Crocodylians are surviving members of a 230-million-year lineage called crocodylomorphs, a group that includes living crocodylians (i.e. crocodiles, alligators and gharials) and their many extinct relatives.
Crocodylian ancestors persisted through two mass extinction events: the end-Triassic mass extinction (201.4 million years ago) and the end-Cretaceous mass extinction (about 66 million years ago) — a feat requiring evolutionary agility to adapt to a rapidly changed world. One secret to crocodylian longevity is their remarkably flexible lifestyles, both in what they eat and the habitat in which they get it. "Lots of groups closely related to crocodylians were more diverse, more abundant, and exhibited different ecologies, yet they all disappeared except these few generalist crocodylians alive today," said Dr. Keegan Melstrom, a researcher at the University of Utah. "Extinction and survivorship are two sides of the same coin. Through all mass extinctions, some groups manage to persist and diversify. What can we learn by studying the deeper evolutionary patterns imparted by these events?" Earth has experienced five mass extinctions in its history. Experts argue that we're living through a sixth, driven by habitat destruction, invasive species and changing climates. Identifying traits that boost survivorship during planetary upheaval may help scientists and conservationists better protect vulnerable species today. Historically, the field has regarded mammals as the poster children for understanding mass extinction survival, lauding their generalist diet and ability to thrive in different ecological niches. Despite their resilience, research has largely ignored the crocodylomorph clade. In a new study, Dr. Melstrom and colleagues reconstructed the dietary ecology of crocodylomorphs to identify characteristics that helped some groups persist and thrive through the end-Triassic and the end-Cretaceous mass extinctions. "There's a danger of trying to draw conclusions from millions of years ago and directly apply it to conservation. We have to be cautious," said University of Utah's Professor Randy Irmis. "If people study mammals and reptiles and find the same…