''Krzyzanowskisaurus'' (meaning "Stan Krzyżanowski's lizard") is the name given to a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

archosaur Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avi ...

from the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...

-aged

Chinle Formation The Chinle Formation is an Upper Triassic continental geological formation of fluvial, lacustrine, and palustrine to eolian deposits spread across the U.S. states of Nevada, Utah, northern Arizona, western New Mexico, and western Colorado. In ...

and it is a tooth taxon, based on fossils only of teeth (such as the holotype tooth NMMNH P-29357) and these teeth have been found in the U.S. states of

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a U.S. state, state in the Southwestern United States. It is the list of U.S. states and territories by area, 6th largest and the list of U.S. states and territories by population, 14 ...

(including the type locality) and

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

. The original report described it as a "probable

ornithischia Ornithischia () is an extinct order of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name ''Ornithischia'', or "bird-hipped", reflects this similarity and is derived from the Greek ...

n" and Heckert (2005) suggests that ''Krzyzanowskisaurus'' teeth have

biostratigraphic Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Bio ...

utility as an

index fossil Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Bio ...

of the St. Johnsian sub-LVF ( land-vertebrate faunachron). The type species, ''Krzyzanowskisaurus hunti'', was reevaluated by Heckert in

2005 File:2005 Events Collage V2.png, From top left, clockwise: Hurricane Katrina in the Gulf of Mexico; the Funeral of Pope John Paul II is held in Vatican City; "Me at the zoo", the first video ever to be uploaded to YouTube; Eris (dwarf planet), Er ...

,Heckert, A.B., (2005). ''Krzyzanowskisaurus'', a new name for a probable ornithischian dinosaur from the Upper Triassic Chinle Group, Arizona and New Mexico, USA. ''New Mexico Museum of Natural History and Science Bulletin'' 29: 77-83. after previously being described by him as ''Revueltosaurus hunti'' in

2002 File:2002 Events Collage.png, From left, clockwise: The 2002 Winter Olympics are held in Salt Lake City; Queen Elizabeth The Queen Mother and her daughter Princess Margaret, Countess of Snowdon die; East Timor gains independence from Indonesia and ...

. The name was changed when it was discovered that the type species of ''

Revueltosaurus ''Revueltosaurus'' ("Revuelto lizard") is an extinct genus of suchian pseudosuchian from Late Triassic (late Carnian to middle Norian stage) deposits of New Mexico, Arizona and North Carolina, United States. Many specimens, mostly teeth, have be ...

'', ''R. callenderi'', was a

pseudosuchian Pseudosuchia is one of two major divisions of Archosauria, including living crocodilians and all archosaurs more closely related to crocodilians than to birds. Pseudosuchians are also informally known as "crocodilian-line archosaurs". Prior to ...

rather than an ornithischian

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

(Parker ''et al.'' 2005).Parker, W. G., R. B. Irmis, S.N. Nesbitt, J. W. Martz & L. S. Browne. (2005). The pseudosuchian ''Revueltosaurus callenderi'' and its implications for the diversity of early ornithischian dinosaurs. ''Proceedings of the Royal Society London'' B272 (1566): 963–969. According to Heckert, "R." ''hunti'' displays an orithischian-like feature not present in ''R. callenderi'' (teeth possessing a cingulum), suggesting that it represents a new genus of early ornithischian. This was challenged by Irmis ''et al.'' (2006), who found that the cingulum differed from that in true early ornithischians, and noted that some teeth had been found with skull bones and

osteoderm Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinc ...

s that matched those of ''Revueltosaurus''.* Irmis, R.B., Parker, W.G., Nesbitt, S.J., and Liu, J. (2006). Early ornithischian dinosaurs: the Triassic record. ''Historical Biology'', 19(1):3-22. Thus, they found that it was not a dinosaur, and provisionally retained it in ''Revueltosaurus''; it may once again be ''R. hunti.''

References

{{Taxonbar, from=Q5221716 Triassic archosaurs Crurotarsans Late Triassic archosaurs of North America Fossil taxa described in 2005