Archaeopteryx of "Archaeopteryx" bones appear poorly vascularized; in living vertebrates, poorly vascularized bone is correlated with slow growth rate. They also assume that all known skeletons of "Archaeopteryx" come from juvenile specimens. Because the bones of "Archaeopteryx" could not be histologically sectioned in a formal skeletochronological (growth ring) analysis, Erickson and colleagues used bone vascularity (porosity) to estimate bone growth rate. They assumed that poorly vascularized bone grows at similar rates in all birds and in "Archaeopteryx". The poorly vascularized bone of "Archaeopteryx" might have grown as slowly as that in a mallard (2.5 micrometres per day) or as fast as
Archaeopteryx in similar feathers"). In German, this ambiguity is resolved by the term "Schwinge" which does not necessarily mean a wing used for flying. "Urschwinge" was the favoured translation of "Archaeopteryx" among German scholars in the late nineteenth century. In English, "ancient pinion" offers a rough approximation. Since then twelve specimens have been recovered: The Berlin Specimen (HMN 1880/81) was discovered in 1874 or 1875 on the Blumenberg near Eichstätt, Germany, by farmer Jakob Niemeyer. He sold this precious fossil for the money to buy a cow in 1876, to innkeeper Johann Dörr, who again sold it to Ernst Otto Häberlein,