CHINA — A clutch of 28 dinosaur eggs found in the Qinglongshan fossil reserve in central China is about 86 million years old, according to scientists who used an “atomic clock” method to date the samples.
The dating technique used on the eggs, known more formally as carbonate uranium-lead, or U-Pb, dating, is a common process for determining the age of carbonate minerals — those containing calcium, iron, manganese and magnesium.
By evaluating the ratio of uranium to lead, they were able to of determine the age of the eggs.
Scientists have used U-Pb dating on rocks that are from 1 million to hundreds of millions of years old, with a high level of certainty about their results, Zhao said.
Recent advances have made U-Pb dating more accessible, but it is still not widely available for fossil analysis, according to Zhao.
CHINA — Researchers have dated a clutch of 28 dinosaur eggs discovered in the Qinglongshan fossil reserve in central China using an “atomic clock” method, estimating the eggs’ age to be around 86 million years. The method used to determine the eggs’ age, according to the researchers, may now help to shed light on how dinosaurs in China’s Yunyang Basin adapted to a cooler climate.
A common method for figuring out the age of carbonate minerals, which include calcium, iron, manganese, and magnesium, is carbonate uranium-lead, or U-Pb, dating, which is the dating method used on the eggs. Within these minerals is uranium, which eventually transforms into lead.
Researchers vaporized the mineral fragments after shaving off pieces of fossilized eggshell samples with a micro-laser, and then they counted the uranium and lead atoms. They were able to ascertain the age of the eggs by analyzing the uranium to lead ratio.
According to research published Thursday in the journal Frontiers in Earth Science, the fossil eggshells’ recent discovery of calcite, a type of calcium carbonate, indicated that the eggs would make suitable candidates for U-Pb dating. From the Qinglongshan fossil reserve, which comprises three sites with over 3,000 eggs, the eggs are the first fossils to be accurately dated. Most of the eggs are semi-exposed and preserved in three dimensions, with most of their original shapes still intact.
Based on the eggs rather than a dinosaur’s fossilized skeleton, the majority of the eggs there are classified as Placoolithus tumiaolingensis, a species in the Dendroolithidae family. There is currently no known identity for the dinosaur that laid the eggs. The eggs have mineralized shells that are no thicker than 0.009 inches and are slightly flattened spheres that range in length from 4 to 6 points.
When Earth was already beginning to cool down during the Cretaceous period (145 million to 66 million years ago), this ancient ecosystem may have been revealed by the fact that eggshells in this group are generally relatively porous for dinosaur eggs.
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Paleontologists frequently use the sediments in which the organic material was preserved to determine the age of plant and animal fossils. Fossils may, however, be older or younger than the location where they were discovered because they may arrive there before or after the formation of the surrounding rocks, lava, or ash deposits.
Study coauthor Bi Zhao, a researcher at the Hubei Institute of Geosciences in Wuhan, China, told CNN via email that their plan to test U-Pb dating on calcite in the fossilized eggs “emerged somewhat serendipitously through conversations with researchers who specialize in stalagmite chronology using carbonate U-Pb methods.”. “We chose to test it on the Qinglongshan eggs, not anticipating such definite and trustworthy outcomes. “.
“The most accurate dating method is geochronology,” which uses U-Pb analysis to determine the ages of rocks and minerals, according to Heriberto Rochín-Bañaga, a research associate in the Earth sciences department at the University of Toronto. The technique has been applied to the analysis of ancient corals and belemnites, an extinct order of squid-like cephalopods, by Rochín-Bañaga, who was not involved in the new study.
U-Pb dating has been applied to rocks ranging in age from one million to hundreds of millions of years, and the results are highly certain, according to Zhao. Though Rochín-Bañaga stated in an email that “the U-Pb system is considered to be the most accurate,” there are other radioactive decay systems for ancient geologic analysis.
According to Zhao, U-Pb dating is still not commonly available for fossil analysis, despite recent advancements making it more accessible. According to him, “it requires highly sophisticated equipment and stringent laboratory conditions,” and samples need to be carefully gathered and analyzed to prevent contamination with other materials that could throw the chronology off course. Furthermore, this analysis was made possible by the calcite found in the eggshells, but it might not be the case for other kinds of fossils.
“Other fossils that contain primary carbonate minerals could theoretically be treated with this technique. We haven’t tried this yet, though,” Zhao stated. “The geological setting and the preservation of the carbonate material determine the viability. “,”.
A glimpse into the Cretaceous epoch.
A unique terrestrial snapshot of the Cretaceous period, the Qinglongshan site demonstrates how groups of Cretaceous dinosaurs interacted with their surroundings and how they nestled.
It is unclear whether having porous eggs was advantageous or disadvantageous as their environment cooled, but it is possible that this unnamed dinosaur species evolved to have them.
Following the study’s confirmation that U-Pb dating is a reliable technique for estimating the age of fossil eggs, the researchers intend to use the method at other nearby Cretaceous sites “to better understand the origin and evolution of these distinctive eggs” and the nesting habits of the dinosaurs that laid them, Zhao said. With over 200 dinosaur egg sites found worldwide, only a small number of them have been precisely dated. U-Pb dating may be a useful new technique for examining preserved dinosaur egg laying examples and determining how that may have evolved over time.
“If extensively used,” Zhao stated, “this method could contribute to the development of a strong chronological framework for dinosaur reproduction behavior.”. “.”.
