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Hadrosaurid jaw mechanics

100%

Weishampel D. B.

Acta Palaeontologica Polonica

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1983

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tom 28

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nr 1-2

Jaw systems in hadrosaurids can be treated as chewing machines operating in three dimensions. As such, different possibilities of jaw mechanisms can be tested by using kinematic analyses to make predictions about tooth wear for each mechanism, ranging from akinetic monimostylic skulls to kinetic streptostylic skulls. A hadrosaurid jaw mechanism that includes a degree of lateral rotation of the maxilla-premaxilla joint, as well as laterocaudal streptostyly and mobility of other articulations, accounts for tooth wear present in these animals better than the currently-accepted propalinal mechanism. Lateral rotation of the maxilla and concomittant motion of other cranial segments is powered by mandibular adduction, and is best seen as a solution to a transverse power stroke constrained by an isognathous jaw system.

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First evidence of azhdarchid pterosaurus from the Late Cretaceous of Hungary

51%

Osi A., Weishampel D. B., Jianu C. M.

Acta Palaeontologica Polonica

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2005

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tom 50

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nr 4

777-787

New remains of an azhdarchid pterosaur were discovered from the Upper Cretaceous (Santonian) Csehbánya Formation at the Iharkút vertebrate locality in the Bakony Mountains, western Hungary. Among the isolated bones, consisting principally of 21 symphyseal jaw fragments, four cervical vertebrae, a right radius, and some fragmentary limb bones, is a complete articulated mandible that represents one of the best−preserved mandibular material of any presently known azhdarchid pterosaur. The complete edentulous jaw, referred to Bakonydraco galaczi gen. et sp. nov. posesses several features diagnostic for azhdarchids which prove that Bakonydraco belongs to this group. The cervical vertebrae exhibit azhdarchid features and consequently are referred to as Azhdarchidae indet. The discovery of these fossils helps to understand the construction of the azhdarchid mandible and provides new insight for studying the feeding style of the edentulous azhdarchid pterosaurs.

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The dinosaur Hadrosaurus foulkii, from the Campanian of the East Coast of North America, with a reevaluation of the genus

51%

Prieto-Marquez A., Weishampel D. B., Horner J. R.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 1

Hadrosaurus foulkii was the first dinosaur known outside Europe from partially complete skeletal elements. It is the holotype of the family Hadrosauridae and the subfamily Hadrosaurinae. The history of its discovery and taxonomy is reviewed, and the holotype of H. foulkii is redescribed. The holotype of H. foulkii lacks distinguishing characters; therefore, this taxon is a nomen dubium. It is not synonymous with species of Gryposaurus and/or Kritosaurus. We also reevaluate the taxonomy and osteology of H. tripos, H. minor, H. cavatus, H. breviceps, H. paucidens, and Ornithotarsus immanis. In agreement with previous studies, these taxa are considered nomina dubia due to the absence of distinguishing characters and are therefore referrable only to Hadrosauridae indeterminate; H. paucidensis referrable to Lambeosaurinae indeterminate. Finally, our phylogenetic analysis indicates that the holotype of H. foulkii belongs to a member of Euhadrosauria and, tentatively, of Hadrosaurinae.

Ograniczanie wyników

3 Acta Palaeontologica Polonica

3 Weishampel D. B.

1 Horner J. R.

1 Jianu C. M.

1 Osi A.

1 Prieto-Marquez A.

1 2006

1 2005

1 1983

Hadrosaurid jaw mechanics

First evidence of azhdarchid pterosaurus from the Late Cretaceous of Hungary

The dinosaur Hadrosaurus foulkii, from the Campanian of the East Coast of North America, with a reevaluation of the genus