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Definitive fossil evidence for the extant avian radiation in the Cretaceous
A rare, partial skeleton from the Maastrichtian of Antarctica is identified as the first Cretaceous fossil definitively placed within the extant bird radiation, and phylogenetic analyses supported by independent histological data indicate that a new species, Vegavis iaai, is a part of Anseriformes (waterfowl) and is most closely related to Anatidae, which includes true ducks.
A Basal Dromaeosaurid and Size Evolution Preceding Avian Flight
- A. Turner, D. Pol, J. Clarke, G. Erickson, M. Norell
- Biology, Environmental ScienceScience
- 7 September 2007
Change in theropod body size leading to flight's origin was not unidirectional, and the two dinosaurian lineages most closely related to birds, dromaeosaurids and troodontids, underwent four independent events of gigantism, and in some lineages size increased by nearly three orders of magnitude.
Growth curve of Psittacosaurus mongoliensis Osborn (Ceratopsia: Psittacosauridae) inferred from long bone histology
The first reconstruction of a growth curve (mass vs. age) for a dinosaur was made for this taxon using a new method called Developmental Mass Extrapolation, and the results suggest P. mongoliensis had an S-shaped growth curve characteristics of most extant vertebrates, and had maximal growth rates that exceeded extant reptiles and marsupials, but were slower than most avian and eutherian taxa.
Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs
- G. Erickson, P. Makovicky, P. Currie, M. Norell, S. Yerby, C. Brochu
- Environmental Science, GeographyNature
- 12 August 2004
Growth patterns within the Tyrannosauridae are studied and it is determined that Tyrannosaurus rex's great stature was primarily attained by accelerating growth rates beyond that of its closest relatives.
A basal tyrannosauroid dinosaur from the Late Jurassic of China
The tyrannosauroid fossil record is mainly restricted to Cretaceous sediments of Laurasia, although some very fragmentary Jurassic specimens have been referred to this group. Here we report a new…
A Jurassic ceratosaur from China helps clarify avian digital homologies
A new basal Ceratosaur from the Oxfordian stage of the Jurassic period of China is reported, representing the first known Asian ceratosaur and the only known beaked, herbivorous Jurassic theropod, and possesses a strongly reduced manual digit I, documenting a complex pattern of digital reduction within the Theropoda.
Assessing dinosaur growth patterns: a microscopic revolution.
- G. Erickson
- Geography, Environmental ScienceTrends in ecology & evolution
- 1 December 2005
Coincident development of sesamoid bones and clues to their evolution
Examination of radiographs of 112 people demonstrated that the relatively infrequent appearances of the fabella and os peroneum are related within individuals, suggesting that the tendency to form sesamoids may be linked to intrinsic genetic factors.
Evolution of the biomechanical material properties of the femur
Material properties of the first long bones 475 million years ago were conserved throughout evolution, and major locomotory challenges to femora during vertebrate evolution were almost solely accomplished by modifications of element size and shape.
The ontogeny of bite-force performance in American alligator (Alligator mississippiensis)
The bite-force values for adult A. mississippiensis are the highest measured for any living animal and represent the first measures for a large crocodilian, and provide the first documentation of how bite force changes during ontogeny in a reptile.