120myo dino fossil with a surprise in its guts

[rogue06]

A new analysis of the 120 myo fossilized remains of a Microraptor zhaoianus fossil, discovered in the Jiufotang Formation in western China and first described in 2000 (it's the holotype -- or first of its species to be found and named), has revealed the earliest evidence of a dinosaur dining on a mammal yet discovered.

Microraptors are themselves small, roughly crow-sized dinosaurs that possessed four wings (basically front and rear limbs) that are part of the Dromaeosauridae family of dinosaurs -- predatory dinosaurs that includes Velociraptor. It is believed to have lived in trees, gliding around the Cretaceous forests in search of food on both branches as well as on the ground, and have been discovered containing the partially digested remains of ancient birds, fish, and lizards, but this is the first mammal.

This particular fossil is missing the middle portion of its body, but the rib cage is still visible and, lodged within it scientists discovered the bones of a tiny mammalian right foot, less than half an inch in size. Obviously, being chewed up and partly digested is not something that usually result in very well-preserved fossil remains, so identification of the Microraptor's last meal is problematic.

The foot, roughly the size of a mouse's foot, was completely intact (likely swallowed whole) and possessed gracile digits which are similar to tiny, extinct, possum-like mammals known as Sinodelphys or the more mouse-like Eomaia, but the researchers feel that the digits aren't long enough to be either of these creatures. The foot also doesn't appear to be adapted to an arboreal life, so it was likely that Microraptor swooped down to the ground to get it. Further, while the size of the foot fits into size-range of creatures that researchers think Microraptor's would have hunted and eaten, there is no way to determine if it had been hunted or just scavenged

Hans Larsson, a paleontologist at McGill University and associated with Queen Mary University of London as well as being the study’s lead author, said, "It really demonstrates the generalist diet in this small feathered dinosaur. Adding mammals to the menu shows just how un-specialized this dinosaur was." They were anything but picky eaters.

Alex Dececchi, from Mount Marty College in South Dakota, and another of the study authors, put it another way "The great thing is that -- like your housecat, which was about the same size -- Microraptor would have been an easy animal to live with but a terror if it got out, as it would hunt everything from the birds at your feeder to the mice in your hedge or the fish in your pond."

Source: Very rare discovery unveils one of the first records of a dinosaur eating a mammal

It's not uncommon for scientists to uncover new fossils from the ages of dinosaurs, but every now and then, a discovery reveals much rarer information.

Scientists unearthed the fossil of the small and feathered microraptor zhaoianus back in 2000, but only recently did one researcher catch a "very rare discovery" — another animal inside of its remains. Professor Hans Larsson of Montreal's McGill University found that the fossil actually displayed the foot of an ancient mammal right between the ribs.

But don't worry — researcher David Hone of the Queen Mary University of London said it "would absolutely not have been a human ancestor."

Microraptors lived in forests of what is now China about 120 million years ago. They were roughly the size of a crow, with long feathers, and are thought to have glided through the trees to hunt for small animals. But that's what makes this particular finding so interesting, researchers said.

After analyzing the digested animal's foot, it seems as though it was a mouse-sized creature bound to the ground and not a particularly good climber, indicating that the microraptor likely would have abandoned its tree-top search for a land-based snack. Past studies of the feathered dinosaur have revealed they consumed birds, lizards and fish.

"It's so rare to find examples of food inside dinosaurs so every example is really important as it gives direct evidence of what they were eating," Hone said. "...This study paints a picture of a fascinating moment in time – one of the first record of a dinosaur eating a mammal — even if it isn't quite as frightening as anything in Jurassic Park."

A press release from Hone's university said that the finding makes it clear this particular kind of dinosaur had a "diverse diet and was not a specialist on any given option." However, the university also noted that researchers are uncertain whether the small mammal in the raptor's belly was a direct prey or an already-dead animal that had been scavenged.

Fellow researcher T. Alex Dececchi of South Dakota's Mount Marty College compared the dinosaur to a house cat, a creature of about the same size.

"Microraptor would have been an easy animal to live with but a terror if it got out as it would hunt everything from the birds at your feeder to the mice in your hedge or the fish in your pond," Dececchi said.


Source

© Copyright Original Source

The paper, Generalist diet of Microraptor zhaoianus included mammals can be read in its entirety by clicking the hyperlink, while the abstract is made available below

ABSTRACT

Gut contents are extremely important for inferring trophic interactions between extinct species. These are, however, very rare in the fossil record and it is not always possible to accurately identify both the carnivore and the consumed organisms. Here we describe the remains of a small fossil mammal foot preserved inside the body cavity of the holotype specimen of the small feathered dinosaur Microraptor zhaoianus. This adds to the known diversity of diet for this genus, which also consumed birds, fish, and lizards. Previous interpretations that Microraptor was an arboreal hunter of birds and adept hunter of fish are not supported. Although the various known stomach contents would be plausible prey items based on size, there is no clear evidence that any of them were predated rather than scavenged, and Microraptor likely did both and foraged in multiple habitats.

And a diagram of the picture of the foot

ujvp_a_2144337_f0001_oc.jpeg

[rogue06]

Trouble with the images contained in the article so let's try it again

64dfa1a3-fa8f-4e05-aceb-1334fe1959ec.jpg



5fb4802f-94c1-4575-8d9a-11e41aaf9d22.jpg
The foot is in the center

[shunyadragon]

Interesting, but not surprising that mammals were common meals of carnivorous dinos, because everything else was in one way or another.

[rogue06]

Interesting, but not surprising that mammals were common meals of carnivorous dinos, because everything else was in one way or another.

There has been evidence of dinosaurs eating mammals later on (and even evidence of mammals eating dinosaurs).