Zhongjianornis an enlarged, keeled breastbone in more advanced birds. However, later analysis of the anatomy of "Z. yangi" cast doubt on this interpretation of the bird as very primitive. Research published in 2012 found that some of the apparently primitive features were due to poor preservation of the bones, and that "Zhongjianornis" is more similar in anatomy to primitive euornitheans like "Chaoyangia" and "Schizooura". A phylogenetic analysis showed that a very primitive position in the bird family tree for "Z. yangi" is unlikely given current evidence. Zhongjianornis Zhongjianornis is a genus of beaked, pigeon-sized birds from the early Cretaceous period of
The Structure of Scientific Revolutions falsifiability as the most important criterion for distinguishing between that which is scientific and that which is unscientific. Kuhn also addresses verificationism, a philosophical movement that emerged in the 1920s among logical positivists. The verifiability principle claims that meaningful statements must be supported by empirical evidence or logical requirements. Kuhn's approach to the history and philosophy of science focuses on conceptual issues like the practice of normal science, influence of historical events, emergence of scientific discoveries, nature of scientific revolutions and progress through scientific revolutions. What sorts of intellectual options and strategies were available to people during a given period?