TORONTO -- Scientists have discovered that ancient and extinct sabre-toothed cats have something in common with many parents today: they have offspring that stay at home longer than expected.

Adolescent Smilodon fatalis, a large long-toothed predator found through much of North America and South America, including Canada, were “more momma’s cubs than independent warriors,” according to a press release from the Royal Ontario Museum.

The study by researchers at the ROM and the University of Toronto, published this month in the journal iScience, documents the life of what is believed to be a family group of fossils discovered by ROM scientists in Ecuador in 1961.

Described as “supersized ice age cats,” the animals died out about 10,000 years ago. They are believed to have grown quickly. Based on their fossils, the two young cats weighed 132 kilograms and 141 kilograms.

Based on a rare genetic extra tooth, the scientists believe the fossils they studied belong to three related cats: one adult and two adolescents. It’s believed they were a mother and her offspring.

Researchers determined the younger cats were at least two years old when they died, an age at which cats that exist today, such as tigers, are already independent.

The researchers concluded that the deposit of fossils discovered in Ecuador, on an ancient coastal plain, is “likely derived from a catastrophic mass-death event” – possibly flooding or drought – in which all the fossilized remains are from animals that died at the same time.

“As this preserves a snapshot of an ecosystem, fossils like these can provide new and unique insights into the behaviour of extinct species,” reads the ROM press release.

Most Smilodon specimens have been collected from “predator trap” deposits, such as the famous La Brea Tar Pits in Los Angeles, but the nature of those pits makes it “virtually impossible to identify associated individuals or even multiple bones from single individuals,” the scientists wrote in their study.

“The social lives of these iconic predators have been mysterious, in part because their concentration in tar seeps leaves so much room for interpretation,” said Kevin Seymour, assistant curator of vertebrate paleontology at the ROM and a co-author of the study.

“This historic assemblage of sabre-cat fossils from Ecuador was formed in a different way, allowing us to determine the two juveniles likely lived, and died, together—and were therefore probably siblings.”