Longisquama

Longisquama is an extinct genus of lizard-like reptile. There is only one species, Longisquama insignis, known from a poorly preserved skeleton and several incomplete fossil impressions from the Middle to Late Triassic Madygen Formation in Kyrgyzstan. It is known from a type fossil specimen; slab and counterslab (PIN 2548/4 and PIN 2584/5), and five referred specimens of possible integumentary appendages (PIN 2584/7 through 9). All specimens are in the collection of the Paleontological Institute of the Russian Academy of Sciences in Moscow.

Longisquama means "long scales"; the specific name insignis refers to its small size. The Longisquama holotype is notable for a number of long structures that appear to grow from its skin. These structures have been interpreted as either primitive feathers suggesting Longisquama is a close relative of birds, or as feather-like structures that have evolved independently and do not indicate a close relationship with birds. Longisquama has been used in a heavily publicized debate on of the origin of birds. To some, Longisquama is the gliding, cold-blooded, protobird predicted by Gerhard Heilmann's hypothetical "Proavis" in 1927, and it proves that birds are not dinosaurs. The current opinion is that Longisquama is an ambiguous diapsid and has no bearing on the origin of birds.