Dinosaur egg size (usually not much longer than a centimeter or two) and lack of an eggshell with its typical anatomy. Stones: The erosive effects of water can sometimes round rocks into egg-like shapes. Paleontologists' knowledge of the structure of dinosaur eggs is limited to the hard shell. However, it can be inferred that dinosaur eggs had an amnion, chorion, and an allantois, the three major membranes in modern bird and reptile eggs. Dinosaur eggs vary greatly in size and shape, but even the largest dinosaur eggs ("Megaloolithus") are smaller than the largest known bird eggs, which were laid by the extinct
Specimens of Archaeopteryx than flight. Pennaceous feathers thus represent an exaptation and were only later adapted for aerodynamic capabilities, a function that was apparently convergent among different groups within Avialae. In February 2014, the existence of a twelfth specimen was announced from an Altmannstein quarry near the Schamhaupten district of Bavaria. This specimen was unearthed by a private collector in 2010.. Based on a new diagnosis for the genus Archaeopteryx, by the German paleontologist Oliver Rauhut c.s., the Berlin, Eichstätt, Solnhofen, Munich, Daiting, Thermopolis, 11th, and 12th specimens can be referred to this genus with high certainty. Specimens of Archaeopteryx Archaeopteryx fossils from