DINOWEB - палеозойские и мезозойские тетраподы

The skull of Anshunsaurus huangnihensis Cheng, 2007, especially the skull roof, is described in detail in this paper. Compared to other genera and species of Askeptosauroidea, Anshunsaurus huangnihensis has some important transitional characters from Askeptosaurus italicus to Anshunsaurus huangguoshuensis: the rostral length related to the skull length between Askeptosaurus italicus and Anshunsaurus huangguoshuensis; the postfrontal existing but distinctly reduced; the posterolateral process relatedly short and overlapping the parietal. The phylogenetic analysis weakly supports the evolutional progress from Anshunsaurus huangnihensis to Anshunsaurus huangguoshuensis. The skeletal ratios indicated that the node among the Askeptosauridae ingroup. The evolutional direction of Askeptosauridae should be from Askeptosaurus italicus to Anshunsaurus huangguoshuensis. The skeletal ratios indicated that the evolutional progress is Askeptosaurus italicus – Anshunsaurus huangnihensis – Anshun ... Читать дальше »

The medial Permian (?270–260 Ma: Guadalupian) was a time of important tetrapod faunal changes, in particular reflecting a turnover from pelycosaurian- to therapsid-grade synapsids. Until now, most knowledge on tetrapod distribution during the medial Permian has come from fossils found in the South African Karoo and the Russian Platform, whereas other areas of Pangaea are still poorly known. We present evidence for the presence of a terrestrial carnivorous vertebrate from the Middle Permian of South America based on a complete skull. Pampaphoneus biccai gen. et sp. nov. was a dinocephalian "mammal-like reptile” member of the Anteosauridae, an early therapsid predator clade known only from the Middle Permian of Russia, Kazakhstan, China, and South Africa. The genus is characterized, among other features, by postorbital bosses, short, bulbous postcanines, and strongly recurved canines Phylogenetic analysis indicates that the Brazilian dinocephalian occupies a middle position within t ... Читать дальше »

We describe the new aetosaur Aetobarbakinoides brasiliensis gen. et sp. nov. from the early Late Triassic (late Carnianearly Norian) Brazilian Santa Maria Formation. The holotype is composed of a partial postcranium including several cervical and dorsal vertebrae and ribs, one anterior caudal vertebra, right scapula, right humerus, right tibia, partial right pes, and anterior and mid-dorsal paramedian osteoderms. Aetobarbakinoides is differentiated from other aetosaurs by the presence of cervical vertebrae with widely laterally extended prezygapophyses, mid-cervical vertebrae with anterior articular facet width more than 1.2 times wider than the posterior one, anterior caudal vertebrae with extremely anteroposteriorly short prezygapophyses, elongated humerus and tibia in relation to the axial skeleton, and paramedian osteoderms with a weakly raised anterior bar. A cladistic analysis recovered the new species as more derived than the South American genera Aetosauroides (late Carnia ... Читать дальше »

Background: Sauropod dinosaurs were the largest animals ever to walk on land, and, as a result, the evolution of their

remarkable adaptations has been of great interest. The braincase is of particular interest because it houses the brain and inner ear. However, only a few studies of these structures in sauropods are available to date. Because of the phylogenetic position of Spinophorosaurus nigerensis as a basal eusauropod, the braincase has the potential to provide key evidence on the evolutionary transition relative to other dinosaurs.

Methodology/Principal Findings: The only known braincase of Spinophorosaurus (‘Argiles de l’Irhazer’, Irhazer Group;

Agadez region, Niger) differs significantly from those of the Jurassic sauropods examined, except potentially for Atlasaurus imelakei (Tilougguit Formation, Morocco). The basisphenoids of Spinophorosaurus and Atlasaurus bear basipterygoid processes that are comparable in being directed strongly caudally ... Читать дальше »

Background: Associated postcranial skeletons of pachycephalosaurids, most notably those of Stegoceras and Homalocephale, reveal enigmatic osseous structures not present in other tetrapod clades. The homology and functional

significance of these structures have remained elusive as they were originally interpreted to be abdominal ribs or gastralia, and more recently have been interpreted as de novo structures in the tail.

Principal Findings: Analysis of these structures in nearly all pachycephalosaurid skeletons has facilitated a complete

description of their architecture, and the establishment of patterns consistent with those of myorhabdoid ossifications —

ossifications of the myoseptal tendons associated with myomeres. The presence and structure of myorhabdoid ossifications are well established for teleost fish, but this marks their first recognition within Tetrapoda. These elements are both structurally and histologically distinct from the ... Читать дальше »

The present study re-evaluates Chuanjiesaurus anaensis Fang et al., 2000 from the Middle Jurassic of Lufeng,Yunnan, Southwest China. The holotype and a new referred specimen are described in detail, and re-examined osteologically and phylogenetically. In this report, the author proposes several emended diagnoses based on close observations and comparisons of the specimens. Some osteological features reveal that Chuanjiesaurus belongs to Mamenchisauridae. Compared to other mamenchisaurid dinosaurs, C. anaensis possesses relatively primitive characters. The phylogenetic position of C. anaensis was determined according to the present analysis. In addition,the data sets of some taxa of Mamenchisauridae from southwestern China are modified in the present research. The present analysis reveals that C. anaensis, Mamenchisaurus, Tienshanosaurus and Yuanmousaurus constitute a monophyletic group that belongs to relatively derived Eusauropoda. This suggests that Mamenchisauridae could be pos ... Читать дальше »