Crop (anatomy) Crop (anatomy) A crop (sometimes also called a croup or a craw, or ingluvies) is a thin-walled expanded portion of the alimentary tract used for the storage of food prior to digestion. This anatomical structure is found in a wide variety of animals. It has been found in birds, and in invertebrate animals including gastropods (snails and slugs), earthworms, leeches, and insects. Cropping is used by bees to temporarily store nectar of flowers. When bees "suck" nectar, it is stored in their crops. In a bird's digestive system, the crop is an expanded, muscular pouch near the gullet or throat.
The Origin of Birds feature could not have been lost and regained again over the course of evolution. Based on this law, he therefore rejected the possibility of a direct theropod ancestor of birds, though he acknowledged that theropods and birds must have shared a close relationship. Throughout this section, Heilmann examines several groups of possible ancestors in addition to coelurosaurs, including pterosaurs, predentates, and pseudosuchians. Based on his rejection of theropods due to the wishbone issue as well as what Heilmann saw as striking morphological similarities between the skull of "Archaeopteryx", "Aetosaurus" and "Euparkeria", Heilmann concludes that a pseudosuchian origin of birds is