Robert DePalma and Anton Oleinik are in North Dakota. Credit: Florida Atlantic University
The extinction of dinosaurs and 75 percent of life on Earth were caused by the catastrophic Chicxulub asteroid, according to a study led by researchers at Florida Atlantic University. The 165-million-year reign of dinosaurs was ended by the season of new beginnings.
The results of the study were published in the journal Scientific Reports. Robert DePalma is a senior author and an associate professor in the Department of Geosciences at FAU.
"Time of year plays an important role in many biological functions such as reproduction, feeding strategies, host-parasite interactions, seasonal dormancy, and breeding patterns," said DePalma. The time of year for a global-scale hazard can play a big role in how harshly it impacts life. The story of the end-Cretaceous extinction is dependent on the seasonal timing of the Chicxulub impact. The answer to that question has remained unclear.
It has been known for a long time that the asteroid hit the peninsula 66 million years ago. The impact caused the third-greatest extinction in Earth's history, changing global flora in ways that relate to the current ecological crisis. The details of what happened after impact and how it led to the third-worst mass extinction in Earth's history are very hazy.
The new study began in the year of 2014, and used traditional and cutting-edge techniques to piece together a trail of clues to identify the season for the impact event. The Tanis research locality in southwestern North Dakota is one of the most detailed Kpg boundary sites in the world. New data is provided by the research while building new academic bridges.
There was a lot of new and exciting information on this site. Oleinik said that the field data collected at the site gave them a detailed insight into what happened at the boundary. Multiple lines of independent evidence suggested that the year was 66 million years ago when the asteroid hit the planet. One of the great things about science is that it allows us to look at seemingly well-known facts and events at different angles and with different precision, so we can better understand the natural world. It proves that paleontology is still a science of discovery in the 21st century.
The research team laboriously determined in a previous study that the Tanis site was dated from the end-Cretaceous.
The study showed that a huge surge of water caused a drape of silt that locked the event in time and preserved the only known impact-caused mass-death. The tangle of plants, animals, trees, and asteroids allowed for a unique opportunity to work out the details of the event, the biota that succumbed to it, and the environment in which they lived.
The fossil record is a key to understanding the response to global-scale hazards, without which we would be ill-equipped to respond or react to modern events. The modern utility of the fossil record is highlighted by the fact that we are currently at the threshold of another episode of global biotic stress.
The pattern of the growth lines in the fossil fish bones was similar to a barcode, and it showed that all of the fish died during the spring-summer growth phase. Independent confirmation of this was provided by the high-tech analysis of the growth lines.
Multiple additional lines of evidence were added to support the findings. The study of juvenile fossil fish was supported by cutting-edge X-ray florescence that was performed at theSSRL.
The team was able to predict how long the fish would be buried by comparing the sizes of the youngest and oldest fish. They were able to deduce the range of the season from the bones, just as they had done with known modern spawning seasons.
"Any great discovery such as this is a chance to give back to the scientific community and the world," said DePalma. It answers important questions, but also sparks new minds to reach forward and achieve.
More upcoming projects hope to uncover more details about this interesting and significant slice of time, as research at the site is far from complete. Multiple researchers from other institutions, who are not part of the main study, have examined the site in addition to the primary research team, and there is no indication that this rich collaborative process will end anytime soon.
Robert A. DePalma and his team have a Seasonal Calibration of the end-cretaceous Chicxulub impact event. There is a DOI: 10.1038/s41598-021-03232-9.
Scientific reports are in the journal.
The timing of the asteroid impact was pinpointed by a study.
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