Ironically, the dinosaur-killing asteroid that plunged Earth into a prolonged ‘impact winter’ likely occurred in the late Spring to early Summer 66 million years ago.
The University of Manchester led a study of deposits at Tanis, a North Dakota fossil site that was formed during the impact.
Multiple analyses were performed by the team to narrow the time frame of impact.
They coupled this with evidence of certain behaviours of insects — such as the mining of leaves and the spawning of mayflies — that have a seasonal component.
This mass extinction marked the transition between Cretaceous and Palaeogene times and resulted in the death of 75% of all species that were alive.
The 6.2-mile-wide asteroid slammed into the Earth in what we know today as Mexico’s Yucatán Peninsula, leaving behind the 93-mile-wide Chicxulub crater.
Ironically, the dinosaur-killing asteroid (depicted) that plunged Earth into a prolonged ‘impact winter’ likely occurred in the late Spring–early Summer 66 million years ago
This conclusion was reached by a University of Manchester team who examined deposits from North Dakota’s Tanis Fossil Site. These were formed during the time of the impact. Pictured: palaeontologists Robert DePalma (left) and Phil Manning (right), who are sitting in front of a rock outcrop containing the iridium-rich clay layer formed as a result of the impact event
Robert DePalma (University of Manchester) and his associates carried out the research.
‘The end-Cretaceous Chicxulub impact triggered Earth’s last mass-extinction, extinguishing around 75 per cent of species diversity and facilitating a global ecological shift to mammal-dominated biomes,’ the team wrote in their paper.
The ‘Temporal Details of the Impact Event on a Fine Scale (hour-today) […]previous researches have been largely ignored.
It is essential to determine the precise timing of an impact event so that we can better understand the initial course of the mass-extinction.
This is because time plays a vital role in many biological functions, such as when to reproduce and hibernation, which feeding strategies to pick and even the nature of host–parasite interactions.
Given this, the timing of a global-scale hazard can affect how harshly the disaster impacts life, which species end up going extinct and exactly how well the remainder of the biota can recover in the wake of the event.
Understanding when the Chicxulub impactor hit Earth could therefore refine our predictions of how life today might respond should a similar catastrophe befall the Earth in the future.
Phil Manning, University of Manchester, noted that ‘the hindsight the fossil record gives can yield crucial data that can be applied now so that we might prepare for tomorrow’.
In their study, the team present evidence from the first-ever recorded ‘vertebrate mass-death assemblage’ from within hours of the impact — preserved in a rock layer corresponding in time to the boundary between the Cretaceous and the Palaeogene.
This “assemblage” is composed of densely packed animal and plant fossils as well as material from the impact that were quickly buried due to an impact-associated earthquakes.
The deposit also features a cap of clay that is rich in iridium, an element that is rare on Earth yet abundant in many asteroids, formed when the Chicxulub impactor was vaporised and dispersed around the atmosphere to latter settle to the ground.
It was this global iridium layer — with concentrations hundreds of times greater than normal for the Earth — that cemented the hypothesis of father-and-son team Luis and Walter Alvarez that an asteroid was the cause of the end-Cretaceous extinction.
One of the deposits that the team studied is a cap made from clay, which is rich in Iridium (pictured). This element is uncommon on Earth but abundant in asteroids. It was formed by dispersing the Chicxulub Impactor around the atmosphere until it settles to the ground.
Analysis of the fossil remains enabled the team to narrow down the times of year in which the mass-death assemblage could have been deposited and, by extension, when the concurrent asteroid impact took place.
First, they looked at fossilised fish bones from the site, focussing on growth lines which — like the rings round in tree trunks — provide an record of each animal’s life history and can be used to determine in which season they stopped growing.
Inspection of the growth lines indicated that all the fish examined died during the Spring–Summer growth season, a conclusion backed up by an isotopic analysis of the lines, which confirmed that they formed following a distinct annual pattern.
The team looked at fossilised fish bones from the site (pictured, middle row), focussing on growth lines which — like the rings round in tree trunks — provide an record of each animal’s life history and can be used to determine in which season (bottom row) they stopped growing. Inspection of the growth lines indicated that all the fish examined died during the Spring–Summer growth season, a conclusion backed up by an isotopic analysis of the lines (top row), which confirmed that they formed following a distinct annual pattern
Further verification came from using a chemical analysis technique called ‘synchrotron-rapid-scanning X-Ray fluorescence’ on the bones of the youngest fossil fish, allowing the team to identify growth stages based on trace metal signatures. These were then compared to modern fish taxa analogous to help determine how long the creature had been buried.
Further verification came from using a chemical analysis technique called ‘synchrotron-rapid-scanning X-Ray fluorescence’ on the bones of the youngest fossil fish, allowing the team to identify growth stages based on trace metal signatures.
The team was able to compare these data to modern fish to determine how long the creature had been hidden after hatching.
When you consider the modern timings of spawning, it is clear that Tanis’ fossil fish died in Spring or early Summer.
‘Animal behaviour can be a pretty powerful tool, so we overlapped even more evidence — this time of seasonal insect behaviour, such as leaf mining and mayfly activity,’ added paper author and University of Kansas palaeontologist Loren Gurche.
“They were all in sync. All evidence points to the fact the impact occurred during the northern equivalent of [the]From Spring through Summer.
![Animal behaviour can be a pretty powerful tool, so we overlapped even more evidence — this time of seasonal insect behaviour, such as leaf mining and mayfly activity,' added paper author and University of Kansas palaeontologist Loren Gurche. 'They all matched up. Everything points to the fact that the impact happened during the northern hemisphere equivalent of [the] Spring to Summer months.' Pictured: the combined sources of evidence](https://i.dailymail.co.uk/1s/2021/12/10/11/51589993-10295703-image-m-23_1639135676499.jpg)
Animal behaviour can be a pretty powerful tool, so we overlapped even more evidence — this time of seasonal insect behaviour, such as leaf mining and mayfly activity,’ added paper author and University of Kansas palaeontologist Loren Gurche. All of them matched. All evidence points to the fact the impact occurred during the northern equivalent of [the]The seasons are from Spring to the Summer. The combined evidence sources
DePalma stated that the project was a massive undertaking, but it was well-worth it.
“For years we’ve been collecting and processing data. Now we have strong evidence that alters how we see the KPg. [Cretaceous–Palaeogene]He added that it was an event.
These findings can help us to better plan for the future of ecological and other environmental dangers, he said.
‘Extinction can mark the end of a dynasty, but we must not forget that our own species might not have evolved if it weren’t for the impact and the timing of events that saw the end of the dinosaurs.’
In the journal, the full results of the study are published. Scientific Reports.
EARTH HAS HAD FIVE IMPORTANT EXTINCTION EVENTS, INCLUDING THE MOST FAMOUS DINOSAUR KILLING STEROID
A mass extinction is a process that wipes out large swathes of human life, which has occurred five times.
End-Ordovician mass extinction
The second of five major extinctions, occurring around 540 million year ago, is probably the most serious. The sea was home to almost all living things at the time. Around 85% of those species disappeared.
Late Devonian mass extinction
Major environmental shifts occurred around 375-359million years ago. This wiped out many fish species, and stopped the formation of coral reefs for over 100 millions years.
A mass extinction is a process that wipes out large swathes of life on the planet five times. One of the most well-known is probably the End-Cretaceous. It wiped out all dinosaurs. Artist’s impression
End-Permian mass death (The Great Dying)
252 million year ago, the greatest extinction and one which had the most devastating impact on the Earth’s ecology was the event that caused the biggest extinction. 97% percent of all species with fossil records disappeared for good.
End-Triassic mass extinction
The Early Triassic was the first time that dinosaurs appeared. However, large amphibians were dominant over mammal-like reptiles and large amphibians. This was changed by the mass extinction of 201 million people a century ago.
End-Cretaceous mass extinction
A 66-million year old asteroid crashed into Earth, ending the rule of dinosaurs.