|The Microraptor fossil with the as of yet unidentified bird in its stomach|
It was covered in feathers and had two sets of wing-like limbs, a smaller back pair and larger front pair. The fossils are beautifully preserved and wonderfully expressive, the wings are outstretched and the back arched. Some fossils display just the skeleton, others show the markings of feathers. Now a fossil of a previously unknown bird species has been discovered within the stomach of a particularly complete Microraptor specimen.
Analysis carried out on the fossil by Jingmai O'Connor, from the Institute of Palaeontology and Palaeoanthropology in Beijing, revealed that the Microraptor had eaten a bird before it had died. The bird's species remains undescribed, but it is rather interesting. Further analysis showed that it had a very long third toe. A long third toe is a trait shared by all tree-dwelling birds. The fact that the Microraptor fed upon arboreal prey provides very strong evidence that it too was a tree dweller.
The Microraptor would need an effective method to get from tree to tree. So by extension, the fossil bird provides evidence that Microraptor could also fly or at the very least glide. O'Connor revealed her findings at the annual meeting of the Society of Vertebrate Palaeontology. It is still inconclusive as to whether birds first evolved in trees or on land, yet O'Connor's findings add another avian to evolutionary history and provides fantastic new evidence about the diet and lifestyle of Microraptor.