I have been thinking about wemic origins. I had heard that lion-centaurs appeared in ancient Assyrian art, so I sent e-mail messages to some experts, and I got some great info. I am incredibly grateful to the two professors who wrote back to me! Thank you!
I heard from Prof. Zainab Bahrani, the Edith Porada Associate Professor of Ancient Near Eastern Art and Archaeology, Director of Art Humanities, Department of Art History and Archaeology, Columbia University, Manhattan, N.Y.
Yes, the Lion centaur was a mythological creature in ancient Mesopotamia, and his image appears in the arts of the Assyrians and Babylonians. The best place to look this up is in a book by Jeremy Black and Anthony Green, Gods, Demons and Symbols of Ancient Mesopotamia. The book is a listing in alphabetical order so just look up the entry for lion.
But before I got the chance to get my hands on the book by Black and Green, I heard back from another professor. This response came from Prof. John M. Russell, Chair, Critical Studies Department, Massachusetts College of Art, Boston, Mass.
I've attached a couple of pages about this creature, the urmahlillu, from a book on protective creatures in Mesopotamia:
Wiggermann, F. A. M., Mesopotamian Protective Spirits: The Ritual Texts, (Cuneiform Monographs, 1), Groningen: Styx, 1992
I also give a picture of one rolled out from a Middle Assyrian cylinder seal (ca. 1300 BC) and one on a stone wall slab in a bathroom of the palace of king Assurbanipal at Nineveh (ca. 640 BC), now in the British Museum.
Here are the pictures Prof. Russell sent me:
This is the bathroom wall slab (above). Click on image for bigger version.
This is the cylinder seal image (above). Click on image for bigger version.
Prof. Russell was also kind enough to send me scans of two passages discussing lion centaurs in Ancient Assyria, both from "Mesopotamian Protective Spirits" by F. A. M. Wiggermann. In this passage, on page 181, Wiggermann describes the "Lion-Man," or "urmahlullu," as an extremely rare "unwinged lion-centaur" -- evidently there are winged versions as well, which may or may not be referred to as urmahlullu as well. And in this passage, on page 98, Wiggermann writes that the urmahlullu is a creature that protects bathrooms, possibly from the evil demon Sulak, which looks like a mundane lion.
Next up, I have to hunt down the book by Black and Green.