Dinosaurs With Feathers: The Ancestors of Modern Birds
BIRDS IN THE AGE OF DINOSAURS One hundred fifty million years ago a crow-size bird glided on feather-covered wings across a tropical lagoon in what is now southern Germany Along the lagoon’s muddy shore dragonflies hovered bees buzzed and small meat eating dinosaurs hunted for lizards Sharing the sky with the bird were flying reptiles called pterosaurs which soared on narrow skin-covered wings For some reason that we will never know the bird did not complete its journey across the lagoon Instead it plunged into the water and died It sank to the bottom where fine-grained chalky mud gently covered its body almost perfectly preserving the delicate skeleton as well as an impression of feathers
There the bird lay encased in its muddy tomb until its discovery millions of years later The ancient bird lived during a period of the Earth’s history called the Mesozoic Era a time when dinosaurs were the dominant land animals Scientists divide the Mesozoic Era into three periods the Triassic about 250 to 208 million years ago the Jurassic about 208 to 144 million years ago and the Cretaceous about 144 to 65 million years ago The ancient bird that fell into the sea lived at the end of the Jurassic Period During the Cretaceous Period that followed there was a great expansion of bird species ranging from sparrow-size tree dwellers dwellers to loon-like water birds Recent fossil discoveries of ancient birds and of dinosaurs that were their close relatives are helping helping us to learn about the amazing diversity of life in the Mesozoic Era and how adaptations such as feathers may have helped some of these animals in their daily lives
BURIED IN LIMESTONE The lagoon in which the ancient bird was buried slowly dried up and the chalky deposits turned into limestone a rock that people often use for building Limestone that is especially fine-grained is used to make lithographic plates for printing In 1861 workers in a lithographic limestone quarry near the small town of Solnhofen Germany cut a slab of rock and split it open As they care fully examined each surface for imperfections they discovered the imprint of feathers and tiny bones Although they were accustomed to finding the remains of insects fish and even small dinosaurs embedded in the limestone they had never seen a fossil like this one It was the skeleton of an animal that resembled a small dinosaur except that it had long feathers fanning out from its arms and tail They had found the remains of the ancient bird The skeleton in the limestone slab was arranged in an almost lifelike pose The bird’s leg bones one of which ended in a perfectly formed foot were spread on either side of the long tail and the arm bones were raised above the body A long line of tiny vertebrae as well as the feathers that extended outward from them were clearly visible in the tail Feathers also extended from the arms mak ing them into wings Some of the bones including those of the skull had become detached and scattered but the specimen was otherwise nearly complete and amazingly well preserved Scientists named the new fossil Archaeopteryx from Greek words meaning ancient wing This remarkable discovery provided the first clear proof that birds had been alive in the Age of Dinosaurs Archaeopteryx is still the oldest known bird Only seven fossil skeletons and one feather imprint of Archaeopteryx have ever been found The original 1861 discovery is on exhibit at the British Museum of Natural History in London The best preserved Archaeopteryx fossil was unearthed in 1876 in a quarry not far from Solnhofen It is on display at the Humboldt Museum of Natural History in Berlin In this specimen even the skull of the bird is clearly visible as are the clawed wings and toes
The Archaeopteryx fossil discovered in the Solnhofen quarry was about 22 inches high
