Praeornis
Encyclopedia
Praeornis is a dubious
genus
of possible early bird
, named on the basis of a single possible feather discovered in the Balabansai Formation
of Kazakhstan
by Sharov in 1971. In 1978, Rautian officially named the feather (cataloged as specimen PIN 2585/32) Praeornis sharovi. He believed it belonged to a bird more primitive than Archaeopteryx
, and assigned it to its own sublcass (Praeornithes), order (Praeornithiformes) and family (Praeornithidae). However, in 1986, Bock published a paper arguing that the "feather" was in fact the leaf of a cycad
. This opinion was followed by Doludenko and colleagues in 1990, who noted that it was similar to the leaves of the cycad species Paracycas harrisii. L.A. Nessov, in 1992, also suggested that it belonged to a cycad, but synonymized it with the species Cycadites saportae. The opinion that it represents a leaf has since been followed by Alan Feduccia
in 1996 and Peter Wellnhofer
in 2004.
Two studies since the original description has supported the identification of Praeornis as a feather, rather than a leaf. In 1991, Glazunova and colleagues examined the specimen using an electron microscope
, and found that the microstructure had features in common with the primitive feathers of ratite
birds. In a 2001 paper, Kurochkin also accepted its identity as a feather.
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of possible early bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
, named on the basis of a single possible feather discovered in the Balabansai Formation
Balabansai Formation
The Balabansai Fomration is a geological formation in Asia whose strata date back to the Late Jurassic. Dinosaur remains are among the fossils that have been recovered from the formation.-Vertebrate paleofauna:...
of Kazakhstan
Kazakhstan
Kazakhstan , officially the Republic of Kazakhstan, is a transcontinental country in Central Asia and Eastern Europe. Ranked as the ninth largest country in the world, it is also the world's largest landlocked country; its territory of is greater than Western Europe...
by Sharov in 1971. In 1978, Rautian officially named the feather (cataloged as specimen PIN 2585/32) Praeornis sharovi. He believed it belonged to a bird more primitive than Archaeopteryx
Archaeopteryx
Archaeopteryx , sometimes referred to by its German name Urvogel , is a genus of theropod dinosaur that is closely related to birds. The name derives from the Ancient Greek meaning "ancient", and , meaning "feather" or "wing"...
, and assigned it to its own sublcass (Praeornithes), order (Praeornithiformes) and family (Praeornithidae). However, in 1986, Bock published a paper arguing that the "feather" was in fact the leaf of a cycad
Cycad
Cycads are seed plants typically characterized by a stout and woody trunk with a crown of large, hard and stiff, evergreen leaves. They usually have pinnate leaves. The individual plants are either all male or all female . Cycads vary in size from having a trunk that is only a few centimeters...
. This opinion was followed by Doludenko and colleagues in 1990, who noted that it was similar to the leaves of the cycad species Paracycas harrisii. L.A. Nessov, in 1992, also suggested that it belonged to a cycad, but synonymized it with the species Cycadites saportae. The opinion that it represents a leaf has since been followed by Alan Feduccia
Alan Feduccia
Alan Feduccia is a paleornithologist, specializing in the origins and phylogeny of birds. He is now Professor Emeritus at the University of North Carolina. Feduccia's principal authored works include two books, The Age of Birds and The Origin and Evolution of Birds, and numerous papers in various...
in 1996 and Peter Wellnhofer
Peter Wellnhofer
Peter Wellnhofer is a German paleontologist at the "Bayerische Staatssammlung fur Paläontologie" in Munich. He is best known for his work on the various fossil specimens of Archaeopteryx or "Urvogel", the first known bird...
in 2004.
Two studies since the original description has supported the identification of Praeornis as a feather, rather than a leaf. In 1991, Glazunova and colleagues examined the specimen using an electron microscope
Electron microscope
An electron microscope is a type of microscope that uses a beam of electrons to illuminate the specimen and produce a magnified image. Electron microscopes have a greater resolving power than a light-powered optical microscope, because electrons have wavelengths about 100,000 times shorter than...
, and found that the microstructure had features in common with the primitive feathers of ratite
Ratite
A ratite is any of a diverse group of large, flightless birds of Gondwanan origin, most of them now extinct. Unlike other flightless birds, the ratites have no keel on their sternum—hence the name from the Latin ratis...
birds. In a 2001 paper, Kurochkin also accepted its identity as a feather.