An illustration of Microraptor, a 120-million-year-old dinosaur found with a stomach full of fish.
A 120-million-year-old dinosaur has been found with a stomach full of fish, according to a paper in the latest issue of the journal Evolution.
The dinosaur, Microraptor, now joins a small number of other dinos in the fossil record that have been found with clearly visible food remains in their guts.
In this case, "The gut contents consist of a jumbled mass of fish bones, not an intact fish skeleton, and some of these bones show evidence of being dissolved by digestive acid," project leader Scott Persons told Discovery News.
Persons, a University of Alberta paleontologist, examined the Microraptor, found well-preserved in China within volcanic ash.
Its teeth were perfectly designed for killing and eating fish, he determined. The teeth were serrated on just one side, in addition to being angled forward. The dinosaur could then impale fish on its teeth without ripping the fish apart during the inevitable struggle.
Each fish meal would have been like a sushi slider.
"Microraptor could simply raise its head back, (and) the fish would slip off the teeth and be swallowed whole, no fuss or muss," he explained.
The dinosaur, which was a member of the Dromaeosaur dino family, looked a lot like a modern bird, but not entirely.
Similar to many of today's birds, Microraptor had short insulating feathers covering its body, and long feathers on its wings and legs.
Previously it was thought that this dinosaur, which was not a direct ancestor of modern birds, lived in trees and preyed exclusively on small birds and mammals.
Now it's known that Microraptor operated in a varied terrain, hunting different types of prey. Clearly fish was a favorite, but other evidence suggests it also gobbled up birds and terrestrial animals about the size of squirrels.
An illustration of Microraptor, a 120-million-year-old dinosaur found with a stomach full of fish.Scott Persons
Its habitat was a forested environment filled with fresh-water lakes and swamps, likely packed full of fish.
To catch fish, the dinosaur probably did not wade into the water like a stork would today. It also didn’t grasp fish in its talons, like a living bald eagle or osprey would.
"Maybe Microraptor speared fish in shallow water from ambush on the bank, like a little green heron, or maybe it would dive for fish, like a kingfisher; we just don’t know," Persons said.
Thomas Holtz, Jr., a vertebrate paleontologist at the University of Maryland, agrees that Microraptor was a non-bird dinosaur that consumed fish, but also other prey.
In terms of diet, he likened the dinosaur to a house cat.
"Small cats are probably a good ecological analogue for little dromaeosaurs and the primitive birds as well: creatures that are pouncers and capable of ambushing small prey of all sorts, and with claws and jaws capable of hauling small fish and the like out of the water," Holtz told Discovery News, saying that he bets salamanders and frogs will also be found in Microraptor stomachs before long.
Holtz added that the dinosaur was "a generalist predator: a terror of the tiny fauna of the Early Cretaceous."
"Unlike a bird, it had a long tail with specialized bony rods that helped to support it," Persons said. "And unlike a modern bird, Microraptor had toothed jaws -- not a beak -- and had a large sickle-shaped claw on each foot, and clawed fingers."