''Megapaloelodus'' is an extinct genus of

stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushro ...

flamingo Flamingos or flamingoes are a type of Wader, wading bird in the Family (biology), family Phoenicopteridae, which is the only extant family in the order Phoenicopteriformes. There are four flamingo species distributed throughout the Americas ...

of the family

Palaelodidae Palaelodidae is a family of extinct birds in the group Phoenicopteriformes, which today is represented only by the flamingos. They have been described as "swimming flamingos." They can be considered evolutionarily, and ecologically, intermediate ...

. ''Megapaloelodus'' is primarily known from

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, from

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota people, Lakota and Dakota peo ...

and

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

in the north to

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

in the south, but the species ''Megapaloelodus goliath'' was found in Europe. Additionally, one unnamed species was discovered in Miocene sediments from

Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...

. 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 Alden Holmes Miller (February 4, 1906 – October 9, 1965) was an American ornithologist and director of the Museum of Vertebrate Zoology at the University of California, Berkeley for 25 years. He published over 250 papers on the biology, distribut ...

in 1944 on the basis of a fossil

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...

and

tarsometatarsus The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) and meta ...

collected from the lower

Rosebud Formation The Rosebud Formation is a geologic formation in South Dakota. It preserves fossils dating back to the Neogene period. See also * List of fossiliferous stratigraphic units in South Dakota * Paleontology in South Dakota Paleontology in South Da ...

. Recognizing similarities to fossils of ''

Palaelodus ''Palaelodus'' is an extinct genus of bird of the Palaelodidae family, distantly related to flamingos. They were slender birds with long, thin legs and a long neck resembling their modern relatives, but likely lived very different livestyles. Th ...

'', 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 Flamingos or flamingoes are a type of wading bird in the family Phoenicopteridae, which is the only extant family in the order Phoenicopteriformes. There are four flamingo species distributed throughout the Americas (including the Caribbean) ...

. In 1950

Loye H. Miller Loye Holmes Miller (18 October 1874 – 6 April 1970), was an American paleontologist and zoologist who served as professor of zoology at the University of California, Los Angeles, University of California, Berkeley, and University of California ...

described the fragment of a tibiatarsus and an ulna from the late Miocene of

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

, 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 An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or f ...

"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 Juntura is an unincorporated community in Malheur County, Oregon, United States on U.S. Route 20. The word ''juntura'' is Spanish for "juncture", and the community was named for its proximity to the confluence of the Malheur River with the North ...

Pierce Brodkorb William Pierce Brodkorb (September 29, 1908, Chicago – July 18, 1992, Gainesville, Florida) was an American ornithologist and paleontologist. Interested in birds since childhood, he was taught to prepare birds at the age of 16. Later, he rec ...

, ''M. opsigonus''. This species may have also occured further south in

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. In 1983 Jacques Cheneval published a major revision of the palaelodids of

Saint-Gérand-le-Puy Saint-Gérard-le-Puy (; oc, Sant Geran del Puèi) is a commune in the Allier department in Auvergne-Rhône-Alpes in central France. Geography Much of the local rock is limestone common in the Auvergne, known as ''indusial'', because of the ...

. Besides agreeing with prior studies that synonymized many of the European species, he also transfered ''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 specimen from Argentina previously only identified as an indetermined phoenicopterid were described as the species ''Megapaloelodus peiranoi''. The name ''Megapaloelodus'' combines the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

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 In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

of ''Megapaloelodus'', ''M. connectens'', was first described from the late

Arikareean The Arikareean North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 30,600,000 to 20,800,000 years BP, a period of . It is usuall ...

Rosebud Formation of South Dakota. Later fossil discoveries also suggested its presence in the late Miocene

Barstow Formation The Barstow Formation is a series of limestones, conglomerates, sandstones, siltstones and shales exposed in the Mojave Desert near Barstow in San Bernardino County, California.Dibblee, T.W., Jr. (1967). Areal Geology of the Western Mojave De ...

San Bernardino County San Bernardino County (), officially the County of San Bernardino, is a county located in the southern portion of the U.S. state of California, and is located within the Inland Empire area. As of the 2020 U.S. Census, the population was 2,181, ...

. 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 The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

to the Middle Miocene, and is the only named species outside of the Americas. It was described based on several remains from

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

, with more material being later identified from Germany. While it was initially described as a species of ''Palaelodus'', it was later transfered to ''Megapalaelodus'' by Cheneval. This has been called into question however, with some researchers arguing that the referal is largely dependent on the animal's size. *''M. opsigonus'' :A later species, ''M. opsigonus'', was found in the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Juntura Formation at Juntura,

. 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 Hildegarde Howard (April 3, 1901 – February 28, 1998) was an American pioneer in paleornithology, mentored by the famous ornithologist, Joseph Grinnell, at the Museum of Vertebrate Zoology (MVZ) and in avian paleontology.Joyce Harvey & Marilyn O ...

also tentatively assigned material from the Miocene to

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Almejas Formation of

Cedros Island Cedros Island (''Isla de Cedros'', "island of cedars" in Spanish) is an island in the Pacific Ocean belonging to the state of Baja California, Mexico. The dry and rocky island had a population of 1,350 in 2005 and has an area of which includes ...

(

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

) 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 Andalhualá is a village and municipality in Catamarca Province in northwestern Argentina.Ministerio del Interior

...

of Catamarca,

. 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 Notarium or os dorsale is a bone consisting of the fused vertebra of the shoulder in birds and some pterosaurs. The structure helps brace the chest against the forces generated by the wings. In birds, the vertebrae are only in contact with adjace ...

meanwhile appears to have been more similar to the basal ''

Juncitarsus ''Juncitarsus'' is an extinct genus of wading birds from the Eocene of the United States and Germany. Though previously considered a kind of prehistoric flamingo,Olson, S.L. And Feduccia, A. 1980. Relationship and evolution of flamingos (Aves: P ...

'' 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 Kern County is a county located in the U.S. state of California. As of the 2020 census, the population was 909,235. Its county seat is Bakersfield. Kern County comprises the Bakersfield, California, Metropolitan statistical area. The county sp ...

(California), while others were discovered in the

Ituzaingó Formation The Ituzaingó Formation ( es, Formación Ituzaingó), in older literature also described as Entre Ríos or Entrerriana Formation, is an extensive geological formation of Late Miocene (Tortonian, or Huayquerian in the SALMA classification) age in ...

of Argentina prior to the description of ''P. peiranoi''. One possible species of ''Megapaloelodus'' might have even been present in the Northern Sperrgebiet of

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 The tibiotarsus is the large bone between the femur and the tarsometatarsus in the leg of a bird. It is the fusion of the proximal part of the tarsus with the tibia. A similar structure also occurred in the Mesozoic Heterodontosauridae. These sm ...

. Both have noticable 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 Trochlea (Latin for pulley) is a term in anatomy. It refers to a grooved structure reminiscent of a pulley's wheel. Related to joints Most commonly, trochleae bear the articular surface of saddle joint, saddle and other joints: * Trochlea of hume ...

that articulates with the

carpal bones The carpal bones are the eight small bones that make up the wrist (or carpus) that connects the hand to the forearm. The term "carpus" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, th ...

, this tubercle is present as a rounded point that is located on the upper rim of the bone. The articulation point between the

coracoid A coracoid (from Greek κόραξ, ''koraks'', raven) is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is prese ...

and the

clavicle The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the rig ...

overhangs two distinct pits that are much shallower in ''Palaelodus'' and missing entirely in modern flamingos, yet also present in the early '' Adelalopus''. When compared to the same bones in other modern forms, "straight-legged" birds such as cranes and

seriemas The seriemas are the sole living members of the small bird family Cariamidae, which is also the only surviving lineage of the order Cariamiformes. Once believed to be related to cranes, they have been placed near the falcons, parrots and passeri ...

shows a tendency to flatten the profile of the internal condyle of the tibiotarsus. This has been associated with the tendency of these birds to hold their tibiotarsus and

relatively straigt against one another. 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. A similar hook may have also been present on the profile of the external trochlea. 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''. There is however overlap between some of the species, for example between ''Palaelodus ambiguus'' and ''Megapaloelodus goliath'' that add to the doubts around the later's genus designation. ''Megapaloelodus opsigonos'' likewise overlaps in size with the larger ''Palaelodus'' species. The Belgian ''Adelalopus'', the oldest known palaelodid, is similar in size to ''Megapaloelodus'' and was described as slightly larger than ''M. goliath''. ''Megapaloelodus'' species were generally similar in size to the

greater flamingo The greater flamingo (''Phoenicopterus roseus'') is the most widespread and largest species of the flamingo family. It is found in Africa, the Indian subcontinent, the Middle East, and in southern Europe. Taxonomy The greater flamingo was desc ...

Phylogeny

''Megapaloelodus'' is placed in the family

, a group of primarily

Neogene The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...

stem-flamingos that are considered to be an important link between modern flamingos and

grebes Grebes () are aquatic diving birds in the order (biology), order Podicipediformes . Grebes are widely distributed freshwater birds, with some species also found in sea, marine habitats during Bird migration, migration and winter. Some flightless ...

, which form the group

Mirandornithes Mirandornithes () is a clade that consists of flamingos and grebes. Many scholars use the term Phoenicopterimorphae for the superorder containing flamingoes and grebes. Determining the relationships of both groups has been problematic. Flamingos ...

. 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 In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

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. It is possible that ''Megapaloelodus'', much like many other phoenicopteriforms, inhabited lakes which at times may have been highly saline or brackish. The shallow lake that formed the sediments of the Barstow Formation may have been freshwater given the presence of freshwater molluscs and the absence of any salts in the deposits, but has been suggested to have undergone cycles of dry periods that concentrated the water. Still conditions are not fully understood, as the local climate may have been wetter than today to allow the presence of palm trees. In the French locality of Saint-Gérand-le-Puy, ''Megapaloelodus goliath'' is known to have inhabited a brackish

lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

environment that underwent cyclical wet and dry periods. Here ''Megapaloelodus'' shared its environment with at least two other genera of flamingo. ''Palaelodus'', which may be present in the form of several species, and the more derived flamingo ''Harrisonavis'', which had already developed the curved beak the group is known for. 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

{{Taxonbar, from=Q3501993 Palaelodidae Bird genera Neogene birds of Europe Miocene birds of North America Clarendonian Hemingfordian Neogene Mexico Fossils of Mexico Neogene United States Fossils of the United States Miocene birds of South America Huayquerian Neogene Argentina Fossils of Argentina Ituzaingó Formation Fossil taxa described in 1944 Taxa named by Alden H. Miller