Name: Kelenken ‭(‬After a diety‭)‬.
Phonetic: Kell-en-ken.
Named By: Bertelli et al.‭ ‬-‭ ‬2007.
Classification: Chordata,‭ ‬Aves,‭ ‬Cariamae,‭ ‬Phorusrhacidae,‭ ‬Phorusrhacinae.
Species: K.‭ ‬guillerm (‬type‭)‬.
Diet: Carnivore.
Size: Between‭ ‬2.28‭ ‬and‭ ‬3‭ ‬meters tall.‭ ‬Skull is‭ ‬71‭ ‬centimetres long‭ (‬45.7‭ ‬centimetres of which is beak‭)‬.
Known locations: Argentina.
Time period: Mid Miocene.
Fossil representation: Almost complete skull with‭ ‬tarsometatarsus‭ (‬foot bone adapted to extend the length of the lower leg‭) ‬and toe bone.

       Although not certain,‭ ‬Kelenken is a strong contender for the tallest‭ ‘‬terror bird‭’ (‬phorusrhacid‭) ‬known.‭ ‬This has seen Kelenken firmly placed within the Phorusrhacinae sub group of terror birds,‭ ‬and its remains suggest that it had a more gracile build when compared to the Brontornithinae group that contains large but more robust members such as Brontornis and Paraphysornis.
       Not much material is known for Kelenken and much of its reconstruction depends upon comparison with other phorusrhacids of similar size and build,‭ ‬something that has resulted in a great variation of size quotations for this bird.‭ ‬Kelenken does however have quite a well preserved skull that at seventy-one centimetres long is currently the largest known skull for a terror bird,‭ ‬something that is seen to suggest a comparatively large body size.‭ ‬The tarsometatarsus is forty-five centimetres long.‭ ‬This bone was part of the modified foot that would have given the terror bird a digitigrade stance which would have increased the length of the lower leg.
       Kelenken has a variety of killing techniques attributed to it,‭ ‬and these included using the hook tip of its large beak to inflict penetrating strikes against critical areas of its prey,‭ ‬to violently shaking small prey in its beak to even throwing it against the ground to kill and break its bones before swallowing.‭ ‬Kelenken probably also scavenged carcasses when able,‭ ‬but the phorusrhacids in general seem to have been visually orientated animals with underdeveloped senses of smell.‭ ‬This leans more towards a trend of active predation rather than a reliance upon scavenging.‭ ‬The more gracile build of Kelenken also suggests a greater reliance of speed over power when tackling prey and it seems that Phorusrhacinae phorusrhacids like Kelenken were capable of higher and prolonged speeds over their more heavily built brethren.
       The first Kelenken remains were discovered in‭ ‬1999‭ ‬by Guillermo Aguirrezabala near the village of Comallo.‭ ‬After the recovery the remains went on display in a museum in the city of Bariloche,‭ ‬but it was not until several years later that they were realised to be a completely new genus.‭ ‬The new genus was named after a god in local mythology while the species name was in honour of the discoverer of the remains.‭

Further reading
- A new phorusrhacid (Aves: Cariamae) from the middle Miocene of Patagonia, Argentina. - Journal of Vertebrate Paleontology. 27(2):409-419. - S. Bertelli, L. M. Chiappe, and C. Tambussi - 2007.


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