Byronosaurus
Encyclopedia
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 Byronosaurus was discovered in 1993 at Ukhaa Tolgod, Gobi Desert
, Mongolia
; a second was found in 1996 at Bolor's Hill, about 8 kilometers away (5 miles).
Byronosaurus was a small, agile dinosaur that was probably only 1.5 meters long (5 ft) and 50 centimeters high (17 in). It weighed only about 4 kilograms (9 lbs). Unlike most other troodontids, its teeth seem to lack serrations. They are instead needle-like, probably best suited for catching small bird
s, lizard
s and mammal
s. Specifically, they resemble those of Archaeopteryx
, the bird-like dinosaur.
The remains of two adult individuals have been found, including two skull
s. One, measuring 23 centimeters long (8 inches), is better preserved than any other troodontid skull found to date. It has a chamber in the snout where air enters from the nostrils before passing through to the mouth - another feature similar to that found in birds. Additionally, two hatchling skulls have been identified as juvenile Byronosaurus.
"Flaming Cliffs" of the Djadokhta Formation of Mongolia
. The nest is quite certainly that of an oviraptorosaur, since an oviraptorid embryo is still preserved inside one of the eggs. The two partial skulls were first described by Norell et al. (1994) as dromaeosaurids, but reassigned to Byronosaurus after further study. The juvenile skulls were either from hatchlings or embryos, and fragments of eggshell are adhered to them although it seems to be oviraptorid eggshell. The presence of tiny Byronosaurus skulls in an oviraptorid nest is an enigma. Hypotheses explaining how they came to be there include that they were the prey of the adult oviraptorid, that they were there to prey on oviraptorid hatchlings, or that Byronosaurus may have been nest parasites.
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 troodontid
Troodontidae
Troodontidae is a family of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and scrappy and they have therefore been allied, at various times, with many dinosaurian lineages...
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...
which lived during the Late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
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 Byronosaurus was discovered in 1993 at Ukhaa Tolgod, Gobi Desert
Gobi Desert
The Gobi is a large desert region in Asia. It covers parts of northern and northwestern China, and of southern Mongolia. The desert basins of the Gobi are bounded by the Altai Mountains and the grasslands and steppes of Mongolia on the north, by the Hexi Corridor and Tibetan Plateau to the...
, 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...
; a second was found in 1996 at Bolor's Hill, about 8 kilometers away (5 miles).
Byronosaurus was a small, agile dinosaur that was probably only 1.5 meters long (5 ft) and 50 centimeters high (17 in). It weighed only about 4 kilograms (9 lbs). Unlike most other troodontids, its teeth seem to lack serrations. They are instead needle-like, probably best suited for catching small bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s and mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s. Specifically, they resemble those of Archaeopteryx
Archaeopteryx
Archaeopteryx , sometimes referred to by its German name Urvogel , is a genus of theropod dinosaur that is closely related to birds. The name derives from the Ancient Greek meaning "ancient", and , meaning "feather" or "wing"...
, the bird-like dinosaur.
The remains of two adult individuals have been found, including two skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
s. One, measuring 23 centimeters long (8 inches), is better preserved than any other troodontid skull found to date. It has a chamber in the snout where air enters from the nostrils before passing through to the mouth - another feature similar to that found in birds. Additionally, two hatchling skulls have been identified as juvenile Byronosaurus.
Hatchling skulls
Mark Norell and colleagues described two "perinate" (hatchlings or embryos close to hatching) specimens of Byronosaurus (specimens IGM 100/972 and IGM 100/974) in 1994. The two specimens were found in a nest of oviraptorid eggs in the Late CretaceousLate Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
"Flaming Cliffs" of the Djadokhta Formation of 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 nest is quite certainly that of an oviraptorosaur, since an oviraptorid embryo is still preserved inside one of the eggs. The two partial skulls were first described by Norell et al. (1994) as dromaeosaurids, but reassigned to Byronosaurus after further study. The juvenile skulls were either from hatchlings or embryos, and fragments of eggshell are adhered to them although it seems to be oviraptorid eggshell. The presence of tiny Byronosaurus skulls in an oviraptorid nest is an enigma. Hypotheses explaining how they came to be there include that they were the prey of the adult oviraptorid, that they were there to prey on oviraptorid hatchlings, or that Byronosaurus may have been nest parasites.