| Kayentavenator Temporal range: Early Jurassic, 189 Ma |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | Dinosauria |
| Order: | Saurischia |
| Suborder: | Theropoda |
| Branch: | Tetanurae |
| Genus: | †Kayentavenator Gay, 2010 |
| Species: | †K. elysiae |
| Binomial name | |
| Kayentavenator elysiae Gay, 2010 |
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Kayentavenator (meaning "Kayenta hunter") is a small carnivorous dinosaur genus which lived during the Early Jurassic Period; fossils were recovered from the Kayenta Formation of northeastern Arizona and were described in 2010.[1]
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The holotype specimen of K. elysiae is a juvenile, as shown by unfused neural spines[1] and would have stood about .5 metres (1.6 ft) high at the hip. The adult size of Kayentavenator is unknown. The inclusion of a pubic fenestra is one of the characteristics that Gay uses to set Kayentavenator apart from the contemporaneous, and better known Dilophosaurus.[1] As Dilophosaurus lacks a pubic fenestra as a subadult or an adult,[2] it is unlikely that it had one during any stage of ontogeny. Apomorphies include an ellipsoid acetabulum, the greater trochanter and the head of the femur having been fused, a mediodistal crest that extends 50% of the length of the femur, as well as a prominent accessory condyle on the medial femoral condyle, a groove in dorsal surface of the femoral head that extends out from the centerline of the body, and highly constricted ("waisted") caudal vertebra centra[1].
The only known fossils of Kayentavenator were excavated by the University of California Museum of Paleontology from the Navajo Reservation in Arizona. It was described in 2010 based on a partial fossil skeleton, consisting of part of the pelvis, partial hindlimbs, and vertebrae.
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Cladogram of Theropods
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Timothy Rowe originally assigned the holotype specimen of Kayentavenator to the coelophysoid Syntarsus kayentakatae (now known as Megapnosaurus)[3]. It is unlikely that Kayentavenator is actually cogeneric with Megapnosaurus due to the number of tetanuran characters that Kayentavenator possesses and M. kayentakatae lacks, such as the pubic fenestra and a sharp ridge on the medial side of the tibia[1]. A cladistic analysis of the remains showed Kayentavenator to lie outside of Coelophysidae, and was closer to Allosaurus.[1] This would make Kayentavenator the oldest known tetanuran from North America. The fragmentary remains of Kayentavenator make this open to further interpretation.
Gay, Robert. 2003. A new theropod from the lower Jurassic Kayenta Formation of Arizona. Unpublished undergraduate thesis, Northern Arizona University, Flagstaff, Arizona.