Longicrusavis was a ground dwelling carnivore, a wader, and part of biological family Hongshanornithidae, considered to have been a dominant species in the Jehol Biota, the prehistoric Chinese ecosystem which supported them.

The skeleton is nearly complete and belongs to an adult individual, with carbonized feathers preserved in full plumage with visible colouration around the head and forelimbs.

Although no teeth are preserved, they were likely present in the upper jaw owing to the presence of alveoli, or tooth sockets, in the premaxilla and maxilla.

[5] The holotype evidencing the discovery is held at the Beijing Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) as part of a collection.

The Longicrusavis fossil was part the Jehol Biota from which is unearthed a whole range of palaeontological finds including dinosaurs, mammals, birds, fishes and invertebrates.