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
Archaeopteryx be black throughout, with heavier pigmentation in the distal tip. The feather studied was most probably a dorsal covert, which would have partly covered the primary feathers on the wings. The study does not mean that "Archaeopteryx" was entirely black, but suggests that it had some black colouration which included the coverts. Carney pointed out that this is consistent with what we know of modern flight characteristics, in that black melanosomes have structural properties that strengthen feathers for flight. In a 2013 study published in the "Journal of Analytical Atomic Spectrometry", new analyses of "Archaeopteryx"'s feathers revealed that the animal