Phoeniconaias proeses

Phoeniconaias proeses; Temporal range: Pliocene PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Phoenicopteriformes
Family:	Phoenicopteridae
Genus:	Phoeniconaias
Species:	†P. proeses
Binomial name
	†Phoeniconaias proeses; (De Vis, 1905)

Last updated August 27, 2023

Phoeniconaias proeses is an extinct species of flamingo from the Pliocene of Australia. Fossil material was described under several names including Ocyplanus proeses and Phoeniconaias gracilis, which were eventually found to be synonymous. Only material from the Tirari Formation has been dated, while most other material lacks precise information on its age. P. proeses was one of the smallest species of flamingo, smaller than the modern lesser flamingo which it may be related to.

History

Phoeniconaias proeses was first described by Charles Walter De Vis in 1905 alongside a variety of other fossil birds. At the time De Vis was under the impression that the material, a left distal tarsometatarsus only described to have been found in the Lake Eyre basin without precise locality or age, belonged to a type of shorebird. Rich and colleagues argue that this identification may have been a result of De Vis' limited reference collection, which did not include bones of flamingos. Subsequently, De Vis was incapable of comparing his material with extant flamingos and instead had to assign it to the most similar group available to him. The material, named Ocyplanus proeses by De Vis, was then placed in the family Laridae by Lambrecht in 1933, an assignment then supported by Pierce Brodkorb in 1967. Around the same time Miller named the first recognized flamingo fossils from Australia, erecting several species including Phoeniconaias gracilis from Lake Kanunka in the Lake Eyre basin.^[1] In 1975 Condon proposed that Ocyplanus proeses was not a shorebird at all and instead represented a type of rail. In 1987, Rich and colleagues examined the material and determined that the description and size of O. proeses matches Miller's diagnosis for Phoeniconaias gracilis, rendering the later a synonym of De Vis' taxon. In the same publication the authors examine Ibis (?) conditus, also named by De Vis in 1905 based on a femur from Wurdulumankula and placed in Threskiornithidae. The team argues that the femur, stouter than in ibises, more closely resembles flamingos and also assign it to Ocyplanus proeses, which is of similar size.^[2] Although the name Ocyplanus was initially kept due to the differences in the tibiotarsus and femur distinguishing it from the modern lesser flamingo, the combination Phoeniconaias proeses was used in later publications due to the fact that the name Ocyplanus is occupied by a beetle.^[3]

Description

Based on the surface texture of the fossil, the holotype of Phoeniconaias proeses is thought to have belonged to a juvenile approximately the size of a beach stone-curlew. According to Rich et al., this fossil matches the diagnosis given by Miller for Phoeniconaias gracilis. This diagnosis included that the tarsometatarus was smaller and more slender than the corresponding bone in the lesser flamingo. The posterior extension of the second trochlea is not as rounded and on the plantar surface of the fourth trochlea the articular surface does not extend as far back. The additional material identified by Miller generally matches the corresponding bones in the extant Phoeniconaias species.^[1] Rich and colleagues however do point out that the features of the trochlea are very variable in extant genera, before agreeing that the mediolateral compression of the species most closely resembles the lesser flamingo out of all modern genera. They also add that certain features of the referred material serve as additional differentiation from modern flamingos. This includes the placement of the ligamental groove, the flattened state of the distal end and the sloping of the condyles.^[2]

The femur originally named Ibis (?) conditus shows the stout morphology typical for flamingos as well as sharply curved line near the popliteal fossa. However, unlike Miller's tarsometatarus which is incredibly similar to Phoeniconaias, this element shows several differences that clearly set it apart from all modern flamingos. For instance, the intermuscular line remains straight over most the femur's length until it makes a drastic concave turn to contact the trochanter. The front of the shaft is deeply excavated in the proximal region and lacks a foramen that in other flamingos aids with skeletal pneumaticity. The pit for the ligament at the fibular condyle is deep, proximal to which lie a prominent ridge and well defined channel. The ridge is only weakly present in modern flamingos and the well defined channel absent.^[2]

Both Miller and Rich et al. describe Phoeniconaias proeses as being among the smallest known flamingo, fossil or otherwise. The type material of P. proeses is clearly smaller than the same bone in the extant lesser flamingo. The femur described by De Vis is also smaller than in modern Phoeniconaias and subsequently matches what was described for P. proeses. Miller writes that it's approximately 10% smaller than the smallest individuals of the lesser flamingo and also smaller than the small American forms Phoenicopterus minutus and Phoenicopterus stocki . Due to this Miller argues that P. proeses, at least based on the Lake Kanunka material, was the smallest known flamingo in the fossil record. Rich and colleagues, who worked with more material of the species, disagree with this, stating that Leakeyornis from Miocene Kenya was even smaller.^[2] Miller did identify a humerus that in size would match the modern lesser flamingo, but also notes that this fossil would not only fall within the range of variation for P. proeses, but might also be deceptive, as the wings may not reflect the small and gracile build of the rest of the body.^[1]

Paleobiology

Material assigned to Phoeniconaias proeses is known from various localities in Australia. During the Pliocene at Lake Kanunka it coexisted with at least two other species of flamingo, the large greater flamingo and Xenorhynchopsis minor , which is approximately the size of the lesser flamingo. It was again found alongside greater flamingos at Wurdulumankula, Lower Wolf Creek, though the precise age of that site is unknown. Although it is unknown when precisely Phoeniconaias proeses went extinct, flamingos as a whole disappeared from Australia during the Quaternary, when increasing aridification destroyed the shallow lakes these birds require to feed and nest.^[1]^[2]

Related Research Articles

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, and two species native to Afro-Eurasia.

The lesser flamingo is a species of flamingo occurring in sub-Saharan Africa and western India. Birds are occasionally reported from further north, but these are generally considered vagrants.

Dromornis is a genus of large to enormous prehistoric birds native to Australia during the Oligocene to Pliocene epochs. The species were flightless, possessing greatly reduced wing structures but with large legs, similar to the modern ostrich or emu. They were likely to have been predominantly, if not exclusively, herbivorous browsers. The male of the largest species, Dromornis stirtoni, is a contender for the tallest and heaviest bird, and possibly exhibited aggressive territorial behaviour. They belong to the family Dromornithidae, extinct flightless birds known as mihirungs.

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. They had straight, conical beaks not suited for filter feeding and legs showing some similarities to grebes. Their precise lifestyle is disputed, with researchers in the past suggesting they may have been divers, while more recent research suggests they may have used their stiff toes as paddles for swimming while feeding on insect larvae and snails. This behavior may have been key in later phoenicopteriforms developing filterfeeding bills. The genus includes between five and eight species and is found across Europe, Australia, New Zealand, Asia and possibly South America. However some argue that most of the taxa named from Europe simply represent differently sized individuals of one single species. Palaelodus was most abundant during the Late Oligocene to Middle Miocene periods, but isolated remains from Australia indicate that the genus, or at least a relative, survived until the Pleistocene.

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.

Mesembriornis is a genus of intermediate-sized phorusrhacids that grew up to 1.5 metres (4.9 ft) in height. They represent a well-distinct lineage of terror birds, differing from the massive large groups and the smaller Psilopterinae. In general proportions, they most resembled the Patagornithinae which flourished somewhat earlier, mainly to the south of the range of Mesembriornis. Fossils of the terror bird have been found in Montehermosan deposits of the Monte Hermoso Formation in Argentina.

Phoeniconotius is an extinct genus of flamingo that lived in Australia from the late Oligocene to the early Miocene. Unlike modern flamingos and the contemporary Phoenicopterus novaehollandiae, it was likely less well adapted for swimming and deep water wading. Phoeniconotius was a robust flamingo with bones more massive than those of the modern greater flamingo. Only a single species is recognized, Phoeniconotius eyrensis.

Palaelodidae is a family of extinct birds in the group Phoenicopteriformes, which today is represented only by the flamingos. They were widespread during the Neogene, with fossil remains found on all continents other than Antarctica. The oldest remains referred to this group appeared in the fossil record during the Oligocene in Egypt and Belgium, before palaelodids reached their peak diversity during the Miocene. Following this the group declined in the early Pliocene before going extinct on most continents. However, remains found near Cooper Creek in the Lake Eyre Basin indicate that palaelodids managed to survive in Australia until the Pleistocene. Currently three genera are recognized by scientists: Adelalopus, Palaelodus and Megapaloelodus. Most fossil remains stem from Europe and have been assigned to the type species, Palaelodus ambiguus. Due to the fragmentary nature of most of these species, little is known about their ecology. They appear to have preferred brackish lakes and lagoons. Palaelodus has previously been thought to be a wader or diver, but recent research indicates that they were better suited for swimming and possibly fed on insect larvae and other aquatic invertebrates. At least Megapaloelodus appears to have adaptations for "locking" their legs in a standing position.

Juncitarsus is an extinct genus of wading birds from the Eocene of the United States and Germany. Though previously considered a flamingo, it is likely a stem-flamingo, possibly a relative of the group which contains both flamingos and grebes (Mirandornithes).

Phoeniconaias is a genus of birds in the flamingo family Phoenicopteridae. The genus contains one extant species, the lesser flamingo, occurring in sub-Saharan Africa and western India, and an extinct species, Phoeniconaias proeses, from the Pliocene of Australia, which is thought to have been even smaller.

Phoenicopterus minutus is an extinct species of flamingo which inhabited California during the Late Pleistocene. It was originally discovered in San Bernardino County, California in the Lake Manix beds, where it coexisted with a second, larger flamingo species.

Leptoptilos falconeri is an extinct species of large-bodied stork that existed during the Pliocene, having persisted until just over 2.58 million years ago. Although not the oldest fossil species of the genus Leptoptilos it was the first fossil species of the genus to be described. Furthermore, it was the largest known species of stork ever and amongst the tallest and heaviest flying birds known to have existed, having reached at least 2 m in height.

Harrisonavis is an extinct genus of flamingo that lived during the Late Oligocene and Early Miocene periods in what is now France. Despite being one of the oldest known members of the flamingo family, it already shows a skull remarkably similar to that of the modern greater flamingo. Although generally similar, it subtly differs in the curvature of the bill and the size of the ventral keel of the maxilla, both signs that Harrisonavis was not yet as adapted towards filter feeding as modern species are. Harrisonavis inhabited brackish lakes alongside the more basal Palaelodidae. It contains the single species Harrisonavis croizeti, first described in 1852.

Phoeniconaias siamensis is an extinct species of flamingo that lived in northern Thailand during the Miocene period. Its closest living relative is the lesser flamingo.

Leakeyornis is an extinct genus of flamingo from the early to middle Miocene of Kenya, primarily in the area of modern day Lake Victoria. Initially described as a species of Phoenicopterus based on an incomplete skull and various limb bones, it was later found to show a mixture of traits found across modern flamingo genera and subsequently placed in its own genus. It contains a single species, Leakeyornis aethiopicus.

Phoenicopterus novaehollandiae is an extinct species of flamingo from the late Oligocene or early Miocene Etadunna Formation of Australia. It was a large species similar in size to large specimens of the modern greater flamingo, but differed by likely having had a much better developed hallux which is typically reduced or absent in modern flamingos.

Phoenicopterus stocki, also known as Stock's flamingo, is an extinct species of flamingo from the Pliocene of Chihuahua, Mexico. It was described in 1944 as a small bodied flamingo species known from assorted fragmentary remains, including bones of the tibia and the wings. The discovery of juvenile remains suggests that the locality where the fossils were found represents a shallow lagoon or mudflat that housed a breeding colony.

Phoenicopterus floridanus is an extinct species of flamingo that lived during the Pliocene in what is now Florida and potentially North Carolina.

Xenorhynchopsis is an extinct genus of flamingo from the Pliocene to Pleistocene Lake Eyre basin of Australia. Initially described as species of stork, the two known Xenorhynchopsis species are vastly different in size. X. minor is the older and small of the two species, ranging from the Pliocene to Pleistocene and being described as having reached a size smaller than that of the lesser flamingo. X. tibialis meanwhile appears to have been restricted to Pleistocene strata and was notably bigger, being counted as one of the biggest known flamingos in the fossil record.

References

1 2 3 4 Miller, A.H. (1963). "The fossil flamingos of Australia" (PDF). The Condor. 65 (4): 289–299. doi:10.2307/1365355. JSTOR 1365355.
1 2 3 4 5 Rich, P.V.; van Tets, G.F.; Rich, T.H.V.; McEvey, A.R. (1987). "The Pliocene and Quaternary Flamingos of Australia". Memoirs of the Queensland Museum. 25 (1): 207–225.
↑ Worthy, T.H.; Nguyen, J.M.T. (2020). "An annotated checklist of the fossil birds of Australia". Transactions of the Royal Society of South Australia. 144 (1): 66–108. doi: 10.1080/03721426.2020.1756560 . S2CID 221065815.

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[M63-1] 1 2 3 4 Miller, A.H. (1963). "The fossil flamingos of Australia" (PDF). The Condor. 65 (4): 289–299. doi:10.2307/1365355. JSTOR 1365355.

[RTRM87-2] 1 2 3 4 5 Rich, P.V.; van Tets, G.F.; Rich, T.H.V.; McEvey, A.R. (1987). "The Pliocene and Quaternary Flamingos of Australia". Memoirs of the Queensland Museum. 25 (1): 207–225.

[WN20-3] Worthy, T.H.; Nguyen, J.M.T. (2020). "An annotated checklist of the fossil birds of Australia". Transactions of the Royal Society of South Australia. 144 (1): 66–108. doi: 10.1080/03721426.2020.1756560 . S2CID 221065815.

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