Today’s crocodile ancestors survived two major extinction events. Research reveals the secrets of their longevity

Most people consider crocodiles to be living fossils. It is an inbearable prehistoric relic that has dominated the world’s wettest horns for millions of years. But their evolutionary history tells a different story, according to a new study led by the University of Central Oklahoma (UCO) and the University of Utah.

Crocodiles are surviving members of a 230 million-year-old lineage called the Crocodile Diromorph, a group that contains living crocodiles (i.e., crocodiles, alligators, and Garialists) and their many extinct relatives. The crocodile ancestors survived through two major extinction events. This is a feat that requires evolutionary agility to adapt to a rapidly changing world.

The authors of this study found that one of the secrets of crocodile longevity is their highly flexible lifestyle, both in what they eat and in the habitats they obtain.

“Many groups closely associated with crocodiles exhibited more diverse, more abundant and different ecology, but they disappeared except for these few generalist crocodiles who live today,” said Keegan Melstrom, the lead author and assistant professor at UCO.

“Extinction and survival rate are two aspects of the same coin. Through all mass extinctions, some groups can last and diversify. What can we learn by studying the deeper evolutionary patterns given by these events?”

The Earth has experienced five mass extinctions in its history. Experts claim we are alive throughout the sixth, driven by habitat destruction, invasive species and climate change. Identifying traits that increase survival rates during planetary upheavals could help scientists and conservationists better protect today’s vulnerable species.

Historically, the field has seen mammals as poster children to understand the survival of mass extinction. Despite their resilience, research has largely ignored alligator clades.

The paper published in Journal Palaeontology is the first to reconstruct the dietary ecology of crocodiles to identify traits that help several groups to persist and thrive through two mass extinctions, or approximately 2014 million years ago (MA), and the final Cretsic, about 66 MA.

“There is a risk that we will draw conclusions millions of years ago and try to apply them directly to protection. We must be careful.”

“If people study mammals and reptiles and find the same pattern in terms of extinction survival, they might predict that species with a generalist diet could be better.

The hidden past of alternative lifestyles

The living crocodile is a semi-aquatic generalist who thrives in lakes, rivers and marsh-like environments, and is famous for waiting to ambush unsuspecting prey. Noisy people, they aren’t.

Young people enjoy tadpoles, insects, crustaceans and more before graduating to a larger fare, including fish, deer and even fellow crocodiles. However, the uniform lifestyle of crocodiles today obscures the massive amount of food ecology in which crocodiles flourished in the past.

During the late Triassic period (237-201.4 MA), Pseudosuchia, a broader evolutionary group, which includes early crocodiles and many other extinct strains, dominated the land. Early crocodiles were small to medium-sized creatures, rare in the ecosystem, and were mainly carnivorous animals that ate small animals.

In contrast, other pseudosu bone groups dominated the land, occupying a broad ecological role, exhibiting diverse body types and sizes of vertigo.

Despite their superiority, once a serious extinction hit, the non-crocodylomorph fake su did not survive. Hypercarnivore crocodile also seemed to die, while generalists on earth went through it. The authors assume that this ability to eat almost anything allowed them to survive, but many other groups have become extinct.

“Then it becomes a banana,” Melstrom said. “Aquatic high carnivores, terrestrial generalists, terrestrial carbides, terrestrial herbivores – the crocodillomorphs have evolved a vast number of ecological roles throughout the age of dinosaurs.”

Something happened in the late Cretaceous period and the crocodile faded. Diverse ecology-focused lineages have begun to disappear even among the generalists on the ground.

Due to the mass extinction event of Cretatuas (separated by meteors that killed non-bird dinosaurs), most of the survivors are semi-predictive generalists and a group of aquatic carnivorous animals. Nearly all 26 live crocodiles today are semi-rated generalists.

Beyond the crocodile’s smile

How do scientists analyze food on menus that are millions of years old? They analyze the shape of fossilized teeth and skulls to collect the basics of the animal’s diet. The jaws stacked with small knives could have sliced ​​the flesh and drilled holes.

Mortars and breeding grills probably destroyed the plant tissue. The shape of the skull determines how the animal moves its mouth and provides clues to its eating habits. Deciphering the ancient animal diet reveals where it hunted.

It was a massive job. The author visited museum collections of zoology and paleontology across seven countries and four continents to obtain the necessary fossil specimens. They examined skulls of 99 extinct alligator species and 20 living crocodile species, creating a fossil dataset that spans 230 million years of evolutionary history.

Researchers previously constructed a database of living non-Crocodilians, including 89 mammals and 47 lizard species. The specimens represent a variety of vegetative ecology, ranging from strict carnivorous to mandatory herbivores and a wide variety of skull shapes.

As semi-rated ambush predators, crocodiles today primarily occupy a similar ecological role in many different environments. They continue to have a very flexible diet. Perhaps it is a remnant of their deep, diverse evolutionary past.

For endangered species of crocodiles like the Cuban crocodile in the Himalayas’ hills and the swamps of the country’s Zapata, dietary flexibility may give them the opportunity to continue their current sixth mass extinction. The biggest challenges these species face are habitat loss and human hunting.

“I hope that, rather than thinking about ferocious beasts or expensive handbags, when I see living crocodiles and crocodiles, people will appreciate their astonishing 20 million years of evolution and how they survived so many turbulent events in Earth’s history,” Ilmisu said.

“Crocodilli people are equipped to survive many future changes if they are willing to help maintain their habitat.”