What is the bird-like animal named Unenlagia comahuensis?

Unenlagia comahuensis, or the half-bird from northwest Patagonia, was a dinosaur living approximately 90 million years ago. Similar to many other recent reptile discoveries, the animal had bird-like characteristics that interest scientists.

Some scientists believe that Unenlagia comahuensis is the actual missing link between birds and dinosaurs. Although apparently too big to fly, the Unenlagia comahuensis had several characteristics in common with birds, including arms that could flap like wings and a bird-like pelvis. In particular, the 5-foot- (1.5-meter-) tall dinosaur had a shoulder blade (scapula) that shared some characteristics with birds; the forearm socket in this bone pointed out toward the side rather than down and back, as seen in other primitive, bird-like dinosuars such as the Deinonychus. In addition, the Unenlagia's triangular pelvis looks like a cross between those in the Deinonychus and Archaeopteryx.

What is the bird-like animal named Sinosauropteryx primal

Fossils of a Sinosauropteryx prima, found in China, are of a theropod dinosaur with what appears to be feathers. At first, scientists believed feathers ran down the dinosaurs back. Upon closer study, it is now thought the animal actually had feath- er-like structures. The reason for this arrangement is debated. Some scientists believe the structures were used for movement; other scientists believe they were probably protofeathers, an early step toward the evolution of bird feathers. The Sinosauropteryx is one of the Chinese feathered dinosaurs and is a more recent evolutionary development than the Archaeopteryx. Some scientists believe they are one of the most primitive coelurasaurs, as seen from their skeletal features.

It is believed that feathers were originally used by dinosaurs like this Gigantoraptor erlianensis for ornamentation or possibly insulation, and not for flying (Big Stock Photo).

What do the Sinosauropteryx and other similar dinosaurs tell us about the evolution of feathers?

The protofeathers like the ones on the Sinosauropteryx appear to be covered with hollow filaments. These may have been the forerunners of bird feathers; or, as some scientists believe, feathers used for insulation, not the precursors to flight. Dinosaurs like the Sinosauropteryx, other similar dinosaurs, and fossil feathers from the same period, give scientists a better idea about the evolution of feathers.

In particular, it is thought that feathers evolved rapidly in terms of geologic time.

Feathers possessed properties that were highly advantageous to survival; they gave the animals an aerodynamic body and provided insulation for warmth, two features needed to survive a tough, predator-ridden world.

What was the original purpose of feathers on dinosaurs?

Based on the recent fossil discoveries of feathered, flightless dinosaurs, some paleontologists now think feathers were originally developed for insulation or ornamentation purposes.

Were birds the only animals that sported feathers?

Because geologic time takes in so many millions of years, some scientists believe there were other early animals that sported some type of feather or protofeather.

Many researchers believe that modern birds are direct descendants of two-legged, meat-eating dinosaurs, and since there was a wide range of these prehistoric theropods, theres a chance other dinosaurs had feathers, either as juveniles or all their lives. Some species kept their feathers (ancestors of birds, for example), while others did not. The reason for the lack of evidence may be because feathers were not preserved, or maybe such fossils have yet to be discovered.

How did early feathered animals eventually develop flight?

There are several theories on how early feathered animals developed flight. One theory states that gliding creatures increased their surface area from the body outward, but flying animals increased it away from their center of gravity, giving them lift and more maneuverability to escape predators. Another theory states that wing motions evolved from the hunting techniques of the coelurosaurs. The skeletal structure of these dinosaurs allowed them to swing their arms down from above and behind their shoulders, allowing for easier grabbing of prey. Both these theories imply that birds developed flight from the ground up, not from the trees down, which is also known as the cursorial theory.

Other paleontologists believe that flight developed in animals that lived in trees (the arboreal, or tree, theory); jumping out of these trees provided enough acceleration to generate lift. Still others believe that some animals ran and flapped their wings, increasing their angle of attack on the down stroke and generating enough lift to fly, especially if they were running downhill.

What carnivorous dinosaur fossils had traces of a bird-like beak?

In the Red Deer River Badlands of Canada, the remains of a carnivorous ornithomimid dinosaur were found that included traces of keratin around the front of the animals skull. Keratin, the material found in hair and fingernails, is also found in the beaks of birds. This was also the first carnivorous dinosaur with evidence of a beak, and it showed that dinosaurs could make the transition from teeth to a beak-like structure.

What does the internal structure of Scipionyx samniticus reveal about the ancestry of birds?

Studies of the 113-million-year-old Scipionyx samniticus fossils interior structure and unique metabolism has led some scientists to say that none of the known groups of dinosaurs could have been the ancestors of birds. This is because birds have an entirely different lung structure than the Scipionyx samniticus (a small coelurosaurid theropod), and a much different metabolism. However, this is based on the findings from one fossil, one of very few to have internal parts preserved (parts of the windpipe, intestines, muscles, and liver). These results will have to be carefully integrated with other findings, such as the presence of feathers and common skeletal features, to come to any useful conclusions.

 
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