Genus: Istiorachis LOCKWOOD, MARTILL & MAIDMENT, 2025
Etymology: Greek, istion, “sail”, and Greek, rachis, “spine or backbone”: in reference to the probable sail-back appearance of the dinosaur.

Species: macarthurae LOCKWOOD, MARTILL & MAIDMENT, 2025
Etymology:In honor of Dame Ellen MacAthur, an English sail who in 2005 set a world record for the fastest solo non-stop voyage aroudn the workd on her first attempt and who also founded the Ellen MacArthur Cancer trust for young people on the Isle of Wight.

Holotype: MIWG 6643

Locality: "Black Band" (bed L11 in Stewart 1978), east of Grange Chine, Isle of Wight, Isle of Wight County, England, Southern United Kingdom.

Horizon: From a plant debris bed cropping out c. 100 m east of Grange Chine, Wessex Formaton, Wealden Group.

Biostratigraphy:

Age: Probably Barremian Stage, Lower Gallic Subepoch, Middle Early Cretaceous Epoch, Early Cretaceous.

Material: 1 cervical, 8 dorsal, 7 caudal vertebrae, 3 doral rib heads, a partial sacrum, both pubes and both ischia.