[D] Saurornithoides junior [Su]
Describer
Barsbold, 1974
Time
Cretaceous Late ?Campanian Maastrichtian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Troodontidae
Diet
Carnivore
Fossilsite
Nemegt Formation, Bügiin Tsav, Omnogov, Mongolia
Fall Under
Zanabazar junior
Length
>2 meter
Info
Skull
Zanabazar junior (Norell, Makovicky, Bever, Balanoff, Clark, Barsbold & Rowe 2009) > Saurornithoides junior (Barsbold, 1974)
Skull with fragmantary postcranial skeleton. This species has more teeth than Saurornithoides mongoliensis. There is no siginicant overlap in the known specimens of Tochisaurus nemegtensis, Borogovia gracilicrus and Saurornithoides junior, which were recovered from the same geographic area, and it is conceivable that they all represent the same species.
Barsbold, 1983 Holotype PST GIN AH MNR 100/1; incomplete skull and part of lower jaw; sacral vertebrae; incomplete series of caudal vertebrae; fragments of right tibia and metatarsus. Moderately large saurornithoidid with 19-20 teeth in the upper and 33-35 teeth in the lower jaw. 12 and 15-17 serrations along 5 mm of posterior edge of teeth.
Description
Skull with elongated, narrowing facial region. Maxillary fenestrae widen posteriorly. Premaxilla lacks ventral process. Maxilla limits the posteroventral part of the external nares and forms their ventrally widened, closed edges. In the base of the skull, a large, hollow basisphenoid capsule with a narrow frontal (basisphenoid) process is found, carrying a narrow longitudinal furrow dorsally that marks the base of the sphenethmoid.
The hypophyseal cavity is located immediately above the posterior end of the furrow. Shortened, widened, horizontally-directed basipterygoid processes enter into the ventral end of the capsule, supposedly participating in the formation of the incurrent fenestrae for the parabasal canals.
The large, elongated middle ear cavity is located in the lower part of the lateral walls of the cranium, and limited posteriorly by the paroccipital processes. At the medial wall, the middle ear cavity bears a series of foramina of which the posterior one borders directly on the closed wall of the paroccipital, and is identified as the foramen ovale.
The exit for cranial nerve VII is located in the wall of the upper edge of the cavity, anterior to the foramen ovale. A large opening, supposedly identified with the opening for the basisphenoidal air sinuses, is found anterior and ventral to the foramen ovale, in the middle ear cavity. The large opening in the lateral wall of the braincase is immediately above the upper edge of the cavity, and is identified as the exit for cranial nerve V.
The lateral wall is constructed from the prootic and laterosphenoid, which form an immobile articulation with the parietal. A small, unpaired bone is found anterior to the laterosphenoid, in the proximal end of the olfactory nerve passage, supposedly identified as the presphenoid. The anterior section of the lower jaw is elongated and narrow, and composed mostly of the dentary.
The splenial, with a large, posterior lower process and an elongate, V-shaped, narrow anterior end, bears the fenestra for entrance into Meckel\\\\\\\'s canal and extends to the symphysis. The teeth are small and close, and those most posterior are recurved, with smooth anterior and serrated posterior edges; 12 and 15-17 serrations are found along 5 mm of the upper and lower teeth. There are 19-20 teeth in the upper jaw, 33-35 in the lower.
There are six fused sacral vertebrae. Caudal vertebrae are platycoelous, lack ossified tendons, and are shortened proximally but increase in length distally. The chevrons of the proximal vertebrae are dorsoventrally elongated, while in the distal section they are gradually shortened up to the point of becoming flattened, elongated structures.
There is a mesotarsal joint of typical theropod appearance, represented by an astragalus with a high ascending process and a calcaneum connected to the distal end of the large tibia; this latter is closely adjacent to the end of the small, narrow fibula. The proximal metatarsus is thickened, the end of III is highly laterally compressed and displaced posteriorly, while the adjacent bones contact each other anteriorly. Differentiated from Saurornithoides mongoliensis by its larger size and greater tooth count. Besides the holotype, remains of the postcranial skeleton of another specimen, no. 100/2.
Barsbold, 1974
Time
Cretaceous Late ?Campanian Maastrichtian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Troodontidae
Diet
Carnivore
Fossilsite
Nemegt Formation, Bügiin Tsav, Omnogov, Mongolia
Fall Under
Zanabazar junior
Length
>2 meter
Info
Skull
Zanabazar junior (Norell, Makovicky, Bever, Balanoff, Clark, Barsbold & Rowe 2009) > Saurornithoides junior (Barsbold, 1974)
Skull with fragmantary postcranial skeleton. This species has more teeth than Saurornithoides mongoliensis. There is no siginicant overlap in the known specimens of Tochisaurus nemegtensis, Borogovia gracilicrus and Saurornithoides junior, which were recovered from the same geographic area, and it is conceivable that they all represent the same species.
Barsbold, 1983 Holotype PST GIN AH MNR 100/1; incomplete skull and part of lower jaw; sacral vertebrae; incomplete series of caudal vertebrae; fragments of right tibia and metatarsus. Moderately large saurornithoidid with 19-20 teeth in the upper and 33-35 teeth in the lower jaw. 12 and 15-17 serrations along 5 mm of posterior edge of teeth.
Description
Skull with elongated, narrowing facial region. Maxillary fenestrae widen posteriorly. Premaxilla lacks ventral process. Maxilla limits the posteroventral part of the external nares and forms their ventrally widened, closed edges. In the base of the skull, a large, hollow basisphenoid capsule with a narrow frontal (basisphenoid) process is found, carrying a narrow longitudinal furrow dorsally that marks the base of the sphenethmoid.
The hypophyseal cavity is located immediately above the posterior end of the furrow. Shortened, widened, horizontally-directed basipterygoid processes enter into the ventral end of the capsule, supposedly participating in the formation of the incurrent fenestrae for the parabasal canals.
The large, elongated middle ear cavity is located in the lower part of the lateral walls of the cranium, and limited posteriorly by the paroccipital processes. At the medial wall, the middle ear cavity bears a series of foramina of which the posterior one borders directly on the closed wall of the paroccipital, and is identified as the foramen ovale.
The exit for cranial nerve VII is located in the wall of the upper edge of the cavity, anterior to the foramen ovale. A large opening, supposedly identified with the opening for the basisphenoidal air sinuses, is found anterior and ventral to the foramen ovale, in the middle ear cavity. The large opening in the lateral wall of the braincase is immediately above the upper edge of the cavity, and is identified as the exit for cranial nerve V.
The lateral wall is constructed from the prootic and laterosphenoid, which form an immobile articulation with the parietal. A small, unpaired bone is found anterior to the laterosphenoid, in the proximal end of the olfactory nerve passage, supposedly identified as the presphenoid. The anterior section of the lower jaw is elongated and narrow, and composed mostly of the dentary.
The splenial, with a large, posterior lower process and an elongate, V-shaped, narrow anterior end, bears the fenestra for entrance into Meckel\\\\\\\'s canal and extends to the symphysis. The teeth are small and close, and those most posterior are recurved, with smooth anterior and serrated posterior edges; 12 and 15-17 serrations are found along 5 mm of the upper and lower teeth. There are 19-20 teeth in the upper jaw, 33-35 in the lower.
There are six fused sacral vertebrae. Caudal vertebrae are platycoelous, lack ossified tendons, and are shortened proximally but increase in length distally. The chevrons of the proximal vertebrae are dorsoventrally elongated, while in the distal section they are gradually shortened up to the point of becoming flattened, elongated structures.
There is a mesotarsal joint of typical theropod appearance, represented by an astragalus with a high ascending process and a calcaneum connected to the distal end of the large tibia; this latter is closely adjacent to the end of the small, narrow fibula. The proximal metatarsus is thickened, the end of III is highly laterally compressed and displaced posteriorly, while the adjacent bones contact each other anteriorly. Differentiated from Saurornithoides mongoliensis by its larger size and greater tooth count. Besides the holotype, remains of the postcranial skeleton of another specimen, no. 100/2.