Germany was an archipelago with a Florida like climate Because it had characteristics of both birds and reptiles A. lithographica was considered a transitional fossil that linked dinosaurs with modern birds Eleven more A. lithographica fossils have since been found in Germany The bird was raven sized weighing approximately two pounds 1 kg It had broad rounded wings and a tail up to 20 inches 50 cm long 2 Fluffy feathers covered its body and legs Scientists aren't sure if it had head or neck feathers DINOSAURS ARE NOT EXTINCT In 2018 an international group of Dr. Christopher Eppig says that when scientists using state of the art technology people eat chicken or turkey they are at a facility in France tried to understand eating dinosaurs Birds are not simply similar to dinosaurs he says They are not the flying abilities of A. lithographica Using merely related to dinosaurs They actually synchrotron microtomography a type of are dinosaurs Since the mid 1990s evidence for birds X ray imaging the scientists were able to dinosaur origins has grown Pieces of this create a three dimensional 3 D image that evidence have included shared skeletal features and the discovery of dinosaur allowed them to see inside the fossilized bones feathers According to the Understanding without damaging them They discovered that Evolution website at University of California Berkeley Birds are simply a twig on the dinosaurs branch of the tree of life 3
A. lithographica's wing bones were much thinner than those of ground dwelling dinosaurs They were actually very similar to modern pheasant bones Pheasants are not strong fliers They use short flights to evade predators or cross barriers THEROPODS GIVE RISE TO BIRDS There are two theories about how flight evolved In one theory a tree dwelling ancestor began by gliding to the ground It could remain in the air longer when it flapped its forelimbs A second theory suggests that a small ground dwelling ancestor ran on two legs and extended its forelimbs as it leaped to catch prey or avoid predators Feathers would have improved lift making flight easier Fossils help scientists find more answers about the origins and evolution of flight Birds have a very limited fossil record because their thin lightweight bones tend to disintegrate rather than form fossils Paleontologists piece together the bones that have survived providing a clearer picture of bird origins Scientists found the first A. lithographica fossil just after the 1859 publication of Charles Darwin's On the Origin of Species But A. lithographica was not the origin of modern birds True birds probably arose from the end of the Triassic 251.9-201.3 MYA to the beginning of
Velociraptor had feathers the Jurassic periods but their ancestors likely began to diverge or become different from dinosaurs anywhere from 227 to 174 MYA These ancestors were probably a group of theropod dinosaurs called coelurosaurs Theropods which include Tyrannosaurus rex and Velociraptor were carnivorous and bipedal meaning two footed which freed the front limbs for other uses including flight Coelurosaurs probably began decreasing in size approximately 200 MYA about 50 million years before A. lithographica appeared Small size was probably essential for flight A series of morphological or physical changes followed as theropods evolved into birds First long bones became hollow and the first foot digit lost its role in supporting weight Second the function of grasping hands improved with the evolution of a rotating wrist joint Third the coracoid bone of the shoulder and the sternum or breastbone expanded which helped support bigger stronger muscles and more feathers Fourth vaned feathers appeared arranged by precise
types and layers Fifth the trunk shortened and the tail became stiffer which improved balance and maneuverability Sixth changes in the shoulder joint the development of a wing and asymmetrical feathers and the reversal of the inner toe supported basic flight and perching These changes all occurred very early in bird evolution The sixth group of changes appears in A. lithographica Further refinements of physical structures lending themselves to powered flight and perching followed Beginning approximately 150 MYA the thorax or chest became deeper Bones of the shoulder and pelvis became strut shaped for better support Then new adaptations formed including a tendon for wing muscle attachment feathers to control airflow fan shaped tail feathers and a fully opposable inner toe for perching Next the shoulder blades fused to form the wishbone A deep ridge called a keel extended from the breastbone enabling huge chest muscles to develop which are essential for powered flight All of these adaptations were in place during the Cretaceous period 145-66 MYA but the explosion in bird diversity didn't begin until the end of that period shortly after an asteroid strike caused the extinction of the larger dinosaurs The few survivors of the asteroid served as the basis for the thousands of bird species to come For example a fossil of Vegavis iaai found in Antarctica in 2005 was dated to 67 MYA just before the asteroid hit Earth Very similar to the modern day duck V. iaai is considered to be part of today's line of birds
