''Mesophthirus'' is an extinct genus of insect known from Burmese amber from

Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John C. Wells, Joh ...

during the mid- Cretaceous period, about 100 million years ago. Its sole species, ''Mesophthirus engeli'', is known from multiple specimens preserved with

feather Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and a premier ...

s of dinosaurs. It was originally considered that ''Mesophthirus'' fed on the feather as evidenced from the damaged dinosaur feathers preserved with it. However, later studies considered it as nymphal

scale insect Scale insects are small insects of the order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the infraorder Coccomorpha which is considered a more convenient grouping than the ...

, probably belongs to

Xylococcidae Xylococcidae is a family of scales and mealybugs in the order Hemiptera Hemiptera (; ) is an order (biology), order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, ...

, and not a parasitic insect that fed on feather.

Description

''Mesophthirus engeli'' is only known from nymphs, and adults of this insect is unknown. Up to 229 μm long, it has tiny eyes, short legs, short antenna and no wings. Its claws and antenna are covered in long, stiff bristles. Its overall body shape is oval to oblong, with no constriction between head, thorax, and abdomen. It was originally considered to have huge mandibles with at least four teeth. However, this is later found to be a misidentification, and it actually have sucking mouthpart instead. In addition, its claws are not specialized like a lice, rather are identical to those of scale insects.

Classification

Although only known from nymphs, according to overall morphology it was originally considered to have characters shared with Liposcelidae and Phthiraptera. However, in 2021 it was considered as scale insect instead, as multiple characters suggested. In 2022 it was classified to scale insect family Xylococcidae, although authors of original description still supported its identification as lice-like insect.

Paleoecology

''Mesophthirus'' specimens have been found with damaged dinosaur feathers. Original description suggested that morphology of insects and damaged feathers show that those insects fed on feathers. This interpretation was denied in 2021 as it actually lacked chewing mandibles. As scale insect nymph, it climbed on plants leaf litter, tree trunks, and even fallen feathers. Damaged feathers would be eaten by

dermestid Dermestidae are a family of Coleoptera that are commonly referred to as skin beetles. Other common names include larder beetle, hide or leather beetles, carpet beetles, and khapra beetles. There are over 1,100 species described. Dermestids have ...

beetle nymphs instead. In 2022, it was considered that wind transport caused multiple nymphs on the same feather. Its small size and very long femoral setae are adapted for aerial dispersal. These nymphs probably climbed on feathers caught on the bark and fluttering in the wind, and used it to travel to another trunks, like "magic carpet".

References

{{Taxonbar, from1=Q101549425, from2=Q86677093, from3=Q101549423 Fossils of Myanmar Fossil taxa described in 2019 Prehistoric insect genera Burmese amber