WASHINGTON: After the demise of the dinosaurs following an asteroid strike 66 million years in the past, mammals grew to become Earth’s dominant land animals. However that doesn’t imply they went unchallenged. In South America, for example, nightmarish land-living crocs – cousins of as we speak’s crocodiles and alligators – grew to become apex predators.
This lineage of terrestrial crocs, referred to as sebecids, lasted longer than beforehand believed, in accordance with researchers who described fossils lately unearthed within the Dominican Republic that reveal that the islands of the Caribbean served as an sudden final refuge for these ferocious predators.
Till now, the latest fossils of sebecids have been present in Colombia and dated to about 10.5-12.5 million years in the past. The Dominican Republic fossils date to about 5-7 million years in the past. The most important of the sebecids reached roughly 6m lengthy, although the partial stays from the Dominican Republic point out an animal as much as about 2m lengthy.
“These have been the kind of predators that one thinks have been from the dinosaur instances,” mentioned Lazaro Viñola Lopez, a graduate scholar in palaeontology on the College of Florida and lead creator of the analysis printed this week within the journal Proceedings of the Royal Society B.
As a substitute, Viñola Lopez mentioned, sebecids have been on the high of the meals chain in South America through the age of mammals alongside terror birds, big flightless birds as much as about 3m tall with large hooked beaks, and sabre-toothed marsupials, counterparts to the sabre-toothed cats of North America and elsewhere.
Varied sorts of crocs have inhabited Earth courting again to the Triassic Interval greater than 200 million years in the past. Most, like those alive as we speak, lived a semiaquatic way of life. However some conquered the marine realm and others lived solely on land, just like the sebecids.
The sebecids have been constructed in a different way than the standard semiaquatic crocs.
That they had longer legs and a extra upright stance, able to working shortly to chase down prey. That they had a slender and deep cranium – superficially resembling that of a meat-eating dinosaur and far totally different from fashionable crocs which have a wider and shallower cranium. And the tooth of sebecids have been tall and slender with advantageous serrations working alongside the perimeters for slicing by meat, additionally much like carnivorous dinosaurs.
Like many different crocs, they’d protecting armour made from bony plates referred to as scutes embedded of their pores and skin.
The fossils discovered within the Dominican Republic in 2023 have been a single tooth that carefully resembled these of South American sebecids and two vertebrae with traits that enabled the researchers to definitively conclude that these stays belonged to a sebecid.
“It’s wonderful to suppose that these fast-moving, dinosaur-like terrestrial crocs with serrated tooth specialised for slicing meat survived within the Caribbean looking sloths, rodents and no matter else was round up till just some million years in the past,” mentioned examine co-author Jonathan Bloch, curator of vertebrate paleontology on the Florida Museum of Pure Historical past on the College of Florida.
The researchers mentioned that fossils of two tooth apparently from a sebecid courting to about 18 million years in the past that have been beforehand found in Cuba and an analogous one courting to round 29 million years beforehand present in Puerto Rico recommend that this lineage was widespread within the islands of the West Indies.
However how did land-living crocs from South America handle to get there? The researchers mentioned their presence on the islands is one other clue indicating there could have been a pathway of momentary land bridges or a series of islands that permitted land animals to journey from South America to the Caribbean round 32-35 million years in the past.
“The space between the islands and northern South America was considerably shorter than what it’s as we speak. This possible facilitated the dispersal of sebecids from South America,” Viñola Lopez mentioned. “This exhibits how vital islands may be as a biodiversity museum, preserving the final members of some teams which have gone extinct all over the place.”
