Arambourgiania (meaning "Camille Arambourg's") is a genus of pterosaur, an extinct group of flying reptiles, that inhabited Jordan during the Maastrichtian age of the Cretaceous period, around 72 to 66 million years ago. Additional fossil remains from the United States and Morocco have also been found, but their assignment to Arambourgiania is only tentative. The holotype (name-bearing) specimen was discovered in 1943 by a railway worker near Russeifa, Jordan. After examination of the specimen by paleontologist Camille Arambourg, he described it as belonging to a new genus and species in 1959, Titanopteryx philadelphiae. The generic name means "titan wing", as the fossil was initially misidentified as a wing metacarpal (it would be later identified as a cervical (neck) vertebra), while the specific name refers to the ancient name of Amman (the capital of Jordan), Philadelphia. The genus name "Titanopteryx" would later be problematic, as it had already been taken by a fly. Because of this, paleontologist Lev Nessov in 1989 renamed the genus to Arambourgiania, in honor of Arambourg. Since 1943, additional isolated remains including vertebrae, wing bones, and hindlimb bones have been assigned to the genus.
Due to the fragmentary nature of the Arambourgiania fossils, there is little direct information about its anatomy. Its cervical vertebrae are extremely elongated, with the holotype vertebra measuring in length. Based on the complete neck of its relative Quetzalcoatlus, Arambourgiania had a total neck length of , longer than those of giraffes. Its vertebrae were also more lightly built and weakly muscled than those of its robust, short-necked relative Hatzegopteryx. Arambourgiania is one of the largest flying animals ever discovered. Initial wingspan estimates ranged from , which would have made it the largest known pterosaur. However, given the fragmentary remains, more recent research has suggested wingspans anywhere between , which would still place the genus among the largest known flying animals.
Arambourgiania is a member of the family Azhdarchidae, which includes some of the largest known pterosaurs. Azhdarchids are thought to have had a terrestrial stalker lifestyle, similar to that of extant storks, though some studies have pointed out that azhdarchids are frequently found in marine deposits. This includes Arambourgiania, whose fossils are exclusively known from oceanic or coastal localities, indicating that azhdarchids may have consumed aquatic prey as well. The bones of Arambourgiania are extremely hollow and lightly built with adaptations for soaring. One of the closest relatives of Arambourgiania is Quetzalcoatlus, as multiple studies have found both pterosaurs to be grouped together within Quetzalcoatlinae. In Jordan, Arambourgiania fossils are known from the Ruseifa Formation which had deep marine environment that was deposited during the Maastrichtian. At this time, Jordan was submerged under the Tethys Sea and had a diverse composition of marine life, including mosasaurids, elasmosaurids, bony fish, and selachians. Arambourgiania is one of two pterosaurs known from Jordan, the other being Inabtanin.
History of research
In 1943, during phosphate mining operations near the town of Ruseifa, Jordan, a railway worker found several fossil fragments associated with an incomplete fossilized cervical (neck) vertebra measuring in length. Later in the same year, these fossils were acquired by Amin Kawar, the director of a nearby phosphate mine. Kawar brought the fossils to the attention of Dr. Gerald Lankester Harding, the Director of Antiquities at the British Residence in Amman (at the time Jordan was a British protectorate) who then examined the remains. The vertebra generated some publicity — it was even shown to Abdullah I of Jordan. Subsequently, the fossils were transferred to the Hebrew University of Jerusalem where reports of their origin, anatomy, and location were filed, with copies then sent to the Jordan Phosphates Mines Company. Unfortunately, these reports have since been destroyed, though there may be existing records at the Hebrew University. The phosphates in which the fossil was found belong to the Ruseifa Formation, which dates to the Maastrichtian age (72–66 million years ago) of the Late Cretaceous period.
In 1953, the vertebra was sent to the National Museum of Natural History in Paris, France, where it was examined by French paleontologist Camille Arambourg. In 1954, Arambourg interpreted the vertebra as the wing metacarpal of a giant pterosaur, and in 1959 named the new genus and species Titanopteryx philadelphiae. The generic name Titanopteryx comes from the ancient Greek roots titan, in reference to the giant Greek Titans, and pteryx meaning "wing", while the specific name refers to the ancient name of Amman that was used by the Greeks: Philadelphia. The new species was based on the misidentified wing metacarpal, making this fossil the holotype specimen; several more elements had been found at the time but were undescribed and unidentified. Arambourg had a plaster cast made and then sent the fossil back to the offices of the Jordan Phosphates Mines Company; this latter aspect was later forgotten, and the bone was assumed lost.
Even though Arambourg recognized that his pterosaur was a giant, the pteranodontid Pteranodon remained widely recognized as the largest pterosaur known to science until the description of Quetzalcoatlus. In 1975 while studying Quetzalcoatlus, American paleontologist Douglas A. Lawson correctly concluded that the holotype was not a metacarpal but a cervical vertebra. In the 1980s, an entomologist informed Russian paleontologist Lev Nessov that the name Titanopteryx had already been given to a fly from the Simuliidae family in 1935. Therefore, in 1989, he created the new genus name Arambourgiania, honoring Arambourg, with -iania being a suffix indicating possession. However, the name "Titanopteryx" was informally kept in use in the West despite being a preoccupied name.
In 1995, paleontologists David Martill and Eberhard Frey traveled to Jordan in an attempt to find the vertebra and to clarify the identity of Arambourgiania. In a cupboard of the office of the Jordan Phosphate Mines Company, Martill and Frey 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 in 1996, after the departure of Martill and Frey to Europe, Rashdie Sadaqah, the engineer of the mine, found out that the holotype had been purchased by the geologist Hani N. Khoury in 1969, who then donated it to the University of Jordan in 1973. The fossil was still present in the collection of this institute, and therefore could be restudied by Martill and Frey. In their redescription, the two authors affirmed that Arambourgiania was a distinct taxon.
Additional specimens
Afro-Arabia
In 2018, a set of fragmentary azhdarchid specimens housed in the Bavarian State Collection for Palaeontology and Geology of Munich, Germany were described by paleontologists David Martill and Markus Moser. These fossils were obtained by Jean Otto Haas in 1955 and came from the same location where the holotype of Arambourgiania was found; though it is uncertain whether Haas found the specimens by himself or purchased them, they were later catalogued in his personal collection before ending up in the Bavarian State Collection in 1966. The azhdarchid fossils in the collection include six fragmentary specimens referred to as cf. A. philadelphiae (meaning that it compares well to A. philadelphiae but is not necessarily assignable to that species). These specimens consist of an incomplete metacarpal IV (SNSB-BSPG 1966 XXV 501), a potential cervical vertebra fragment (SNSB-BSPG 1966 XXV 503), a left femur (thighbone) fragment (SNSB-BSPG 1966 XXV 506), a possible radius (forearm bone) fragment (SNSB-BSPG 1966 XXV 507), another cervical vertebra fragment (SNSB-BSPG 1966 XXV 508), and a potential neural arch (SNSB-BSPG 1966 XXV 512). It is possible that these specimens come from the same individual as the holotype based on their same origin and comparable size, but the authors cannot verify this due to the lack of overlapping material and detailed data on their origin.
In 1992, Lewy and colleagues described a pair of endocasts (a natural cast of the brain cavity) which had been unearthed from upper Campanian or early Maastrichtian-aged phosphates belonging to the Mishash Formation located near Mitzpe Ramon, Israel. Lewy referred these endocasts to Titanopteryx (=Arambourgiania) sp. (sp. meaning an indeterminate species) on the basis of their similarity to the endocasts of pterosaurs. However, these endocasts have no overlap with any described fossils of Arambourgiania and, according to a 2014 study, most likely belong to birds instead on the basis of their length of around and bird-like structure.
In 2018, paleontologists Nicholas Longrich, David Martill, and Brian Andres described an incomplete left ulna of the "Sidi Chennane azhdarchid" from the Ouled Abdoun Basin of Morocco which they tentatively identified as ?Arambourgiania. This ulna came from the Sidi Chennane mine located in the basin, a group of phosphatic sandstones dating to the Maastrichtian, which contains a host of other pterosaur genera from several different families.
In 2024, the describers of the genus Inabtanin reported a partial right humerus of a large pterosaur in the Ruseifa Phosphate Mines, near the Jordanian capital of Amman, which was where the holotype of Arambourgiania was recovered. They concluded that the specimen belonged to A. philadelphiae and that it is comparable in size and shape to the humerus of the type species of Quetzalcoatlus, Q. northropi.
North America
On 15 August 1982, Ralph Johnson unearthed an azhdarchid cervical vertebra (YPM VPPU 023497) from rock layers of the Maastrichtian-aged Navesink Formation located in Monmouth County, New Jersey in the United States. In 1983, this vertebra was referred to Titanopteryx (=Arambourgiania) sp. on the basis of its elongation and lateral compression, though it is extremely poorly preserved. The assignment of this specimen came into question in the 2025 description of Infernodrakon, where the authors considered the specimen as aff. Arambourgiania sp. (meaning that it has affinity to an undetermined species of Arambourgiania) due to its broader cross section than the known specimens of Arambourgiania and the lack of further study of the fossil. Between 1971-73, two amateur fossil collectors John Brzostoski and Harold Mendryk discovered a cervical vertebra (YPM-PU 21820), a humerus (YPM-PU 22359), and an associated femur and tibia (YPM-PU 21821) in the Early Campanian-aged Merchantville Formation of New Castle County, Delaware in the United States. Initially described as pterosaur specimens that are similar to Pteranodon, Gallagher tentatively identified them as cf. ?Titanopteryx in 1993, while Averianov identified them as indeterminate azhdarchids in 2014. In 2021, Averianov and colleagues suggested that the cervical vertebra (YPM-PU 21820) belongs to a pteranodontid or even Pteranodon itself based on its pneumaticity, a referral also suggested previously by Bennett (1994) and Barrett and colleagues (2008).