how much mixing took place.<\/p>\n

\u201cWhat continually amazes me is just how much time a bunch of fossils collected from a single sediment layer can represent. In some cases, well-preserved fossil organisms that are found next to each other might have lived hundreds or thousands of years apart,\u201d wrote Rafal Nawrot, a paleontologist at the University of Vienna.<\/p>\n

The mixing of fossils that lived at different times but are preserved together is called time averaging.<\/p>\n

According to Daniele Scarponi, a colleague of Nawrot\u2019s and an associate professor at the University of Bologna, time averaging dictates the types of questions paleontologists can ask.<\/p>\n

\u201cBefore interpreting a fossil assemblage, we need to know the interval it represents. Some fossil assemblages are like the ruins of Pompeii \u2014 buried rapidly and thus providing a snapshot of past communities frozen in time. Others are more akin to a prehistoric graveyard used continuously over centuries, in which human remains from different generations are slowly accumulating over time. Both types can provide valuable insights into the past, but the kinds of data we can extract from them will be different in each case,\u201d Scarponi wrote.<\/p>\n

In addition to burrowing animals, several other factors influence time averaging, including:<\/p>\n

\tThe durability of organic material is important. Most organisms decompose or get picked apart by scavengers before they become fossilized. For this reason, both the marine and terrestrial fossil records are primarily composed of hard skeletal material, like shells and bones. But even these break and disintegrate if they aren\u2019t preserved quickly enough.
\n\tAnother important factor is the rate of sedimentation, which occurs unevenly in different parts of the ocean and changes through time. Deltas, for example, have high rates of sedimentation, whereas other areas might only receive a fine dusting over long periods of time. If sedimentation is slow, skeletal remains of organisms accumulate over long periods of time, but if sedimentation is fast, the remains are buried quicker, and age mixing is reduced.
\n\tBiological productivity is also crucial. The number of fossils paleontologists can expect to find while digging in one spot is strongly correlated with the number of organisms that were previously around to be fossilized in the first place.<\/p>\n

Through a project<\/a> that was 20 years in the making, members of an international consortium of scientists say they have determined which of these factors is the most important for time averaging and thus primarily controls the temporal resolution of paleontological data.<\/p>\n

\u201cOur results demonstrate that if we know how quickly sediment accumulates \u2014 which can be deduced from the environmental context \u2014 we can determine how much time is captured by a given fossil assemblage: The faster individual shells or bones are buried below the sediment surface, the less likely it is that remains from multiple generations of organisms will accumulate and be preserved together,\u201d Nawrot wrote.<\/p>\n

Sedimentation rates have long been anticipated to be an important component of time averaging, but gathering data needed to rigorously and comprehensively assess this issue is difficult, time-consuming and very expensive.<\/p>\n

By integrating multiple projects, the authors analyzed more than 7,500 fossils, which were dated using radiocarbon and other methods and collected from a variety of oceanic environments around the world, from shallow coastal settings to the edges of continental shelves.<\/p>\n

The various research groups involved in the project \u2014 which includes scientists based in Australia, Austria, the Bahamas, Brazil, Italy, Germany, Slovakia and the United States \u2014 separately collected, studied and published papers on the fossils over a period of two decades. When they learned of each other\u2019s work, they decided to join forces and share data.<\/p>\n

\u201cNothing of this scale has ever been attempted before because it\u2019s simply not feasible to do so, but thanks to the fact that we had a whole bunch of teams that worked on similar topics and used similar methods, we were able to compile it,\u201d said the study\u2019s co-lead author, Michal Kowalewski, the Thompson chair of invertebrate paleontology at the Florida Museum of Natural History.<\/p>\n

Radiometric dating, one of the primary methods the authors used, takes advantage of the fact that radioactive atoms always decay into more stable, non-radioactive atoms at a steady, predictable rate. This allows scientists to estimate the age of minerals and fossils.<\/p>\n

Many animals have skeletons that contain a type of radioactive isotope called carbon-14. Plants absorb carbon-14 during photosynthesis and use it to make more of themselves. Herbivores get carbon-14 secondhand by eating plants, carnivores get it from herbivores, and decomposers get it from all of the above. This list includes humans. Any part of your body that contains carbon \u2014 which is every part of your body \u2014 is radioactive. Fortunately, carbon-14 emits radiation in the form of electrons, which for us is kind of like receiving a constant but imperceptibly low-level electric shock \u2014 not at all like the cell-shredding gamma rays emitted by uranium.<\/p>\n

Carbon-14 has a half-life \u2013 the amount of time it takes for half of any given number of radioactive atoms to decay \u2014 of around 5,730 years. That meant the authors were restricted to the most recent fossil record, up to 55,000 years old, which is about the cutoff when any remaining carbon-14 in a fossil can be reliably measured.<\/p>\n

The researchers also used a technique known as amino-acid racemization, which uses ratios of amino acids. As in the case of carbon isotopes, the ratio of different forms of a given amino acid also changes through time in a predictable way.<\/p>\n

The reason no one has attempted dating on such a grand scale before is primarily due to the high cost of radiocarbon and amino-acid dating. Most research groups can afford to obtain data for only a few dozen specimens, but thousands of specimens are needed to fully evaluate the scale and drivers of time averaging. Distributing the cost across multiple labs over two decades helped significantly reduce this barrier, as did recent technological advances in radiometric dating that lowered the cost and made it possible to use much smaller samples than was previously possible.<\/p>\n

Through this unique collaboration, Kowalewski and his colleagues have what is possibly the largest collection of fossil carbon dates ever compiled, which can now be used on a variety of research topics that would have been intractable otherwise.<\/p>\n

\u201cThe dataset is incredibly powerful. We\u2019re now working on multiple follow-up projects that explore various aspects of time averaging and related processes. You can use it to answer a lot of questions, but of course, we started with the big one,\u201d he said.<\/p>\n

After compiling the carbon dates from their fossil specimens, the authors simulated age distributions by varying the rates of bioturbation (mixing caused by burrowing animals), sedimentation and fossil destruction. Then they compared the real age distribution of carbon-dated fossils with the different simulated distributions to see which of the models most closely matched the actual patterns observed in the data.<\/p>\n

The results were unambiguous.<\/p>\n

\u201cSometimes life turns out to be more exciting than you thought,\u201d Kowalewski said. \u201cIn this case, the outcome is beyond any dreams we may have had when we started.\u201d<\/p>\n

Knowing that the rate of sedimentation is the single most important factor in determining the extent to which fossils of different ages become mixed will unlock research avenues that were previously restricted. And assuming the same pattern holds true for oceans further back in time, the results can be extended to fossils that are much older than the ones that still contain residual amounts of carbon-14.<\/p>\n

The authors published their results<\/a> in the journal Proceedings of the National Academy of Sciences.<\/p>\n

Additional co-authors of the study are: Adam Toma\u0161ov\u00fdch of the Slovak Academy of Sciences; Martin Zuschin, Bettina Bachmann, Michaela Berensmeier and Jan Steger of the University of Vienna; Paolo Albano of the Stazione Zoologica Anton Dohrn; Quan Hua of the Australian Nuclear Science and Technology Organisation; Darrell Kaufman of Northern Arizona University; Susan Kidwell of the University of Chicago; Matias Ritter of the Universidade Federal do Rio Grande do Sul; Marcello Sim\u00f5es of the Universidade Estadual Paulista; Luis Torres Jr. of the Florida Museum of Natural History; Lukas Schweigl of the University of Bologna; Troy Dexter of the University of The Bahamas; Ivo Gallmetzer of the Natural History Museum Vienna; Claudio Pellegrini of the National Research Council of Italy; and Matthew Kosnik of Macquarie University.<\/p>\n

Journal<\/p>\n

Proceedings of the National Academy of Sciences<\/p>\n

Article Title<\/p>\n

Sediment accumulation rate predicts the temporal resolution of marine fossil assemblages<\/p>\n

Article Publication Date<\/p>\n

29-Jul-2026<\/p>\n","protected":false},"excerpt":{"rendered":"image:\u00a0 Scientists carbon-dated more than 7,500 marine fossils from ocean beds around the world and used that data…\n","protected":false},"author":2,"featured_media":599467,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[103,61,60],"class_list":["post-599466","post","type-post","status-publish","format-standard","has-post-thumbnail","category-health","tag-health","tag-ie","tag-ireland"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/599466","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=599466"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/599466\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/599467"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=599466"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=599466"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=599466"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}