Growth Dynamics of Australia's Polar Dinosaurs

Analysis of bone microstructure in ornithopod and theropod dinosaurs from Victoria, Australia, documents ontogenetic changes, providing insight into the dinosaurs' successful habitation of Cretaceous Antarctic environments. Woven-fibered bone tissue in the smallest specimens indicates rapid growth rates during early ontogeny. Later ontogeny is marked by parallel-fibered tissue, suggesting reduced growth rates approaching skeletal maturity. Bone microstructure similarities between the ornithopods and theropods, including the presence of LAGs in each group, suggest there is no osteohistologic evidence supporting the hypothesis that polar theropods hibernated seasonally. Results instead suggest high-latitude dinosaurs had growth trajectories similar to their lower-latitude relatives and thus, rapid early ontogenetic growth and the cyclical suspensions of growth inherent in the theropod and ornithopod lineages enabled them to successfully exploit polar regions

Nitrogen isotope analysis of 125,000-year-old tooth enamel from the Middle Palaeolithic Neanderthal site of Neumark-Nord 2, Germany

This study represents one of the first applications of a novel oxidation-denitrification method to measure the nitrogen isotope composition of tooth enamel in the archaeological record. Efforts to measure nitrogen isotopes in tooth enamel via traditional methods have not been feasible given the low nitrogen content of enamel (!0.01 % wt.) Here we present nitrogen isotope data of tooth enamel, which signiܪcantly expands the existing geochemical dataset at Neumark Nord, a high-resolution Middle Paleolithic (c125 kyr) site in Germany and provides insight into the structure of the paleo-food web at this locality, allowing us to make inferences about the environmental and ecological context of Neanderthals prior to the arrival of anatomically modern humans in Europe. In our study, we measured Ƚ 15 N enamel values in the tooth enamel of representative herbivore (n " 5), omnivore (n " 1), and carnivore taxa (n " 2) to reconstruct the paleoecology of the fauna at Neumark Nord 2. Our results show that herbivores have, on average, lower mean Ƚ 15 N enamel values (x" 5.3 ± 0.9 ‰) than omnivores (x" 7.7 ± 1.6 ‰) and carnivores (x" 6.6 ± 1.8 ‰). A previous study of herbivore Ƚ 15 N collagen at Neumark Nord 2 by Britton et al., 2012 found evidence for differences in dietary behavior between bovids and equids. We found similar patterning in Ƚ 15 N enamel values for the same taxa although the magnitude of the difference between taxa is somewhat smaller in enamel (1.2 vs. 2.0 ‰) compared to collagen