View source for Anomalure

{{Short description|Family of rodents}}
{{use dmy dates|date=May 2024}}
{{More citations needed|date=November 2007}}
{{Automatic taxobox
| name = Anomalures
| fossil_range = [[Late Eocene]] to recent<ref>
{{cite web
 |title = Anomaluridae
 |department = Fossil finds
 |website = mindat.org
 |publisher = [[Hudson Institute of Mineralogy]]
 |place = Keswick, VA
 |type = beta test
 |url=https://www.mindat.org/taxon-9429.html
 |access-date=2021-06-12}}</ref>{{Fossil range|38|0}}
| image = AnomalurusBeecroftiWolf.jpg
| image_caption = ''Anomalurus beecrofti'', [[Beecroft's flying squirrel]]<br /><small>Artist: [[Joseph Wolf]], 1851</small>
| taxon = Anomaluridae
| authority = [[Paul Gervais|Gervais]] in [[Alcide d'Orbigny|d'Orbigny]], 1849
| type_genus = ''[[Anomalurus]]''
| type_genus_authority = [[George Robert Waterhouse|Waterhouse]], 1843
| subdivision_ranks = Genera
| subdivision = *''[[Anomalurus]]''
*''[[Idiurus]]''
}}

The '''Anomaluridae''' are a family of [[rodent]]s found in central Africa.<ref>
{{MSW3 Anomaluridae
 | id = 13100010
 | page = 1533
}}
</ref> They are known as '''anomalures''' or '''scaly-tailed squirrels''' or '''African flying squirrels'''. The six extant species are classified into two genera: [[Anomalurus]], and the smaller, [[Flying mouse|Idiurus]].

All anomalurids have membranes between their front and hind legs like those of the [[Boreal forest|boreal]] [[flying squirrel]]s, but they are not closely related to the flying squirrels that form the separate tribe [[flying squirrel|Petauristini]] of the family [[Sciuridae]]. They are distinguished by two rows of pointed, raised scales on the undersides of their tails.<ref name=EoM>
{{cite book
 |last = Fleming |first = Theodore
 |year = 1984
 |section = {{grey|[article title not cited]}}
 |title = The Encyclopedia of Mammals
 |editor = Macdonald, D.
 |publisher= Facts on File
 |location= New York, NY
 |page = [https://archive.org/details/encyclopediaofma00mals_0/page/632 632]
 |isbn= 0-87196-871-1
 |section-url = https://archive.org/details/encyclopediaofma00mals_0/page/632
 |url = https://archive.org/details/encyclopediaofma00mals_0
 |url-access = registration
 |via = [[Internet Archive]]
}}
</ref><ref name="Panyutina-2020" /> The anatomy of their [[zygomasseteric system|heads]] is quite different from that of the [[Sciuridae|sciurid]] [[flying squirrel]]s. 

By extending their limbs, anomalures transform themselves into a gliding platform that they control by manipulating the membranes and tail.<ref>
{{cite encyclopedia
 | title=Anomalure
 |department = Rodent
 |encyclopedia = [[Encyclopædia Britannica|Britannica]]
 |edition = online
 |url=https://www.britannica.com/animal/anomalure
}}
</ref> Like North American flying squirrels, these species have a [[cartilage|cartilaginous]] rod that aids them in maintaining the extension of the [[patagium]] when in flight; unlike flying squirrels, their cartilage originates at the elbow joint rather than at the wrist.<ref name="Sallam-2010" /><ref>
{{cite journal
 |last = Waterhouse |first = George Robert
 |date = 27 September 1842
 |title = Descriptions of new species of quadrupeds collected by Mr.&nbsp;Fraser at Fernando Po
 |journal = [[Proceedings of the Zoological Society of London]]
 |volume=10 |page=125
 |url=https://www.biodiversitylibrary.org/item/96442#page/277/mode/1up
 |access-date=9 December 2023
}}
</ref>

Most anomalurid species roost during the day in hollow trees, with up to several dozen animals per tree. They are primarily [[herbivore|herbivorous]], and may travel up to {{convert|6|km|mi|abbr=on}} from their roosting tree in search of leaves, flowers, or fruit, although they also eat a small amount of insects. They give birth to litters up to three young, which are born already furred and active.<ref name=EoM/>

Anomalurids represent one of several [[convergent evolution|independent evolution]]s of gliding ability in [[mammal]]s, having evolved from climbing animals.<ref name=Fabre2018>
{{cite journal
 |last1 = Fabre |first1 = Pierre-Henri
 |last2 = Tilak |first2 = Marie-Ka
 |display-authors = etal
 |date = June 2018
 |title = Flightless scaly-tailed squirrels never learned how to fly: A reappraisal of Anomaluridae phylogeny
 |journal = [[Zoologica Scripta]]
 |volume = 47  |issue = 4  |pages = 404–417
 |doi = 10.1111/zsc.12286  |s2cid = 89754034
}}
</ref><ref>
{{cite journal
 | last1=Coster | first1=Pauline M.C.         | last2=Beard     | first2=K. Christopher
 | last3=Salem  | first3=Mustafa J.           | last4=Chaimanee | first4=Yaowalak
 | last5=Jaeger | first5=Jean-Jacques
 | year=2015
 | title=New fossils from the Paleogene of central Libya illuminate the evolutionary history of endemic African anomaluroid rodents
 | journal=Frontiers in Earth Science
 | volume=3 | page=56
 | doi=10.3389/feart.2015.00056 | doi-access=free
 | bibcode=2015FrEaS...3...56C  | hdl=1808/22093 | hdl-access=free
}}
</ref> The others include the "true" or [[Sciuridae|sciurid]] [[flying squirrel]]s of [[Boreal ecosystem|boreal]] [[Eurasia]] and North America, the [[colugo]]s or "flying lemurs" of Southeast Asia, and [[marsupial]] [[gliding possum]]s of [[Australia (continent)|Australia]].

== Taxonomy ==

Taxonomy follows {{harvp|Fabre|Tilak|Denys|Gaubert|Nicolaus|Marivaux|2018}}.<ref>
{{cite journal
 |last1=Fabre    |first1=Pierre-Henri           |last2=Tilak   |first2=Marie-Ka
 |last3=Denys    |first3=Christiane             |last4=Gaubert |first4=Philippe
 |last5=Nicolas  |first5=Violaine               |last6=Douzery |first6=Emmanuel J.P.
 |last7=Marivaux |first7=Laurent
 |date=July 2018
 |title=Flightless scaly-tailed squirrels never learned how to fly: A reappraisal of Anomaluridae phylogeny
 |journal=Zoologica Scripta
 |volume=47  |issue=4  |pages=404–417
 |doi=10.1111/zsc.12286  |s2cid=89754034
}}
</ref><ref>
{{cite journal
 | last1 = Heritage     | first1 = S.          | last2 = Fernández | first2 = D.
 | last3 = Sallam       | first3 = H.M.        | last4 = Cronin    | first4 = D.T.
 | last5 = Esara Echube | first5 = J.M.        | last6 = Seiffert  | first6 = E.R.
 | year=2016
 | title = Ancient phylogenetic divergence of the enigmatic African rodent Zenkerella and the origin of anomalurid gliding
 | journal = PeerJ
 | volume = 4 | article-number = e2320
 | pmc = 4991859  | pmid = 27602286
 | doi = 10.7717/peerj.2320 | doi-access = free }}</ref>

*'''Family Anomaluridae'''
**Genus ''[[Anomalurus]]''
***[[Beecroft's flying squirrel]], ''Anomalurus beecrofti''
***[[Lord Derby's scaly-tailed flying squirrel]], ''Anomalurus derbianus''
***[[Pel's flying squirrel]], ''Anomalurus pelii''
***[[Dwarf scaly-tailed squirrel]], ''Anomalurus pusillus''
**Genus ''[[Idiurus]]''
***[[Long-eared flying mouse]], ''Idiurus macrotis''
***[[Pygmy scaly-tailed flying squirrel]], ''Idiurus zenkeri''

=== Fossil genera ===
Several fossil genera are also known:{{cn|date=July 2025}}

* Genus †''[[Argouburus]]''
* Genus †''[[Kabirmys]]''<ref name="Sallam-2010">{{cite journal |last1 = Sallam |first1 = Hesham M. |last2 = Seiffert |first2 = Erik R. |last3 = Simons |first3 = Elwyn L. |last4 = Brindley |first4 = Chloe |date = September 2010 |title = A large-bodied Anomaluroid rodent from the earliest late Eocene of Egypt: Phylogenetic and biogeographic implications |journal = [[Journal of Vertebrate Paleontology]] |volume = 30 |issue = 5 |pages = 1579–1593|doi = 10.1080/02724634.2010.501439 |bibcode = 2010JVPal..30.1579S }}</ref>
* Genus †''[[Paranomalurus]]''
* Genus †''[[Pondaungimys]]''
* Genus †''[[Shazurus]]''

== Specialized morphology ==

=== Patagium ===
The gliding membrane (patagium) of scaly-tailed squirrels consists of three distinct sections: the anterior propatagium extending from the shoulder along the forelimb, the large middle plagiopatagium spanning from forelimb to hindlimb, and the posterior uropatagium connecting the hindlimb to the proximal portion of the tail.

Anomalurids are unique among all other gliding mammals in having a cartilaginous elbow spur, called the unciform element, which projects laterally from the ulna to support the anterior edge of the membrane during flight. This spur differs from the wrist-based styliform cartilage found in flying squirrels, having evolved from the triceps tendon rather than skeletal elements. 

The membrane attachment patterns vary between genera, with ''Anomalurus'' species having more extensive connections to the hindlimbs compared to the smaller ''Idiurus'' species. A specialized brush of stiff hairs on the membrane's dorsal surface just behind the elbow spur serves an aerodynamic function, passively thickening the wing's leading edge to improve airflow during gliding.<ref name="Panyutina-2020">{{Cite journal |last1=Panyutina |first1=Aleksandra A. |last2=Chernova |first2=Olga F. |last3=Soldatova |first3=Irina B. |date=2020 |title=Morphological peculiarities in the integument of enigmatic anomalurid gliders (Anomaluridae, Rodentia) |journal=Journal of Anatomy |language=en |volume=237 |issue=3 |pages=404–426 |doi=10.1111/joa.13211 |issn=0021-8782 |pmc=7476187 |pmid=32458532}}</ref>

=== Tail ===
Unlike the rougher-barked trees found in habitats of other gliding mammals, Anomalurids live on trees with relatively smooth bark like ''[[Milicia excelsa]]'' that offer fewer natural grip points for claws. This has resulted in them evolving an adaption to aid them in the form a distinctive [[Keratin|keratinous]] scaly organ on the ventral surface of their tail base that gives scaly-tailed squirrels get their common name.<ref name="Schulz-2025" /> 

This unique structure varies significantly across species in both form and function. In the smaller ''Idiurus'' species, the organ consists of dozens of transverse rows of small, smooth, drop-shaped scales occupying one-seventh to one-eighth of the tail length. In contrast, the larger ''Anomalurus'' species possess exactly 14 large, triangular scales arranged in two alternating longitudinal rows creating a checkerboard pattern, with each scale equipped with a sharp posterior spike for enhanced grip on tree bark. The scaly organ is supported by enlarged sebaceous glands that provide lubrication to maintain scale flexibility and prevent mechanical damage.<ref name="Panyutina-2020" /> 

Experimental studies find that these scales function as a specialized anti-skid mechanism which enhances their ability to hold on to surfaces by up to 58% where these have the intermediate roughness of the "smooth-bark" trees found in West African rainforests. The organ acts as a fifth point of contact that improves static stability. This allows the animals to maintain perching positions at inclinations up to 82.5° without active claw engagement—nearly 3° steeper than possible without the scales. 

This adaptation seems to be specifically evolved for the drought-tolerant tree species with smoother bark textures that predominate in the upper Guinea rainforest. Scale size and spike development correlate with both body weight and the mechanical demands of gripping these difficult to grasp surfaces.<ref name="Schulz-2025">{{Cite journal |last1=Schulz |first1=Andrew K. |last2=Chellapurath |first2=Mrudul |last3=Khandelwal |first3=Pranav C. |last4=Rezaei |first4=SeyedReza |last5=Merker |first5=Stefan |last6=Jusufi |first6=Ardian |date=2025 |title=Scaly-tail organ enhances static stability during Pel's scaly-tailed flying squirrels' arboreal locomotion |journal=Journal of the Royal Society Interface |language=en |volume=22 |issue=227 |article-number=20240937 |doi=10.1098/rsif.2024.0937 |pmid=40555385 |issn=1742-5662|pmc=12187390 }}</ref>

== References ==
{{reflist|25em}}

== External links==
* {{cite magazine
 <!-- |author = {{grey|author name not listed}} -->
 |date = 4 March 2015
 |title = Meet the scaly-tail glider  |department = Zoology
 |magazine = [[Scientific American]]   |type = blog
 |url = https://blogs.scientificamerican.com/tetrapod-zoology/meet-the-scaly-tail-gliders/
 |quote = Among the weirdest and most fascinating of rodents are the scalytails / scaly-tails, scaly-tailed squirrels, or anomalures, properly termed ‘Anomaluridae’.
}}

{{Rodents}}
{{Anomaluridae nav}}
{{Taxonbar|from=Q135251}}
[[Category:Anomalures| ]]
[[Category:Extant Eocene first appearances]]
[[Category:Rodents of Africa| ]]
[[Category:Taxa named by Paul Gervais]]