Lampriformes - Systematics and Evolution

Systematics and Evolution

The order Lampriformes is anatomically similar to some Acanthopterygii at a first glance. But more detailed studies reveal that they are not as advanced, and many authors assign them to a basal position inside the advanced spiny-rayed Teleostei clade called Acanthomorpha, as monotypic superorder "Lampridiomorpha". Unlike their presumed relatives they lack fin spines, however, and other authors have considered them to form a lineage just outside the Acanthomorpha, and the sister taxon of the Myctophiformes. Molecular data also supports the view that the Lampriformes are close to the advanced Teleostei. But the data does not agree on their exact relationships, and the Myctophiformes are also inferred to be close to the Protacanthopterygii, one of the core groups of moderately advanced teleosts. As modern taxonomy tries to avoid a profusion of small taxa, and the delimitation of the Euteleostei (Protacanthopterygii sensu stricto and their allies) versus Acanthopterygii remains uncertain, the systematics and taxonomy of the Lampriformes among the teleosts are in need of further study.

The lampriforms diverged from other teleosts in the Cretaceous, perhaps 80 Ma (million years ago) or slightly more, considering that the oldest known lampriforms, Nardovelifer, dates from the late Campanian epoch and is already clearly assignable to the present order. The basal lampriforms were bathysomes, while the taeniosome body shape is apomorphic and seems to have evolved only once. The order underwent its main radiation in the Paleocene period; the opah-like Turkmenidae were a family of lampriforms thriving at that time, but going extinct around the start of the Neogene, about 23 Ma. Other fossil Lampridiformes are Bajaichthys, Palaeocentrotus and Veronavelifer.