Calyptrate flies in fossil resin from Mexico and Tanzania

Fossil Calyptratae flies are exclusively found in the Cenozoic. Calyptrates arose around the K-T boundary and rapidly diversified in the early Tertiary. Only a few species of fossil Calyptratae are known from fossil resins such as Baltic amber, Dominican amber, and East African copal or Defaunation resin. However, these preserved organisms provide valuable insights into the evolutionary and ecological history of calyptrate flies. In this study, we describe Mesembrinella guimaraesi sp. nov. (Mesembrinellidae) from Miocene Mexican amber, representing the first record of a calyptrate from this fossiliferous site; and we report Dichaetomyia immaculiventris Malloch as the first occurrence of Dichaetomyia Malloch (Muscidae) in Tanzanian copal. We also briefly discuss the abundance of calyptrate flies in resins and actualistic experiments.