Dinosaurs Wiped out by Extraterrestrial Impact
An international panel of experts having reviewed the current evidence related to the Cretaceous mass extinction event have come down strongly on the side of those scientists that claim it was a huge space impact that led to the extinction of the dinosaurs.
The team of experts published their conclusions following a review of the last twenty year’s research into the extinction event located at the K/T boundary. Their findings were discussed at the 41st Lunar and Planetary Science Conference held in Texas.
According to this eminent group, the dinosaurs, flying reptiles, marine reptiles and a number of other major groups of animals became extinct 66 million years ago, when an extraterrestrial object, an asteroid or meteorite, smashed into the Gulf of Mexico. This huge rocky object, estimated at over 10 kilometres wide; blasted a hole more than 100 kilometres across in the Earth’s crust and hit the Earth with the estimated force of 100 million hydrogen bombs. Geophysical analysis of the Chicxulub crater (the site of the impact), suggests that the object from space was travelling at more than 30 kilometres a second when it crashed into the sea. Analysis of the impact crater suggests that this object approached at a low angle from the southeast, a furrow in the south west segment of the crater provides the tell-tale evidence of the direction of the impact.
The first scientists to put forward the theory of a space impact causing the mass extinction event marking the end of the age of reptiles and wiping out approximately 50% of all the species on the planet was father and son team, Luis and Walter Alvarez. In 1980, they publicised the discovery of a worldwide layer of clay rich in the rare element iridium. They speculated that the iridium had been deposited as the result of a huge collision with a large, rocky object from outer space. A number of theories for the demise of much of the mega fauna approximately 65 million years ago have been put forward. A strong candidate was the potential global catastrophe caused by repeated volcanic eruptions in India – the Deccan Traps. The changes in the climate would have had a significant impact on life on Earth, but the scientists meeting in Texas have strongly endorsed the space impact theory as being the primary cause of the death of the likes of Tyrannosaurus rex, the ammonites and the mosasaurs.
Commenting on this new report, Dr Gareth Collins from the Department of Earth Science and Engineering at Imperial College London stated:
“The asteroid was about the size of the Isle of Wight and hit Earth 20 times faster than a speeding bullet. The explosion of hot rock and gas would have looked like a huge ball of fire on the horizon, grilling any living creature in the immediate vicinity that couldn’t find shelter. Ironically, while this hellish day signalled the end of the 160 million year reign of the dinosaurs, it turned out to be a great day for mammals, who had lived in the shadow of the dinosaurs prior to this event. The KT extinction was a pivotal moment in Earth’s history, which ultimately paved the way for humans to become the dominant species on Earth.”
The object from space would have caused fire storms and earthquakes, and blasted material high into the atmosphere, blocking out the Sun to trigger a “nuclear winter” that would have killed off much of the Earth’s life in a matter of days.
Scientists have speculated that most of the large animals in North America would have perished within a short period of time following the impact. Other types of creature, living in areas further away from the impact would have become extinct over a longer period of time. Ammonites for example, already under pressure according to the lack of fossils and lack of diversity of genera in Upper Cretaceous sediments may have persisted for another 250,000 years before finally becoming completely extinct.
Last year, we reported on the publishing of a scientific paper that refuted the claim that an extraterrestrial collision caused the mass extinction. It seems that this debate is set to continue for a long time.
To read the article challenging the impact theory: Published Study Rejects Asteroid Impact Theory.
In another controversial twist to the arguments being presented, a team of scientists from the U. S. Geological Survey, published a paper last year on their research into the survival of some types of dinosaur into the Cenozoic. This team reported on the findings of hadrosaur fossils that may have been found in post-Cretaceous strata. Whether this was evidence of some types of dinosaur surviving the mass extinction event or whether this is evidence of fossil re-deposition has been hotly debated.
To read more about dinosaurs surviving beyond the Cretaceous: Did some Dinosaurs survive into the Palaeogene?