Asteriornis Temporal range: Late Maastrichtian | |
---|---|
Skull in lateral view | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Infraclass: | Neognathae |
Clade: | Pangalloanserae |
Genus: | † Asteriornis Field et al. 2020 |
Type species | |
†Asteriornis maastrichtensis Field et al. 2020 |
Asteriornis ("Asteria's bird" [1] ) is an extinct genus of bird from the Late Cretaceous of Belgium which is known from a single species, Asteriornis maastrichtensis. It was closely related to birds of the extant superorder Galloanserae such as chickens and ducks. Members of the genus were small, long-legged birds (~394 grams [13.9 oz]) [1] [2] that lived near the coastline and co-existed with more "primitive" types of birds such as Ichthyornis. Asteriornis is one of the oldest-known birds irrefutably belonging to the group Neornithes, which encompasses all modern birds. It possesses characteristics of both galliformes (chicken-like birds) and anseriformes (duck-like birds), indicating its position as a close relative of the last common ancestor for both groups. [1] [3]
Asteriornis may shed light on why Neornithes were the only dinosaurs to survive the Cretaceous–Paleogene extinction event. Its coexistence with non-neornithean birds such as Ichthyornis implies that competition was not a primary factor for the extinction of non-neornitheans, which resembled modern birds in most respects but died out with other non-avian dinosaurs. Small size, [4] a terrestrial lifestyle, [5] and a generalist diet [6] have all been inferred as ecological advantages possessed by early neornithes, allowing them to survive and diversify in the wake of the extinction. [3] [7] Asteriornis fulfills these qualities, suggesting that such suspicions were justified. [1] Asteriornis is also evidence against a different hypothesis stating that modern birds originated from southern continents. This was supported by biogeographic ancestral reconstructions using phylogenies [8] and the discovery of Vegavis (a possible neornithean from Antarctica), [9] but Asteriornis's presence in Europe suggests that modern birds may have been widespread in northern continents in their early evolution. [1]
Asteriornis is based on specimen NHMM 2013 008, held in the Maastricht Natural History Museum (Dutch: Natuurhistorisch Museum Maastricht), which consists of an almost complete skull and fragments of leg bones and a radius. It was retrieved from four blocks of sediment found at the CBR-Romontbos quarry near Eben-Emael in the Maastricht Formation of Belgium, [1] and was first unearthed in 2000, [10] by amateur paleontologist Maarten van Dinther, [11] who donated it to the museum. [1] This geological formation is the namesake of the Maastrichtian stage, which was the last stage of the Cretaceous period and the Mesozoic era. It is dated to around 66.8 to 66.7 million years old, [12] less than a million years before the arrival of the asteroid that caused the Cretaceous–Paleogene extinction event, killed off all non-avian dinosaurs (and many other animals), and began the Cenozoic era. [1]
The genus name, Asteriornis, was constructed from ornis, the Greek word for bird, [13] and from Asteria, a Greek goddess who was associated with falling stars, and about whom there is a famous myth in which she transforms herself into a quail. The Asteri part of genus name thus alludes to the Chicxulub impactor (a "falling star"), and also alludes to quails which are members of the galloanserans. The species name A. maastrichtensis is named after the Maastricht Formation. [1] The researchers who discovered and described the fossil gave Asteriornis the nickname "Wonderchicken", which was picked up by various news outlets. [10] [14]
The beak was slightly downcurved and lightweight. Unlike galloanserans, the beak did not have any specialized connections to the rest of the skull, nor a hooked tip. Instead its front tip was slightly rounded. The skull was narrowest over the orbits (eye sockets), where the frontal bones were incised by a V-shaped part of the nasal bones. The bones forming the jaw joint were very galloanseran-like. The quadrate bone (the cranium's contribution to the jaw joint) connected to the skull roof via two pronounced knobs, which were adjacent to a third smaller knob, the tuberculum subcapitulare. The mandible (lower jaw) connected to the quadrate with a pair of sockets, and the rear end of the lower jaw had a large hooked rearward-facing retroarticular process as well as a smaller inward-facing medial process. All of these characteristics are considered unique to (or at least most common in) galloanserans. [1]
In some respects the skull seems more similar to galliform birds such as chickens and pheasants. These include unfused snout bones and nasal bones which fork in front of the eyes. In other respects it resembles anseriform birds such as ducks and geese. Such features include the hooked retroarticular process of the jaw and a postorbital process (the portion of bone forming the rear edge of the eye socket) which curves forward at its lower extent. These demonstrate a principle of evolution that animals close to the common ancestor of two groups share some similarities with each group. [1]
The radius fragment flattens and widens towards the wrist, where it possesses a large hooked bump. Leg bones are elongated and slender, similar in proportions and structure to modern ground-living birds. The femur has well-developed muscle ridges and a large, angular medial condyle. The tibiotarsus is widest towards the knee, while the tarsometatarsus is thinner and covered with ridges. [1]
A phylogenetic analysis placed Asteriornis near the base of Galloanserae, an expansive superorder containing birds such as chickens, ducks, pheasants, and other types of fowl and gamebirds. The precise placement varied based on whether the analysis used parsimony or Bayesian protocol. Parsimony placed it as the sister taxon to Galloanserae, meaning that it was a distant relative of the last common ancestor of chickens and ducks. Bayesian protocol instead placed it within Galloanserae, specifically as the sister taxon to Galliformes. This means that it was more closely related to chickens than to ducks, but also that was not a direct ancestor of modern chicken-like birds. [1]
Classifying Asteriornis as a relative of chickens and ducks means that it is unequivocally a neornithean. This is important because Neornithes originated at the last common ancestor of all living birds, and corresponds to the term "bird" as it refers to modern-day animals. Pre-neornithean birds such as Ichthyornis, enantiornitheans, or Archaeopteryx generally resemble modern birds but retain primitive features such as teeth or wing claws. [3] Neornithean fossils are extremely rare from the Mesozoic age, and are generally fragmentary or poorly described. The oldest known neognath, specifically a stem-anseriform, is the presbyornithid Teviornis from the Nemegt Formation of Mongolia around 70 million years ago. [15] Vegavis from the Late Cretaceous (~66.5 Ma) of Antarctica was originally described as a relative of ducks and geese, [9] but the classification of vegaviids is controversial and some paleontologists do not consider it a proper neornithean, [16] or at least not an anseriform or a galloanserine. [17] [18] Asteriornis is based on diagnostic and well-preserved skull material and its status is less unstable, so it can be considered among the oldest known undisputed fossil of a modern-style neornithean bird. [1]
At least two studies in 2021 and 2024 recovered Asteriornis as a paleognath, sister to Lithornithidae and Tinamidae, albeit "with limited support". [19] [20] Other researchers still support Asterornis as a neornithean closely related to or within Galloanserae based on morphometric and phylogenetic analyses. [21] [22] A 2024 cladistic analysis placed Asteriornis within the crown-group Galloanserae, specifically as a stem-galliform, though reexaminations of its mandible suggested that it lacked a key galloanserine feature. [23]
Fowl are birds belonging to one of two biological orders, namely the gamefowl or landfowl (Galliformes) and the waterfowl (Anseriformes). Anatomical and molecular similarities suggest these two groups are close evolutionary relatives; together, they form the fowl clade which is scientifically known as Galloanserae or Galloanseres. This clade is also supported by morphological and DNA sequence data as well as retrotransposon presence/absence data.
Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae, Anseranatidae, and Anatidae, the largest family, which includes over 170 species of waterfowl, among them the ducks, geese, and swans. Most modern species in the order are highly adapted for an aquatic existence at the water surface. With the exception of screamers, males have penises, a trait that has been lost in the Neoaves, the clade consisting of all other modern birds except the galliformes and paleognaths. Due to their aquatic nature, most species are web-footed.
Hesperornithes is an extinct and highly specialized group of aquatic avialans closely related to the ancestors of modern birds. They inhabited both marine and freshwater habitats in the Northern Hemisphere, and include genera such as Hesperornis, Parahesperornis, Baptornis, Enaliornis, and Potamornis, all strong-swimming, predatory divers. Many of the species most specialized for swimming were completely flightless. The largest known hesperornithean, Canadaga arctica, may have reached a maximum adult length of 2.2 metres (7.2 ft).
Vegavis is a genus of extinct bird that lived in Antarctica during the Maastrichtian stage of the Late Cretaceous. The type species is Vegavis iaai. Vegavis was initially considered to be a member of Anseriformes within Galloanserae, but this claim has not been supported by some recent studies.
Dromornithidae, known as mihirungs and informally as thunder birds or demon ducks, were a clade of large, flightless Australian birds of the Oligocene through Pleistocene epochs. All are now extinct. They were long classified in Struthioniformes, but are now usually classified as galloanseres. Dromornithids were part of the Australian megafauna. One species, Dromornis stirtoni, was 3 m tall. Only a single species, Genyornis newtoni survived into the Late Pleistocene. They are thought to have been herbivorous.
Palaeognathae is an infraclass of birds, called paleognaths or palaeognaths, 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 contains five extant orders consisting of four flightless lineages, termed ratites, and one flying lineage, the Neotropic tinamous. There are 47 species of tinamous, five of kiwis (Apteryx), three of cassowaries (Casuarius), one of emus (Dromaius), two of rheas (Rhea) and two of ostriches (Struthio). Recent research has indicated that paleognaths are monophyletic but the traditional taxonomic split between flightless and flighted forms is incorrect; tinamous are within the ratite radiation, meaning flightlessness arose independently multiple times via parallel evolution.
Neognathae is an infraclass of birds, called neognaths, within the class Aves of the clade Archosauria. Neognathae includes the majority of living birds; the exceptions being the tinamous and the flightless ratites, which belong instead to the sister taxon Palaeognathae. There are nearly 10,000 living species of neognaths.
The evolution of birds began in the Jurassic Period, with the earliest birds derived from a clade of theropod dinosaurs named Paraves. Birds are categorized as a biological class, Aves. For more than a century, the small theropod dinosaur Archaeopteryx lithographica from the Late Jurassic period was considered to have been the earliest bird. Modern phylogenies place birds in the dinosaur clade Theropoda. According to the current consensus, Aves and a sister group, the order Crocodilia, together are the sole living members of an unranked reptile clade, the Archosauria. Four distinct lineages of bird survived the Cretaceous–Paleogene extinction event 66 million years ago, giving rise to ostriches and relatives (Palaeognathae), waterfowl (Anseriformes), ground-living fowl (Galliformes), and "modern birds" (Neoaves).
Ichthyornithes is an extinct group of toothed avialan dinosaurs 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.
Presbyornithidae is an extinct group of birds found in North America, South America, East Asia, Australia and possibly North Africa. They had evolved by the Maastrichtian age of the Late Cretaceous and became extinct during the Aquitanian age of the Early Miocene. The family contains the oldest known neognath, Teviornis from the Nemegt Formation of Mongolia.
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.
The Pelagornithidae, commonly called pelagornithids, pseudodontorns, bony-toothed birds, false-toothed birds or pseudotooth birds, are a prehistoric family of large seabirds. Their fossil remains have been found all over the world in rocks dating between the Early Paleocene and the Pliocene-Pleistocene boundary.
John Alan Feduccia is a paleornithologist specializing in the origins and phylogeny of birds. He is S. K. Heninger Distinguished Professor Emeritus at the University of North Carolina. Feduccia's authored works include three major books, The Age of Birds, The Origin and Evolution of Birds, and Riddle of the Feathered Dragons.
Ornithurae is a natural group that includes modern birds and their very close relatives such as Ichthyornis and the hesperornithines. This clade is defined in the PhyloCode by Juan Benito and colleagues in 2022 as "the smallest clade containing Ichthyornis dispar, Hesperornis regalis, and Vultur gryphus".
Neoaves is a clade that consists of all modern birds with the exception of Palaeognathae and Galloanserae. This group is defined in the PhyloCode by George Sangster and colleagues in 2022 as "the most inclusive crown clade containing Passer domesticus, but not Gallus gallus". Almost 95% of the roughly 10,000 known species of extant birds belong to the Neoaves.
Pangalliformes is the scientific name of a provisional clade of birds within the group Galloanserae. It is defined as all birds more closely related to chickens than to ducks, and includes all modern chickens, turkeys, pheasants, and megapodes, as well as extinct species that do not fall within the crown group Galliformes.
Anzu is a monospecific genus of caenagnathid dinosaur from North Dakota, South Dakota and Montana that lived during the Late Cretaceous in what is now the Hell Creek Formation. The type species and only species, Anzu wyliei is known from numerous skeletons that preserve cranial and postcranial elements. It was named in 2014 by Matthew C. Lamanna, Hans-Dieter Sues, Emma R. Schachner, and Tyler R. Lyson.
Vegaviidae is an extinct family of birds of uncertain phylogenetic placement, which existed during the Late Cretaceous and possibly the Paleocene. Definitive fossils attributed to the family have only been found in Antarctica, though other fossils from the Southern Hemisphere including Chile and New Zealand may represent this group. The putative Campanian vegaviid from Canada known as Maaqwi, more likely belongs to the Procellariformes.
Julia Allison Clarke is an American paleontologist and evolutionary biologist who studies the evolution of birds and the dinosaurs most closely related to living birds. She is the John A. Wilson Professor in Vertebrate Paleontology in the Jackson School of Geosciences and a Howard Hughes Medical Institute Professor at the University of Texas at Austin.
Janavis is an extinct toothed bird, belonging to the Ichthyornithes, from the Late Cretaceous of Belgium. The genus has one named species, Janavis finalidens that was discovered in the 1990s, reported in 2002, and described in 2022. Recovered almost simultaneously from the same area and age as Asteriornis maastrichtensis, then the oldest known modern bird, it provides information on the evolution and divergence of basal and modern birds, especially on the evolutionary modifications of bird skulls.