Arambourgiania

In the early 1940s, a railway worker during repairs on the Amman-Damascus railroad, near the city of Russeifa in Jordan, found a fossil bone measuring 60.96 cm (2 ft).

This specimen was acquired in 1943 by the director of a nearby phosphate mine, Amin Kawar, who brought it to the attention of British archeologist Fielding after the Second World War.

[1] In 1953, the fossil was sent to the National Museum of Natural History in Paris, France, where it was examined by French paleontologist Camille Arambourg.

Arambourg let a plaster cast be made and then sent the fossil back to the phosphate mine; this last aspect was later forgotten and the bone was assumed lost.

[1] While studying and describing the closely related pterosaur Quetzalcoatlus from Texas in 1975, American paleontologist Douglas A. Lawson concluded that the bone was not a metacarpal but a cervical (neck) vertebra.

[2] In the 1980s, Russian paleontologist Lev Nesov was informed by an entomologist that the name Titanopteryx had already been given by Günther Enderlein to a fly from the Simuliidae family in 1935.

In a cupboard of the office of the Jordan Phosphate Mines Company they discovered some other pterosaur bones: a smaller vertebra and the proximal and distal extremities of a wing phalanx — but not the original material of Arambourgiania.

However, after their departure to Europe, engineer of the mine Rashdie Sadaqah investigated further and in 1996 he established that the original fossil had been bought from the company in 1969 by geologist Hani N. Khoury, who had then donated it in 1973 to the University of Jordan.

[5][6][4] Later, Frey and Martill rejected the suggestion that Arambourgiania was a nomen dubium or an identical pterosaur to Quetzalcoatlus, affirming its validity to replace the preoccupied name "Titanopteryx".

[5][4] In 2016, an azhdarchid cervical vertebra (MPPM 2000.23.1) was described from the Coon Creek Formation of McNairy County in Tennessee, United States.

[4] Frey and Martill estimated the total length of the holotype to have been 78 cm (2 ft 7 in), using for comparison the relative position of the smallest diameter of the shaft of the fifth cervical vertebra of Quetzalcoatlus.

From the relatively slender vertebra, the length dimension was then selected to be compared to that of Quetzalcoatlus as well, estimated at 66 cm (2 ft 2 in) long, which results in a ratio of 1.18.

[15] Unaware of the creation of Azhdarchinae, American paleontologist Kevin Padian created the family Titanopterygiidae, which included both "Titanopteryx" and Quetzalcoatlus.

[16][17] Two years later, in 1986, Padian would become aware of the existence of Azhdarchinae and would make Titanopterygiidae a junior synonym of it, as he believed that the diagnoses of the cervical vertebrae for both groups were identical.

One of the closest relatives of Arambourgiania is Quetzalcoatlus, as both pterosaurs have consistently been found together in multiple phylogenetic analyses, either as sister taxa or close to each other.

The first one is based on the phylogenetic analysis by American paleontologist Brian Andres in 2021, which places Arambourgiania within Quetzalcoatlinae as the sister taxon to both species of Quetzalcoatlus, Q. northropi and Q.

[17] The second cladogram is based on the 2023 study by paleontologist Rodrigo Pêgas and colleagues, in which they placed Arambourgiania in a trichotomy with Mistralazhdarcho and Aerotitan within Quetzalcoatlinae, contrasting its placement as the sister taxon of Quetzalcoatlus.

Azhdarcho lancicollis Albadraco tharmisensis Aerotitan sudamericanus Mistralazhdarcho maggii Aralazhdarcho bostobensis Phosphatodraco mauritanicus Eurazhdarcho langendorfensis Zhejiangopterus linhaiensis Wellnhopterus brevirostris Cryodrakon boreas Hatzegopteryx thambema Arambourgiania philadelphiae Quetzalcoatlus lawsoni Quetzalcoatlus northropi Topology 2: Pêgas and colleagues (2023).

Holotype cervical vertebra of Arambourgiania (F) compared to those of other azhdarchids
Arambourgiania was named after paleontologist Camille Arambourg
Skeletal reconstructions of Arambourgiania (C) and the related Hatzegopteryx (A), and Quetzalcoatlus lawsoni (D), with known parts in gray
Ulna bone from the Ouled Abdoun Basin of Morocco that may belong to Arambourgiania
Length of the holotype cervical vertebra of Arambourgiania (first above) compared to other azhdarchid cervical vertebrae
Estimated size of Arambourgiania (dark turquoise; upper left) compared to contemporary pterosaurs , birds, and a human. Hatzegopteryx and Quetzalcoatlus northropi are also depicted (dark brown; lower left)
Quetzalcoatlus is among the closest relatives of Arambourgiania , with numerous studies recovering them as sister taxa
Life reconstruction of two Arambourgiania fighting over a small theropod