It had a black facial mask and partially white tail feathers, but the colouration of the body, wings and head in the living bird is unclear.

Descriptions from life indicate the body and head were ash grey, and the white part of the tail had two dark central feathers.

[2] Early writers claimed the Mascarene parrot was found on Madagascar, an idea that led the French naturalist René Primevère Lesson to coin the junior synonym Mascarinus madagascariensis in 1831.

In 2007, the English palaeontologist Julian Hume suggested the possibility that this might have been a lesser vasa parrot, if not a discoloured old Mascarene grey parakeet (Psittacula bensoni).

X-rays of the two existing stuffed Mascarene parrots made it possible to compare the remaining bones with the subfossils and showed these were intermediate in measurements in comparison to the modern specimens.

[10] The binomial name was emended from M. mascarinus to M. mascarin by the IOC World Bird List in 2016, to conform with how other species epithets by Linnaeus have been treated.

Hume supported their common origin in the radiation of the Psittaculini tribe based on morphological features and the fact that Psittacula parrots have managed to colonise many isolated islands in the Indian Ocean.

As suggested by the British ecologist Anthony S. Cheke and Hume in 2008, the Psittaculini could have invaded the area several times, as many of the species were so specialised that they may have evolved significantly on hotspot islands before the Mascarenes emerged from the sea.

If the Mascarene parrot had in fact evolved into a distinct genus on Réunion prior to the volcanic eruption, it would have been one of the few survivors of this extinction event.

It also found that the Mascarene parrot line diverged 4.6 to 9 million years ago, prior to the formation of Réunion, indicating this must have happened elsewhere.

[16] In 2012, Leo Joseph and colleagues acknowledged the finding but pointed out that the sample might have been damaged and that further testing was needed before the issue could be fully resolved.

[7] In 2017, the German biologist Lars Podsiadlowski and colleagues sampled the Vienna specimen for a new genetic study and found that the Mascarene parrot was indeed part of the Psittacula group as suggested by Hume, clustering with the extinct Seychelles parakeet (P. wardi) and Asian subspecies of the Alexandrine parakeet (P. eupatria).

[19] To solve the issue that the genera Mascarinus, Tanygnathus, as well as Psittinus fell within the genus Psittacula according to genetic studies, making that genus paraphyletic (an unnatural grouping), the German ornithologist Michael P. Braun and colleagues proposed in 2019 that Psittacula should be split into multiple genera, thereby retaining Mascarinus.

They suggested that Psittaculinae originated in the Australo–Pacific region (then part of the supercontinent Gondwana), and that the ancestral population of the Psittacula–Mascarinus lineage were the first psittaculines in Africa by the late Miocene (8–5 million years ago), and colonised the Mascarenes from there.

[2] In 1760, Brisson published the following description based on a captive bird (which may have been the specimen now preserved in Paris): Upperparts of head and neck clear (ash) grey.

Back, rump, underparts of neck, breast, belly, sides, legs, scapular feathers, upper coverts of tail very-dark (ash) grey.

[2]Instead of grey, several later authors described the body as brown and the head as bluish lilac, based on stuffed specimens, and this has become the "orthodox image" of the bird.

Hume proposed that this colouration is an artifact of the taxidermy specimens having aged and being exposed to light, which can turn grey and black to brown.

The Vienna specimen is a pale brown on the head and body overall, with an irregular distribution of white feathers on the tail, back, and wings.

Forbes based his description on the Paris specimen which had its skull and mandible removed for study by the French zoologist Alphonse Milne-Edwards prior to 1866.

The mandibular fenestra (opening at the side of the mandible) was absent, and the back end of the mandibular symphysis (where the two halves of the lower jaw connected) was broadly oval, the angulus mandibulae (the lower margin at the back of the mandible) was flattened instead of angled, and the symphysis was sharply angled downward.

[27] That the Vienna specimen was partially white may have been the result of food deficiency during a long period in captivity; the clipped primary wing feathers indicate it was caged.

The small Mauritian flying fox and the snail Tropidophora carinata lived on Réunion and Mauritius but vanished from both islands.

[2] In 1834, the German zoologist Carl Wilhelm Hahn published an often-cited account of a live Mascarene parrot in the possession of King Maximilian I Joseph of Bavaria.

[1] The veracity of Hahn's claim was questioned as early as 1876, and the illustration appears to be plagiarised from the plate by François-Nicolas Martinet which was published at least 50 years earlier.

The fact that Martinet's image was copied and that no mounted specimen exists (though such a rare bird would probably have been preserved) makes Hahn's account dubious.

[7] One of the last definite accounts of live specimens is the following 1784 description by Mauduyt based on captive birds: The Mascarin is found at Ile Bourbon [Réunion]; I have seen several alive in Paris, they were rather gentle birds; they had in their favour only that the red beak contrasted agreeably with the dark background of their plumage; they had not learnt to talk.

[2]Contrary to Feuilley's claims, Dubois mentioned that the Mascarene parrot was not edible which may have led to Réunion visitors mostly ignoring it.