NUMBER NINETY-TWO: Birds of a feather flock together, but
Longisquama wasn't a bird so flock off
- Animal: Longisquama insignis
- Name Pronunciation: Lon-ge-skwar-mah
- Name Meaning: "Long scale"
- Named By: Aleksandr Grigorevich Sharov - 1970
- Classification: Life, Eukaryota, Animalia, Chordata, Vertebrata, Gnathostomata, Osteichthyes, Tetrapodomorpha, Tetrapoda, Reptiliomorpha, Amniota, Sauropsida, Eureptilia, Sauria, Archosauromorpha, Diapsida
- When: ~ 230,000,000 B.C.E. (Late Triassic epoch)
- Where: Asia (Kyrgyzstan (Madygen Formation))
- Size: 6 inches (15.24 cm)
- Diet: Insectivore
Longisquama would of looked like a small lizard (despite having no relation to Squamata) with one noticeable difference, the long appendages that seemed to of attached to the neural spines of the dorsal vertebrae. The nature of these appendages has been debated ever since the creature was first described in 1970, with some considering them to be elongated scales, and others thinking them to represent one of the first known appearances of feathers. These interpretations in turn have not only led to various theories as to how
Longisquama lived, but how it fits in to wider evolutionary theory. Since the early 1900s a popular idea for the first birds was that of "Proaves," a fictional creature that was essentially a lizard with long flight feathers of birds growing from its arms which it used to glide amongst trees. That creature never actually existed, it was simply an idea given visual form so that a wider range of people could understand it. There was no malicious intent, scientists just wanted to show what they expected the ancestors to birds look like. The large appendages of
Longisquama were once interpreted as a double row of either scales or feathers that extended out to the side to form a series of "wings." The idea was that
Longisquama used these appendages to glide amongst the trees, and in turn may represent an actual ‘Proaves’ that was ancestral to birds. However since last two decades of the twentieth century the idea that birds originated from some point within the theropod dinosaurs has become accepted fact within the wider scientific community. This means that if the appendages of
Longisquama are indeed feathers, then it is likely that they are a product of a separate evolution. More modern analysis of
Longisquama has yielded the conclusion that there was just one row of appendages that ran vertical down the back of
Longisquama. If this is indeed true then immediately the idea that this species was a glider figuratively flies out of the window (ba dum tss). Therefore an alternative function for these appendages would perhaps most obviously be as a display feature, something that may have helped
Longisquama set up territories and signal to one another at range, a definitive advantage given the apparent small size of the body. Another interpretation could be that the appendages were a scare device that was flashed at the moment that predators attacked. There has been just as much debate over exactly how these appendages where formed to even if they were actually part of the animal. As briefly mentioned above, the appendages seem to have attached to the neural spines of vertebrae. These appendages then seem to have been rooted inside follicles in the same way that hairs and feathers are known to. These appendages have been and continue to be described as elongated scales or feathers, depending upon the author. The longest of these appendages seem to have been over 11.8 inches (30 cm) long, much longer than the perceived full length of the actual body. The more complete of these seem to curve around at the end so that many authors describe them as shaped like hockey sticks. However not all researchers are convinced that the appendages on the back actually belonged to the animal, instead suggesting that they may actually be fronds of a plant and that a lizard may have simply died on top of them. Indeed, only the holotype specimen is known to have had both skeleton and appendages preserved together. Further specimens of the appendages have been found completely separate from further skeletons. There are two problems with the idea that these appendages are parts of plants. The first is that when plants are preserved it is usually as a carbon film, and the appendages of
Longisquama are not preserved in this way. The second is that there is so far only one plant preserved in rocks of the Madygen Formation, that has fronds that are similar to the appendages of
Longisquama, but these do not have the distinctive hockey stick shape.
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