Scientists find a mammal’s foot inside a dinosaur, a fossil first

An illustration of Microraptor chewing on the foot of a mammal.

an illustration of microraptor biting the foot of a mammal.
Illustration: Ralph Attanasi

Paleontologists taking a second look at a species of small quadruped dinosaur has found a fossilized mammalian foot in the predator’s stomach.

It’s the first concrete evidence of dinosaurs eating mammals, researchers say. dinosaur specimens, Microraptor zhaoinusI’ve got been discovered containing ancient birds, fish and lizards, so the mammalian find is only the last known source of protein for this brave hunter. The team that re-examined the microraptor fossil published their findings today in the Journal of Vertebrate Paleontology.

“It really demonstrates the generalist diet in this small feathered dinosaur,” said Hans Larsson, a paleontologist at McGill University and lead author of the study, in an email to Gizmodo. “Adding mammals to the menu shows just how unspecialized this dinosaur was.”

the house of trees microraptor lived during the early Cretaceous, and specimens have been found in what is now northeast China. The fossil-rich region is called Jehol Biota, and its well preserved treasureyes They are a great resource for understanding the nuances of dinosaur anatomy, as well as details about the ecological niches of different animals.

microraptor believed to have lived in trees, gliding through Cretaceous forests in search of morsels both on the branches and on the ground. The recently studied specimen is the holotype, meaning it was first of its kind to be found and named. It has recently been revisited after its discovery in 2000. The new analysis revealed the foot of mammals, an apparently unprecedented phenomenon to find.

The mammalian foot (center) inside the Microraptor fossil.

The mammalian foot (center) within the microraptor fossil.
Photo: hans larson

The researchers were unable to identify thim in particular mammal species, but the foot preservation within microraptor allowed them to understand its ecological niche and, obviously, its predators.

“Intestinal contents are amazing snapshots of the diet of fossil animals, but they are so rare that it can be difficult to determine whether the ‘last meal’ preserved represents the animal’s normal diet or a rare and unique event that was lucky enough to get fossilized. Stephanie Drumheller-Horton, a paleontologist at the University of Tennessee, Knoxville, who was not affiliated with the recent article, said in an email to Gizmodo.

“Microraptor is shaping up to be a very interesting exception to that rule, with multiple beautifully fossilized specimens retaining different ‘last meals,'” Drumheller-Horton added. “Taken together, the authors make a compelling case that this small theropod was not a particularly picky eater, eating all manner of small-bodied animals in its environment.”

Another illustration of Microraptor with its prey.

another illustration of microraptor with his prey.
Illustration: hans larson

The mammalian foot apparently did not belong to a distant human ancestor; the team said it had similarities to the morphologies of synodelfis, yanoconodontY Eomaiaall ancient species of early mammals that looked more or less like possums or rodents.

The foot belonged to an animal the size of a mouse. The team’s analysis found the crittis would not have been a good climber, an indicator that microraptor may have occasionally swooped down to the forest floor to feed.

“The foot appears fully intact and was therefore swallowed whole. How much of the mammal was swallowed is unknown,” Larsson said. “However, there were several other unidentified bones around the foot in the ribcage, so I suspect more of that mammal was consumed.”

Investigators were unable to determine if the animal was hunted and killed. or if the feathered dinosaur had swept away his body.

Given how lucky paleontologists have had with Jehol Biota so far, it may only be a matter of time before another food-laden specimen offers more insight into the Cretaceous food scene.

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