[3] The genus name means ‘reptile-puppy’, from the Ancient Greek herpeto- (ἑρπετόν, ‘creeping animal’) and skylax (σκύλαξ, ‘young dog’).

[2] It displays primitive features such as a convex curve to the skull roof when viewed from the side, a “deep snout,”[2] a small temporal opening, and the absence of a freestanding coronoid process on the lower jaw.

[2] Four premaxillary teeth are present with few serrations (likely from attrition), but it is suggested there was an additional tooth based on a gap noted in the region.

[6] Sidor and Rubidge comment that the morphology of Herpetoskylax’s jugal (cheek bone) is easiest to see compared to other biarmosuchians.

[2] Across non-mammal therapsids, of which Herpetoskylax is part of, in terms of the braincase, the inside shape of the skull is generally primitive.

[2] It was found on a farm, and it was determined that the skull was from the Cistecephalus Assemblage Zone, which was used as evidence for the conclusion that its age was Late Permian.

[9] Biarmosuchians, including Herpetoskylax, had skulls specialized for a carnivorous diet, with their large canines and enlarged jaw muscles.

[13] In 1986, a paper by Bennett and Ruben asserted that the Permian was sufficiently warm to support ectothermy (cold-bloodedness), additionally noting that other successful fauna of the time were ectothermic.

[14] Herpetoskylax did not possess nasal turbinals, a trait associated with endothermy in extant mammals and birds, as this character has only been confirmed in more derived therapsids.

[15] Vegetation along streams and lakes were theorized to provide a diet for reptilians and acted as a foundation for carnivorous non-mammal therapsids like Herpetoskylax.