Answer the following question: Information: - Chimaeras are cartilaginous fishes in the order Chimaeriformes, known informally as ghost sharks, rat fish (not to be confused with the rattails), spookfish (not to be confused with the true spookfish of the family Opisthoproctidae), or rabbit fish (not to be confused with the true rabbitfishes of the family Siganidae). - Trewavasia carinata is an extinct pycnodontid that lived during the lower Cenomanian of what is now Lebanon . It had a large , forward - pointing horn - like spine between its eyes , and a massive stump - like spine emanating from the back of its head . T. carinata is closely related to the very similar looking genera Ichthyoceros and Hensodon , as well as Coccodus . - The Late Cretaceous (100.566 Ma) is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series. The Cretaceous is named after the white limestone known as chalk which occurs widely in northern France and is seen in the white cliffs of south-eastern England, and which dates from this time. - The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding age. Both age and stage bear the same name. - Coccodus is an extinct genus of extinct pycnodontid fish that lived during the lower Cenomanian. The various species had a pair of massive, curved spines emanating from the lower sides of the head, and one curved spine on the top of its head. Unlike most pycnodontids (which tend to have short, marine butterflyfish-like bodies), "Coccodus" species had a comparatively long body, giving the living animals a superficial resemblance to a scaly chimaera. - The butterflyfishes are a group of conspicuous tropical marine fish of the family Chaetodontidae; the bannerfishes and coralfishes are also included in this group. The approximately 129 species in 12 genera are found mostly on the reefs of the Atlantic, Indian, and Pacific Oceans. A number of species pairs occur in the Indian and Pacific Oceans, members of the huge genus "Chaetodon". What is the relationship between 'trewavasia' and 'species'?
Answer:
taxon rank