SCIENTISTS at a Southampton university may have discovered what wiped out early dinosaurs.

Not the Tyrannosaurus Rex or the Triceratops - but their distant cousins in the Triassic period hundreds of millions of years before.

Before the famous extinction 65 million years ago, popularly thought to be caused by a meteor striking the Earth, there was another mass extinction around 200 million years ago that killed half of all plant, animal and marine life on the planet.

Now researchers at the University of Southampton believe changes in the chemical balance of the ocean were a crucial factor, causing the waters to become toxic.

Coupled with a surge in carbon dioxide (CO2) levels, it created major problems with food chains, according to the scientists.

Dinosaurs from the Triassic period are less well-known than some of the famous creatures depicted in films like Jurassic Park - such as the Herrerasaurus, Procompsognathus and Riojasaurus - but are still their close relatives despite the evolutionary gap of millions of years.

Spiders, scorpions, centipedes and some of the earliest-known mammals also existed during this period.

The study, published in the upcoming edition of Geology, reveals that a condition called 'marine photic zone euxinia' took place in the Panathalassic Ocean- the larger of the two oceans surrounding the then-supercontinent Pangaea.

It was caused by surface waters becoming devoid of oxygen and poisoned by hydrogen sulphide - a by-product of a bacteria that lives without oxygen.

University of Southampton's Prof Jessica Whiteside, who co-authored the study, said: “As tectonic plates shifted to break up Pangaea, huge volcanic rifts would have spewed carbon dioxide into the atmosphere, leading to rising temperatures from the greenhouse effect. The rapid rises in CO2 would have triggered changes in ocean circulation, acidification and deoxygenation.

“These changes have the potential to disrupt nutrient cycles and alter food chains essential for the survival of marine ecosystems.

“The same CO2 rise that led to the oxygen depleted oceans also led to a mass extinction on land, and ultimately to the ecological take-over by dinosaurs, although the mechanisms are still under study.”

The international team of researchers studied fossils extracted from sedimentary rocks off the coast of British Columbia, Canada, which previously were on the bottom of the prehistoric ocean.

Daily Echo: