Piksi Temporal range: Late Cretaceous, | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Order: | † Pterosauria |
Suborder: | † Pterodactyloidea |
Genus: | † Piksi Varricchio, 2002 |
Species: | †P. barbarulna |
Binomial name | |
†Piksi barbarulna Varricchio, 2002 | |
Piksi is a potential pterosaur [1] genus containing the single species Piksi barbarulna (meaning "strange elbowed big bird", from Blackfoot piksi, "big bird" or, specifically, "chicken" and Latin barbarus "strange, outlandish" + ulna, elbow [2] ). It lived roughly 75 million years ago in what is now Montana, United States. Known from parts of a right wing – the humerus, ulna and radius bones – the only specimens found so far are housed in the Museum of the Rockies (collection number MOR 1113). The genus Piksi is monotypic at present.
The fossils were found in 1991 by Gloria Jean Siebrecht in the Blackfeet Indian Reservation, namely at Bob's Vacation Site locality TM-088, Glacier County. Recovered from an old stratum of the upper Two Medicine Formation, they are probably from an individual that died in or near a small pool. It was described in 2002 by David J. Varricchio.
The bones are fragmentary and represent roughly the elbow area. Comparing the fossils' size to the wing bones of other ground birds, P. barbarulna would have been relatively small, with a wingspan reaching 1 m (3.3 ft). [1]
The original description of the fossils found its affinities unresolvable except that it was probably an ornithothoracine bird. Agnolin and Varricchio (2012) reinterpreted Piksi barbarulna as a pterosaur rather than a bird, most likely a member of Ornithocheiroidea. [3] However, it has since been noted that the humerus of Piksi possesses features which found in some theropods but not in any pterodactyloid pterosaurs. [4]
However, more recent studies have recovered it as a pterosaur again. [1]
The deposit in which the bones were found was a silty claystone. This was formed from sediments deposited during what seems to have been a rather cool phase of the Late Cretaceous: [5] sea levels of the Western Interior Seaway at least were apparently very low for Mesozoic standards, though this may also have been due to strong tectonic uplift in the Cordilleran Overthrust Belt. The location was inland, with the Western Interior Seaway's coast at least 350 km (220 miles) away.
Judging from the stratigraphical, sedimentological and faunal data, the environment was thus probably semi-humid, possibly (seasonally?) semi-arid grassland or shrubland in a tropical or subtropical climate. The claystone apparently formed from sediment of a small floodplain, such as an ephemeral pool.[ citation needed ]
A diverse fauna utilized the location as a habitat. Other theropods were plentiful, including Troodon (the nest of which was recovered), tyrannosaurids, and dromaeosaurids. Orodromeus was also abundant; herds might have come to the pool to drink or breed, as adults, juveniles and hatchlings were found together. Early mammals – metatherians and multituberculates – occurred in the area, as well as lizards. That there was a temporary though not permanent body of water is indicated by the presence of articulated frog skeletons and the absence of fish and other aquatic animals.[ citation needed ]
Avisaurus is a genus of enantiornithine bird from the Late Cretaceous of North America.
The Maastrichtian is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age 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 from 72.1 to 66 million years ago. The Maastrichtian was preceded by the Campanian and succeeded by the Danian.
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 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.
Ornithocheirus is a pterosaur genus known from fragmentary fossil remains uncovered from sediments in the United Kingdom and possibly Morocco.
The Two Medicine Formation is a geological formation, or rock body, in northwestern Montana and southern Alberta that was deposited between 83.5 ± 0.7 Ma and 70.6 ± 3.4 Ma, during Campanian time. It crops out to the east of the Rocky Mountain Overthrust Belt, and the western portion of this formation is folded and faulted while the eastern part, which thins out into the Sweetgrass Arch, is mostly undeformed plains. Below the formation are the nearshore deposits of the Virgelle Sandstone, and above it is the marine Bearpaw Shale. Throughout the Campanian, the Two Medicine Formation was deposited between the western shoreline of the Late Cretaceous Interior Seaway and the eastward advancing margin of the Cordilleran Overthrust Belt. The Two Medicine Formation is mostly sandstone, deposited by rivers and deltas.
Eurolimnornis is the name given to a monotypic genus of pterosaurs from the Early Cretaceous. The only known species E. corneti probably was originally identified as a primitive but essentially modern bird, although alternative theories later suggested that it was a non-avialan theropod or pterosaur. The identification as a pterosaur was supported by a re-evaluation of the fossil remains published in 2012.
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.
The Pteranodontidae are a family of large pterosaurs of the Cretaceous Period of North America and Africa. The family was named in 1876 by Othniel Charles Marsh. Pteranodontids had a distinctive, elongated crest jutting from the rear of the head. The spectacularly-crested Nyctosaurus is sometimes included in this family, though usually placed in its own family, the Nyctosauridae.
Montanazhdarcho is a genus of azhdarchoid pterosaur from the Late Cretaceous period of what is now the state of Montana, United States. Montanazhdarcho is known from only one species, M. minor.
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.
Yixianopterus is a pterodactyloid pterosaur genus from the Barremian-Aptian-age Lower Cretaceous Yixian Formation of Liaoning, China. It is known from a single specimen, holotype JZMP-V-12, housed at the Benxi Geological Museum. This specimen was modified before acquisition, with much of the skull being fabricated. The Jinggangshan bedding in which the specimen was found is basaltic with siliciclastic sediments. Many organisms associated with this layer of the Yixian Formation are aquatic, indicating a marine environment with much volcanic activity.
Torotix is a Late Cretaceous genus of aquatic birds. They lived along the shores of the Western Interior Seaway, but it is not clear whether they were seabirds or freshwater birds, as the genus is only known from a humerus. Consequently, the genus contains only one known species, Torotix clemensi. T. clemensi is represented by a single fossil specimen, a partial humerus recovered from the Lance formation of Wyoming. Its deposits are dated to the very end of the Cretaceous period, 66 million years ago.
The Bauxite of Cornet is a geological formation in Romania whose strata date back to the Early Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation. It exists as karstic sediments infilling fissures and caves in limestone.
The Gosau Group is a geological stratigraphic group in Austria, Germany and western Slovakia whose strata date back to the Late Cretaceous to Eocene. It is exposed in numerous sporadic isolated basins within the Northern Calcareous Alps. It is divided into two subgroups, the Lower Gosau Subgroup which dates from the Turonian to Campanian, approximately 90 to 75 Ma and the Upper Gosau Subgroup which dates to the Santonian to Eocene, about 83.5 to 50 Ma. The formations within each subunit vary significantly between basins. The sequence is largely marine, but the Grünbach Formation represents a terrestrial deposit. Many of the units of the group are fossiliferous, typically providing marine fossils such as ammonites, though terrestrial remains including those of dinosaurs are known from the Grünbach Formation and Schönleiten Formation.
The Tahora Formation is a Late Cretaceous geologic formation that outcrops in northeastern New Zealand near Napier. It is Haumurian in age according to the New Zealand geologic time scale. It forms part of the Upper Cretaceous to Teurian (Danian) Tinui Group. It unconformably overlies the Jurassic to Lower Cretaceous Urewera Group or the Upper Cretaceous Matawai Group. It is conformably overlain by the Haumurian to Teurian Whangai Formation. It consist of three members, the Maungataniwha Sandstone Member, the Mutuera Member and the Houpapa Member. It is named for Tahora Station, south of Matawai in the Gisborne Region. The aptly named Maungataniwha Sandstone Member is known for its rich reptile fossil remains, first investigated by amateur palaeontologist Joan Wiffen.
Continuoolithus is an oogenus of dinosaur egg found in the late Cretaceous of North America. It is most commonly known from the late Campanian of Alberta and Montana, but specimens have also been found dating to the older Santonian and the younger Maastrichtian. It was laid by an unknown type of theropod. These small eggs are similar to the eggs of oviraptorid dinosaurs, but have a distinctive type of ornamentation.
Euornithes is a natural group which includes the most recent common ancestor of all avialans closer to modern birds than to Sinornis.
Pteranodontoidea is an extinct clade of ornithocheiroid pterosaurs from the Early to Late Cretaceous of Asia, Africa, Europe, North America and South America. It was named by Alexander Wilhelm Armin Kellner in 1996. In 2003, Kellner defined the clade as a node-based taxon consisting of the last common ancestor of Anhanguera, Pteranodon and all its descendants. The clade Ornithocheiroidea is sometimes considered to be the senior synonym of Pteranodontoidea, however it depends on its definition. Brian Andres in his analyses, converts Ornithocheiroidea using the definition of Kellner (2003) to avoid this synonymy.
Paleontology in Montana refers to paleontological research occurring within or conducted by people from the U.S. state of Montana. The fossil record in Montana stretches all the way out to sea]] where local bacteria formed stromatolites and bottom-dwelling marine life left tracks on the sediment that would later fossilize. This sea remained in place during the early Paleozoic, although withdrew during the Silurian and Early Devonian, leaving a gap in the local rock record until its return. This sea was home to creatures including brachiopods, conodonts, crinoids, fish, and trilobites. During the Carboniferous the state was home to an unusual cartilaginous fish fauna. Later in the Paleozoic the sea began to withdraw, but with a brief return during the Permian.
The Aoufous Formation is a geological formation that contains some of the vertebrate assemblage of the Kem Kem Group, of Late Cretaceous date. Two other formations comprise the Kem Kem beds: the underlying Ifezouane Formation and the overlying Akrabou Formation.