Asteroid that killed dinosaurs wiped out another big species
Dinosaurs were not the only species that were wiped out from Earth after the massive asteroid crashed over Earth. The giant structure tumbling through space was responsible for several other changes on the planet, and notable among them is the death of another species.
A new study published in Nature Communications has overturned the long-held belief that ammonites were in decline before their extinction 66 million years ago.
The research, led by paleontologists at the University of Bristol, suggests that these iconic marine molluscs were flourishing right up until their sudden demise alongside the dinosaurs.
Ammonites are an extinct group of marine mollusks that belonged to the class Cephalopoda, which also includes modern-day squid, octopus, and cuttlefish
Dr. Joseph Flannery-Sutherland, the lead author, emphasised the challenges in understanding biodiversity changes through time, noting that the fossil record can be an unreliable narrator.
Ammonites basking under the Late Cretaceous sun. (Photo: UoB)
To address this, the team assembled a new database of Late Cretaceous ammonite fossils, drawing on museum collections to fill sampling gaps and provide a more accurate picture of ammonite biodiversity.
The study revealed that ammonite speciation and extinction rates varied across different geographic regions and through geological time. This finding contradicts previous assumptions of a global decline, which were based on limited data primarily from North America.
Dr. James Witts of the Natural History Museum, London, highlighted the importance of considering regional differences in ammonite diversification. He stated that while ammonites may have appeared to be struggling in some areas, they were thriving in others, suggesting their extinction was truly a chance event rather than an inevitable outcome.
The research also explored factors influencing ammonite diversity, considering both environmental conditions (the Court Jester Hypothesis) and biological processes (the Red Queen Hypothesis).
The team found that the causes of ammonite speciation and extinction were as geographically varied as the rates themselves, emphasizing the complexity of their evolutionary history.
This study points to the importance of analyzing fossil datasets at regional scales to capture a more nuanced picture of biodiversity changes across space and time. It challenges simplistic narratives in paleontology and provides a new perspective on the final chapter of ammonite evolution before their abrupt extinction.
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