fossils

The odd little reptiles of the Triassic forests: Longisquama

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Vasika
Udurawane

Lead Writer
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Julio
Lacerda

Staff Artist and Writer
Longisquama insignis is one of the most enigmatic reptiles in the fossil record. Scientists thought it was a tree-dwelling animal with weird back appendages and then a tiny flying relative of birds, and back again. Nobody is as yet sure how it used its defining features: The elongated “skin appendages” on its back.

Among the oddest animals to exist just before the first dinosaurs appeared is a small reptile that lived during the Mid-Triassic around 235 million years ago. It was named Longisquama insignis, and is known from a few good and reasonably complete remains.


The fossils hail from the widely explored Madygen Formation of Kyrgyzstan. This location preserves a lakeside or riverside forest environment and is known for some exceptional remains of smaller Triassic animals like insects, other reptiles and fish. Longisquama is certainly one of the weirdest animals from the Madygen forests. Longisquama was described by Russian paleontologist Aleksandr Grigorevich Sharov in 1970, and all specimens of the animal’s fossils are currently contained in the Paleontological Institute of the Russian Academy of Sciences in Moscow.


When its fossils were discovered, it was named after a series of tall structures on its back. These odd appendages resembled a set of little hockey sticks stuck to the animal’s back. The first-known specimen, known from half a body, shows seven preserved appendages while the second-known specimen preserves five and others have far fewer. The purpose of its weird appendages was a matter of debate among paleontologists for a number of years.


At one time it was thought to be a so-called “Proaves”, a hypothetical missing link between birds and reptiles that had still not been found by that time in paleontology. There was once a reconstruction of a flying or at least gliding-capable Longisquama by Haubold and Buffetaut in 1987. This showed the animal as having a pair of fan-like structures that it used to glide or fly through the air like a modern flying lizard.


For a while it was even supposed that these structures were actually plant remains that were fossilized alongside the dead animal. But a 2012 study by Michael Buchwitz and Sebastian Voigt from Freiberg University of Mining and Technology revealed that these odd appendages were not in fact plant remains. The study also noted that the appendages were superficially similar to a feather, with a vane down the middle and special attachment points deep inside the animal’s body  None of these structures are bony in nature and neither are they scales. Rather, they are made of skin.


Looking even deeper into the skin structures reveals that they were anchored to the spine by tiny knobs or anchorage points that were once thought to be similar to those of bird feathers or mammalian hair. The inner section of the appendages are also vaned, just like a bird’s feather. According to Buchwitz, Longisquama may have been experimenting with the feather gene or a variant of the feather gene even before the appearance of the dinosaurs.


At the same time, he also adds that the edges of the structures are too thick and not like proper avian and non-avian dinosaur feathers. In fact, the same team does not even classify Longisquama as a distant dinosaur relative. Rather, it is still regarded as an ambiguous sauropsid or reptile, still unclassified and still holding a great deal of mysteries.


Despite this, many artistic restorations of the animal exist and it has a minor place in culture, with appearances in popular books. The animal is reconstructed as a tree-climber with a pointy head, large eyes and long limbs. It thus had a standard reptilian form and was around 10 centimeters long and probably fed on insects that scurried among the trees and the undergrowth. By this reconstruction, the creature had a single row of structures along its back which it probably used as a display organ among members of the same species.

3986b46bb4f35aa1ff4d42167a12e0fc

Vasika
Udurawane

Lead Writer


http://sulc.us/q024q
http://www.eartharchives.org/articles/the-odd-little-reptiles-of-the-triassic-forests-longisquama/