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| Sooinichthys varii Alvarado-Ortega, Otero & Mayrinck, 2025 |
Abstract
We describe a new genus and species, Sooinichthys varii, based on well-preserved specimens from the Albian marine limestones of Tlayúa Quarry, Mexico. This fish possesses a Weberian apparatus, supporting its inclusion in the clade Otophysi, and a unique combination of skeletal features not found in any living or extinct known otophysan group. This new species represents the first known Early Cretaceous otophysan discovered in North America and one of the oldest found worldwide. Our findings enhance our understanding of the early diversity within the Otophysan group. The new species is significant for ongoing discussions about the history of Otophysi because it highlights a geographical region where the otophysan fossil record is scarce; therefore, it may help answer questions about the relationships between fossils and living species, their geographic distribution, the transition from shallow marine waters to inland environments, and the ecological factors that contributed to their diversity as the most varied group of freshwater fish on Earth.
Keywords: Albian, Tlayúa, Otophysi, Sooinichthys varii, Mexico
Sooinichthys varii
Genus Sooinichthys nov.
Derivation of name. The genus name originates from the Mixtec words So’o (meaning ‘ear’) and ini (meaning ‘internal’), combined with the Greek ichthys (meaning ‘fish’), which togetherform ‘fish with an inner ear’. The name is pronounced /sɒˈ.ɒ.ɪn.ɪk.hi.ə.s/.
Jesús Alvarado-Ortega, Olga Otero and Diogo Mayrinck. 2025. A New otophysan from the Tlayúa Quarry, Mexico: A North American clue to the early Diversification of this group of Freshwater Fishes. Papers in Palaeontology. DOI: doi.org/10.1002/spp2.70056 [11 December 2025]
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