Christopher T. Griffin
Virginia Tech
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Publications 12
1 CitationsSource
Large body sizes among nonavian theropod dinosaurs is a major feature in the evolution of this clade, with theropods reaching greater sizes than any other terrestrial carnivores. However, the early evolution of large body sizes among theropods is obscured by an incomplete fossil record, with the largest Triassic theropods represented by only a few individuals of uncertain ontogenetic stage. Here I describe two neotheropod specimens from the Upper Triassic Bull Canyon Formation of New Mexico and ...
#1Christopher T. Griffin (VT: Virginia Tech)H-Index: 4
#2Lauren S. Bano (VT: Virginia Tech)H-Index: 1
Last. Sterling J. Nesbitt (VT: Virginia Tech)H-Index: 31
view all 6 authors...
1 CitationsSource
#1Christopher T. Griffin (VT: Virginia Tech)H-Index: 4
#2Kenneth D. Angielczyk (FMNH: Field Museum of Natural History)H-Index: 30
Constraint is a universal feature of morphological evolution. The vertebral column of synapsids (mammals and their close relatives) is a classic example of this phenotypic restriction, with greatly reduced variation in the number of vertebrae compared with the sauropsid lineage. Synapsids generally possess only three sacral vertebrae, which articulate with the ilium and play a key role in locomotion. Dicynodont anomodonts are the exception to this rule, possessing seven or more sacral vertebrae ...
1 CitationsSource
#1Matthew A. McLainH-Index: 1
#2David R. Nelsen (Southern Adventist University)H-Index: 4
Last. Arthur V. Chadwick (Southwestern Adventist University)H-Index: 12
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ABSTRACT A recently discovered tyrannosaurid metatarsal IV (SWAU HRS13997) from the uppermost Cretaceous (Maastrichtian) Lance Formation is heavily marked with several long grooves on its cortical surface, concentrated on the bone's distal end. At least 10 separate grooves of varying width are present, which we interpret to be scores made by theropod teeth. In addition, the tooth ichnospecies Knethichnus parallelum is present at the end of the distal-most groove. Knethichnus parallelum is caused...
2 CitationsSource
8 CitationsSource
#1Christopher T. Griffin (VT: Virginia Tech)H-Index: 4
#2Candice M. Stefanic (SBU: Stony Brook University)H-Index: 2
Last. Michelle R. Stocker (VT: Virginia Tech)H-Index: 11
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The sacrum – consisting of those vertebrae that articulate with the ilia – is the exclusive skeletal connection between the hindlimbs and axial skeleton in tetrapods. Therefore, the morphology of this portion of the vertebral column plays a major role in the evolution of terrestrial locomotion. Whereas most extant reptiles only possess the two plesiomorphic sacral vertebrae, additional vertebrae have been incorporated into the sacrum multiple times independently among early-diverging archosauria...
4 CitationsSource
Abstract Compared with all other living reptiles, birds grow extremely fast and possess unusually low levels of intraspecific variation during postnatal development. It is now clear that birds inherited their high rates of growth from their dinosaurian ancestors, but the origin of the avian condition of low variation during development is poorly constrained. The most well-understood growth trajectories of later Mesozoic theropods (e.g., Tyrannosaurus, Allosaurus) show similarly low variation to ...
20 CitationsSource
ABSTRACTThe ontogeny of early-diverging dinosauromorphs is poorly understood because few ontogenetic series from the same species-level taxon are known and what is available has not been extensively documented. The large numbers of skeletal elements of the silesaurid Asilisaurus kongwe recently recovered from Tanzania provide an opportunity to examine the ontogenetic trajectory of the earliest known member of Ornithodira and one of the closest relatives to Dinosauria. We examined the ontogeny of...
31 CitationsSource