Giant dinosaurs and super galaxies

SARAH WILD

Scientists turned to digital modelling to study the Dreadnoughtus dinosaur and have finally defined where our galaxy is in the universe.

It weighed more than seven Tyrannosaurus rex dinosaurs, making Dreadnoughtus schrani the largest known accurately measured land animal. Excavated over four years in Argentina, this 26m-long herbivore weighed nearly 60 000kg, more than a Boeing 737. One of its femurs is longer than a tall man, at almost two metres.

“Shockingly, skeletal evidence shows that, when this 65-tonne specimen died, it was not yet full grown,” said Kenneth Lacovara, a professor at Drexel University in the US who headed up the research that was published in the journal Scientific Reports.

Even though it was a herbivore, scientists have named the dinosaur after the fearsome battleship of the early 20th century. “With a body the size of a house, the weight of a herd of elephants and a weaponised tail,Dreadnoughtus would have feared nothing,” he said.

To study this giant creature, which lived in the late Cretaceous period, between 84-million and 66-million years ago, the researchers had to go digital.

“Digital modelling is the wave of the future. It’s only going to become more common in palaeontology, especially for the studies of giant dinosaurs such as Dreadnoughtus where a single bone can weigh hundreds of pounds,” said Matthew Lamanna from the Carnegie Museum of Natural History in the US.

Although we should be impressed by the sheer proportions of this creature, the biggest known mammal remains the blue whale. It’s longer by a few metres and almost double the weight of Dreadnoughtus. So, although we consider the prehistoric landscape to be fraught with dangers, dinosaurs and certain death, remember that the sea is also peppered with gigantic primordial creatures, and they are not fossils.

Where are we now?
After thousands of years of scientific inquiry, it seems peculiar that we have only recently figured out where we are in the universe.

We know that our planet orbits the sun, which is one of billions of stars in the Milky Way galaxy, and that galaxies themselves form clusters in groups ranging from dozens to hundreds, known as superclusters.

In research published last week in the scientific journal Nature, scientists have finally defined the boundaries of our supercluster, in effect marking where our galaxy is in the universe. It is part of a newly identified gigantic supercluster of galaxies the researchers have named Laniakea, meaning “immense heaven” in Hawaiian.

“We have finally established the contours that define the supercluster of galaxies we can call home,” said lead researcher R Brent Tully, an astronomer at the University of Hawaii at Manoa.

“This is not unlike finding out for the first time that your home town is actually part of a much larger country that borders other nations.”

These superclusters are among the largest structures in the known universe and, although scientists “know that they are interconnect, they have poorly defined boundaries”, said the United States’s National Radio Astronomy Observatory, which was involved in the research.

“To better refine cosmic mapmaking, the researchers are proposing a new way to evaluate these large-scale galaxy structures by examining their impact on the motions of galaxies,” it said.

“A galaxy between structures will be caught in a gravitational tug-of-war in which the balance of the gravitational forces from the surrounding large-scale structures determines the galaxy’s motion.”