After surviving the meteor impact that wiped out the dinosaurs millions of years ago, crocodiles are one of the most resilient animals on Earth.
But their success is not due to evolutionary progress. Rather, it is a lack of change, which means that reptiles continue to thrive.
This is the conclusion of a study published in Nature Communications Biology diary.
According to the paper, crocodiles have found a body type that suits them through an evolutionary pattern known as “dotted balance”.
Lead author Dr Max Stockdale of the University of Bristol’s School of Geographical Sciences said: “Our analysis used an machine learning algorithm to estimate rates of evolution.
“The evolutionary rate is the amount of change that has taken place over time, which we can calculate by comparing fossil measurements and taking into account how old they are.
He added: “For our study, we measured body size, which is important because it interacts with how fast animals grow, how much food they need, how large their populations are and how likely they will disappear.”
The findings seem to show that the limited diversity of crocodiles and their apparent lack of evolution is the result of a slow evolutionary rate.
Crocodiles are well suited for land and water and can spend long periods without food. This flexibility can help explain why they survived their ancestors.
Dr Stockdale added: “Our research strongly suggests that crocodiles have remained unchanged for such a long time because they have landed in a state of equilibrium that does not require them to change often.”
“It is fascinating to see how complicated a relationship is between the earth and the creatures we share it with.
“Crocodiles have landed on a lifestyle versatile enough to adapt to the enormous environmental changes that have taken place since the dinosaurs existed.”