Bonefish (Elopomorpha, Albuliformes) remains from Late Cretaceous outcrops of San Carlos Quarry, Coahuila, Northern Mexico: evidence of a new giant Teleost in the Western Interior Seaway

Abstract

The discovery of suspensorium bones, comprising the hyomandibular and metapterygoid, indicates the presence of a giant species belonging to the order Albuliformes in the Late Cretaceous outcrops of Northern Coahuila. The taxonomic designation in the order Albuliformes is due to the presence of the metapterygoid cup, a postero-dorsal concavity on the metapterygoid bone which, together with its articulation with the hyomandibular, composes the hyomandibular-metapterygoid fenestra. Although the function of this structure has been debated, its presence represents a diagnostic feature for both fossil and extant Albuliformes species. Comparing the hyomandibular-metapterygoid fenestra with other bonefish is evidence that this structure is quite variable inside the order. The hyomandibular length indicates that this specimen measured approximately 3.9 meters in length, which represents three times the size of †Farinichthys gigas, the largest bonefish known to date, collected in Paleocene outcrops from Brazil. This taxon represents a new giant form inside the Western Interior Seaway, which differs from the other large teleostean fishes of this ancient sea for being a secondary consumer.