In the end, they decide to abandon Xarmus's cart and donkey - the danger of the donkey upsetting the canoe at an inopportune moment was just too high. Qawasha whispers in the beast's ear before they left, but it stands at the shore, looking bewildered, as the canoes head back into the morning glare on the river.
As the day progresses, the river begins to narrow. Tributaries join the Tiryki regularly, some of them nearly the width of the main river. The jungle becomes denser; from the boat, there are long stretches where the shoreline that look completely impenetrable. Qawasha points out interesting trees and vines from his seat at the front of the lead canoe.
Around midafternoon, the river widenes again, the western bank clearing of vegetation. A dozen stegosaurus stood at the watering "hole", drinking the silty water. Easily as tall as an elephant, but twice as long, the huge dinosaurs flicked their tails lazily as the stood belly-deep in the river. A few looked up curiously as you paddled by.
A shadow crosses the rear canoe, there and gone again, too quickly to be a cloud.
Spoiler: rear canoe, perception check 13+
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You look up to see a large bird wheel about over the river. Two more join it, flying together in a line. Their wingspan is enormous, fully 40 feet from wingtip to wingtip. The lead bird begins a steep dive towards the river, as if diving for an enormous fish. No, wait, not towards the river - towards the canoe! And there aren't feathers on those wings - these are quetzalccoatlus!