scholarly journals The BrachyopoidHadrokkosaurus bradyifrom the Early Middle Triassic of Arizona, and a Phylogenetic Analysis of Lower Jaw Characters in Temnospondyl Amphibians

2008 ◽  
Vol 53 (4) ◽  
pp. 579-592 ◽  
Author(s):  
Marcello Ruta ◽  
John R. Bolt
Keyword(s):  
Phylogenetic Analysis ◽  
Middle Triassic ◽  
Lower Jaw ◽  
Early Middle Triassic

A kannemeyeriid dicynodont from the Middle Triassic Yerrapalli Formation

1988 ◽  
Vol 320 (1198) ◽  
pp. 185-233 ◽  
Keyword(s):  
Comparative Study ◽  
Small Area ◽  
Middle Triassic ◽  
Postcranial Skeleton ◽  
Total Length ◽  
Lower Jaw ◽  
Godavari Valley ◽  
Solitary Males ◽  
Early Middle Triassic ◽  
Single Locality

Wadiasaurus indicus is so far the only kannemeyeriid known for certain from India, from the early Middle Triassic Yerrapalli Formation of the Pranhita-Godavari valley. Recently, a large number of bones have been recovered from a single locality very close to the site from where the type skull of Wadiasaurus had been collected earlier. These new specimens indicate that modification of the skull characters given in previous descriptions is necessary, and also give information about the lower jaw and postcranial skeleton which confirms the familial status as earlier suggested. The parietal crest of the skull is quite specialized, forming a narrow median crest anteriorly but diverging posteriorly, half-way along its total length, to form two long rounded lobe-like bars separated by a bay. Maxillary flanges of the male members are triangular, thick and swollen, with stout cylindrical tusks; those of females are weak, laterally compressed and tuskless. A comparative study of Wadiasaurus and other kannemeyeriid genera indicates that it might have been most closely related to Kannemeyeria erithrea . A taphonomic study of the bone assemblage reveals that a herd of Wadiasaurus , including some juveniles and young animals, was trapped in the soft muds of a floodplain and buried in a small area. The herd was composed only of females, with some juvenile members. Taphonomic and osteological studies tend to indicate that the female individuals of Wadiasaurus lived in herds, whereas the solitary males joined the herds only during the mating seasons.

scholarly journals Integrated bio- and cyclostratigraphy of Middle Triassic (Anisian) ramp deposits, NW Bulgaria

2019 ◽  
Vol 70 (4) ◽  
pp. 325-354 ◽  
Author(s):  
George Ajdanlijsky ◽  
André Strasser ◽  
Annette E. Götz
Keyword(s):  
Middle Triassic ◽  
Time Frame ◽  
Small Scale ◽  
Lateral Migration ◽  
Sea Level Changes ◽  
Orbital Cycles ◽  
Sequence Boundaries ◽  
Bounding Surfaces ◽  
Early Middle Triassic ◽  
Major Sequence

Abstract A cyclostratigraphic interpretation of peritidal to shallow-marine ramp deposits of the early Middle Triassic (Anisian) Opletnya Member exposed in outcrops along the Iskar River gorge, NW Bulgaria, is presented. Based on facies trends and bounding surfaces, depositional sequences of several orders can be identified. New biostratigraphic data provide a time frame of the studied succession with placement of the boundaries of the Anisian substages and show that the Aegean (early Anisian) substage lasted about 1.6 Myr. In the corresponding interval in the two studied sections, 80 elementary sequences are counted. Five elementary sequences compose a small-scale sequence. The prominent cyclic pattern of the Opletnya Member can thus be interpreted in terms of Milankovitch cyclicity: elementary sequences represent the precession (20-kyr) cycle and small-scale sequences the short eccentricity (100-kyr) cycle in the Milankovitch frequency band. Medium-scale sequences are defined based on lithology but only in two cases can be attributed to the long eccentricity cycle of 405 kyr. The transgressive-regressive facies trends within the sequences of all scales imply that they were controlled by sea-level changes, and that these were in tune with the climate changes induced by the orbital cycles. However, the complexity of facies and sedimentary structures seen in the Opletnya Member also implies that additional factors such as lateral migration of sediment bodies across the ramp were active. In addition, three major sequence boundaries have been identified in the studied sections, which can be correlated with the boundaries Ol4, An1, and An2 of the Tethyan realm.

The oldest Diptera (Insecta) from the Upper Buntsandstein (early Middle Triassic) of Europe

Zootaxa ◽  
2021 ◽  
Vol 5067 (1) ◽  
pp. 135-143
Author(s):  
ELENA D. LUKASHEVICH
Keyword(s):  
Fossil Record ◽  
New Genus ◽  
Middle Triassic ◽  
Insect Fauna ◽  
The Family ◽  
Lower Franconia ◽  
Grès À Voltzia ◽  
Early Middle Triassic

The fossil record of Triassic Diptera is still poor, with the oldest dipteran assemblage described from the Upper Buntsandstein of the ‘Grès à Voltzia’ Formation (early Anisian, France). From the stratigraphically closest insect fauna of the Röt Formation of Lower Franconia, Germany, the first Diptera, Bashkonia franconica gen. et sp. nov. is described based on an isolated wing. The new genus is assigned to the family Nadipteridae, bridging the gap between two other genera included.  

The species of Rhyncosaurus , a rhynchosaur (Reptilia, Diapsida) from the Middle Triassic of England

1990 ◽  
Vol 328 (1247) ◽  
pp. 213-306 ◽  
Keyword(s):  
Body Length ◽  
Middle Triassic ◽  
Cladistic Analysis ◽  
Total Body Length ◽  
Late Triassic ◽  
Occipital Condyle ◽  
Stratigraphic Sequence ◽  
Skull Length ◽  
Aeolian Deposits ◽  
Lower Jaw

The rhynchosaur Rhynchosaurus articeps Owen, 1842, from the Middle Triassic of Grinshill, northern Shropshire, England, was a small reptile, about 0.5 m long. About 17 individual animals are represented by skulls, complete skeletons and partial skeletons, and these have permitted detailed restorations. The skull (60-80 mm long) is low and broad at the back, and it shows all of the typical rhynchosaur features of beak-like premaxillae, single median naris, fused parietal, broad maxillary tooth plate and dentary, both with multiple rows of teeth, and a deep lower jaw. The skeleton shows adaptations for fast terrestrial locomotion with a semi-erect hindlimb posture and for scratch-digging with the hind-foot. The skeleton is relatively more slender than that of most other middle and late Triassic rhynchosaurs, but this is probably an allometric effect of its much smaller size (they are typically 1-2 m long). A further species of Rhynchosaurus from Warwick, named here R. brodiei , is represented by 15 specimens of partial skulls, tooth-bearing elements, and isolated postcranial bones. It was slightly larger than R. articeps , with a typical skull length of 90 mm, and estimated body length of 0.6 m, but the skull length ranged up to 140 mm. It differs from R. articeps in having a much larger jugal in the cheek area, and in the greater height and breadth of the skull. The isolated maxillary fragments from Bromsgrove probably also belong to R. brodiei . The third species of Rhynchosaurus from Devon, named here R. spenceri , is now known from numerous specimens of at least 25 individuals, most of which were collected recently. These show a range in estimated skull length from 40 to 170 mm, but most specimens are at the upper end of that range, with an average skull length of 140 mm, and an estimated total body length of 0.9-1.0 m R. spenceri differs from R. articeps and R. brodiei in having a skull that is broader than it is long (otherwise a character of late Triassic rhynchosaurs), and it shares the large jugal character with R. brodiei . Teeth are not well preserved in R. articeps, but several specimens of R. brodiei and R. spenceri give detailed information. The pattern of wear, and the nature of the jaw joint, suggest that Rhynchosaurus had a precision-shear bite, as in other rhynchosaurs, with no back and forwards motion. The maxilla had two grooves, a major and a minor one, which received two matching ridges of the dentary on occlusion. The multiple rows of teeth on maxilla and dentary, and the surrounding bone, wore down as uniform units. The diet was probably tough vegetation, which was dug up by scratch-digging, raked together with the hands or the premaxillary beak, and manipulated in the mouth by a strong tongue. Rhynchosaurus is found variously in fluvial-intertidal deposits with evidence of desiccation (Grinshill, Warwick, Bromsgrove), and fluvial-aeolian deposits laid down in arid conditions with occasional flash floods (Devon). The bones have generally been transported (Warwick, Bromsgrove, Devon), but the Grinshill specimens are largely complete and undisturbed. The associated floras and faunas at Warwick, Bromsgrove, and Devon include pteridophytes, gymnospermopsids, bivalves, scorpions, freshwater fish, temnospondyl amphibians and reptiles (macrocnemids, thecodontians, ?procolophonids). Rhynchosaurs are archosauromorph diapsids, possibly related to the enigmatic Trilophosaurus, and a sister group to Prolacertiformes + Archosauria. A cladistic analysis of Rhynchosauria reveals one major subgroup, the Hyperodapedontinae ( Hyperodapedonand and Scaphonyx ), which is late Triassic in age. The earlier rhynchosaurs, including the middle Triassic Stenaulorhynchus and Rhynchosaurus , appear to form successively closer outgroups to the Hyperodapedontinae. The three species of Rhynchosaurus share only one possible synapomorphy in comparison with Stenaluorhynchus : The dentary is well over half the length of the lower jaw. The ‘Rhynchosaurinae’ ( Stenaulorhynchus and Rhynchosaurus ) was not established as a monophyletic group in the present analysis. These two genera share two postulated synapomorphies: the occipital condyle lies well in front of the quadrates, and there are two grooves on the maxilla and two ridges on the dentary. A third postulated synapomorphy, the presence of a single row of teeth on the pterygoid, has not been confirmed in this study for either Rhynchosaurus or Stenaulorhynchus . However, these postulated synapomorphies are outweighed by the synapomorphies that Rhynchosaurus shares with the Hyperodapedontinae. The specimens of Rhynchosaurus have been used as biostratigraphic indicators for the English middle Triassic, indicating Anisian to early Ladinian ages. The three species can be arranged in a sequence from ‘most prim itive’ to ‘most advanced’, but this cannot be used confidently to give a stratigraphic sequence.

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