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[dinosaur] Rhynchosaur maxillary tooth from Ischigualasto Formation + Sharpeyâs fibers in amphibians + creating 3D models





Ben Creisler
bcreisler@gmail.com



Some recent non-dino papers:





Adriel R. Gentil & MartÃn D. Ezcurra (2018)

A new rhynchosaur maxillary tooth plate morphotype expands the disparity of the group in the Ischigualasto Formation (Late Triassic) of Northwestern Argentina.

Historical Biology (advance online publication)

doi:Â https://doi.org/10.1080/08912963.2018.1438425ÂÂ

http://www.tandfonline.com/doi/full/10.1080/08912963.2018.1438425

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Rhynchosaurs are a clade of quadruped, herbivorous stem-archosaur diapsids restricted to the Triassic Period. The group became globally distributed and the numerically dominant tetrapods of several terrestrial ecosystems before their extinction. Derived rhynchosaurs are characterized by a specialized masticatory apparatus, composed of a blade-and-groove occlusion with multiple longitudinal maxillary tooth rows. The morphology of the maxillary tooth plate has shown to be taxonomically and phylogenetically informative. So far, two rhynchosaur maxillary tooth plate morphotypes are known in Argentina, one belonging to an unnamed stenaulorhynchine from the ChaÃares Formation and the other to the hyperodapedontine Hyperodapedon sanjuanensis, the single rhynchosaur species currently name for the Ischigualasto Formation. Here we describe a new rhynchosaur maxillary tooth plate morphotype based on an indeterminate hyperodapedontine specimen from the Ischigualasto Formation. This maxillary tooth plate (PVL 2728) possesses a single longitudinal groove that divides symmetric lateral and medial tooth-bearing areas with relatively large tooth crowns, which is an uncommon combination of features among hyperodapedontines. These qualitative observations in addition to quantitative analyses show that the morphology of PVL 2728 differs from that of, at least, other sampled South American rhynchosaurs. Therefore, this specimen expands the morphological disparity of rhynchosaurs in northwest Argentina and southwestern Pangaea.

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Free pdf:

Krzysztof Kolenda, Anna Najbar, Beata Rozenblut-KoÅcisty, Ewa Serwa & Tomasz SkawiÅski (2018)

Common occurrence of Sharpeyâs fibres in amphibian phalanges.

Zoomorphology (advance online publication)

DOI: https://doi.org/10.1007/s00435-018-0400-4

https://link.springer.com/article/10.1007%2Fs00435-018-0400-4

https://link.springer.com/content/pdf/10.1007%2Fs00435-018-0400-4.pdf

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Sharpeyâs fibres are known mainly as providing anchorage between tooth and the periodontal ligament but they occur also in other types of bones. In the postcranial skeleton these fibres are usually present at the muscle or tendon attachment sites. They were reported in all major groups of extant vertebrates, as well as in putative lissamphibian ancestorsâtemnospondyls and lepospondyls. However, it was recently stated that their presence was very rarely described in extant amphibians. In limbs, they were reported predominantly from proximal bones. They have not yet been reported from phalanges, which are the most commonly sectioned amphibian bones. Here, we describe phalangeal histology of nine species representing most major clades of lissamphibians. These results show that Sharpeyâs fibres occur commonly in lissamphibian phalanges. In shaft, they are radially oriented and occur in the periosteal bone, at sites of tendon attachment. They can also occur in the metaphysis and contact the cartilage. This may provide a basis for foot muscle reconstructions in fossil amphibians.




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Free pdf:

Maximilian Albrecht, Marlene HÃhle, Norbert Hauschke & Wolfgang Gossel (2018)

Zum Einsatz photogrammetrischer Methoden bei der Erzeugung von 3D-Modellen palÃontologischer Objekte aus den Geologisch- PalÃontologischen Sammlungen der Martin-Luther-UniversitÃt Halle-Wittenberg.

[Using photogrammetric methods in the production of 3D models of paleontological objects from the geological-paleontological collections of Martin Luther University Halle-Wittenberg]

Hallesches Jahrbuch fÃr Geowissenschaften 41: 35-54 (in German)

http://public.bibliothek.uni-halle.de/index.php/hjg/article/view/1928



In a first step, laserscanner systems were applied to produce 3D models of palaeontological objects, which are part of the Geological and Palaeontological Collections of Martin-Luther-University Halle-Wittenberg. This paper deals with photogrammetric methods, which were tested in a second step. It was of special interest, to create 3D models of fossils with different size and relief. Most of the fossils came into the University collections on the initiative of Hermann Burmeister (1807-1892), who was a professor of zoology at Halle University. Skulls of the two extinct stereospondyl amphibian species Trematosaurus brauni and Parotosuchus nasutus from the Middle Buntsandstein of Bernburg (Saale) with a maximum size of 60 cm belong to the smaller objects. In contrast, the extinct teleosaurid crocodyliform species Steneosaurus bollensis from the Early Jurassic of Bad Boll and Holzmaden measures up to 3.5 m. The advantages of photogrammetric over laserscanner methods are discussed.


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