Platypterygius

Restoration of P. australis

As Platypterygius contains multiple species not especially close to each other, little can be said in terms of shared characteristics. According to an analysis by Fischer (2012), all anatomical features used to unify Platypterygius species are either not actually present in each species, or much more widespread among unrelated ophthalmosaurs. Generally, species referred to this genus were large bodied macropredators based on their robust dentition.[2] This is also supported by P. australis having been found with remains of sea turtles and birds (specifically, of the genus Nanantius) in its guts,[3] as well as an unidentified pterosaur fossil with tooth marks that may be from this genus.

In 1998, Arkhangelsky estimated that P. platydactylus was about 5 metres (16 ft) long, while "P." americanus was about 5.5 metres (18 ft) long.[4] In 2010, Zammit and colleagues estimated that "P." australis was about 7 metres (23 ft) long.[5]

Skull of P. sp., Sternberg Museum of Natural History

The type species of Platypterygius was described in 1922 based on remains found in upper Aptian strata around Hannover, Germany. These remains however were not adequately described and to complicate matters further, destroyed during World War 2. In the time after its discovery however Platypterygius has become a catch-all genus for Cretaceous ichthyosaurs, creating the misconstrued view of post-Jurassic ichthyosaurs as being a single global genus lacking in diversity. Later research conducted in the 2000s and 2010s has repeatedly shown this to be false, with all of the autapomorphies previously used to define Platypterygius either not being present in all assigned species or also being present in other ophthalmosaurids.[6] As the holotype was destroyed, a redescription of the material attempting to identify valid autapomorphies is out of the question and leaves the genus in a problematic state. Furthermore, the inclusion of later described genera of Cretaceous, platypterygiine ichthyosaurs has shown Platypterygius to be paraphyletic, with the different species not clading closely to one another. Subsequently, many redescriptions of referred Platypterygius species have found them to be their own distinct genera.

One notable attempt at revising Platypterygius was conducted by Arkhangel'sky in 1998, who split the genus into 3 new subgenera. Longirostria (including the Australian "P." longmani, a synonym of "P." australis, and the Argentinian "P." hauthali), Tenuirostria ("P." americanus) and Pervushovisaurus (which included the newly described "P." bannovkensis). Both Platypterygius platydactylus,"P." kiprianoffi and "P." hercynicus were placed in the subgenus Platypterygius.[4]

"Platypterygius" bannovkensis was eventually elevated to its own genus Pervushovisaurus in 2014, utilizing Arkhangel'sky's proposed subgenus name[7] and "P." campylodon was also assigned to this genus by a study published in 2016.[8] "P." kiprianoffi was also assigned to P. campylodon (now Pervushovisaurus).[9][10][11] Simbirskiasaurus was originally described in 1985 and later sunk into Platypterygius before being declared distinct in the same paper as Pervushovisaurus.[7] "Platypterygius" ochevi, described in 2008 by Arkhangel'sky et al., was found to be a junior synonym of Maiaspondylus cantabrigiensis[12] and in 2021 "Platypterygius" sachicarum was described by Cortés et al. as Kyhytysuka sachicarum.[13] It is argued that the inclusion of oldest species "P." hauthali requires reinvestigation,[11] for it lacks a skull to attribute.[14] Because of this, recent analyses on ichthyosaur classification neglect this species.[15][16]

Accepted species

Opalized vertebral column assigned to an immature P. cf. longmani (a synonym of P. australis)

• Platypterygius platydactylus Broilli, 1907 (type)
• Platypterygius americanus Nace, 1939 (=Tenuirostria)
• Platypterygius australis McCoy, 1867 (=Longirostria)
• Platypterygius hercynicus Kuhn, 1946

Skeleton in Museum and Art Gallery of the Northern Territory

The following cladogram shows the internal relationships of ophthalmosaurian ichthyosaurs according to an analysis performed by Zverkov and Jacobs (2020) which shows that P. americanus is too distantly related compared to the other three species.[16]

• List of ichthyosaurs
• Timeline of ichthyosaur research

• Long, J.A., Dinosaurs of Australia and New Zealand, UNSW Press, Australia 1998

• Dann's Dinosaurs
• Platypterygius