Voyage of the Basilisk by Marie Brennan

Six years after her perilous exploits in Eriga, Isabella embarks on her most ambitious expedition yet: a two-year trip around the world to study all manner of dragons in every place they might be found, from feathered serpents in the ruins of a fallen civilization to the mighty sea serpents of the tropics. Facing storms, shipwrecks, and warfare, she makes a discovery that offers a revolutionary new insight into the ancient history of dragons.