Diabolepis

{{Short description|Extinct genus of fishes}} {{Italic title}} {{Speciesbox | name = ''Diabolepis'' | fossil_range = {{fossil range|415|410.8|Lochkovian}} | image = | image_caption = | taxon = Diabolepis speratus | grandparent_authority = Schultze, 1993 (name only) | parent_authority = Chang & Yu, 1987 | authority = (Chang & Yu, 1984) | synonyms = * {{extinct}}''Diabolichthys'' <small>Chang & Yu, 1984</small> (preoccupied) }}

'''''Diabolepis''''' is an extinct genus of very primitive marine lungfish which lived during the Early Devonian period. It contains a single species, '''''D. speratus''''' of Yunnan, China, from the mid-late Lochkovian of the Xitun Formation.<ref name=":0">{{Cite web |title=PBDB Taxon |url=https://paleobiodb.org/classic/basicTaxonInfo?taxon_no=372941 |access-date=2024-08-13 |website=paleobiodb.org}}</ref><ref>{{Cite journal |last=Cai |first=Jiachen |last2=Sun |first2=Haoran |last3=Zhao |first3=Wenjin |last4=Wang |first4=Jianhua |last5=Zhu |first5=Min |date=2024-05-06 |title=The Early Devonian Xitun Vertebrate Fauna in South China inhabited a shallow marine environment with changing salinity |url=https://www.lyellcollection.org/doi/10.1144/jgs2023-146 |journal=Journal of the Geological Society |language=en |volume=181 |issue=3 |doi=10.1144/jgs2023-146 |issn=0016-7649|url-access=subscription }}</ref> It is one of the oldest known lungfish genera. It is the only member of the family '''Diabolepididae''' and the order '''Diabolepidiformes<ref name=":1">{{Cite book |last=Nelson |first=Joseph S. |url=http://dx.doi.org/10.1002/9781119174844 |title=Fishes of the World |last2=Grande |first2=Terry C. |last3=Wilson |first3=Mark V. H. |date=2016-02-22 |publisher=Wiley |isbn=978-1-118-34233-6}}</ref>''', although neither of these parent taxa have been officially described, despite their names being in scientific usage.<ref>{{Cite journal |last=Laan |first=Richard Van Der |date=2018-10-11 |title=Family-group names of fossil fishes |url=https://zenodo.org/records/5557557 |journal=European Journal of Taxonomy |volume=466 |pages=1–167 |doi=10.5852/ejt.2018.466|doi-access=free }}</ref>

== Taxonomy == ''Diabolepis'' was originally described as ''Diabolichthys'', but this name was found to be preoccupied by a now-outdated genus name given to the manta ray in the 19th century, thus necessitating a new genus name.<ref>{{Cite book |last=M-M Chang |url=http://archive.org/details/biostor-67584 |title=Structure and phylogenetic significance of Diabolichthys speratus gen. et sp. nov., a new dipnoan-like form from the Lower Devonian of eastern Yunnan, China |last2=X Yu |date=1984}}</ref><ref>{{Cite journal |last=Chang |first=Mee-mann |last2=Yu |first2=Xiaobo |date=1987 |title=A Nomen Novum for ''Diabolichthys'' Chang ''et'' Yu, 1984 |url=http://www.ivpp.cas.cn/cbw/gjzdwxb/xbwzxz/200903/W020090813373462594175.pdf |journal=Vertebr. Palasiat.}}</ref>

It is generally considered the most basal known dipnoan, although some other studies instead find ''Youngolepis'' to be more basal.<ref name=":2">{{Cite journal |last=Kemp |first=Anne |last2=Cavin |first2=Lionel |last3=Guinot |first3=Guillaume |date=2017-04-01 |title=Evolutionary history of lungfishes with a new phylogeny of post-Devonian genera |url=https://www.sciencedirect.com/science/article/pii/S0031018216304138 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=471 |pages=209–219 |doi=10.1016/j.palaeo.2016.12.051 |issn=0031-0182|doi-access=free }}</ref> In addition, some studies do not find it to be a lungfish, but rather a more basal dipnotetrapodomorph.<ref name=":0" /><ref>{{Cite journal |last=Campbell |first=K. S. W. |last2=Barwick |first2=R. E. |date=2001-07-20 |title=Diabolepis and its relationship to the Dipnoi |url=http://www.tandfonline.com/doi/abs/10.1671/0272-4634%282001%29021%5B0227%3ADAIRTT%5D2.0.CO%3B2 |journal=Journal of Vertebrate Paleontology |language=en |volume=21 |issue=2 |pages=227–241 |doi=10.1671/0272-4634(2001)021[0227:DAIRTT]2.0.CO;2 |issn=0272-4634|url-access=subscription }}</ref><ref>{{Cite journal |last=Campbell |first=K. S. W. |last2=Wragg |first2=Sharyn |date=2014-01-08 |title=Structural details of Early Devonian dipnoans |url=https://www.publish.csiro.au/zo/ZO13055 |journal=Australian Journal of Zoology |language=en |volume=62 |issue=1 |pages=18–25 |doi=10.1071/ZO13055 |issn=1446-5698|url-access=subscription }}</ref> However, other studies have continued to recover it as an early lungfish.<ref name=":1" /><ref name=":2" /><ref>{{Cite journal |last=Cui |first=Xindong |last2=Friedman |first2=Matt |last3=Qiao |first3=Tuo |last4=Yu |first4=Yilun |last5=Zhu |first5=Min |date=2022-05-02 |title=The rapid evolution of lungfish durophagy |url=https://www.nature.com/articles/s41467-022-30091-3 |journal=Nature Communications |language=en |volume=13 |issue=1 |pages=2390 |doi=10.1038/s41467-022-30091-3 |issn=2041-1723|pmc=9061808 }}</ref>

==Characteristics== A rather small fish, the fossil has risen to prominence as it has four nares like most fish, while modern lungfish have only two, the hindmost pair having moved on to the palate serving as choanae. This proved that the internal nares of lungfish had evolved independently of those in tetrapods. This has made the internal nares a case of parallel evolution rather than a homology between lungfish and tetrapods.<ref>{{cite news |date=2004 |title=EVOLUTION: ON THE EVOLUTION OF INTERNAL NOSTRILS (CHOANAE) |url=http://scienceweek.com/2004/sa041224-3.htm |url-status=dead |archive-url=https://web.archive.org/web/20120320190643/http://scienceweek.com/2004/sa041224-3.htm |archive-date=20 March 2012 |access-date=14 February 2013 |newspaper=ScienceWeek}}</ref>

''Diabolepis'' has a prominent snout; the more recurvature the snout, the greater is the proportion of the premaxilla that is included within the mouth cavity. The teeth within the premaxilla are folded with polyplocodont structure. The maxilla was either toothless or absent or there may have been a gap between the premaxilla and the maxilla. There is an intracranial joint or ventral fissure, two external nostrils, and separate ectopterygoids. One or several bones lie lateral to the anterior end of the postparietals. The skull roof has an incipient "B" bone between the postparietals. The rest of the skull roof has a tendency towards fragmentation into small bones. The endocranium is divided. The anterior nostril lies at the mouth margin. There can only be a narrow space between nostril and mouth, and an interrupted canal has been scored for ''Diabolepis''.{{cn|date=July 2024}}

==References== {{Reflist}}

Category:Prehistoric lungfish genera Category:Early Devonian sarcopterygians Category:Devonian sarcopterygians of Asia Category:Lochkovian life Category:Fossils of China Category:Fossil taxa described in 1987