Editing Alvarezsauridae (section)

==Description==
[[File:Alvarezsaurid scale martyniuk.png|thumb|left|Size comparison of several parvicursorines: ''Parvicursor remotus'' (green), ''Ceratonykus oculatus'' (red), ''Shuvuuia deserti'' (blue), and ''Mononykus olecranus'' (violet).]]
Alvarezsaurids ranged from {{convert|50|cm|in}} to {{convert|2|m|ft}} in length, although some possible members may have been larger, including the European ''[[Heptasteornis]]'' that may have reached {{convert|2.5|m|ft}} long. Fossils attributed to alvarezsaurids have also been found in [[North America|North]] and [[South America]] and [[Asia]], and range in age from about 86 to 66 million years ago.<ref>{{cite journal | last1 = Hutchinson | last2 = Chiappe | year = 1998 | title = The first known alvarezsaurid (Theropoda: Aves) from North America | journal = Journal of Vertebrate Paleontology | volume = 18 | issue = 3| pages = 447–450 | doi=10.1080/02724634.1998.10011073}}</ref>

===Feathers===
At least one specimen of alvarezsaurid, from the [[species]] ''[[Shuvuuia|Shuvuuia deserti]]'', preserved down-like, [[feather]]y, [[integument]]al structures covering the fossil. Schweitzer ''et al.'' (1999) subjected these filaments to microscopic, morphological, mass spectrometric, and immunohistochemical studies and found that they consisted of [[beta-keratin]], which is the primary protein in [[feather]]s.<ref name="Schweitzeretal1999">{{cite journal |last1=Schweitzer |first1=M. H. |last2=Watt |first2=J. A. |last3=Avci |first3=R. |last4=Knapp |first4=L. |last5=Chiappe |first5=L. |last6=Norell |first6=M. |last7=Marshall |first7=M. |title=Beta-keratin specific immunological reactivity in feather-like structures of the Cretaceous Alvarezsaurid, Shuvuuia deserti |journal=Journal of Experimental Zoology |date=1999 |volume=285 |issue=2 |pages=146–157 |doi=10.1002/(SICI)1097-010X(19990815)285:2<146::AID-JEZ7>3.0.CO;2-A |pmid=10440726 }}</ref>