John L. Sorenson argues that "dragon" in the Book of Mormon is a reference to the crocodile or caiman.
John L. Sorenson, An Ancient American Setting for the Book of Mormon (Salt Lake City and Provo: Deseret Book and the Foundation for Ancient Research and Mormon Studies, 1985), 187-88
Another bit of Mesoamerican atmosphere appears in a figure of speech the writer used in Mosiah 20:11. "Like dragons did they fight," he wrote (see also Alma 43:44). What kind of "dragons" did he have in mind? The reference was probably to the crocodile or caiman. There are a number of reasons to think so. One colonial period observer described these saurians thus: "Very ferocious, and greatly feared. . . . Some of the caymans are from twenty to thirty feet and upwards in length . . . and covered with scales through which a musket ball cannot pierce. Their tails are very powerful and dangerous; and their mouths are large, with three rows of formidable teeth." But this "dragon" was much more than a dangerous bit of the natural world. In Mesoamerican mythology a giant creature of crocodilian form was thought to float on the supposed subterranean sea. His back was the surface of the earth, and his connection with earth and waters tied him symbolically with productivity and fertility. This "earth monster" is repeatedly shown at the base of relief carvings at Izapa (on the Chiapas/Guatemala border), in early Maya sculpture, and even in Olmec art, hence the idea is very old and fundamental. Mayan art represented an aspect of this being by a mere jawbone symbol. (Incidentally, the name Lehi means "cheekbone" or perhaps "jawbone." To be able to say that one was descended from "Jawbone," Lehi, would have been impressive among Mesoamericans.) The Book of Mormon and the Near Eastern cultural background from which it developed represents a crocodile-related monster in similar ways. Second Nephi 9:9-10, 19, and 26 picture "the devil" as a dragon or monster dwelling beneath the earth's surface. The Israelites shared with their Near Eastern neighbors the idea and image of this being as a symbol of chaos and evil. The Old Testament name of the creature is sometimes given as "leviathan." Its scaly back formed the ridges and hills of earth's surface. The "high places" where early Palestinian inhabitants worshipped were named from a root that meant "back of an animal." The sea creature—chaos—was thought to have been conquered by Jehovah in an ancient epic struggle (Isaiah 27:1; 51:9; Psalm 74:13-14). This is surely the dragon referred to in 2 Nephi 9:9 and the "old serpent" in Mosiah 16:3. The entire topic of dragons, monsters, and serpents is obviously too complex to do more than touch on here. We can at least note two things about Zeniff's dragon imagery: (1) it had powerful meaning to his listeners—beyond being a mere literary phrase, and (2) the complex of ideas is represented not only in the Book of Mormon but in Palestine and in Mesoamerica as well.