Look far enough back in time, and a pattern may emerge. After studying thousands of ancient fossils, paleontologist Jack Sepkoski identified just such a thing in 1981: a vast series of life and death, carved into the skeleton of the past 500 million years .
The late Sepkoski, a professor at the University of Chicago, discovered the three giant evolutionary fauna of marine animals – a trio of continuous explosions in ocean biodiversity over the course of the Phanerozoic Eon.
These great blooms of marine life have been triggered by catastrophes at a changing rate in the world: extinct events wreaking havoc on major animal deaths – while illuminating the world. a platform for new creatures to emerge and thrive in the places they left behind.
But it doesn’t have to happen that way, a new study suggests. Equally powerful forces – able to shape macroevolutionary processes with planetary influence – do not always require asteroids or supervolcanoes.
Sometimes the fire comes from within.
“The fossil record tells us that some of the key transitions in life history were triggered by sudden changes induced by sudden external factors,” explains paleontologist Michal Kowalewski of the University of Florida.
“But this study shows that some of these major transitions were more gradual and may have been driven by biological interactions between organisms.”
The issue at this point is called the Mesozoic Marine Revolution. Beginning around 150-200 million years ago, this transition represents the macroevolutionary changes that occurred as marine predators such as bony fish, crustaceans, and predatory snails evolved in numbers. , causing their invertebrate prey, such as molluscs, to defend against burrows and shell crushing attacks.
In the new research, which used modeling to illustrate the network of relationships between large collections of prehistoric marine life forms, the team found that the Mesozoic Marine Revolution effectively represents a fourth non- known for complying with biodiversity within the Phanerozoic – equivalent in its power to the three rings marked by Sepkoski’s great evolution decades ago.
“We unite the two hypotheses – the Mesozoic Marine Revolution and the three evolutionary lawns in one story,” explained first author and paleontologist Alexis Rojas from Umeå University in Sweden.
“Instead of three stages of life, the model shows four.”
Ultimately, although the Mesozoic Marine Revolution was marked by gradual ecological changes brought about by interactions of marine life over millions of years, the researchers say that it nevertheless encouraged a long biochemical change that was similar in size to the end-Permian movement.
This program, often referred to as the Great Dying, occurred about 250 million years ago and was the worst extinction event on Earth, destroying about 80 percent of the population. all marine species (and 70 percent of terrestrial vertebrates).
After that, life was revived by the third great evolutionary animal, known as modern animal time, according to the Sepkoski framework.
But according to Rojas, Kowalewski, and their team, the modern era was intertwined with the Mesozoic Marine Revolution, contributing to a known transition in biodiversity in marine life the Earth in central Cretaceous, about 129 million years ago.
“What we really built is an abstract fossil record that gives a unique perspective on the organization of marine life,” Rojas says.
“At the most basic levels, this map shows marine regions with specific animals,” he says. “The building blocks of our study are the individual animals themselves.”
The results are reported in Communication Biology.