Oechsleria unterfeldensis, gen. et sp. nov., a sailfin velifer fish (Lampridiformes, Veliferidae) from the Oligocene of the Unterfeld (“Frauenweiler”) clay pit

Abstract

These are the first and so far only records of a sailfin velifer fish from the Lower Oligocene of the Unterfeld (“Frauenweiler”) clay pit at Rauenberg (S Germany), and only the fourth fossil skeletal finds of this group worldwide. The new genus and species †Oechsleria unterfeldensis is described in detail, diagnosed, and compared to other fossil and extant representatives of the Veliferidae. It appears to be a comparatively small-sized fish, which differs from the other representatives of this family, apart from body proportions, by having a lower number of vertebrae and dorsal-fin rays, the absence of massive spines in the dorsal and anal fins, four anal-fin pterygiophores in front of the anteriormost haemal spine, and a different morphology and size of various skeletal elements. Amongst others, the following character states are of relevance: a supraoccipital that is laterally sculptured by strong surface ridges; a weak ascending process of the premaxilla that is shorter than in the other veliferid taxa; compound (fused) anteriormost dorsal- and anal-fin pterygiophores, together with spineless dorsal and anal fins with unornamented rays (no spinules), of which the majority are bilaterally paired and both halves are fused only proximally but separate and segmented distally; a short coracoid that does not reach the ventral body margin; a broad and anterodorsally directed pelvic bone that bears a well-developed postpelvic process, and probably also the presence of a short pointed neural spine (in contrast to a distally blunt one and/or a low crest) on the second preural centrum. All in all, the new fossil records remarkably increase the known biodiversity of the Veliferidae. They also expand the known palaeogeographic range of this family as far as to the Western Paratethys. With reference to the occurrence and life habits as deduced from the extant forms, they seem to be another Indo-Pacific (respectively Palaeo-Mediterranean, when referring to the fossil forms) element of the Grube Unterfeld fish fauna with a preference for deeper waters and affinities to temperate to tropical climates.