Kelenken

In the provided sources the name Kelenken originates from Tehuelche mythology, where it is said to refer to a spirit represented as a giant bird of prey; that ethnographic statement is brief and is cited by the describers when they named a newly identified fossil bird. Separately, paleontologists assigned the genus and species name Kelenken guillermoi to a middle Miocene phorusrhacid discovered near Comallo in Río Negro Province, Argentina, explicitly stating that the genus name refers to the Tehuelche spirit. The supplied materials do not record any traditional Tehuelche narrative, origin myth, or cosmological role for the spirit beyond this short descriptive phrase.

As a mythic referent the only description recorded in the cited material is that Kelenken is represented as a giant bird of prey (no further corporeal or symbolic attributes are documented in the sources). As the fossil taxon Kelenken guillermoi the holotype includes an exceptionally large, nearly complete skull measured at 716 mm (2.3 ft) long—described as the largest known bird skull at the time—with a tall, long, sideways-compressed, strongly hooked beak and a convex culmen. The associated left tarsometatarsus is 437 mm (17 in) long; overall body-size estimates are about 3 m (9.8 ft) tall and in excess of 100 kg (220 lb). Distinguishing osteological features cited include a supraorbital ossification that fits into a socket of the postorbital process and an almost triangular foramen magnum; the skull is somewhat crushed dorsoventrally with most palatal bones behind the orbits missing.

No supernatural abilities or behaviors are attested for the Tehuelche spirit beyond its identification as a giant bird of prey in the cited sources. Paleobiological inferences for Kelenken guillermoi indicate a flightless, ground-dwelling, cursorial bird: long hind limbs and a slender, long tarsometatarsus suggest it could run relatively fast for a large phorusrhacid and could chase down smaller animals. Phorusrhacids are interpreted as ground predators or scavengers and may have been apex terrestrial predators in Cenozoic South America. Comparative studies with related Andalgalornis indicate very rigid skull morphology in large phorusrhacids, implying feeding mechanics such as swallowing small prey whole or attacking larger prey with repetitive strikes of the beak; the Kelenken skull stiffness is invoked to support similar inferences.