Photo: Joseph Novak Flickr.com

The mass extinction of dinosaurs has been featured in movies, books and cartoons. Usually an asteroid smashes into the earth and wipes them out. Recent studies now show that this may not be the only reason.

Through the use of new analytical methods together with fossil record information, researchers from the University of Reading and University of Bristol found that dinosaurs started to decline 50 million years before the asteroid that wiped them from the earth. They calculated that the rate at which dinosaur species were becoming extinct was quicker than the rate at which new species were emerging from the old ones.

The decline in species may have been influenced by the break-up of continental plates and continuous volcanic activity that transformed the environment. The decrease in the species number affected the three major dinosaur groups at different rates. The long-necked giant sauropod dinosaurs declined the fastest while theropods, including T-rex, declined the slowest.

When the asteroid struck the earth, huge amounts of dust were scattered into the atmosphere, temporarily covering the sun and cooling the atmosphere, which resulted in vegetation loss. With no food, plant-eaters died out, together with those who fed on them.

The asteroid impact is still thought to have been the major reason to wipe out the dinosaurs but the smaller number of species made them more prone to extinction. The dinosaurs (apart from birds) were unable to adapt quickly enough to survive the final destructive event.

Dinosaurs and mammals roamed the earth at the same time, with dinosaurs dominating. After the asteroid impact, the switch to mammalian domination was immediate. This study suggests that mammals might have still won in the long run without an impact, though more dinosaurs might be with us today.

“Our study strongly indicates that if a group of animals is experiencing a fast pace of extinction more so than they can replace, then they are prone to annihilation once a major catastrophe occurs. This has huge implications for our current and future biodiversity, given the unprecedented speed at which species are going extinct, owing to the ongoing human-caused climate change,” said Dr Manabu Sakamoto, the study’s lead paleontologist.

Did you know…

• Of the thousands of planets found outside of our solar system, 33 might be habitable; we are not alone.

• Human beings and fruit flies share nearly 75 per cent of genes that cause disease in humans, because of this we can use flies to learn about humans.

• Marijuana has been used for medical reasons since the Arabic Golden Age that spanned from the eighth to the 13th centuries AD. Now it is studied worldwide, even locally, for medical treatments.

• Every day DNA naturally develops around 1,000 errors. The body naturally fixes most of these. Those that it doesn’t can lead to diseases like cancer.

For more trivia: www.um.edu.mt/think

Sound bites

• Dozens of Maltese have already had their genome (all the genes in their body) sequenced. Their information has helped establish that Maltese come from a 12th century Sicilian Arabic origin and gives insight into heart disease and the blood disorder thalassaemia. There are now plans to sequence around 4,000 people, or one per cent of the whole population. Malta might soon become the best genetically documented population in the world.

www.um.edu.mt/think/special-feature-the-maltese-genome/

• A handful of tiny teeth found in Israel’s Negev desert led an international team of researchers to describe a new species of rodent which has been extinct for nearly 18 million years. It has unique features that offer fresh insight into the migration patterns of ancient animals from Asia to Africa. Around 19 million years ago many mammals were already travelling between the two continents through Israel.

www.eurekalert.org/pub_releases/2016-04/thuo-a1m041316.php