Ischnacanthiformes Berg, 1940

Voichyshyn, Victor & Szaniawski, Hubert, 2018, New ischnacanthiform jaw bones from the Lower Devonian of Podolia, Ukraine, Acta Palaeontologica Polonica 63 (2), pp. 327-339 : 329

Order Ischnacanthiformes Berg, 1940 Family Podoliacanthidae nov.

Type genus: Podoliacanthus Voichyshyn and Szaniawski, 2012 ; Early Devonian , Podolia, Ukraine .

Genera included: The type genus, Drygantacanthus gen. nov., and Kasperacanthus gen. nov.

Diagnosis.—Small ischnacanthiforms. Lingual tooth row consists of groups of denticles, with one bigger (central) denticle and usually two or more smaller ones. The denticle groups of the lingual row have a common elongate base which is surrounded by small pores of the vascular canal system. Variable additional dentiform structures frequently, but not always, occur on the medial teeth side, at the base or lower third. These structures are a small robust denticle, a set of these, or a short vertical ridge.

Remarks.—Judging by the diagnostic features of both established families of the order Ischnacanthiformes , Ischnacanthidae and Poracanthodidae , as well as Acritolepidae (family of uncertain affinity), none of them is adequate to accommodate Podoliacanthus -like taxa (see Discussion below). Considering that we are dealing with related but strongly diversified material, which evidently includes more than one genus we are of the opinion that it is necessary to establish a new family.

Stratigraphic and geographic range.—Lower Devonian of Podolia ( Ukraine) and Greenland ( Denmark).