Pycnodontiformes

Pycnodontiformes
Temporal range: Late Triassic–Eocene
Pycnodontiform diversity
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Subclass: Neopterygii
Order: Pycnodontiformes
Berg, 1937
Families

Pycnodontiformes is an extinct order of primarily marine bony fish. The group first appeared during the Late Triassic and disappeared during the Eocene. The group has been found in rock formations in Africa, Asia, Europe, North and South America.[1]

They were small to middle-sized fish, generally with laterally-compressed deep bodies, some with almost circular outlines,[2] adapted for manuverability in reef-like environments, though the group was morphologically diverse.[3] Most, but not all members of the groups had jaws with round and flattened teeth,[4] well adapted to crush food items (durophagy), such as echinoderms, crustaceans and molluscs.[3] Some pyncodontiformes developed piranha like teeth used for eating flesh.[5][6] Most species inhabited shallow marine reef environments, while a handful of species lived in freshwater or brackish conditions.

While rare during the Triassic and Early-Middle Jurassic, Pycnodontiformes became abundant and diverse during the Late Jurassic, exhibiting a high but relatively static diversity during the Early Cretaceous. At the beginning of the Late Cretaceous they reached their apex of morphological and species diversity (much of this due to fossils found in the Sannine Formation of Lebanon, such as Gebrayelichthyidae and Ichthyoceros), after which they began to gradually decline, with a more sudden decline at the end of the Cretaceous due to the collapse of reef ecosystems, finally becoming extinct during the Eocene. They are considered to belong to the Neopterygii, but their relationship to other members of that group is uncertain.[3]

  1. ^ "Pycnodontiformes". Palaeos vertebrates. Archived from the original on 25 October 2008. Retrieved 27 July 2009.
  2. ^ "Pycnodontid fishes from the Kansas Cretaceous". Oceans of Kansas. 16 April 2009. Retrieved 29 July 2009.
  3. ^ a b c 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.
  4. ^ McMenamin, M. A. S. (2009). Paleotorus: The Laws of Morphogenetic Evolution. Meanma Press. ISBN 978-1-893882-18-8.
  5. ^ Kölbl-Ebert, Martina; Ebert, Martin; Bellwood, David R.; Schulbert, Christian (2018-11-05). "A Piranha-like Pycnodontiform Fish from the Late Jurassic". Current Biology. 28 (21): 3516–3521.e2. doi:10.1016/j.cub.2018.09.013. ISSN 0960-9822. PMID 30344113. S2CID 53045425.
  6. ^ Vullo, Romain; Cavin, Lionel; Khalloufi, Bouziane; Amaghzaz, Mbarek; Bardet, Nathalie; Jalil, Nour-Eddine; Jourani, Essaid; Khaldoune, Fatima; Gheerbrant, Emmanuel (2017-07-28). "A unique Cretaceous–Paleogene lineage of piranha-jawed pycnodont fishes". Scientific Reports. 7 (1): 6802. doi:10.1038/s41598-017-06792-x. ISSN 2045-2322. PMC 5533729. PMID 28754956.