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New sauropod trackways from the Middle Jurassic of Portugal

100%

Santos V. F., Moratalla J. J., Royo-Torres R.

Acta Palaeontologica Polonica

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2009

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tom 54

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nr 3

409-422

The Galinha tracksite reveals a sequence of Bajocian–Bathonian limestones belonging to the Serra de Aire Formation (West−Central Portugal) and is one of the few sites in the world where Middle Jurassic sauropod dinosaur tracks can be found. This tracksite is characterised by the presence of long, wide gauge sauropod trackways, the Middle Jurassic age of which suggests these dinosaurs were more widely distributed over time than previously thought. Two trackways contain unique pes and manus prints with morphologies that allow a new sauropod ichnotaxon to be described: Polyonyx gomesi igen. et isp. nov. On the basis of different manus/pes prints and trackway features, the proposal is made to subdivide Sauropodomorpha ichno−morphotypes into five groups: Tetrasauropus−like, Otozoum−like, Breviparopus/Parabrontopodus−like; Brontopodus−like, and Polyonyx−like. Polyonyx gomesi igen. et isp. nov. is thought to represent a nonneosauropod eusauropod, with a well developed manus digit I. The posterior orientation of this digit print suggests they were made by a eusauropod dinosaur with a posteriorly rotated pollex. The manus print morphologies observed in two trackways suggest a stage of manus structure intermediate between the primitive non−tubular sauropod manus and the tubular metacarpal arrangement characteristic of more derived sauropods. The low heteropody (manus:pes area ratio 1:2) of the trackway renders it possible they could have been made by eusauropods such as Turiasaurus riodevensis, which has a similar manus:pes area ratio. The Polyonyx igen. nov. trackway was made by non−neosauropod eusauropod, and suggests that wide gauge sauropod trackways were not exclusively made by Titanosauriformes.

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In quest of the Pteraichnus trackmaker: Comparisons to modern crocodilians

80%

Kubo T.

Acta Palaeontologica Polonica

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2008

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tom 53

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nr 3

The Pteraichnustrackmaker is usually hypothesized to be either a pterosaur or a crocodilian. Though the latter interpretation is recently not widely accepted, more experimental work on trackways of extant crocodilians is necessary to settle the debate. Here, the trackways of three species of modern crocodiles (Paleosuchus trigonatus, Crocodylus porosus, and Tomistoma schlegelii) in all major gaits and postures, namely sprawling, walking and running, were compared with Pteraichnus trackways. In all experimentally generated crocodilian trackways pentadactyl manus tracks are recognized, the external width between pes tracks is wider than the corresponding internal width between manus tracks, and tail marks are usually present. All crocodilian trackways collected in the present study revealed significant differences from Pteraichnus, which strongly suggests a non−crocodilian origin of Pteraichnus.

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Crouching theropod and Navahopus sauropodomorph tracks from the Early Jurassic Navajo Sandstone of USA

70%

Milan J., Loope D. B., Bromley R. G.

Acta Palaeontologica Polonica

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2008

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tom 53

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nr 2

Numerous tracks and trackways are preserved in the a cross−strata of the Lower Jurassic Navajo Sandstone of northern Arizona and southern Utah, USA. Tracks and trackways of small theropod dinosaurs are particularly abundant within one 10−m−thick interval. This paper describes a crouching trace from a theropod dinosaur that shows impressions of all four limbs, the ischial callosity, the tail, and tracks leading to and away from the crouching site, and revises the interpretation of a well preserved trackway hitherto referred to the synapsid ichnogenus Brasilichnium and here considered to be from a sauropodomorph dinosaur. It is named Navahopus coyoteensisisp. nov. on the basis of morphological differences from the type ichnospecies N. falcipollex. The ichnofamily Navahopodidae is revised to include Tetrasauropous unguiferus, Navahopus falcipollex, and N. coyoteensis.

Ograniczanie wyników

3 Acta Palaeontologica Polonica

1 Bromley R. G.

1 Kubo T.

1 Loope D. B.

1 Milan J.

1 Moratalla J. J.

1 Royo-Torres R.

1 Santos V. F.

1 2009

2 2008

New sauropod trackways from the Middle Jurassic of Portugal

In quest of the Pteraichnus trackmaker: Comparisons to modern crocodilians

Crouching theropod and Navahopus sauropodomorph tracks from the Early Jurassic Navajo Sandstone of USA