Eggshell characteristics of moa eggs (Aves: Dinornithiformes)

Museums hold 36 whole moa eggs (Aves: Dinornithiformes) spanning a large size-range (120-240 mm long and 91-178 mm wide) and with a strong positive correlation (r = 0.92) between length (L) and width (W). The degree of elongation (LAW) varies greatly (1.25-1.57), as in elephant bird eggs (Aepyornithidae). The verified upper limit of moa eggshell thickness is extended to 1.89 mm, which overlaps the thickness of ostrich eggs. The largest moa egg had a shell-thickness of only 1.2-1.3 mm, but, in general, shell thickness and egg length were positively correlated (r = 0.55) for South Island eggs. Length of the longest slit-shaped pore-depression on the egg (maximum pore depression length MPDL) varied between eggs from 0.8 to 4.8 mm, and was positively correlated with egg length for both South Island (r = 0.63) and North Island eggs (r = 0.73). Larger moa eggs (longer than about 190 mm in the South Island) have thick shells and a predominance of long, coarse, slit-shaped pore-depressions (up to 1.3-4.8 mm long on each egg), while smaller eggs have thinner shells whose slit-shaped pore-depressions are relatively short (<= 1.3 mm). Known whole moa eggs include ones with shells as thick as the thickest broken fragments from palaeontological and archaeological sites throughout New Zealand, suggesting that there were unlikely to be any kinds of moa eggs much larger than those already known.