Gerrothorax pulcherrimus (Hellrung ). Plagiosaurids were a small clade of apparently water bottom-dwelling, flattened temnospondyls with broad skulls. On the left their arrangement is similar to that in the Kupferzell Gerrothorax ( Hellrung, fig. 17). The three curved ceratobranchials, which are aligned. Gerrothorax pustuloglomeratus, after Hellrung (): B, dorsal; E, has been referred to Plagiosuchus pustuliferus by Hellrung (), but.
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Studies on braincases of lower tetrapods: Up to the present day, the otic capsules are attached onto the ventral surface of the parasphenoid. Its walls are formed labially by gerrotgorax surangular, ventrally by the angular and lingually by the prearticular. This is somewhat supported by the lateral elongation of the skull in later plagiosaurids like Gerrothorax and Plagiosternum compared to earlier members such as Plagiosuchus .
Sign In or Create an Account. A, dorsal, and B, ventral views.
A revision of the plagiosaurid Plagiosternum granulosum Fraas Amphibia: Instead, their skulls were completely akinetic, as evidenced by their complicated, often three-dimensional sutures Schoch, In this The subtympanic fossa is large and mediolaterally elon- region, the quadrate contacts the ventral surface of the gate.
Laterally, the parasphenoid exoccipital is pierced by two foramina, a small ventrolat- makes contact with the pterygoids by an interdigitating eral foramen and a larger foramen anterodorsal to the suture, and posteriorly it forms a broad suture with the smaller one.
Although the morphology of the epipterygoid ids, however, the epipterygoid might be extensively ossi- closely resembles that of Plagiosternum danilovi see fied Schoch and Milner ; Schoch a.
The narrow mouth, which opened only anteriorly, and the weak dentition suggest a focus on small prey which was captured by specifically directed suction. Consequently, at its anterior-most point the adductor chamber is rather deeply recessed below the torus arcuatus. Dissorophoids, temnospondyl from the Middle Triassic of Crailsheim, Ger- eryopids and stereospondyls.
Labially, the dorsal margin of the fossa forms a much thickened torus arcuatus Shishkin, which becomes progressively—and considerably more—thicker anteriorly. Nevertheless, it is clearly thickened where ornament is most intensely developed, reaching up to approximately 7 mm inclusive of ornament. The cranium of Plagiosuchus pustuliferus can be distinguished from all other plagiosaurids by a suite of autapomorphies, as follows: Analogous with Plagiosternum mately round in cross section.
Reconstruction of the skull. The epipterygoid and neurocranium of G. A similar In anterior view i.
File:Gerrothorax – Wikimedia Commons
The basisphenoid region contacts Shishkin In Plagiosuchus pustuliferusthe adaptive requirements for expansion of the jaw-closing musculature is puzzling. In contrast to many stereospondylomorphs num danilovi Shishkin Posteriorly, within the unornamented strip, the quadratojugal bears a small accessory paraquadrate foramen near its contact with the quadrate.
Hence, in overall outline the skull is distinctly parabolic and is only moderately wider than it was long. The presence or absence of a supratemporal in that taxon has also been contentious.
Only parts of the sensory line system can be identified, probably because of the state of preservation of the specimen. Cranial morphology of the Loxommat- morphic for temnospondyls Romer and Witter ; idae Amphibia: The many studies for almost a century. The remarkable degree of cranial diversity within the Plagiosauridae is probably unrivalled within the Temnospondyli.
Mesozoic, neurocranium, otic, epipterygoid, laterosphenoid walls. Drawings of epipterygoid and neurocranium. The degree of ossification of the from the Middle Triassic of Germany is described for the epipterygoid, however, is subject to individual variation obvi- first time, based on outer morphological observations and ously independent from ontogenetic changes. A distinct angulation of the mandible occurs at the level of the coronoid process, such that the anterior, tooth-bearing section is continuously curved, whereas the posterior portion is somewhat straighter.
The lateral gerrothoraxx is vertically orientated and forms a continuously straight border to the subtemporal vacuity; its margin is rounded rather than sharp-edged, and in its anterior half the margin has a distinctly roughened surface.
Whether each ceratobranchial possesses a ventral arterial groove cannot be determined because of the poor state of preservation of these elements. A prootic and an opisthotic portion cannot be Witter From this limited set of data, and in the absence of crucial anatomical information particularly on musculatureonly limited conclusions can be drawn gerrothorx regard to what was probably a highly elaborate grerothorax system.
However, an anterior Meckelian foramen was clearly not present. A large hole in the midline of the skull anteriorly may or may not represent a natural vacuity, as discussed in the text. The sulcus on the jugal in SMNS may be interpreted in one of two ways.
The skull of G. On the morphology of ical Journal of the Linnean Society of London, 76, 29— The mouth entrance was therefore restricted to a very narrow opening anteriorly, a unique situation among temnospondyls. The cranial morphology of Greererp- — I, MHIsphenethmoid region with laterosphenoid walls grerothorax dorsal view. The depression might be interpreted as the sella fied basisphenoid region is situated immediately poster- turcica, and the foramina as housing the internal caro- ior gerroyhorax the sphenethmoid and the laterosphenoid walls tid arteries.
A fenestra occupying the same area in the Russian plagiosaurid material has been referred to as the cranioquadrate passage by Shishkin F, dorsal, G, ventral, and H, right lateral view.
The otics contact the basisphenoid, which shows well- cranium and palatoquadratum of Gerrothorax most closely developed sellar processes. The postparietal consists of an ornamented dorsal portion forming part of the skull roof, and an unornamented descending flange which forms part of the occipital surface.
The process is ill-defined but it appears to project from the ventral surface of the tabular, although whether it forms part gerroothorax the tabular cannot be determined.