Halecomorphi
{{Short description|Clade of fishes}}
{{Automatic taxobox
| fossil_range = {{Fossil range|251|present}}
| image = Cipactlichthys scutatus holotype.png
| image_caption = Cretaceous †Cipactlichthys scutatus
| image2 = Amia calva 1908.jpg
| image2_caption = Amia calva (bowfin)
| display_parents = 2
| taxon = Halecomorphi
| authority = Cope, 1872
| subdivision = * Amiiformes
- Amiidae
- {{extinct}}Caturidae
- {{extinct}}Liodesmidae
- {{extinct}}Sinamiidae
- {{extinct}}Ionoscopiformes
- {{extinct}}Furidae
- {{extinct}}Ionoscopidae
- {{extinct}}Oshuniidae
- {{extinct}}Ophiopsidae
- {{extinct}}Subortichthyidae
- {{extinct}}Panxianichthyiformes
- {{extinct}}Panxianichthyiidae
- {{extinct}}Parasemionotiformes
- {{extinct}}Parasemionidae
- {{extinct}}Promecosominidae
}}
Halecomorphi is a taxon of ray-finned bony fish in the clade Neopterygii. The only extant Halecomorph species are the bowfin (Amia calva) and eyespot bowfin (Amia ocellicauda), but the group contains many extinct species in several families (including Amiidae, Caturidae, Liodesmidae, Sinamiidae) in the order Amiiformes, as well as the extinct orders Ionoscopiformes, Panxianichthyiformes, and Parasemionotiformes. The fossil record of halecomorphs goes back at least to the Early Triassic epoch.
File:Watsonulus eugnathoides.png]]
File:Ionoscopus cyprinoides 387.jpg]]
File:Strobilodus giganteus.JPG]]
The Halecomorphi exhibit a combination of ancestral features, such as most heavily mineralized scales, but also by more derived or "modern" features, particularly in the structure of the skull (e.g. position and shape of preopercles). Unique derived traits (synapomorphies) of the Halecomorphi include:{{cite book|last=Ax|first=Peter [translated by Dr.Richard. E. Dunmur]|date=2003 |title=Multicellular Animals|publisher=Gardners Books|location=Berlin|isbn=978-3-642-05515-7|pages=207–210|doi=10.1007/978-3-662-08874-6_29|chapter=Halecomorphi — Teleostei}}
- Unique jaw articulation in which the quadrate and symplectic participate in the joint.
- Lengthened dorsal fins (in some species)
- Two biconcave vertebrae per segment in the posterior body region (a condition known as diplospondyly)
- Fan like arrangement of small bones (hypurals) in the tail.
Systematics and phylogeny
On the systematic position of the Halecomorphi, there are two competing hypotheses:
- The Halecostomi hypothesis proposes Halecomorphi as the sister group of Teleostei, the major group of living neopterygians, rendering the Holostei paraphyletic.Patterson C. Interrelationships of holosteans. In: Greenwood P H, Miles R S, Patterson C, eds. Interrelationships of Fishes. Zool J Linn Soc, 1973, 53(Suppl): 233–305
- The Holostei hypothesis proposes Halecomorphi as the sister group of Ginglymodi, the group which includes gars (Lepisosteidae) and their fossil relatives, rendering the Halecostomi paraphyletic.{{cite journal|author=Olsen P. E.|title= The skull and pectoral girdle of the parasemionotid fish Watsonulus eugnathoides from the Early Triassic Sakemena Group of Madagascar with comments on the relationships of the holostean fishes|journal= J Vertebr Paleontol|year= 1984|volume= 4|issue= 3|pages= 481–499|doi= 10.1080/02724634.1984.10012024|bibcode= 1984JVPal...4..481O|citeseerx= 10.1.1.384.2050}}{{cite journal|last=Grande|first=Lance|author2=Bemis, William E.|title=A Comprehensive Phylogenetic Study of Amiid Fishes (Amiidae) Based on Comparative Skeletal Anatomy. an Empirical Search for Interconnected Patterns of Natural History|journal=Journal of Vertebrate Paleontology |year=1998 |volume=18 |issue=sup001 |pages=1–696 |doi=10.1080/02724634.1998.10011114|bibcode=1998JVPal..18S...1G }}{{cite journal |last1=López-Arbarello |first1=Adriana |last2=Sferco |first2=Emilia |title=Neopterygian phylogeny: the merger assay. |journal=Royal Society Open Science |date=March 2018 |volume=5 |issue=3 |pages=172337 |doi=10.1098/rsos.172337|pmid=29657820 |pmc=5882744 |bibcode=2018RSOS....572337L |doi-access=free }}
The latter hypothesis is more widely accepted.{{cite web | author = Betancur-R | title = Phylogenetic Classification of Bony Fishes Version 4 | url = https://sites.google.com/site/guilleorti/classification-v-4 | date = 2016 | access-date = 2021-06-06 | archive-date = 2017-07-11 | archive-url = https://web.archive.org/web/20170711171156/https://sites.google.com/site/guilleorti/classification-v-4 | url-status = dead }}{{cite book| last = Nelson| first = Joseph, S.| title = Fishes of the World| year = 2016| publisher = John Wiley & Sons, Inc| isbn = 978-1-118-34233-6 }}{{ITIS |id=161061 |taxon=Actinopterygii |access-date=3 April 2006}}{{cite web | editor = R. Froese and D. Pauly| title = FishBase | url = http://www.fishbase.org |date=February 2006}}
{{clade| style=font-size:100%;line-height:100%;
| label1=Neopterygii
| 1={{clade
|label2=Holostei
|2={{clade
|1=Ginglymodi (gars and their fossil relatives) 130px
|2=Halecomorphi (bowfin and its fossil relatives) 130px
}}
}} }}
The following cladogram{{cite journal |last1=Sun |first1=Zuoyu |last2=Tintori |first2=Andrea |last3=Xu |first3=Yaozhong |last4=Lombardo |first4=Cristina |last5=Ni |first5=Peigang |last6=Jiang |first6=Dayoung |title=A new non-parasemionotiform order of the Halecomorphi (Neopterygii, Actinopterygii) from the Middle Triassic of Tethys. |journal=Journal of Systematic Palaeontology |date=April 2017 |volume=15 |issue=3 |pages=223–240 |doi=10.1080/14772019.2016.1181679|bibcode=2017JSPal..15..223Z |s2cid=133176227 }} summarizes the evolutionary relationships of extinct (indicated with a dagger, †) and living orders of Halecomorphi.
{{clade| style=font-size:100%;line-height:100%;
| label1=Halecomorphi
|1={{clade
|1={{extinct}}Parasemionotiformes 110px
|2={{clade
|1={{extinct}}Panxianichthyiformes 110px
|2={{clade
|1={{extinct}}Ionoscopiformes 110px
|2=Amiiformes (bowfin and its fossil relatives) 130px
}} }} }} }}
References
{{Portal|Paleontology|Fish}}
{{Reflist}}
- Brian J. Gardiner, John G. Maisey, D. Tim J. Littlewood: [https://books.google.com/books?id=H20q9rqZENsC&pg=PA117 Interrelationships of Basal Neopterygians.] S. 117-146 in: Melanie L. J. Stiassny, Lynne R. Parenti, G. David Johnson (Hrsg.): Interrelationships of Fishes. Academic Press, 1996, {{ISBN|0-12-670950-5}}
{{Halecomorphi|H.}}
{{Taxonbar|from=Q4040348}}