News Finding: Scanning electron microscopy revealed that the cuticle (the outer most protective layer of the eggshell) was made up of very small spherules of minerals.
Paper Finding: An absence due to seasonal differences in plumage is unlikely-if these feathers are in fact a sexual characteristic, they would be expected to be present either year-round (as suggested by their presence in very young juveniles 69 ) or only present in the breeding plumage.
News Context: Despite being malformed, the egg is excellently preserved, including parts of the eggshell that are rarely seen in the fossil record, such as traces of the egg membrane and the cuticle, which are mostly made of proteins and other organic materials. Scanning electron microscopy revealed that the cuticle (the outer most protective layer of the eggshell) was made up of very small spherules of minerals. Finding this morphology in Avimaia also supports the hypothesis that a cuticle with protective spherules represents the ancestral condition for avian eggs.
Paper Context: It is possible the absence of RDFs in IVPP V25371 is preservational (as is the case in all described specimens lacking this feature), given that feathers are not well preserved in this specimen. An absence due to seasonal differences in plumage is unlikely-if these feathers are in fact a sexual characteristic, they would be expected to be present either year-round (as suggested by their presence in very young juveniles 69 ) or only present in the breeding plumage. Since IVPP V25371 was clearly breeding, the absence of RDFs in this specimen is most likely either a true absence or taphonomic artifact.