Megapaloelodus was named by American Alden H. Miller in 1944 on the basis of a fossil femur and tarsometatarsus collected from the lower Miocene Rosebud Formation of South Dakota.

Miller notes that the California bones presents a sizable gap in both space and time while also not overlapping with any of the type material established six years prior.

The name was chosen to reflect the fact that the first discovered Megapaloelodus remains, belonging to M. connectens, appeared to have been larger than the already big Palaelodus goliath.

For instance, some remains were found in the Sharktooth Hill Bonebed of Kern County (California),[10] while others were discovered in the Ituzaingó Formation of Argentina prior to the description of P.

Both have noticeable furrows along the edge of the pons supratendinous and lack the pits on the cranial surface that are noted for P. kurochkini (which may present a distinct genus of palaelodid).

[13] The articulation point between the coracoid and the clavicle overhangs two distinct pits that are much shallower in Palaelodus and missing entirely in modern flamingos, yet also present in the early Adelalopus.

[14] When compared to the same bones in other modern forms, "straight-legged" birds such as cranes and seriemas shows a tendency to flatten the profile of the internal condyle of the tibiotarsus.

In Megapaloelodus this is taken to an extreme, as the profile is not simply flattened but actually indented by a deep, rounded notch that is accompanied by a large, hooked process.

[2][3] Fossils assigned to this genus are oftentimes identified based on their greater size relative to Palaelodus species, which are generally smaller than those of Megapaloelodus.

[15] † Juncitarsus Podicipediformes † Palaelodidae †Harrisonavis Phoenicopterus Phoenicoparrus Although the exact function of the pronounced notches and hooked processes on the leg bones of Megapaloelodus is not known, Miller mentions the possibility that they may have anchored powerful ligaments.

According to him, a colleague suggested that this may have allowed these birds to "lock" their legs in an upright standing position while sleeping, thus stabilizing their resting posture.

[2] In the French locality of Saint-Gérand-le-Puy, Megapaloelodus goliath is known to have inhabited a brackish lacustrine environment that underwent cyclical wet and dry periods.

[16][15] The precise ecology of Megapaloelodus in this environment remains unknown due to the comparative lack of material, in particular that of the skull.