Better dates for Arctic dinosaurs



The Prince Creek Formation near Ocean Point on the Arctic coastal plain of northern Alaska contains hadrosaur (duck-billed dinosaur) bones, as well as an abundant fauna of mollusks, ostracodes, brachiopods, foraminifers, and palynomorphs. Evaluation of the marine mollusks and ostracodes suggested a Paleocene age for these strata to Marincovich et al. [1985]. A fission-track age on zircon of 50.9 +/− 7.7 Ma from an interbedded tephra [Carter et al., 1977] suggested that they could be as young as early Eocene. If the mollusk, ostracod, and fission-track ages are correct, the hadrosaurs would be of early Cenozoic age—one of the few recorded occurrences of dinosaurs younger than Cretaceous. The foraminifers, pollen, and spores, however, strongly suggest a Late Cretaceous age for their beds [Brouwers et al., 1987].