Two New Species and a Revised Phylogeny of the Ellimmichthyiformes (Teleostei: Clupeomorpha)

Abstract

The Ellimmichthyiformes is an extinct order of clupeomorph fishes. This group includes fossil species from marine, estuarine, and freshwater sediments ranging in time from the Early Cretaceous to the Eocene. In spite of the long history of taxonomic studies on the Clupeomorpha, phylogenetic relationships within the group remain unresolved. Two new species of the Ellimmichthyiformes are described and included in the revised phylogenetic analysis of the order. The updated phylogenetic analysis recovered the Ellimmichthyiformes as a monophyletic group characterized by the medially united parietals, absence of the recessus lateralis, presence of the basipterygoid process, and epurals that are tightly fixed between the neural spines of the preural centra. The new phylogenetic hypothesis revealed patterns in the paleobiogeographic history of this group of fishes, suggesting that the ellimmichthyiforms may have originated in the tropical region of South America and were predominantly euryhaline fishes.