How Crocodile Ancestors Survived The Dinosaur Extinction

Evrim Yazgin Cosmos science journalist

Crocodiles are often thought of as living fossils – unchanged over millions of years. New research has shown that their evolutionary history is a lot more complicated than that.

Crocodilia is the surviving family of a lineage which emerged about 230 million years ago (mya) called crocodylomorphs. This group split from other reptilian species including those that eventually became dinosaurs. Today, the crocodilia include crocodiles, alligators, caiman and gharials.

Ancestors of modern crocodilians survived through 2 mass extinctions, including the one which spelled the end of the “Age of Dinosaurs” 66 mya.

The new study, published in the journal Palaeontology, shows that the secret to success of crocodylomorphs was their adaptability to new food sources and habitats.

“Lots of groups closely related to crocodilians were more diverse, more abundant, and exhibited different ecologies, yet they all disappeared except these few generalist crocodilians alive today,” says lead author Keegan Melstrom from the University of Central Oklahoma.

Today’s crocodilians are semi-aquatic generalists. The thrive in different habitats and aren’t picky eaters.

It was a different story with ancient crocodylomorphs.

The palaeontologists visited museum collections in 7 countries, across 4 continents to understand the evolution of crocodilian ancestors. They examined the skulls of 99 extinct crocodylomorph species and 20 living crocodilians.

Crocodylomorphs exploded after the end-Triassic mass extinction 201 mya which killed off ancient lineages of hypercarnivores and land-based predators.

“After that, it goes bananas,” says Melstrom. “Aquatic hypercarnivores, terrestrial generalists, terrestrial hypercarnivores, terrestrial herbivores – crocodylomorphs evolved a massive number of ecological roles throughout the time of the dinosaurs.”

Toward the end of the time of the dinosaurs, however, crocodylomorphs started to decline.

Most of the specialised crocodylomorphs had died off by the end of the Cretaceous. Almost all 26 remaining species today are semi-aquatic generalists.

“When we see living crocodiles and alligators, rather than thinking of ferocious beasts or expensive handbags, I hope people appreciate their amazing 200+ million years of evolution, and how they’ve survived so many tumultuous events in Earth history,” says co-author Randy Irmis from the Natural History Museum of Utah. “Crocodilians are equipped to survive many future changes – if we’re willing to help preserve their habitats.”

“Extinction and survivorship are 2 sides of the same coin,” Melstrom says. “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?” (snip-More)

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More Library Tidbits (+ a way to be an impediment to the strangling of libraries.)

US blocks Canadian access to cross-border library, sparking outcry

US officials claim move was to curb drug trafficking while Quebec town says it ‘weakens collaboration’ among nations

View image in fullscreen A young girl walks over the Canada-US border line from the Haskell Free Library and Opera House in Derby Line, Vermont, on Friday. Photograph: Christinne Muschi/The Canadian Press via AP

The US has blocked Canadian access to a library straddling the Canada-US border, drawing criticism from a Quebec town where people have long enjoyed easy entry to the space.

The Haskell Free Library and Opera House is located between Stanstead, Quebec, and Derby Line, Vermont. It was built deliberately to straddle the frontier between the two countries – a symbol of cooperation and friendship between Canada and the US. (snip)

Fairhope Public Library supporters raise money to replace funds state plans to withhold

By: Ralph Chapoco – March 25, 2025 11:49 am

A nonprofit says it has raised enough money for Fairhope Public Library to cover state funds that the Alabama Public Library Service Board cut off last week.

Read Freely Alabama, a grassroots free speech advocacy organization that has fought restrictions on library content, said it had collected almost $39,000 from about 550 donors through Tuesday morning. Read Freely is organizing the campaign with EveryLibrary, an Illinois-based organization that promotes library funding and fights restrictions.

“We were trying to figure out what was the amount that they were pausing,” said Cheryl Corvo, a member of Read Freely Alabama and Fairhope resident. “Then, we found out it was $42,000 that they were pausing, and how it would affect our library.”

The Fairhope Public Library said it will have access to funding without interference from the state or any outside groups.

“We had a meeting with EveryLibrary, which is the group that has control of this particular fundraiser, and they take 10% and 90% of it comes to us,” said Randal Wright, a board member of the Fairhope Public Library.

The amount was not enough to severely debilitate the library’s operations, Corvo said. But it is enough to affect “some very vital resources that the library provided.” Corvo said the campaign should also make APLS aware of the magnitude of local support  for the library.

Wright said that if the state continues to withhold money, the funds will go toward computers, books for the collection and paying for guest speakers. (snip)