Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is a subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya and their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, having evolved from earlier theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds.
The Varanidae are a family of lizards in the superfamily Varanoidea and order Anguimorpha. The family, a group of carnivorous and frugivorous lizards, includes the living genus Varanus and a number of extinct genera more closely related to Varanus than to the earless monitor lizard (Lanthanotus). Varanus includes the Komodo dragon, crocodile monitor, savannah monitor, the goannas of Australia and Southeast Asia, and various other species with a similarly distinctive appearance. Their closest living relatives are the earless monitor lizard and chinese crocodile lizard. The oldest members of the family are known from the Late Cretaceous of Mongolia.
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.
Avisaurus is a genus of enantiornithine bird from the Late Cretaceous of North America.
Azhdarchidae is a family of pterosaurs known primarily from the Late Cretaceous Period, though an isolated vertebra apparently from an azhdarchid is known from the Early Cretaceous as well. Azhdarchids are mainly known for including some of the most largest flying animals discovered, but smaller cat-size members have also been found. Originally considered a sub-family of Pteranodontidae, Nesov (1984) named the Azhdarchinae to include the pterosaurs Azhdarcho, Quetzalcoatlus, and Titanopteryx. They were among the last known surviving members of the pterosaurs, and were a rather successful group with a worldwide distribution. Previously it was thought that by the end of the Cretaceous, most pterosaur families except for the Azhdarchidae disappeared from the fossil record, but recent studies indicate a wealth of pterosaurian fauna, including pteranodontids, nyctosaurids, tapejarids and several indeterminate forms. In several analyses, some taxa such as Navajodactylus, Bakonydraco and Montanazhdarcho were moved from Azhdarchidae to other clades.
Palaeocursornis is a monotypic genus of pterosaurs. The only known species, P. corneti, was described in 1984 based on a single bone interpreted as the distal part of a left femur, found in Early Cretaceous (Berriasian rocks from a mine at Cornet near Oradea in northwestern Romania. It was initially assumed to be a flightless paleognathe bird, possibly a ratite, and later as a more primitive ornithuromorph or non-avialan theropod. However, re-evaluation of the specimen suggested that it was not a femur at all, but the upper arm bone of a pterodactyloid pterosaur similar to Azhdarcho.
Gansus is a genus of aquatic birds that lived during the Aptian age of the Early Cretaceous (Aptian-Albian) period in what are now Gansu and Liaoning provinces, western China. The rock layers from which their fossils have been recovered are dated to 120 million years ago. It was first described in 1984 on the basis of an isolated left leg. It is the oldest-known member of the Ornithurae, the group which includes modern birds (Neornithes) and extinct related groups, such as Ichthyornis and Hesperornithes.
Ichthyornithes is an extinct group of toothed avialans very closely related to the common ancestor of all modern birds. They are known from fossil remains found throughout the late Cretaceous period of North America, though only two genera, Ichthyornis and Janavis, are represented by complete enough fossils to have been named. Ichthyornitheans became extinct at the Cretaceous–Paleogene boundary, along with enantiornitheans, all other non-avian dinosaurs, and many other animal and plant groups.
Polarornis is a genus of prehistoric bird, possibly an anserimorph. It contains a single species Polarornis gregorii, known from incomplete remains of one individual found on Seymour Island, Antarctica, in rocks which are dated to the Late Cretaceous.
Alexornis is a genus of enantiornithine birds from the Bocana Roja Formation of Baja California, Mexico. This geological formation has been dated to the late Cretaceous period, and more specifically to the Campanian age, about 73 mya. The type and only known species is Alexornis antecedens. Its name means "Alex's ancestral bird"; Alexornis from the given name of ornithologist Alexander Wetmore + Ancient Greek ornis, "bird", and antecedens, Latin for "going before" or "ancestral".
Zhyraornis is a genus of prehistoric bird from the late Cretaceous period. Its fossils have been found in Bissekty Formation deposits near Dzharakuduk in the Kyzyl Kum, Uzbekistan. Two species have been assigned to this genus: Zhyraornis kashkarovi and Zhyraornis logunovi. Both are known only from partial pelvic bones (synsacra).
Patagopteryx is an extinct monotypic genus of patagopterygiforms that lived during the Late Cretaceous, around 80 mya, in what is now the Sierra Barrosa in northwestern Patagonia, Argentina. About the size of a chicken, it is the earliest known unequivocal example of secondary flightlessness: its skeleton shows clear indications that the ancestors of Patagopteryx were flying birds.
Cretornis is a pterosaur genus from the late Cretaceous period of what is now the Jizera Formation in the Czech Republic, dating to about 92 million years ago. It only contains a single species, Cretornis hlavaci.
Gargantuavis is an extinct genus of large, primitive bird containing the single species Gargantuavis philoinos. It is the only member of the monotypic family Gargantuaviidae. Its fossils were discovered in several formations dating to 73.5 and 71.5 million years ago in what is now northern Spain, southern France, and Romania. Gargantuavis is the largest known bird of the Mesozoic, a size ranging between the cassowary and the ostrich, and a mass of 141 kg (311 lb) like modern ostriches, exemplifying the extinction of non-avian dinosaurs was not a necessary condition for the emergence of giant terrestrial birds. It was once thought to be closely related to modern birds, but the 2019 discovery of a pelvis from what was Hateg Island shows several primitive features.
Parahesperornis is a genus of prehistoric flightless birds from the Late Cretaceous. Its range in space and time may have been extensive, but its remains are rather few and far between, at least compared with its contemporary relatives in Hesperornis. Remains are known from central North America, namely the former shallows of the Western Interior Seaway in Kansas. Found only in the upper Niobrara Chalk, these are from around the Coniacian-Santonian boundary, 85–82 million years ago (mya).
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 1984.
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.
Lithornithidae is an extinct, possibly paraphyletic group of early paleognath birds. They are known from fossils dating to the Upper Paleocene through the Middle Eocene of North America and Europe, with possible Late Cretaceous representatives. All are extinct today; the youngest specimen is the currently unnamed SGPIMH MEV1 specimen from the mid-Eocene Messel Pit site.
Qinornis is a prehistoric bird genus from the early-mid-Paleocene epoch, about 61 million years ago. It is known from a single fossil specimen consisting of a partial hind limb and foot, which was found in Fangou Formation deposits in Luonan County, China.
Brevirostruavis is a genus of Early Cretaceous enenatiornithine bird from the Early Cretaceous Jiufotang Formation of Liaoning, China. The type and only species is Brevirostruavis macrohyoideus.
