Bird eggshell in dominican amber. 2007. G. Poinar, Jr., et al. Paleontology 50 (6), 1381–1383.
Abstract: Here we report an eggshell in Dominican amber, representing the first vertebrate egg in any amber deposit. The eggshell is compared with present-day eggs of lizards, snails and birds. Based on the surface structure and type of shell breakage, it appears that the most likely candidate is a bird, and with that consideration, an avian group that produces eggs similar to the fossil in shape, size and colouration is the Trochilidae (hummingbirds). Several possible explanations of how the fossil could be preserved in amber are provided. If indeed a hummingbird was involved, this discovery would represent the first New World record of a fossil trochilid.