Pterosaurs are an extinct clade of flying reptiles in the order Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous. Pterosaurs are the earliest vertebrates known to have evolved powered flight. Their wings were formed by a membrane of skin, muscle, and other tissues stretching from the ankles to a dramatically lengthened fourth finger.
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 eighty 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.
Nothronychus is a genus of therizinosaurid theropod dinosaurs that lived in North America during the Late Cretaceous period. The type species, Nothronychus mckinleyi, was described by James Kirkland and Douglas G. Wolfe in 2001. It was recovered near New Mexico's border with Arizona, in an area known as the Zuni Basin, from rocks assigned to the Moreno Hill Formation, dating to the late Cretaceous period, around 92 million years ago. A second specimen, described in 2009 as a second species, Nothronychus graffami, was found in the Tropic Shale of Utah, dating to the early Turonian, between one million and a half million years older than N. mckinleyi.
Jeholornis is a genus of avialans that lived between approximately 122 and 120 million years ago during the early Cretaceous Period in China. Fossil Jeholornis were first discovered in the Jiufotang Formation in Hebei Province, China and additional specimens have been found in the older Yixian Formation.
Yungavolucris is a genus of enantiornithean birds. 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".
Eoalulavis is a monotypic genus of enantiornithean bird that lived during the Barremian, in the Lower Cretaceous around 125 million years ago. The only known species is Eoalulavis hoyasi.
Longirostravis is a genus of enantiornithean birds which existed during the early Cretaceous period and is known from fossils found in the middle or upper Yixian Formation in Yixian County, People's Republic of China. It is known from a single specimen housed in the collections of the Institute of Vertebrate Paleontology and Paleoanthropology representing the type species Longirostravis hani.
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.
Cretaceogekko is an extinct monotypic genus of gecko known from a single partial specimen preserved in Burmese amber from the Cenomanian of Myanmar. The specimen was found in the Hukawng Valley in 2001 and the genus and species were named by E. Nicholas Arnold and George Poinar in 2008. The specimen includes a foot and partial tail. Cretaceogekko is the oldest known gecko, predating the Late Cretaceous gecko Gobekko and the Paleogene gecko Yantarogecko, which has also been preserved in amber.
Bauxitornis is an extinct genus of avisaurid enantiornithean birds which lived in what is now Hungary during the late Cretaceous period. Although first mentioned in a 2008 review of Hungarian Cretaceous bird fossils, it was named in a more comprehensive review by Gareth J. Dyke and Attila Ősi in 2010. The type species is Bauxitornis mindszentyae. The generic name "Bauxitornis" refers to the locality at which it was discovered, a Bauxite mine. The specific name "mindszentyae" honors Andrea Mindszenty, Ősi's advisor.
Longipterygidae is a family of early enantiornithean avialans from the Early Cretaceous epoch of China. All known specimens come from the Jiufotang Formation and Yixian Formation, dating to the early Aptian age, 125-120 million years ago.
Bohaiornis is a genus of enantiornithean birds. Fossils have been found from the Lower Cretaceous Jiufotang Formation of western Liaoning, China. The only known species, Bohaiornis guoi, was named by Dongyu Hu, Li Li, Lianhaim Hou and Xing Xu in 2011 on the basis of a fully articulated and well-preserved skeleton of a sub-adult. This specimen, LPM B00167, preserved two long, ribbon-like feathers attached to the tail rather than a fan of shorter pennaceous feathers. It was similar to the slightly older Eoenantiornis, but much larger in size. Bohaiornis is the type species of Bohaiornithidae, a family of large predatory enantiornitheans from the Early Cretaceous.
Hollanda is a genus of small ground birds known from fossils found in the Barun Goyot Formation of Mongolia. Found at Khermeen Tsav, it dates from the late Cretaceous period, about 75 million years ago. Known only from partial hind limbs, Hollanda has long legs with an unusual configuration of the toes. These indicate that it was a fast-running ground bird, possibly similar to the modern Roadrunner. Its relationships are uncertain. Some studies have found that it was an relatively advanced bird, a member of the Ornithurae, related to birds like Ichthyornis. Other studies have recovered it as a member of the primitive family Songlingornithidae. A more expansive study found it as an enantiornithean. Dinosaur Institute at the Natural History Museum of Los Angeles County project lead and researcher, Alyssa Bell, named the new species after the Holland family and the rock band Lucero.
Bohaiornithidae is a group of early predatory enantiornitheans from the early Cretaceous Period of China. All known specimens come from the Jiufotang Formation and Yixian Formation, dating to the early Aptian age, 125–120 million years ago. Bohaiornithidae was first coined as a family of enantiornithean birds by Wang and colleagues in 2014. They defined it as the natural group formed by all descendants of the common ancestor of the type species, Bohaiornis guoi, and Shenqiornis mengi.
Houornis is a genus of enantiornithean birds from the Jiufotang Formation of Liaoning, People's Republic of China. It is known from a single species, Houornis caudatus, which had been once been classified as a species of Cathayornis, and has also been regarded as a nomen dubium.
Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. The amber is of significant palaeontological interest due to the diversity of flora and fauna contained as inclusions, particularly arthropods including insects and arachnids but also birds, lizards, snakes, frogs and fragmentary dinosaur remains. The amber has been known and commercially exploited since the first century AD, and has been known to science since the mid-nineteenth century. Research on the deposit has attracted controversy due to its alleged role in funding internal conflict in Myanmar and hazardous working conditions in the mines where it is collected.
Cruralispennia is an extinct genus of enantiornithean bird. The only known specimen of Cruralispennia was discovered in the Early Cretaceous Huajiying Formation of China and formally described in 2017. The type species of Cruralispennia is Cruralispennia multidonta. The generic name is Latin for "shin feather", while the specific name means "many-toothed". The holotype of Cruralispennia is IVPP 21711, a semi-articulated partial skeleton surrounded by the remains of carbonized feathers.
Avimaia is a genus of fossil birds of the Enantiornithes clade that lived about 115 million years ago in Northwest China. The only known species is A. schweitzerae. The holotype fossil of the bird was found in the Xiagou Formation, and is noted as the first discovered fossil bird with an unlaid egg. Abnormalities, including egg binding in which the egg becomes stuck within the body of the bird causing death, were found in the egg suggesting that the preserved egg may have caused this bird's demise. Egg binding is a serious and lethal condition that is fairly common in small birds undergoing stress.
Oculudentavis is an extinct genus of lizard of uncertain taxonomic placement, originally identified as an avialan dinosaur. It contains two known species, O. khaungraae and O. naga. Each species is known from one partial fossil specimen in Burmese amber, which differ in several proportions. Their skulls measure 1.4–1.7 centimetres (0.55–0.67 in) in length, indicating that Oculudentavis would have been comparable in size with the modern bee hummingbird if it were an avialan. Both specimens were retrieved from 99-million-year-old deposits of the Hukawng Basin in Kachin State, northern Myanmar. The type specimen of O. khaungraae is embroiled in controversy regarding its identity and the ethical issues surrounding the acquisition and study of Burmese amber. The original description advocating for an avialan identity was published in Nature, but has since then been retracted from the journal.
Yuanjiawaornis is an extinct genus of large enantiornithean bird known from the early Cretaceous of present-day China. It is monotypic, with only type species Y. virisosus known.
