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An ankylosaurid dinosaur from Mongolia with in situ armour and keratinous scale impressions

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Arbour V. M., Lech-Hernes N. L., Guldberg T. E., Hurum J. H., Currie P. J.

Acta Palaeontologica Polonica

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2013

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tom 58

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nr 1

A Mongolian ankylosaurid specimen identified as Tarchia gigantea is an articulated skeleton including dorsal ribs, the sacrum, a nearly complete caudal series, and in situ osteoderms. The tail is the longest complete tail of any known ankylosaurid. Remarkably, the specimen is also the first Mongolian ankylosaurid that preserves impressions of the keratinous scales overlying the bony osteoderms. This specimen provides new information on the shape, texture, and ar− rangement of osteoderms. Large flat, keeled osteoderms are found over the pelvis, and osteoderms along the tail include large keeled osteoderms, elongate osteoderms lacking distinct apices, and medium−sized, oval osteoderms. The specimen differs in some respects from other Tarchia gigantea specimens, including the morphology of the neural spines of the tail club handle and several of the largest osteoderms.

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Hands, feet, and behaviour in Pinacosaurus (Dinosauria: Ankylosauridae)

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Currie P. J., Badamgarav D., Koppelhus E. B., Sissons R., Vickaryous M. K.

Acta Palaeontologica Polonica

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2011

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tom 56

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nr 3

Structure of the manus and pes has long been a source of confusion in ankylosaurs, owing to the imperfect preservation or complete lack of these parts of the skeletons in most specimens, and the fact that many species appear to have undergone a reduction in numbers of digits and phalanges. New specimens of Pinacosaurusfrom Alag Teeg in Mongolia confirm that the phalangeal formula of the manus is 2−3−3−3−2. However, there are only three toes in the pes, which has a phalangeal formula of X−3−3/4−3/4−X. Importantly, the number of phalanges in the third and fourth pedal digits can vary between either three or four per digit, even within the same specimen. The Alag Teeg site has yielded as many as a hundred skeletons of the ankylosaur Pinacosaurus, most of which were immature when they died. Each skeleton is preserved in an upright standing position, with the bones of the lower limbs often in articulation. The remainder of the skeleton, including the upper parts of the limbs, is generally disarticulated and somewhat scattered. Based on the presence of large numbers of juvenile Pinacosaurus specimens at Alag Teeg, as well as other Djadokhta−age sites (Ukhaa Tolgod in Mongolia, Bayan Mandahu in China), it seems juvenile Pinacosaurus were probably gregarious.

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A new ankylosaurid from the Late Cretaceous Two Medicine Formation of Montana, USA

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Penkalski P.

Acta Palaeontologica Polonica

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2014

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tom 59

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nr 3

Oohkotokia horneri gen. et sp. nov. is described based on a specimen in the collections of the Museum of the Rockies, Montana, USA. Oohkotokia exhibits a unique combination of characters not seen in other late Campanian North American ankylosaurids: prominent, horn-like, trihedral squamosal bosses, a small, undistinguished median nasal plate on the dorsal surface of the rostrum, a relatively small occipital condyle, a smooth, finely pitted osteoderm external texture, and triangular lateral osteoderms. Other specimens from the Two Medicine Formation are referable to Oohkotokia. O. horneri, Euoplocephalus tutus, Dyoplosaurus acutosquameus, and Scolosaurus cutleri separate stratigraphically.

Ograniczanie wyników

3 Acta Palaeontologica Polonica

2 Currie P. J.

1 Arbour V. M.

1 Badamgarav D.

1 Guldberg T. E.

1 Hurum J. H.

1 Koppelhus E. B.

1 Lech-Hernes N. L.

1 Penkalski P.

1 Sissons R.

1 Vickaryous M. K.

1 2014

1 2013

1 2011

An ankylosaurid dinosaur from Mongolia with in situ armour and keratinous scale impressions

Hands, feet, and behaviour in Pinacosaurus (Dinosauria: Ankylosauridae)

A new ankylosaurid from the Late Cretaceous Two Medicine Formation of Montana, USA