(Greek: large, great, big, powerful)
When measuring in the metric [decimal] system, it means a million [U.S.] or millionfold [U.K.]: 106 [1 000 000]. The metric symbol for mega- is M.
The thoracic esophagus also loses its normal peristaltic activity and becomes dilated. Also called, cardiospasm.
Specifically, failure of the esophagogastric sphincter to relax when swallowing, because of the degeneration of ganglion cells in the wall of the organ.
2. Creatures that had the dual virtues of being dramatically large and coexistent with prehistoric humans who hunted mammoths and mastodons.
American megafauna once included: mammoths, camels, giant short-faced bears, giant armadillos, stag moose, glyptodonts (resembling giant armadillos), saber-toothed cats, dire wolves (larger and having more massive skulls than modern wolves), giant ground sloths, and horses, among others.