Dapediidae

Dapediidae Temporal range: Ladinian–Tithonian PreꞒ Ꞓ O S D C P T J K Pg N
Fossil specimen of Dapedium politum
Artist's reconstruction of Dapedium politum
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Clade:	Ginglymodi
Order:	† Semionotiformes (?)
Family:	† Dapediidae Lehman, 1966
Genera
† Aetheolepis † Ameghinichthys [1] † Dandya † Dapedium † Guizhoubrachysomus † Hemicalypterus † Heterostrophus † Paradapedium † Sargodon † Scopulipiscis † Tetragonolepis

Dapediidae is an extinct family of neopterygian ray-finned fish, likely belonging to the clade Ginglymodi and thus distantly related to modern gars. They lived from the Middle Triassic to the Late Jurassic (Ladinian to Tithonian). ^[2] Its members were historically placed within the ginglymodian family Semionotidae, but were moved to their own family in 1966, and subsequently to the separate order Dapediiformes in 2016. ^[3]

Description

Dapediids had deep, laterally flattened circular bodies covered in thick ganoid scales, which gave them a resemblance to the pycnodontiforms, a group they may or may not be related to. ^[4] Their teeth were adapted towards a durophagous diet; some dapediids fed on hard-shelled invertebrates, ^[5] while at least one genus ( Hemicalypterus ) may have been herbivorous. ^[6]

Classification

Dapediids are usually considered to be either basal ginglymodians ^{[3] [6]} or stem group representatives of the wider clade Holostei, ^{[4] [7]} but some studies have found them to be early-diverging stem-teleosts instead. ^[4] In 2025 the Ladinian Guizhoubrachysomus was identified as an early-diverging dapediid, and the group was recovered within Semionotiformes as the sister group of Macrosemiidae. ^[8]

References

1. Gouiric-Cavalli, S.; Iglesias, A.; Cariglino, B.; Reguero, M. A. (2024). "A Late Jurassic deep-bodied actinopterygian fish from Antarctica". Acta Palaeontologica Polonica. 69 (3): 467–483. doi: 10.4202/app.01158.2024 .
2. Cawley, John J.; Marramà, Giuseppe; Carnevale, Giorgio; Villafaña, Jaime A.; López‐Romero, Faviel A.; Kriwet, Jürgen (February 2021). "Rise and fall of †Pycnodontiformes: Diversity, competition and extinction of a successful fish clade". Ecology and Evolution. 11 (4): 1769–1796. doi:10.1002/ece3.7168. ISSN   2045-7758. PMC   7882952 . PMID   33614003.
3. Thies, D.; Waschkewitz, J. (2016). "Redescription of Dapedium pholidotum (Agassiz, 1832) (Actinopterygii, Neopterygii) from the Lower Jurassic Posidonia Shale, with comments on the phylogenetic position of Dapedium Leach, 1822". Journal of Systematic Palaeontology. 14 (4): 339–364. doi:10.1080/14772019.2015.1043361. S2CID   130282395.
4. Latimer, A. E.; Giles, S. (2018). "A giant dapediid from the Late Triassic of Switzerland and insights into neopterygian phylogeny". Royal Society Open Science. 5 (8) 180497. Bibcode:2018RSOS....580497L. doi: 10.1098/rsos.180497 . PMC   6124034 . PMID   30225040.
5. Smithwick, F. M. (2015). "Feeding ecology of the deep-bodied fish Dapedium (Actinopterygii, Neopterygii) from the Sinemurian of Dorset, England". Palaeontology. 58 (2): 293–311. Bibcode:2015Palgy..58..293S. doi: 10.1111/pala.12145 . S2CID   86168055.
6. Gibson, S. Z. (2016). "Redescription and Phylogenetic Placement of †Hemicalypterus weiri Schaeffer, 1967 (Actinopterygii, Neopterygii) from the Triassic Chinle Formation, Southwestern United States: New Insights into Morphology, Ecological Niche, and Phylogeny". PLOS ONE. 11 (9) e0163657. Bibcode:2016PLoSO..1163657G. doi: 10.1371/journal.pone.0163657 . PMC   5033578 . PMID   27657923.
7. López-Arbarello, A.; Sferco, E. (2018). "Neopterygian phylogeny: the merger assay". Royal Society Open Science. 5 (3) 172337. Bibcode:2018RSOS....572337L. doi: 10.1098/rsos.172337 . PMC   5882744 . PMID   29657820.
8. Xu, G.; Ma, X.; Liu, L.; Liao, J.; Tan, F.; Sun, C. (2025). "Taxonomic Revision of †Guizhoubrachysomus minor (†Semionotiformes, Ginglymodi) From the Middle Triassic (Ladinian) Xingyi Biota in Guizhou and Yunnan, China". Contributions from the Museum of Paleontology, University of Michigan. 37 (4): 79–92. doi:10.7302/27712.