Megapaloelodus

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, This species may have also occurred further south in Mexico. 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. 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. The species name means "born in a later age" in reference to its appearance during the Pliocene. 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. == Description ==

In many regards the bones of Megapaloelodus closely resembles those of Palaelodus. Both genera for instance share many characteristics of the tibiotarsus. 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). Megapaloelodus differs from its relatives through the pronounced tubercle located on the trochlea that articulates with the carpal bones, this tubercle is present as a rounded point that is located on the upper rim of the bone. 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. Megapaloelodus species were generally similar in size to the greater flamingo. ==Phylogeny==

Megapaloelodus is placed in the family Palaelodidae, a group of primarily Neogene stem-flamingos that are considered to be an important link between modern flamingos and grebes, which form the group Mirandornithes. Other members of this family include the more common Palaelodus and the early Adelalopus. Initially Megapaloelodus was thought to be an intermediate between Palaelodus and the groups modern relatives, but later research discovered that palaelodids instead formed a monophyletic sister group to phoenicopterids. The precise internal relationships between the individual species of this family is not known. Mayr and Smith point to various similarities between Megapaloelodus and Adelalopus, which is currently the oldest known member of this group. Within the genus, M. peiranoi has been suggested to be its most basal member due to some similarities with basal mirandornithes like Juncitarsus. The following phylogenetic tree depicts Mirandornithes as recovered by Torres and colleagues in 2015. }} ==Paleobiology==

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. The precise ecology of Megapaloelodus in this environment remains unknown due to the comparative lack of material, in particular that of the skull. Currently, the only known palaelodid with preserved cranial material is Palaelodus itself, which shows a straight bill very different from that of derived flamingos. It is thought to have fed on insect larvae and other aquatic invertebrates. == References ==