Archaeopteryx that in an ostrich (4.2 micrometres per day). Using this range of bone growth rates, they calculated how long it would take to "grow" each specimen of "Archaeopteryx" to the observed size; it may have taken at least 970 days (there were 375 days in a Late Jurassic year) to reach an adult size of . The study also found that the avialans "Jeholornis" and "Sapeornis" grew relatively slowly, as did the dromaeosaurid "Mahakala". The avialans "Confuciusornis" and "Ichthyornis" grew relatively quickly, following a growth trend similar to that of modern birds. One of the few modern birds that exhibit
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