This species was also wiped out along with dinosaurs in meteor strike

In a new study, the scientists said that ammonites were not declining in numbers when they went extinct.

The marine molluscs with coiled shells, which are one of the great icons of palaeontology, flourished in the oceans of Earth for more than 350 million years till they died out during the same meteorite strike in which the dinosaurs were wiped out nearly 66 million years ago.

Few of the palaeontologists have stated that their extinction was inevitable and that ammonite diversity had decreased before they went extinct till the end of the Cretaceous.

Add WION as a Preferred Source

The new research, which was published inNature Communicationsand headed bypalaeontologistsat the University of Bristol, stated that their fate was not set in stone.

The final chapter in the ammonite evolutionary history is more complex.

Also Read:Jurassic king with a crown? Scientists discover fancy headgear on 78-million-year-old dinosaur

Lead author Dr Joseph Flannery-Sutherland said, "Understanding how and why biodiversity has changed through time is very challenging."

"Thefossil recordtells us some of the story, but it is often an unreliable narrator. Patterns of diversity can just reflect patterns of sampling, essentially where and when we have found new fossil species, rather than actual biological history," he added.

"Analysing the existing Late Cretaceous ammonite fossil record as though it were the complete, global story is probably why previous researchers have thought they were in long-term ecological decline," he said.

How did the team analyse Late Cretaceous ammonite fossils?

A new database of Late Cretaceous ammonite fossils was assembled by the team to fill the sampling gaps in their record.

"We drew onmuseum collectionsto provide new sources of specimens rather than just relying on what had already been published," said co-author Cameron Crossan.

Crossan is the University of Bristol's Palaeobiology MSc programme's 2023 graduate.

"This way we could be sure that we were getting a more accurate picture of their biodiversity prior to their total extinction," he added.

Watch:Japanese scientists create living robot skin with human cells

The team, while using their database, analysed how extinction rates and ammonite speciation varied in different parts of the world.

Throughout the Late Cretaceous, if ammonites were in decline then their extinction rates were generally higher than their speciation rates wherever they checked.

Instead, the team found that the balance of speciation and extinction changed between different geographic regions and through geological time.

Senior author Dr James Witts of the Natural History Museum, London said, "These differences in ammonoid diversification around the world are a crucial part of why their Late Cretaceous story has been misunderstood."

"Their fossil record in parts of North America is very well sampled, but if you looked at this alone, then you might think that they were struggling, while they were actually flourishing in other regions. Their extinction really was a chance event and not an inevitable outcome," he added.

(With inputs from agencies)