First evidence of dinosaurs eating mammals confirmed

(Hans Larsson / https://bit.ly/3PQuQd3)

A team of paleontologists led by Hans Larsson from McGill University found a foot of a small mammal between the ribs of a microraptor.

Previously, fossilized bones of fish, lizards and birds have already been found in the stomachs of these four-winged dinosaurs.

Microraptors lived in the forests of present-day China about 120 million years ago, and were among the most bizarre non-avian dinosaurs.

These small, weighing about a kilogram, were predators covered with blue-black feathers that formed wing-like surfaces on the front and rear limbs.

Paleontologists speculate that the two pairs of wings allowed the microraptors to glide from tree to tree, similar to modern flying squirrels.

However, there is evidence that these dinosaurs have mastered active flight.

More than 300 specimens of microraptors are known, and they belong to three species:

• M. zhaoianus
• M. gui
• M. hanqingi

Although today many scientists are inclined to believe that they all belonged to a single species, M. zhaoianus.

Some of them are so well preserved that you can study the contents of their stomachs.

For example, in the stomach of one microraptor, scientists found fossilized bird bones, another - fish scales, and the third ate a lizard shortly before death.

(Fred Wierum / Wikimedia Commons https://bit.ly/3WL0xXy)

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THE DINNER
Now, Larsson's team has managed to add another item to the microraptor diet.

Analyzing the holotype of the species M. zhaoianus, which was discovered more than 20 years ago, the authors saw foot bones between its ribs that belonged to a small mammal.

According to the authors, the mammal that became the dinner of the microraptor weighed from 13 to 43 grams.

Outwardly, it probably resembled representatives of the genera Eomaia and Sinodelphys.

However, if eomaya and sinodelphis lived on trees, then the owner of the foot from the stomach of a microraptor led a terrestrial lifestyle.

This conclusion was reached after judging by the ratio of the length of the bones and the shape of the only preserved claw.

The results of the study confirm that the diet of microraptors was very broad.

These dinosaurs ate a variety of small vertebrates, from fish and reptiles to birds and mammals.

(Hans Larsson / https://bit.ly/3jopd9D)

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HYPOTHESIS
According to the researchers, it is tempting to infer that microraptors descended from trees to hunt mammals.

However, in reality, the dinosaur could have caught a land mammal that, for some reason, climbed a tree.

In addition, it is possible that he tore off and swallowed a foot from the corpse of an already dead animal.

This version is supported by the fact that the feet are malnourished and among all parts of the body are usually eaten one of the last.

Be that as it may, the find of the researchers is a rare example confirming that non-avian dinosaurs ate mammals.

In conclusion, Larsson’s team points out that although four specimens of microraptors with stomach contents are already known, these valuable finds do not bring paleontologists closer to understanding what exactly these dinosaurs ate and what lifestyle they led.

So far, it is only clear that microraptors consumed a more varied diet than any other theropods.

They, like modern corvids and small canids, were probably general predators and scavengers, that is, they ate any available animal food.

The authors hope that the analysis of enamel microwear and the composition of stable isotopes in the remains of microraptors will make it possible to firmly establish their diet.

Sources:

• Journal of Vertebrate Paleontology: https://www.tandfonline.com/doi/full/10.1080/02724634.2022.2144337
• McGill University: https://www.mcgill.ca/newsroom/channels/news/other-paleo-diet-rare-discovery-dinosaur-remains-preserved-its-last-meal-344495
• CNN: https://edition.cnn.com/2022/12/26/world/dinosaur-mammal-last-meal-scn/index.html

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#science #dinosaurs #paleontology #china #mammals #news #nftmc