The putative lampridiform Iratusichthys ulrikii gen. et sp. nov. from the Stolleklint clay unit of the Ølst Formation, Denmark

The early Eocene Fur and Ølst formations are globally renowned for their exceptionally well-preserved ichthyofaunas. Until now, only one lampridiform genus and species, Palæocentrotus böggildi, has been described from these, exclusively known from the Fur Formation. Here, we describe a new genus and species of lampridiform fish, Iratusichthys ulrikii gen. et sp. nov. from the earliest Eocene Ølst Formation. The single available specimen consists of moderately well-preserved and largely incomplete articulated skeletal remains, lacking most of the axial skeleton. It exhibits a unique set of morphological features that support its recognition as a new lampridiform genus, including a deep anterior concavity of the ethmoid region, orbitosphenoid lacking a ventral keel, presence of tiny, conical teeth in the lower and upper jaws, beryciform foramen piercing the anterior ceratohyal, unique predorsal formula (/0/0/?+1/1/), and absence of parapophyses. Moreover, these characters, especially the presence of tiny conical teeth in the lower and upper jaws might suggest that it should be regarded as a putative stem-lampridiform. However, additional comparative information would be necessary to properly define its phylogenetic position within the lampridiform fishes.