[1] The holotype specimen of Echericetus, MRAHBCS Pal/V119, consists of a partial skull and numerous postcranial elements including vertebrae, ribs and a forelimb.

Aside from this, reworked tuff was also found at the top of bed 2, which was used to radiometrically the layer to 27.95 +- 0.16 Ma, corresponding to the latest Rupelian (late Early Oligocene).

The specific name novellus (Latin, meaning youth or new) refers to the mountain complex of Sierra El Novillo, located east of the type locality.

[1] In the 2024 study describing the animal, Hernández-Cisneros and colleagues conducted a phylogenetic analysis based on a dataset made by Marx and Fordyce in 2015.

Its relationship to other members of the group remains unresolved, forming a polytomy with the other eomysticetid genera Yamatocetus and Micromysticetus.