Tuesday, October 26, 2021

Scientists uncover secret of dinosaur evolution

Image credit: Frijte/Getty Images, CC BY-SA 3.0/Wikimedia Commons

It is well known that in the annals of human evolution, dinosaurs may have their nearest contemporary yet the great pre-human was brought to extinction by the world’s largest volcanic eruption on our planet’s surface. But a study carried out by scientists in Indonesia points to another major player in the evolution of the dinosaurs: volcanoes, and how they are already active today.

Indonesia is one of the last great untapped fossil reserves and the fossil record there has been excellent for a long time. But their absence of a normal climate, through which they are understood to emerge, is all too apparent. Rather than even water features on the landscape, they are largely covered in growing plants and forest. Over the centuries, the increase in soil carbon and increased greenhouse gas increases on Earth have helped increase volcanic activity. Now a new study of remains of a well-known dinosaur at Yogyakarta in the Java archipelago has caused volcanologists to look at a renewed view of the fossil record.

Researchers from Aarhus University, Denmark, found fossilized teeth of a hyolithian, a dinosaur which lived some 60 million years ago. They examined all of its teeth, in order to understand how it lived and also how it died.

When we think of dinosaurs, the titanosaur being the most well-known is the one that we associate with teetering on an outcrop of rock.

They also ended up becoming sauropods, with long necks and necks filled with metal teeth that out of all the dinosaur groups, contributed the most to carbon dioxide, methane and other greenhouse gases. The hyolithian lived in a period of relatively low carbon dioxide levels, which meant that its mouth acids, which it used to eat, were neutral to high in key isotopes of carbon, such as boron.

This balance of acidity depended on Earth’s three key volcanic sources: Venera F, Krakatoa and Erawan.

At volcanoes, volcanism involves the dissolution of rock, forming deep-well pools, that release ground-hugging gases or magma. As a result, volcanic eruption drives water to the surface, where it evaporates and rocks become lighter to the point of staining them black, which over time becomes incorporated into the sediment and fossil deposits. At the same time, fossilisation occurs, retaining the unique geochemical composition of an ancient place at the moment it was exposed to nature.

While this is not directly linked to the development of bicarbonate-based acids, the carbon based acidity levels present in plant matter- an important reason to study dinosaurs – directly lie in the volcanic deposits. So, looking at the hyolithian teeth, the scientists were able to infer that the reptiles had probably eaten sedgeline plants and consumed those that had lost their leaves or were present on the surface.

Perhaps most exciting, after their birth, Hyolithi began to flower, giving fruit and leaves to which later carnivores could easily reach. And that’s important: plants, including the more desirable green ones, provide an income to many plant species, and create or produce micro-organisms, which in turn provide food to a range of other species.

The feature that makes hyolithians particularly attractive to scientists is that they’re known to have lived in extremely warm ecosystems.

Sub-Saharan Africa is the only other major example of a climate that allowed three major volcanic eruptions. This appears to have taken place around 20 and 30 million years ago on a continental scale – significantly less frequent than that of the impact that caused the cataclysmic end of the Cretaceous period, 80 million years ago.

The sedgeline plant has around 85 million years on Earth, and has been known to store around 80 million metric tons of carbon – the equivalent of about nine billion barrels of oil.

What’s more, following the impact, the volcanism formed an equatorial plateau over which wildlife flourished.

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