Megapaloelodus is an extinct genus of stem flamingo of the family Palaelodidae. Megapaloelodus is primarily known from Miocene America, from South Dakota and Oregon in the north to Argentina in the south, but the species Megapaloelodus goliath was found in Europe. Additionally, one unnamed species was discovered in Miocene sediments from Namibia. Due to a lack of skull material, little can be said about the ecology of Megapaloelodus. Species of this genus are typically larger than those of Palaelodus and appear to have inhabited similar brackish lake environments. Additionally, they may have been capable of "locking" their legs in a standing position.
History and naming 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. Recognizing similarities to fossils of Palaelodus, Miller described the material as a new genus of phoenicopteriform he named Megapaloelodus. Initially, Miller was under the impression that Megapaloelodus was a missing link between the basal Palaelodus and derived flamingos. In 1950 Loye H. Miller described the fragment of a tibiotarsus and an ulna from the late Miocene of California, also referring it to M. connectens. 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. However, in the description he refers to the axiom "Things that differ in the same way from the same thing do not differ from each other." Through this he reasoned that, as the Californian fossil differs from Palaelodus in similar ways as the fossils from South Dakota, they could have belonged to the same species. Although this conclusion was acknowledged as being tentative, Miller further explained that it seemed more reasonable than to establish a new species on such fragmentary remains. In addition to further finds from California, a second species was described from Juntura, Oregon by Pierce Brodkorb, M. opsigonus. This species may have also occurred further south in Mexico. In 1983 Jacques Cheneval published a major revision of the palaelodids of Saint-Gérand-le-Puy. Besides agreeing with prior studies that synonymized many of the European species, he also transferred Palaelodus goliath to the genus Megapaloelodus. Czech paleontologist Jiří Mlíkovský disagreed with this assessment in 2002 and instead suggested that Megapaloelodus should be synonymized with Palaelodus. However, this taxonomic treatment of the genus as a whole has been met with criticism and is considered premature by other authors. In 2009 several specimens from Argentina previously only identified as an indetermined phoenicopterid were described as the species Megapaloelodus peiranoi. The name Megapaloelodus combines the Ancient Greek word "mega" meaning "great" with a misspelling of the name Palaelodus, roughly translating to "ancient inhabitant of marshes", after the closely related genus primarily known from European deposits. 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. This is rendered somewhat ironic as subsequent research has placed Palaelodus goliath in Megapaloelodus as well.
Species M. connectens The type species of Megapaloelodus, M. connectens, was first described from the late Arikareean Rosebud Formation of South Dakota. Later fossil discoveries also suggested its presence in the late Miocene Barstow Formation of San Bernardino County, California. The species name connectens was chosen by Alden H. Miller in the belief that this species bridged the gap between Palaelodus and extant flamingos. M. goliath It is the earliest representative of Megapaloelodus, living from the Late Oligocene to the Middle Miocene, and is the only named species outside of the Americas. It was described based on several remains from France, with more material being later identified from Germany. While it was initially described as a species of Palaelodus, it was later transferred to Megapalaelodus by Cheneval. This has been called into question however, with some researchers arguing that the referral is largely dependent on the animal's size. M. opsigonus A later species, M. opsigonus, was found in the Pliocene Juntura Formation at Juntura, Oregon. Brodkorb described the species as being smaller than Megapaloelodus goliath and Palaelodus crassipess (at times considered to simply be a large Palaelodus ambiguus), but larger than the other Palaelodus species. Hildegarde Howard also tentatively assigned material from the Miocene to Pliocene Almejas Formation of Cedros Island (Baja California) to this species. The species name means "born in a later age" in reference to its appearance during the Pliocene. M. peiranoi The most recently described species, M. peiranoi was discovered in the strata of the Late Miocene Andalhualá Formation of Catamarca, Argentina. The holotype consists of a coracoid, sacrum and multiple wing bones, with a variety of other bones referred to the species as well. Unlike Palaelodus and modern flamingos, the forearm of M. peiranoi appears to have been short and robust rather than elongated. The notarium meanwhile appears to have been more similar to the basal Juncitarsus than to other phoenicopterids. Agnolin proposes that M. peiranoi may have been one of the more basal species of Megapaloelodus. It was named after Abel Peirano, a paleontologist who initially found and recovered the bones of this species. Various scant remains possibly belonging to Megapaloelodus are also known from across America. For instance, some remains were found in the Sharktooth Hill Bonebed of Kern County (California), while others were discovered in the Ituzaingó Formation of Argentina prior to the description of P. peiranoi. One possible species of Megapaloelodus might have even been present in the Northern Sperrgebiet of Namibia during the Early Miocene. However this record is based on a partial humerus, which is not known from any other Megapaloelodus species. Subsequently, this assignment was made based on the fossils great size.
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