Genus: Joermungandr MANN, CALTHORPE & MADDIN, 2021
Etymology: 'Joermungandr' the Swedish phoneme of 'Jörmungandr' (gender: masculine) the name of the serpent that dwells in the 'Midgrd Sea' from Norse mythology.

Species: bolti MANN, CALTHORPE & MADDIN, 2021
Etymology: In honor of teh late palaeontologhist John R. Bolt.

Holotype: FMNH 1309 (part and counterpart)

Locality: Mazon Creek, Grundy County, Illinois.

Horizon: Francis Creek Shale, above the Morris (no. 2) Coal, Carbondale Formation.

Biostratigraphy:

Age: Westphalian D, Lower Upper Silesian, Desmoniensean, Myachkovskian Stage, upper Moscovian Epoch, Late Pennsylvanian (Late Carboniferous).

Material: Skull and skeleton with soft body impressions (gastric bolus) and scales.