Afrocascudo
| Afrocascudo Temporal range: Late Cretaceous (early Cenomanian), ~
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|---|---|
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Siluriformes |
| Family: | Loricariidae |
| Genus: | †Afrocascudo Brito et al., 2024 |
| Species: | †A. saharaensis
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| Binomial name | |
| †Afrocascudo saharaensis Brito et al., 2024
| |
Afrocascudo is an extinct genus of ancient loricariid catfishes from the Late Cretaceous Douira Formation (Kem Kem Group) of Morocco. The genus contains a single species, A. saharaensis, known from a nearly complete articulated specimen. Afrocascudo represents the oldest known fossil catfish.
Discovery and naming[edit]
The Afrocascudo holotype specimen, MHNM-KK-OT 36 a—c, was discovered in sediments of the Douira Formation (Jbel Oum Tkout locality) of the Kem Kem Group near Tafraoute Sidi Ali in Errachidia Province, southeastern Morocco. The articulated specimen consists of a nearly complete fish collected in three pieces. It is missing parts of the head and pectoral and pelvic fins.[1]
In 2024, Brito et al. described Afrocascudo saharaensis as a new genus and species of loricariid catfishes based on these fossil remains. The generic name, Afrocascudo, combines the Latin word "Afro", meaning "Africa", with the Portuguese "cascudo", the common name used in Brazil for certain armoured catfishes.. The specific name, saharaensis, references the Sahara Desert of North Africa, from which the holotype was discovered.[1]
Afrocascudo represents the oldest known catfish and, as such, also the oldest known loricarioid. Before the Afrocascudo description, the Argentinian Corydoras revelatus was the oldest known loricarioid, from the Late Paleocene (~58.5 Ma).[2][3] The presence of a crown group loricarioid catfish in the Late Cretaceous indicates that the clade had already significantly diversified much earlier than was previously thought.[1]
Description[edit]
Afrocascudo was a small fish, with an estimated total body length of 74 millimetres (2.9 in). About 35% of the total body length is incorporated by the head. The top and sides of the body and head are covered in odontode-coated bony plates. The skull roof is triangular, with a long, pointed snout and expanded orbit region. It had approximately 30 vertebrae in total. The distalend of the caudal fin, though not entirely preserved, seems to be symmetrically rounded with 14 rays. The dorsal fin includes a small anterior spinelet, a larger spine, and 8-9 rays. The pelvic fin has six parallel rays. A physical anal fin is not preserved, but four rays are observable as impressions.[1]
Classification[edit]
In their phylogenetic analyses, Brito et al. (2024) recovered Afrocascudo within the diverse siluriform (catfish) clade Loricariidae. Loricariids—including Afrocascudo—are regarded as the "armoured catfishes", with around 1,220 extant species. Their results are displayed in the cladogram below:[1]
Paleoecology[edit]
Afrocascudo is known from the Douira Formation (Kem Kem Group) of Morocco, which dates to the Cenomanian age of the late Cretaceous period. This locality represents a fresh water environment that would have dried seasonally. Many other fossil animals have been found in similar outcrops, such as various invertebrates, other fish,[1][4] amphibians,[5] crocodylomorphs, and dinosaurs including the large theropods Carcharodontosaurus and Spinosaurus.[6]
References[edit]
- ^ a b c d e f Brito, Paulo M.; Dutheil, Didier B.; Gueriau, Pierre; Keith, Philippe; Carnevale, Giorgio; Britto, Marcelo; Meunier, François J.; Khalloufi, Bouziane; King, Andrew; de Amorim, Pedro F.; Costa, Wilson J. E. M. (2024). "A Saharan fossil and the dawn of Neotropical armoured catfishes in Gondwana". Gondwana Research. 132: 103–112. doi:10.1016/j.gr.2024.04.008.
- ^ Cockerell, T. D. A. (1925-10-30). "A Fossil Fish of the Family Callichthyidae". Science. 62 (1609): 397–398. doi:10.1126/science.62.1609.397.c. ISSN 0036-8075.
- ^ Lundberg, John G.; Sullivan, John P.; Rodiles-Hernández, Rocío; Hendrickson, Dean A. (2007-06-01). "Discovery of African roots for the Mesoamerican Chiapas catfish, Lacantunia enigmatica, requires an ancient intercontinental passage" (PDF). Proceedings of the Academy of Natural Sciences of Philadelphia. 156 (1): 39–53. doi:10.1635/0097-3157(2007)156[39:DOARFT]2.0.CO;2. ISSN 0097-3157.
- ^ Filleul, Arnaud; Dutheil, Didier B. (2004-06-11). "A peculiar diplospondylous actinopterygian fish from the Cretaceous of Morocco". Journal of Vertebrate Paleontology. 24 (2): 290–298. doi:10.1671/3004. ISSN 0272-4634.
- ^ Lemierre, Alfred; Blackburn, David C. (2022-07-15). "A new genus and species of frog from the Kem Kem (Morocco), the second neobatrachian from Cretaceous Africa". PeerJ. 10: e13699. doi:10.7717/peerj.13699. ISSN 2167-8359. PMC 9291016. PMID 35860040.
- ^ Ibrahim, N.; Sereno, P.C.; Varricchio, D.J.; Martill, D.M.; Dutheil, D.B.; Unwin, D.M.; Baidder, L.; Larsson, H.C.E.; Zouhri, S.; Kaoukaya, A. (2020). "Geology and paleontology of the Upper Cretaceous Kem Kem Group of eastern Morocco". ZooKeys (928): 1–216. doi:10.3897/zookeys.928.47517. PMC 7188693. PMID 32362741.