Archaeornithoides
Encyclopedia
Archaeornithoides is a genus
of maniraptoriform theropod dinosaur
. It was found in Late Cretaceous river sandstones of the Djadokhta Formation beds located in Bayn Dzak, Mongolia
. The remains, consisting of a juvenile skull fragment comprehending paired maxillae and dentaries and also palate bones were described by Elzanowski and Wellnhofer in 1992 and 1993.
The generic name (Archaeornithoides) means “shaped like an ancient bird” in ancient Greek. The specific descriptor (deinosauriscus) alludes to the animal's small size for a dinosaur.
. This conclusion rested on key bird-like features; an interdigitated suture between the premaxilla and maxilla, broad palatal shelves, pneumatic sinuses, lack of interdental plates, and unserrated teeth. Since publication, though, all of these features have been discovered in new fossils of adult and/or juvenile troodonts and dromaeosaurs.
Some scientists had suggested that the juvenile specimen of Archaeornithoides may belong to a previously known species of Mongolian troodontid, either Saurornithoides
or Byronosaurus
. However, studies of a juvenile Byronosaurus skull showed that theropod dinosaurs possess many distinctive adult characteristics even as hatchings or embryos, and that the lack of characters solidly linking Archaeornithoides to known adult specimens shows that it is probably a distinct species. Bever and Norell (in 2009) found no evidence to support the placement of Archaeornithoides close to Avialae, and only weak support for the idea that it is a juvenile troodontid.
) mammal the size of a weasel (adding that these are common in the Bayn Dzak assemblage). Clark and colleagues (2002) noted that it may have also passed through the digestive tract of the predator before fossilization. If true, this may be the first known evidence of Mesozoic
mammals eating dinosaurs (see Repenomamus
).
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of maniraptoriform theropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
. It was found in Late Cretaceous river sandstones of the Djadokhta Formation beds located in Bayn Dzak, Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
. The remains, consisting of a juvenile skull fragment comprehending paired maxillae and dentaries and also palate bones were described by Elzanowski and Wellnhofer in 1992 and 1993.
The generic name (Archaeornithoides) means “shaped like an ancient bird” in ancient Greek. The specific descriptor (deinosauriscus) alludes to the animal's small size for a dinosaur.
Classification
Elżanowski & Wellnhofer (1993) suggested that Archaeornithoides was the closest known relative to birds AvialaeAvialae
Avialae is a clade of dinosaurs containing their only living representatives, birds , and the most immediate extinct relatives of birds.-Competing definitions:...
. This conclusion rested on key bird-like features; an interdigitated suture between the premaxilla and maxilla, broad palatal shelves, pneumatic sinuses, lack of interdental plates, and unserrated teeth. Since publication, though, all of these features have been discovered in new fossils of adult and/or juvenile troodonts and dromaeosaurs.
Some scientists had suggested that the juvenile specimen of Archaeornithoides may belong to a previously known species of Mongolian troodontid, either Saurornithoides
Saurornithoides
Saurornithoides is a genus of troodontid maniraptoran dinosaur, living during the Late Cretaceous period. These creatures were predators, which could run fast on their hind legs and had excellent sight and hearing...
or Byronosaurus
Byronosaurus
Byronosaurus is a genus of troodontid dinosaur which lived during the Late Cretaceous Period. It was named for Byron Jaffe, "in recognition of his family's support for the Mongolian Academy of Sciences-American Museum of Natural History Paleontological Expeditions." The first example of...
. However, studies of a juvenile Byronosaurus skull showed that theropod dinosaurs possess many distinctive adult characteristics even as hatchings or embryos, and that the lack of characters solidly linking Archaeornithoides to known adult specimens shows that it is probably a distinct species. Bever and Norell (in 2009) found no evidence to support the placement of Archaeornithoides close to Avialae, and only weak support for the idea that it is a juvenile troodontid.
Predators
Elzanowski and Wellnhofer noted that the specimen has distinct bite marks, and suggested that its braincase was bitten off by a deltatheridiid (DeltatheridiumDeltatheridium
Deltatheridium is an extinct species of metatherian. It lived in what is now Mongolia during the Upper Cretaceous. It was a basal metatherian, which places it near start of the linage that led to the marsupials, such the kangaroo, koala, and opossum.It had a length of...
) mammal the size of a weasel (adding that these are common in the Bayn Dzak assemblage). Clark and colleagues (2002) noted that it may have also passed through the digestive tract of the predator before fossilization. If true, this may be the first known evidence of Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
mammals eating dinosaurs (see Repenomamus
Repenomamus
Repenomamus is the largest mammal known from the Cretaceous period of Manchuria, and it is the mammal for which there is the best evidence that it fed on dinosaurs. It is not possible to determine if Repenomamus actively hunted live dinosaurs or scavenged dead dinosaurs.-Paleobiology:Repenomamus...
).
External links
- Archaeornithoides at DinoData