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The early evolution of postcranial skeletal pneumaticity in sauropodomorph dinosaurs

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Yates A. M., Wedel M. J., Bonnan M. F.
Acta Palaeontologica Polonica
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2012
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tom 57
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nr 1
Postcranial skeletal pneumaticity (PSP) is present in a range of basal sauropodomorphs spanning the basal sauropodomorph–sauropod transition. We describe the PSP of five taxa, Plateosaurus engelhardti, Eucnemesaurus fortis, Aardonyx celestae, Antetonitrus ingenipes, and an unnamed basal sauropod from Spion Kop, South Africa (hereafter referred to as the Spion Kop sauropod). The PSP of Plateosaurus is apparently sporadic in its occurrence and has only been observed in very few specimens, in which it is of very limited extent, affecting only the posterior cervical vertebrae and possibly the mid dorsals in one specimen. The PSP of Eucnemesaurus, Aardonyx, Antetonitrus, and the Spion Kop sauropod consists of subfossae (fossa−within−fossa structures) that excavate the vertices of the posterior infradiapophyseal fossae of the posterior dorsal vertebrae. These subfossae range from simple shallow depressions (Eucnemesaurus) to deep, steepsided, internally subdivided and asymmetrically developed chambers (Antetonitrus). The middle and anterior dorsal vertebrae of these taxa lack PSP, demonstrating that abdominal air sacs were the source of the invasive diverticula. The presence of pneumatic features within the infradiapophyseal fossae suggest that the homologous fossae of more basal saurischians and dinosauriforms were receptacles that housed pneumatic diverticula. We suggest that it is probable that rigid non−compliant lungs ventilated by compliant posterior air sacs evolved prior to the origination of Dinosauria.
2
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Anatomy of a basal sauropodomorph dinosaur from the Early Jurassic Hanson Formation of Antarctica

80%
Smith N. D., Pol D.
Acta Palaeontologica Polonica
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2007
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tom 52
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nr 4
The anatomy of a basal sauropodomorph (Dinosauria: Saurischia) from the Early Jurassic Hanson Formation of Antarctica is described in detail. The material includes a distal left femur and an articulated right pes, including the astragalus, distal tarsals, and metatarsals I–IV. The material is referable to Sauropodomorpha and represents a noneusauropod, sauropodomorph more derived than the most basal members of Sauropodomorpha (e.g., Saturnalia, Thecodontosaurus, Efraasia, and Plateosaurus) based on a combination of plesiomorphic and derived character states. Several autapomorphies present in both the femur and metatarsus suggest that this material represents a distinct sauropodomorph taxon, herein named Glacialisaurus hammeri gen. et sp. nov. Some of the derived characters present in the Antarctic taxon suggest affinities with Coloradisaurus and Lufengosaurus (e.g., proximolateral flange on plantar surface of metatarsal II, well−developed facet on metatarsal II for articulation with medial distal tarsal, subtrapezoidal proximal surface of metatarsal III). Preliminary phylogenetic analyses suggest a close relationship between the new Antarctic taxon and Lufengosaurus from the Early Jurassic Lufeng Formation of China. However, the lack of robust support for the taxon’s phylogenetic position, and current debate in basal sauropodomorph phylogenetics limits phylogenetic and biogeographic inferences drawn from this analysis. The new taxon is important for establishing the Antarctic continent as part of the geographic distribution of sauropodomorph dinosaurs in the Early Jurassic, and recently recovered material from the Hanson Formation that may represent a true sauropod, lends support to the notion that the earliest sauropods coexisted with their basal sauropodomorph relatives for an extended period of time.
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The titanosaur sauropods from the late Campanian-early Maastrichtian Allen Formation of Salitral Moreno, Rio Negro, Argentina

80%
Garcia R. A., Salgado L.
Acta Palaeontologica Polonica
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2013
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tom 58
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nr 2
The dinosaur record of the Salitral Moreno locality (Río Negro Province, Argentina) is characterized by a high diversity of herbivore taxa, among them hadrosaurs, ankylosaurs, and titanosaur sauropods, but carnivores are rare, consisting of only a few fragmentary bones of small forms. Titanosaurs are represented by Rocasaurus muniozi and Aeolosaurus sp., and at least four other taxa, represented by fragmentary material. The elements preserved include a cervical, dorsal and caudal vertebrae, chevron, humerii, ulnae, radii, metacarpal, femora, tibiae, metatarsal, ischia, pubis, and ilium. The Allen Formation is thought to be correlated with the Marília Formation in Brazil, and their faunas have certain elements in common such as aeolosaurines, but saltasaurines and hadrosaurs, are known exclusively from the Allen Formation. These absences, and particularly that of the saltasaurines, may be because those sauropods originated late in the Cretaceous, probably in southern South America (Northern Patagonia?), and they did not have time to disperse to northern South America.
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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.
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