What Led to Dinosaur Extinction?

The question of what led to the ultimate decline of the dinosaurs has fascinated scientists and laymen alike, leading to an extensive amount of research on the topic of dinosaur extinction. The most popular theory thus far is that an asteroid collided with planet Earth about 65-million years ago, causing a massive dinosaur extinction. Now researchers have introduced a new twist to the tale, claiming that some of the large herbivorous species may have already been suffering from some form of decline, long before this momentous event removed all terrestrial dinosaurs from the planet.

Some Believe Diversity Played a Role in Dinosaur Extinction

This theory of dinosaur extinction is that lineages that showed greater diversity amongst a range of species would have been more competitive, showing healthy rates of evolution. Carnivorous species such as Tyrannosaurus rex fall into this class, as do the herbivores at extreme ends of the size-scale: the smallest species and the largest ones – the Sauropods.

Groups with less diversity amongst species tended towards similarity, which may point towards a gradual decline and an increased risk of extinction. The Ceratopsids (a group that includes Triceratops) and the Hadrasaurs (a group of duck-billed dinosaurs) were both large in stature and showed little selection in feeding-pattern. These groups were shown to already be at risk of dinosaur extinction 12 million years before the actual extinction took place.

Steve Brusatte Leads this Dinosaur Extinction Research Theory

The study that puts this theory forward was recently published by researchers from the American Museum of Natural History, under first author Steve Brusatte, in the journal ‘Nature Communications’. They studied the fossils of 150 different species – representing seven of the major groups of dinosaurs – in terms of structural body variation. This was done in an effort to determine overall population health.

The scientists caution that the findings should be seen in context. It relates to fossils from North America only, which means that the theory may not extrapolate well to other geographic regions. It also does not imply that there was no hope for these dinosaurs, since fluctuations in diversity were evident throughout the Mesozoic; small changes may not have been significant over the time span of 150 million years during which dinosaurs roamed the planet.

This theory does, however, cast a different light on the perception that the dinosaurs were taken from the planet by a catastrophic event at the peak of their reign. As with most aspects of science, things are often more complex than we at first believe and this is definitely the case with dinosaur extinction.