The impact of the asteroid that ended the dinosaurs' reign is one of the most significant impact disasters in Earth's history, and scientists have now identified the time of year when it happened.
The timing of the asteroid's hit appears to have had consequences for how quickly different species recovered, according to new evidence.
The asteroid that struck 66 million years ago caused devastating climate changes that led to the disappearance of 76 percent of species. The timing of the impact may have been a factor in the survival of a number of dinosaur species.
This crucial finding will help to uncover why most of the dinosaurs died out while birds and early mammals survived.
The researchers think that the asteroid could not have come at a worse time for the Northern Hemisphere, with springtime being an important part of the year for reproduction and young offspring.
The researchers looked at the growth patterns in the fossils of the sturgeons and paddlefishes to see if they were related to the asteroid strike.
There were more clues found in the fish's gills. The impact debris was lodged in the stomach, suggesting that the creatures died instantly. A huge seiche or wave of water on a continental scale would have driven the debris that buried the marine life.
The carbon in the fish's skeleton was used to determine how much zooplankton had been eaten, which is useful information during the feeding season.
A fossil from Tanis is a paddlefish. During et al., Nature.
The growth record of this unfortunate paddlefish shows that the feeding season had not yet ended and that the death came in the spring.
The Tanis deposit site is in North Dakota. Many of the samples gathered are well preserved, giving researchers a clear look at their state when they died.
A study published last year agrees that springtime in the Northern Hemisphere was the time of the asteroid impact. The growth patterns in fish fossils were used by the scientists to come to their conclusions.
The K-Pg extinction boundary is still relevant to us today. With the species of Earth facing yet another dramatic change, this research is useful for looking forwards as well as backwards.
The researchers write in their paper thatcoupling short and long-term effects of the bolide impact on the K-Pg mass extinction will aid in identifying extinction risks and modes of ecological degradation caused by the forthcoming global climate change.
The research has been published.