A Crested Theropod Dinosaur from Antarctica

Hammer, William R.; Hickerson, William J.

doi:10.1126/science.264.5160.828

Cited by 109 publications

(67 citation statements)

References 8 publications

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“…Possible Early Jurassic representatives of this clade are the Antarctic genus Cryolophosaurus (Hammer and Hickerson 1994;Sereno et al 1994Sereno et al , 1996 and the Chinese 'Dilophosaurus' sinensis (Hu 1993;Lamanna et al 1998), but more detailed descriptions and phylogenetic analyses of these taxa are needed to establish their tetanuran affinities. The alleged therizinosaur Eshanosaurus from the Lower Jurassic of China (Xu et al 2001) might rather represent a prosauropod (Rauhut 2003b).…”

Section: Evolutionary and Biogeographic Aspectsmentioning

confidence: 99%

Osteology and relationships of a new theropod dinosaur from the Middle Jurassic of Patagonia

Rauhut¹

2005

Palaeontology

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A new taxon of theropod dinosaur is described as Condorraptor currumili gen. et sp. nov., from the Middle Jurassic (Callovian) Cañadó n Asfalto Formation of Chubut Province, Argentinean Patagonia. The taxon is represented by a single fragmentary postcranial skeleton. Although incompletely known, Condorraptor is the second most complete theropod from the Middle Jurassic of Gondwana. The new taxon is characterized by the absence of a posterior incision between the fibular condyle and the medial side of the proximal articular end of the tibia, the pleurocoels in the anterior cervicals being situated posteroventral to the parapophyses, and the presence of a pronounced 'step' between the distal articular facet and shaft of Mt IV. Pneumatic features of the vertebral column show strong variation between the left and right side. Condorraptor gen. nov. can be referred to the Tetanurae and is a representative of a global radiation of basal tetanurans in the Early to Mid Jurassic.

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Section: Evolutionary and Biogeographic Aspectsmentioning

confidence: 99%

Osteology and relationships of a new theropod dinosaur from the Middle Jurassic of Patagonia

Rauhut¹

2005

Palaeontology

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“…The continent was once home to a diverse flora (Quilty 1990) and a fauna that included dinosaurs (Hammer & Hickerson 1994), the earliest representatives of the globe's modern avifauna (Clarke et al 2005), and presumably a wide variety of insects (Ashworth & Kuschel 2003). Likewise, extensive fossil floras characterized the oldest of the sub-Antarctic islands on the Kerguelen Plateau (Chastain 1958;Quilty & Wheller 2000).…”

Section: Variation Through Timementioning

confidence: 99%

Spatial and temporal variability across life's hierarchies in the terrestrial Antarctic

Chown

Convey

2007

Phil. Trans. R. Soc. B

200

197

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Antarctica and its surrounding islands lie at one extreme of global variation in diversity. Typically, these regions are characterized as being species poor and having simple food webs. Here, we show that terrestrial systems in the region are nonetheless characterized by substantial spatial and temporal variations at virtually all of the levels of the genealogical and ecological hierarchies which have been thoroughly investigated. Spatial variation at the individual and population levels has been documented in a variety of genetic studies, and in mosses it appears that UV-B radiation might be responsible for within-clump mutagenesis. At the species level, modern molecular methods have revealed considerable endemism of the Antarctic biota, questioning ideas that small organisms are likely to be ubiquitous and the taxa to which they belong species poor. At the biogeographic level, much of the relatively small ice-free area of Antarctica remains unsurveyed making analyses difficult. Nonetheless, it is clear that a major biogeographic discontinuity separates the Antarctic Peninsula and continental Antarctica, here named the 'Gressitt Line'. Across the Southern Ocean islands, patterns are clearer, and energy availability is an important correlate of indigenous and exotic species richness, while human visitor numbers explain much of the variation in the latter too. Temporal variation at the individual level has much to do with phenotypic plasticity, and considerable lifehistory and physiological plasticity seems to be a characteristic of Antarctic terrestrial species. Environmental unpredictability is an important driver of this trait and has significantly influenced life histories across the region and probably throughout much of the temperate Southern Hemisphere. Rapid climate change-related alterations in the range and abundance of several Antarctic and subAntarctic populations have taken place over the past several decades. In many sub-Antarctic locations, these have been exacerbated by direct and indirect effects of invasive alien species. Interactions between climate change and invasion seem set to become one of the most significant conservation problems in the Antarctic. We conclude that despite the substantial body of work on the terrestrial biodiversity of the Antarctic, investigations of interactions between hierarchical levels remain scarce. Moreover, little of the available information is being integrated into terrestrial conservation planning, which lags far behind in this region by comparison with most others.

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“…Cryolophosaurus ellioti Hammer and Hickerson (1994) originally noted the interesting mosaic of features present in Cryolophosaurus, and though they provided no detailed assessment of the taxon's relationships, they did suggest possible affinities with Middle-Late Jurassic tetanurans. Cryolophosaurus posseses a number of plesiomorphic characteristics with respect to tetanuran theropods, concentrated primarily in the post-cranial skeleton (e.g., amphicoelous cervical centra, a sigmoidal femur with an anteromedially directed head, a low, triangular astragalar ascending process; Smith et al, in press).…”

Section: Phylogenetic Reviewmentioning

confidence: 99%

“…Over the course of two field seasons of collecting , a quarry near the base of the Hanson Formation at approximately 4,100 meters on Mt. Kirkpatrick has yielded a diverse Early Jurassic vertebrate fauna (Hammer and Hickerson, 1994;Smith et al, in press;Hammer and Smith, in review;Smith and Pol, in review). Faunal elements include a nearly complete skeleton of the theropod dinosaur Cryolophosaurus ellioti, a distal left femur and articulated right metatarsus of a basal sauropodomorph dinosaur ( Fig.…”

Section: Introductionmentioning

confidence: 99%

The dinosaurs of the Early Jurassic Hanson Formation of the Central Transantarctic Mountains: phylogenetic review and synthesis

Smith¹,

Makovicky²,

Hammer³

et al. 2007

Open-File Report

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The Hanson Formation of the Central Transantarctic Mountains has yielded a diverse Early Jurassic terrestrial fauna, which includes the nearly complete theropod dinosaur, Cryolophosaurus ellioti, and a fragmentary basal sauropodomorph dinosaur. The Hanson Formation dinosaurs are important for understanding early dinosaur evolution because: 1) they preserve a mosaic of morphological traits that render them useful for interpreting poorly known parts of the dinosaur evolutionary tree; 2) they are from the Early Jurassic, a critical period in early dinosaur evolution about which knowledge is scant; and 3) they are the only known Early Jurassic dinosaurs from Antarctica, making them particularly valuable for understanding patterns of biotic interchange during this time. Recent research suggests that Cryolophosaurus belongs to a geographically widespread clade of mid-sized, Early Jurassic theropods with cranial crests that includes Dilophosaurus wetherilli, 'Dilophosaurus' sinensis, and Dracovenator, and renders Coelophysoidea sensu lato non-monophyletic. The Antarctic sauropodomorph represents a distinct taxon that is a member of a similarly diverse massospondylid clade. This taxon shares a number of features with more derived sauropodomorphs, and provides additional evidence for the paraphyly of Prosauropoda. The phylogenetic relationships of the Antarctic dinosaurs are also consistent with a pattern of worldwide faunal homogeneity between Early Jurassic continental biotas. Furthermore, these analyses support a "ladder-like" arrangement for basal theropod and basal sauropodomorph phylogeny, suggesting that these groups passed through "coelophysoid" and "prosauropod" stages of morphological organization early in their respective evolutionary histories.

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A Crested Theropod Dinosaur from Antarctica

Cited by 109 publications

References 8 publications

Osteology and relationships of a new theropod dinosaur from the Middle Jurassic of Patagonia

Osteology and relationships of a new theropod dinosaur from the Middle Jurassic of Patagonia

Spatial and temporal variability across life's hierarchies in the terrestrial Antarctic

The dinosaurs of the Early Jurassic Hanson Formation of the Central Transantarctic Mountains: phylogenetic review and synthesis

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