Falcarius utahensis

Falcarius utahensis is the discovered in 2005 type of dinosaurs that was the missed point between the evolution of dinosaurs and birds.
The found reptiles lived about 125 million years ago. These were not the biggest dinosaurs as the length of their body was about 4 meters and their height was about 1.5 meters. They used two legs for walking and the plumage that was long and curved decorated their legs. Their legs had the curved nails.
Falcarius utahensis could eat both animals and plants. Scientists think that the appearance of this specie of dinosaurs happened during the time of a great number of good plants appearance.
Falcarius utahensis remains were found in the Utah state in the USA during the archaeological researches. In the result of such expedition big burial place of dinosaurs was discovered. And according to scientists this burial place was the result of the death of a great number of dinosaurs' that happened simultaneously. But till nowadays scientists can't explain the reason for their death that happened at that period.
According to one of theories these dinosaurs lived in families and even in big groups. And they died being poisoned by the water. And the reason for the mass poisoning could be the natural gas, for example.
Anyway this discovery makes the great step forward in dinosaur's investigations.