Dinosaurs that lived in Arctic regions 70 million years ago likely endured long, dark polar winters, a team of researchers has revealed. The team worked with fossils of herbivorous dinosaurs excavated in Alaska. Allison Tumarkin-Deratzian of Temple's Earth and Environmental Science Department analyzed thin layers of the dinosaurs' bone and found evidence that the animals endured shifting Arctic seasons rather than making annual migrations to milder climates. "What we found was that periodically, throughout their life, these dinosaurs were switching how fast they were growing," she said. "We interpreted this as potentially a seasonal pattern."