Dinosaurs once flourished near the North Pole

MOST ARTISTIC impressions of dinosaurs picture them in lush forests or on vast temperate savannahs. That is fair enough. Such landscapes were common during the beasts’ heydays, the Jurassic and Cretaceous periods. These pictures do, though, ignore the fact that dinosaur fossils have, for decades, been dug up in places which were at that time polar. Whether these are the remains of migrants which came for the summer, or of permanent residents, is debated. But a discovery of bone fragments and teeth from dinosaur hatchlings (see picture), just published in by Patrick Druckenmiller of University of Alaska, Fairbanks, and his colleagues, suggests some dinosaurs did indeed make their full-time homes in the Arctic.Modern animals that migrate to polar climes, notably birds, do often breed there. But their eggs hatch quickly and their young develop fast enough to fledge and fly to warmer places before winter arrives. Growth lines in fossilised dinosaur embryos found elsewhere suggest they needed as much as six or seven months of incubation before they were ready to hatch. Palaeontologists therefore reckon any discovery of fossilised eggs or hatchlings near the palaeo-poles would mean the species concerned must have been year-round residents rather than migrants.