| Ginglymodi | |
|---|---|
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| Spotted gar (Lepisosteus oculatus) | |
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| Macrosemimimus fegerti (Semionotiformes) from the Upper Jurassic of Germany | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Infraclass: | Holostei |
| Clade: | Ginglymodi Cope, 1871 |
| Subgroups | |
Ginglymodi is aclade ofray-finned fish containing modern-daygars (Lepisosteidae) and theirextinct relatives (including thefamilyLepidotidae) in theorderLepisosteiformes, the extinct ordersSemionotiformes andKyphosichthyiformes, and various other extincttaxa. Ginglymodi is one of the two major subgroups of theinfraclassHolostei, the other one beingHalecomorphi, which contains thebowfin andeyespot bowfin and theirfossil relatives.[1][2]
Thefossil record of ginglymodians goes back at least to theAnisianstage of theTriassicperiod, over 240 million years ago.[3]Eosemionotus is one of the earliest ginglymodians.Acentrophorus, anothertaxon from the Middle and LatePermian, andParacentrophorus from theEarly Triassicepoch, could be even earlier members of the group. Ginglymodi wasdiverse and widespread during theMesozoicera, but they represent a depauperatelineage today. The group first evolved in marine environments, but several lineages made separate transitions into freshwater environments.[4] The basal ginglymodian order Kyphosichthyiformes is known from a few genera from the Triassic of China, many of which have deep bodies.[5]
Ginglymodi underwent substantial diversification during the Late Triassic and the Late Jurassic, with the Lepisosteiformes and Semionotiformes having likely diverged during theMiddle Triassic.[6] Early non-gar ginglymodians of all groups, but especially early lepisosteiforms, show heavy morphologicalconvergence with moderncypriniforms (carp and relatives), suggesting that they may have had a similar ecological niche. Notably, molecular evidence suggests that the cypriniforms may have originated and diversified around the same time and place (Late Jurassic and Early CretaceousSoutheast Asia) that the similar freshwater ginglymodians showed major diversification.[7] Eventually, some ginglymodians evolved a more predatory lifestyle, with the earliest known true gars from the Late Jurassic.[8] Ginglymodians underwent a major decline during the mid-Cretaceous, eventually leaving gars as the only surviving members of the group.[6] Gar fossils have been found on all continents except Australia and Antarctica. Only seven species exist today, distributed in thefreshwater systems of North America.[8]
Phylogenetic relationships of Ginglymodi to other living neopterygian fish.
| Neopterygii |
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Phylogenetic relationships among different groups of ginglymodians (cladogram after Xu & Ma 2023):[9]
| Ginglymodi | |
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