Avisaurus Temporal range: Late Cretaceous (Maastrichtian), | |
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Holotype tarsometatarsus of A. archibaldi | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Clade: | Avialae |
Clade: | † Enantiornithes |
Family: | † Avisauridae |
Genus: | † Avisaurus Brett-Surman & Paul, 1985 |
Type species | |
†Avisaurus archibaldi Brett-Surman & Paul, 1985 | |
Species | |
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Avisaurus (meaning "bird lizard") is a genus of enantiornithine avialan from the Late Cretaceous of North America. [1]
Avisaurus archibaldi was discovered in the Late Cretaceous Hell Creek Formation of North America (Maastrichtian, from c.70.6-66 million years ago), making it one of the last enantiornithids. It was collected in 1975 in the UCMP locality V73097, in Garfield County, Montana, USA. The holotype is represented by a single fossil of a tarsometatarsus in the collection of the University of California Museum of Paleontology. It has the catalog number UCMP 117600. The species name honors J. David Archibald, its discoverer, from The University of California, Berkeley. It was initially described as the left tarsometatarsus of a non-avian theropod by Brett-Surman and Paul in 1985. It was later redescribed as the right tarsometatarsus of an enantiornithine bird by Chiappe in 1992. [2]
Avisaurus gloriae Varricchio and Chiappe 1995, [3] discovered in the late Campanian Upper Two Medicine Formation of Glacier County, Montana, USA, was renamed Gettyia by Atterholt et al. (2018). [4] In 2024, another species of Avisaurus from the Hell Creek Formation was named as Avisaurus darwini, with the specific name in honor of Charles Darwin. [5]
Avisaurus was a large enantiornithine, with A. darwini weighing up to 1.2 kilograms (2.6 lb) and A. archibaldi weighing up to 1.7 kilograms (3.7 lb). [5] The type specimen of A. archibaldi has a maximum length of 73.9 mm (2.91 in), making it one of the largest known tarsometatarsi of an enantiornithine. [3]
This genus belongs to the enantiornithine family Avisauridae, which also contains similar animals from South America such as Soroavisaurus , Neuquenornis and Intiornis . [5]
Brett-Surman and Paul (1985) explicitly considered the possibility that A. archibaldi was an enantiornithine. The authors described and named UCMP 117600 formally, but they looked at other enantiornithine material, including the "metatarsus" PVL 4690 from Argentina. The authors assigned this latter fossil to Avisaurus sp. From this they concluded that members of the genus Avisaurus existed in both North and South America in the Late Cretaceous. Moreover, the authors concluded that the length/width ratio and degree of metacarpal fusion of these bones were more like those of non — avian dinosaurs. A terrestrial dinosaur genus in both continents would then support Brett — Surman's theory that there had been a land connection between the two continents. [6]
Further discoveries and further study by Chiappe showed that all of the material belonged to enantiornithine birds, and PVL 4690 was given its own genus Soroavisaurus . [2]
Avisaurus remains fossilized in the humid low-lying swamps, lakes, and river basins of the western shore of the Western Interior Seaway, Hell Creek Formation. [5]
Inwardly curved claws of the Avisaurus tarsis resemble those of eudromaeosaurs, indicating that it was predatory. It likely preyed on other vertebrates, with similarity to some modern raptors. [7] [5]
The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans, the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over seventy species of Enantiornithes have been named, but some names represent only single bones, so it is likely that not all are valid. The Enantiornithes became extinct at the Cretaceous–Paleogene boundary, along with Hesperornithes and all other non-avian dinosaurs.
The Xiagou Formation is the middle strata of the Xinminbao Group. It is named for its type site in Xiagou, in the Changma Basin of Gansu Province, northwestern China and is considered Early Cretaceous in age. It is known outside the specialized world of Chinese geology as the site of a Lagerstätte in which the fossils were preserved of Gansus yumenensis, the earliest true modern bird.
Nanantius is a genus of extinct enantiornithean avialan known from the Early Cretaceous of Australia.
Yungavolucris is a genus of enantiornitheans. It contains the single species Yungavolucris brevipedalis, which lived in the Late Cretaceous. The fossil bones were found in the Lecho Formation at estancia El Brete, Argentina."Yungavolucris brevipedalis" means "Short-footed Yungas bird". The generic name, Yungavolucris is after the Yungas region + the Latin volucris, which translates to "bird". The specific name brevipedalis is from the Latin brevis, which means "short", + pedalis, from the Latin pes, meaning "foot".
Lectavis is a genus of enantiornithine avialan. Their fossil bones have been recovered from the Late Cretaceous Lecho Formation at estancia El Brete, Argentina. The genus contains a single species, Lectavis bretincola.
Elsornis is a genus of enantiornithine bird. Only one species is known, Elsornis keni. It lived during the Late Cretaceous. It is known from a partially articulated fossil skeleton found in the Gobi Desert in Mongolia.
Neuquenornis volans is a species of enantiornithean birds which lived during the late Cretaceous period in today's Patagonia, Argentina. It is the only known species of the genus Neuquenornis. Its fossils were found in the Santonian Bajo de la Carpa Formation, dating from about 85-83 million years ago. This was a sizeable bird for its time, with a tarsometatarsus 46.8mm long. Informal estimates suggest that it measured nearly 30 cm (12 in) in length excluding the tail.
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1993.
Pygostylia is a group of avialans which includes the Confuciusornithidae and all of the more advanced species, the Ornithothoraces.
Avisauridae is a family of extinct enantiornithine dinosaurs from the Cretaceous period, distinguished by several features of their ankle bones. Depending on the definition used, Avisauridae is either a broad and widespread group of advanced enantiornithines, or a small family within that group, restricted to species from the Late Cretaceous of North and South America.
Shanweiniao is a genus of long-snouted enantiornithean birds from Early Cretaceous China. One species is known, Shanweiniao cooperorum. There is one known fossil, a slab and counterslab. The fossil is in the collection of the Dalian Natural History Museum, and has accession number DNHM D1878/1 and DNHM1878/2. It was collected from the Lower Cretaceous Dawangzhengzi Beds, middle Yixian Formation, from Lingyuan in the Liaoning Province, China.
Soroavisaurus is a genus of enantiornithean birds related to Avisaurus. It lived during the Late Cretaceous of Argentina. The only known species, S. australis, is known from fossils collected from the Lecho Formation of Estancia El Brete, in the southern tip of the province of Salta, Argentina. A binominal name of this animal means "Southern sister Avisaur".
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Mirarce is a genus of enantornithe bird from the Late Cretaceous of Utah. It contains a single species, M. eatoni. It was similar in size to modern turkeys.
Gettyia is an extinct genus of avisaurid enantiornithean bird from the Late Cretaceous of North America.
Jingmai Kathleen O'Connor is a paleontologist who works as a curator at the Field Museum.
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