{{Short description|Extinct species of bat}} {{pp-pc1}} {{Speciesbox |fossil_range = {{fossilrange|Pleistocene|Holocene}} |image = |image_caption = |genus = Synemporion |parent_authority = [[Alan C. Ziegler|Ziegler]] et al., 2016 |species = keana |authority = [[Alan C. Ziegler|Ziegler]] et al., 2016 |synonyms = }}
'''''Synemporion keana''''' is an extinct species of [[bat]] which lived in what is now [[Hawaii]] from at least 320,000 years ago to around 2,100 years ago. It is the only species in the genus '''''Synemporion'''''.<ref name=paper>{{Cite journal|last1=Ziegler|first1=Alan C.|last2=Howarth|first2=Francis G.|last3=Simmons|first3=Nancy B.|date=2016-03-21|title=A Second Endemic Land Mammal for the Hawaiian Islands: A New Genus and Species of Fossil Bat (Chiroptera: Vespertilionidae)|url=http://digitallibrary.amnh.org/handle/2246/6641|journal=American Museum Novitates|issue=3854|pages=1–52|doi=10.1206/3854.1|hdl=2246/6641|s2cid=56234957|issn=0003-0082}}</ref><ref name=pressrelease>[http://www.amnh.org/content/download/132583/2210546/file/Hawaiian%20bat.pdf Discovery of Extinct Bat Doubles Diversity of Native Hawaiian Land Mammals], at the [[American Museum of Natural History]]; published March 21, 2016; retrieved June 20, 2016</ref>
==Fossil discovery== The first [[fossil]]s of ''Synemporion keana'' were found in a [[lava tube]] on [[Maui]] in 1981.<ref name=pressrelease/> As of 2016, fossils from at least 110 unique individuals of this species have been uncovered.<ref name=paper/>
==Taxonomy and etymology== The genus name ''Synemporion'' is derived from [[Ancient Greek]] "''synemporos''" meaning "fellow traveler or companion." The authors chose this genus name to reflect the fact that the genus traveled on the tectonically active Hawaiian Islands along with the [[Hawaiian hoary bat]] (''Aeorestes semotus''). The [[specific epithet (zoology)|species name]] "''keana''" comes from [[Hawaiian language|Hawaiian]] "''[[wiktionary:ke#Hawaiian|ke]]''" meaning "the" and "''[[wiktionary:ana#Hawaiian|ana]]''" meaning "cave." The name ''keana'' references the fact that the [[holotype]] was discovered in a [[lava tube]].<ref name=paper/>
The relationship of ''Synemporion'' relative to other [[vesper bat]] genera is inconclusive. Researchers have been unable to extract its DNA from fossils, which is the only reliable way to examine phylogenetic relationships in this family of bats. It is unclear if ''Synemporion'' colonized the Hawaiian Islands from the [[Old World]] or the [[New World]]; most likely it belonged to one of the tribes of subfamily [[Vespertilioninae]] which make up the bulk of vesper bats but this is simply assumed because the minor subfamilies of vesper bats as well as the Vespertilioninae tribes were all well distinct from each other already by the time ''Synemporion'' became a separate lineage. But few skeletal characteristics are known to reliably indicate relationships among the vesper bats, so all that can be said at present is that it lacks obvious traits suggesting it belongs to one of the minor vesper bat subfamilies.<ref name=paper/>
==Description== It was a relatively small species of bat, with linear measurements about 25% smaller than the Hawaiian hoary bat which weighs 10-15 grams and has a wingspan of around a dozen cm. Notably, the skull's muzzle is somewhat more narrow than in its fellow species, and the nasal region is markedly concave (instead of barely convex in ''A. semotus''), resulting in the skull having a pronounced snout. How its nose looked in life is unknown; the [[Vespertilionidae]] generally produce [[Animal echolocation|echolocation]] sounds with the voicebox and not with the nose, and consequently lack the elaborate ultrasound-focusing nose appendages of bats that use the latter technique. To what extent this applied to ''Synemporion'' is not clear; most of the tribes it may belong to contain a few species with nose or upper jaw appendages. These are rarely as elaborate as those of [[horseshoe bat]]s (Rhinolophidae), for example, and are sometimes related to [[sexual selection]] rather than echolocation; there is no indication that ''Synemporion'' had marked sexual differences, and altogether its skull shape is not too different from that of Australasian [[big-eared bat]]s (''Nyctophilus'').<ref name=paper/>
One notable difference from all vesper bats it was compared with, however, is the [[sagittal crest]] which seems to be completely absent in ''Synemporion''. The teeth are more delicate than in the Hawaiian hoary bat, especially so in the lower jaw; otherwise their dentitions differ little. Its [[dentition#Dental formula|dental formula]] was {{DentalFormula|upper=1.1.1.3|lower=3.1.2.3}} or {{DentalFormula|upper=1.1.2.3|lower=3.1.2.3}} for a total of 30 or 32 teeth. The missing sagittal crest combined with the weaker dentition makes it almost certain that ''Synemporion'' could not nearly bite as hard as ''A. semotus'', and thus ate different, smaller and/or more soft-bodied prey.<ref name=paper/>
==Geographic range== ''S. keana'' lived on at least 5 Hawaiian islands: [[Kauaʻi]], [[Oʻahu]], [[Molokaʻi]], [[Maui]], and [[Hawaiʻi]].<ref name=paper/>
==Temporal range== While it is unknown when ''Synemporion'' first arrived in the Hawaiian islands, the oldest known fossils are from 320,000–400,000-year-old deposits on Oahu. One bone from another site on Oahu has been [[radiometric dating|dated]] at 2718–2479 years ago, but some undated remains indicate that ''S. keana'' survived until more recently; relatively well-preserved skeletons in a wet, dynamically active cave on Molokai suggest that the bat may have survived until as recently as a few thousand years ago.<ref name=paper/>
==Extinction== Like many Hawaiian fauna, the extinction of ''Synemporion keana'' may have been caused by humans, either directly or indirectly. Possible causes of its extinction include destruction of Hawaiian lowland dry forests and introduction of predators such as rats.<ref name=paper/>
==See also== * [[List of extinct animals of the Hawaiian Islands]]
==References== {{Reflist}}
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[[Category:Fossil taxa described in 2016]] [[Category:Fauna of Hawaii]] [[Category:Bats]] [[Category:Mammals of Hawaii]] [[Category:Paleontology in Hawaii]] [[Category:Holocene extinctions]] [[Category:Extinct mammals]]