''Palaeopteryx'' (meaning "ancient wing") is a genus of theropod dinosaur now considered a ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

''. It was named and misidentified by J. A. Jensen in 1981, then redescribed by Jensen and K. Padian in 1989. At that time the binomial ''Palaeopteryx thomsoni'' was deemed invalid by Jensen. The only referred specimen is a single bone fragment ( BYU 2022). ''Palaeopteryx'' (BYU 2022) has been the subject of much confusion on the internet, in the popular scientific press, and among creationist writers. It has been described as a possible bird older than ''

Archaeopteryx ''Archaeopteryx'' (; ), sometimes referred to by its German name, "" ( ''Primeval Bird''), is a genus of bird-like dinosaurs. The name derives from the ancient Greek (''archaīos''), meaning "ancient", and (''ptéryx''), meaning "feather" ...

'', but it cannot be clearly assigned to Avialae, and its

horizon The horizon is the apparent line that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This line divides all viewing directions based on whether i ...

is younger than that of ''Archaeopteryx'', though it is still from the Jurassic. BYU 2022 is about long. It was described by Jensen in 1981 as an "avian – like"

proximal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

left tibiotarsus. It was then listed by R. E. Molnar in 1985 in a survey of the earliest known birds. Jensen and Padian reidentified it as the

distal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

right radius of "a small

deinonychosaur Deinonychosauria is a clade of paravian dinosaurs which lived from the Late Jurassic to the Late Cretaceous periods. Fossils have been found across the globe in North America, Europe, Africa, Asia, South America, and Antarctica,Case, J.A., Mar ...

or bird" in 1989. BYU 2022 was collected in the 1970s by paleontological expeditions from Brigham Young University directed by J. A. Jensen. It was found in Late Jurassic deposits in the "Dry Mesa" quarry on the Uncompahgre Upwarp in western Colorado (Brushy Basin Member,

Morrison Formation The Morrison Formation is a distinctive sequence of Late Jurassic, Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandsto ...

). It was found among mixed fossil remains that included pterosaur and dinosaur material. One notable specimen found with it is the right femur of a derived maniraptoran theropod (BYU 2023). BYU 2023 is missing the distal end and is about long. It is probably too small to be from the same individual as BYU 2022. BYU 2023 shows apomorphies known only in advanced maniraptorans, including ''

Microvenator ''Microvenator'' (meaning "small hunter") is a genus of dinosaur from the Early Cretaceous Cloverly Formation in what is now south central Montana. ''Microvenator'' was an oviraptorosaurian theropod. The holotype fossil is an incomplete skeleton ...

'', '' Microraptor'', and ''Archaeopteryx''. BYU 2022 and 2023 are important because they are samples of small – bodied maniraptorans from Jurassic North America.

References

1. Jensen, James A. (1981b). Another look at Archaeopteryx as the world's oldest bird. The Journal of the Utah Academy of Sciences: ''Encyclia'', 58:109 – 128. 2. Jensen, James A. & Padian, Kevin. (1989). Small pterosaurs and dinosaurs from the Uncompahgre fauna (Brushy Basin member, Morrison Formation: ?Tithonian), Late Jurassic, western Colorado. ''Journal of Paleontology'' Vol. 63 no. 3 pg. 364 – 373. {{Taxonbar, from=Q2027026 Late Jurassic dinosaurs of North America Dinosaurs of the Morrison Formation Prehistoric paravians Nomina dubia Fossil taxa described in 1981 Paleontology in Colorado