''Limenavis'' is a prehistoric

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

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 nom ...

from the Late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

. It lived about 70 million years ago, around the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval ...

boundary. Known from several broken bones, the remains of the only known

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

''Limenavis patagonica'' were found in rocks of the "lower member" of the

Allen Formation The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous (middle Campanian to early Maastrichtian.Salgado et al., 2007 Dinosaur remains are among the fossils that have been recovered from the formati ...

at Salitral Moreno, 20 km south of

General Roca, Río Negro General Roca is a city in the northeast of the Argentine province of Río Negro, northern Patagonia. It was founded on September 1, 1879, by Colonel Lorenzo Vintter, on the order of War Minister Julio A. Roca, during the Conquest of the Desert. ...

(

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

).LEONA LEONARD, GARETH J. DYKE,1, AND MARCEL VAN TUINEN (2005) "A New Specimen of the Fossil Lithornis from the Lower Eocene". ''American Museum Novitates''. Number 3491, 11 pp., 4 figures AMERICAN MUSEUM OF NATURAL HISTORYCENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024 It is the closest relative, in the fossil record, of the modern birds. Of all the prehistoric birds known to date, this species is among those closest to the common ancestor of all living birds. Its generic name pays tribute to this fact: ''Limenavis'', meaning "bird of the threshold" or "limit-bird", is derived from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''limen'' ("threshold") + ''avis'' ("bird"). The specific name ''patagonica'' refers to the specimen's

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and g ...

n provenance.

Classification

The relationship of ''Limenavis'' to other

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...

birds has been difficult to determine. Analyses published in 2001 and 2002 by Julia Clarke and Luis Chiappe found ''Limenavis'' to be a carinate bird more advanced than ''

Ichthyornis ''Ichthyornis'' (meaning "fish bird", after its fish-like vertebrae) is an extinct genus of toothy seabird-like ornithuran from the late Cretaceous period of North America. Its fossil remains are known from the chalks of Alberta, Alabama, ...

'' but not a member of the modern bird group

Neornithes Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

. A 2013 analysis by O'Connor and colleagues found it to be slightly more primitive than ''Ichthyornis''. It has been suggested that some features link it with

paleognath Palaeognathae (; ) is a infraclass of birds, called paleognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae contain ...

birds, perhaps related to the ancestors of

tinamou Tinamous () form an order of birds called Tinamiformes (), comprising a single family called Tinamidae (), divided into two distinct subfamilies, containing 46 species found in Mexico, Central America, and South America. The word "tinamou" come ...

s or rheas.Leonard, L. Dyke, G.J. & Van Tuinen, M. (2005) "A new specimen of the fossil palaeognath Lithornis from the Lower Eocene of Denmark". 491. ''American Museum Novitates''. pp. 1–11. Though such birds must have existed by that time already, and most likely at least tinamou ancestors ( basal Tinamiformes) did live in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

by the Late Cretaceous, tinamous proper ( Tinamidae) are only known with certainty since the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

.Bertelli, S. and Chiappe, L. (2005). "Earliest tinamous (Aves: Palaeognathae) from the Miocene of Argentina and their phylogenetic position". ''Contributions in Science NHM LA'', 502: 1-20.

References

Bird genera Prehistoric ornithurans Paleognathae Cretaceous birds of South America Allen Formation {{paleo-bird-stub