[D] Kileskus aristotocus [sG] [T]
Averianov, Krasnolutskii & Ivantsov 2010
Jurassic Middle Bathonian
Saurischia Theropoda Tyrannosauria Tyrannosauroidea Proceratosauridae
Itat Formation, Berezovsk Quarry, harypovo District, Krasnoyarsk Territory, West Siberia, Russia
Kileskus aristotocus gen. sp. nov. from the Middle Jurasic (Bathonian) Itat Formation at Berezovsk Quarry Krasnoyarsk Territory (West Siberia, Russia), is based on an associated maxilla and premaxilla, a mandible fragment, and some possible associated postcranial ellements. Kileskus gen nov. is referred together with the Middle Jurassic Proceratosaurus from England and the Late Jurassic Guanlong from China to Proceratosauridae fam. nov. (Tyrannosauroidae, Coelurosauria) which is characterized by sigittal nasal crest (unknown for Kileskus gen. nov.), enlarged external nares, short ventral margin of premaxilla, and depth of the antorbital fossa ventral to the antorbital fenestra that is much greater than the depth of the maxilla below the ventral margin of the antorbital fossa.
Kileskus gen. nov. is more simular to Proceratosaurus than to Guanlong in having anterodorsal process of the premaxilla inclined slightly anterodorsally and nares inclined posterodorsally, but differs from these two genera by having ascending process of the maxilla confluent with anterior rim of maxillary, body and gently sloping posterodorsally. Kileskus gen. nov. has a basal position whitin the Proceratosauridae. Dilong from the Early Cretaceous of China with a parasagittal nasal crests is the sister taxon for the Proceratosauridae. The new taxon is one of the oldest members of Coelurosauria and Tyrannosauroidae in the fossil record.
ZIN PH 5/117, incomplete righy maxilla.
ZIN PH 6/117, left premaxilla. ZIN PH 7/17, posterior fragment of left surangular, ZIN PH 8/117, left metacarpal II. ZIN PH 9/117, left manual phalanx II-1. ZIN PH 10/117, left metatarsal I. ZIN PH 11/117 left metatarsal III. ZIN PH 12/117 left second phalanx of the second pedal digit. ZIN PH 13/117, pedal ungual phalanx.
From Khakas kileskus, a lizard. From Greek, aristotocus, of noble origin, in allusion to the phylogenetic position of Kileskus gen. nov. within the clade of derived theropods (Coelurosauria).
Type locality and horizon
Berezovsk Quarry, 2 km south of Nikol\\\'skoe village, Sharypovo District, Krasnoyarsk Territory, West Siberia, Russia. Grey clays of the upper part of Itat Formation, Middle Jurassic, Bathonian.
Differs from Proceratosaurus and Guanlong by ascending process of the maxilla confluent with anterior rim of maxillary body and gently sloping posterodorsally. Additionally differs from Proceratosaurus by premaxillary teeth with subequal mesial and distal serrations, by fewer maxillary tooth positions (17 compared with 22), by antorbital fossa of the maxilla that does not extend anterior and ventral tot the promaxillary fenestra, by promaxillary foramen lower dorsoventrally than the maxillary fenestra. Similar with Proceratosaurus and differs from Guanlong in having anterodorsal process of the premaxilla inclined slightly anterodorsally and nares inclined posterodorsally at 40o to the skull longitudinal axis.