The Pterodactyloidea are a clade of pterosaurs characterised by elongation of the head and neck, and reduction of the tail.
The ornithocheirids: misunderstood giants
Published 17 January 2012
The pterosaurs of the Ornithocheiridae that lived between the Early and mid-Cretaceous were not the largest pterosaurs to ever live, but with a possible maximum known wingspan of about 7 m (Martill & Unwin 2011) they were certainly big enough (for comparison, an Australian pelican has a wingspan of about 2.5 metres). Ornithocheirids have been recorded from numerous parts of the world—Europe, South America, Africa and China—and, like the large seabirds that are perhaps their closest modern analogues (where ‘closest’ is a relative term), were probably found worldwide.
The ‘misunderstood’ in the title to this post refers specifically to the type genus, Ornithocheirus, which has suffered something of an identity crisis over the years. In the 1800s, ‘Ornithocheirus‘ was used as a catch-all genus for almost all Cretaceous European pterosaurs, many known from only fragmentary remains. Eventually, the name came to be associated with a number of species centred around the British O. compressirostris. However, Unwin (2001) pointed out that, at its earliest publication, only one valid species was associated with Ornithocheirus, O. simus, and that species automatically becomes the type of the genus. Ornithocheirus simus is not currently regarded as congeneric with ‘O.’ compressirostris (and had for many years been treated under the name of Criorhynchus, e.g. Wellnhofer 1991), and so most species previously treated as Ornithocheirus are now treated as a genus Lonchodectes, and not ornithocheirids. Just to confuse matters further, however, some recent authors have continued to treat Ornithocheirus as typified by O. compressirostris, and refer to the ‘Ornithocheiridae’ of Unwin (2001) as the ‘Anhangueridae’. On the other hand, some recent phylogenies have even suggested that Lonchodectes may itself be related to the Ornithocheiridae (e.g. Andres & Ji 2008).
Ornithocheirus simus was originally described from a piece of the front of the rostrum found in the Cambridge Greensand of England. This piece was notably deep, and so O. simus was reconstructed as having a short, deep puffin-like skull. It wasn’t until the later discovery of a more complete skull in a closely-related South American species, Ornithocheirus mesembrinus (alternatively known as Tropeognathus mesembrinus), that a more accurate reconstruction was possible: Ornithocheirus species had a long rostrum, similar to that found in related pterosaurs, but with prominent rounded dorsal and ventral crests at the distal end. Species of another ornithocheirid genus, Anhanguera (also known from England and South America), had rostral crests set further back and differently shaped. These crests most likely served some form of display function; suggestions that they may have aided in the capture of fish on the wing by easing the rostrum’s passage through the water (Wellnhofer 1991) seem unlikely, as other ornithocheirid genera, such as Brasileodactylus and Barbosania, lacked rostral crests entirely (Elgin & Frey 2011). The possibility has been raised that some crested and crestless forms may represent different sexes of the same species, but unfortunately the fossil record of ornithocheirids may not be extensive enough to establish whether this is the case.
The phylogeny of pterosaurs remains a contentious issue but most studies have agreed that ornithocheirids form part of a clade that also includes the Istiodactylidae, Pteranodontidae and Nyctosaurus (though how exactly these taxa are interrelated has not been agreed upon). Ornithocheirids are distinguished from related forms by the arrangement of their teeth, with the first three pairs enlarged to form a terminal rosette. Most ornithocheirids are also distinguished from Pteranodontidae and Nyctosaurus by the absence of a crest on the back of the head. A noteworthy exception is Ludodactylus sibbicki, described by Frey et al. (2003) from a skull possessing a crest at least basally like that of Pteranodon (the skull is preserved on a slab of rock prepared commercially, and the distal portion of the crest [if it had been present] was removed when the slab was cut). However, it is worth noting that Ludodactylus has not (to my knowledge) been included in a formal phylogenetic analysis. Ludodactylus was identified as an ornithocheirid due to its tooth morphology, but the absence of teeth in Pteranodontidae and Nyctosaurus makes them incomparable in this regard. As the Istiodactylidae (with their broad, duck-like rostra) are also reasonably autapomorphic in their skull morphology, I can’t help wondering whether the supposed ornithocheirid characters might be plesiomorphic for the larger pteranodontoid clade. But that, of course, is pure speculation on my part, and something only further study could establish.
Systematics of Pterodactyloidea
Synapomorphies (from Unwin 2003): Narial and antorbital fenestrae confluent; basipterygoids united to form median bar of bone; cervical ribs reduced; caudal vertebral series shorter than dorsal cortex; pteroid long and slender; wing metacarpal at least 80% length of humerus.
<==Pterodactyloidea (see below for synonymy) |--Ctenochasmatoidea [Archaeopterodactyloidea, Euctenochasmatia, Pterodactylidae]RK13 | | i. s.: Mesadactylus Jensen & Padian 1989W13, W91 | | `--M. ornithosphyos Jensen & Padian 1989CU03 | | Cathayopterus grabauiW13 | | Elanodactylus prolatusW13 | | Ningchengopterus liuaeW13 | | Gladiocephaloideus jingangshanensisW13 | |--+--PterodactylusRK13 | | `--Germanodactylus Young 1964RK13, U03 | | |--G. cristatus (Wiman 1925) [=Pterodactylus cristatus]W13 | | `--G. rhamphastinus (Wagner 1851)K03 [=Pterodactylus rhamphastinusW13] | `--+--CtenochasmatidaeRK13 | `--+--+--Cycnorhamphus Seeley 1870RK13, W13 | | | `--C. suevicus (Quenstedt 1855)K03 [=Pterodactylus suevicusW13, Gallodactylus suevicusW91] | | `--Gallodactylus Fabre 1974RK13, W91 [Gallodactylidae] | | `--G. canjuersensis Fabre 1974K03 [=Cycnorhamphus canjuerensisU03] | `--+--Feilongus youngiRK13 | `--Morganopterus zhuianaW13 `--Pteranodontoidea [Pteranodontia]RK13 | i. s.: Cimoliopterus Rodrigues & Kellner 2013RK13 | `--*C. cuvieri (Bowerbank 1851) (see below for synonymy)RK13 | BoreopteridaeW13 | |--Boreopterus cuiae Lü & Ji 2005RK13 | `--Zhenyuanopterus longirostrisW13 |--NyctosauridaeRK13 | |--Muzquizopteryx coahuilensis Frey et al. 2006W13 | `--Nyctosaurus Marsh 1876U03 | |--N. bonneri Miller 1972K03 | |--N. gracilis (Marsh 1876)K03 [=Pteranodon gracilisW13] | |--N. lamegoi Price 1953W91 | `--N. nanusW13 `--+--Nemicolopterus Wang, Kellner et al. 2008RK13, WK08 | `--*N. crypticus Wang, Kellner et al. 2008WK08 `--+--+--DsungaripteroideaRK13 | `--AzhdarchoideaRK13 `--+--+--+--‘Ornithocheirus’ polyodon Seeley 1870 [=Ptenodactylus polyodon Seeley 1869 (n. n.)]RK13 | | `--AnhangueriaRK13 | `--IstiodactylidaeRK13 | |--Nurhachius ignaciobritoiW13, RK13 | |--Longchengpterus zhaoiW13 | |--Hongshanopterus lacustrisW13 | |--Gwaminapterus beardiW13 | |--Liaoxipterus Dong & Lü 2005W13, A08 | | `--L. brachyognathusW13 | |--Haopterus Wang & Lü 2001W13, U03 | | `--H. gracilisW13 | `--Istiodactylus Howse et al. 2001U03 | |--I. latidens (Seeley 1901)K03 [=Ornithodesmus latidensW13] | `--I. sinensisW13 `--PteranodontidaeRK13 |--Ornithostoma Seeley 1871U03 | |--O. sedgwicki Seeley 1891B93 | `--O. seeleyiW91 `--Pteranodon Marsh 1876U03 [incl. DawndracoW13, GeosternbergiaW13] |--P. eatoniW91 |--P. ingens (Marsh 1872) [=Pterodactylus ingens]W91 |--‘Dawndraco’ kanzaiW13 |--P. longiceps Marsh 1876K03 |--‘Geosternbergia’ maiseyiW13 |--P. marshiW91 |--P. occidentalis (Marsh 1872) (see below for synonymy)W91 |--P. oregonensis Gilmore 1928W91 |--P. sternbergi Harksen 1966B93 [=Geosternbergia sternbergiW13] `--P. walkeriW91 Pterodactyloidea incertae sedis: Osteornis diomedeus Gervais 1844 (n. d.) (see below for synonymy)RK13 Lonchodraco Rodrigues & Keller 2013 [Lonchodraconidae]RK13 |--*L. giganteus (Bowerbank 1846) (see below for synonymy)RK13 |--L. machaerorhynchus (Seeley 1870) (see below for synonymy)RK13 `--L. microdon (Seeley 1870) (see below for synonymy)RK13 Ornithocheiridae [Criorhynchidae, Ornithocheirae, Ornithocheirinae]RK13 |--Arthurdactylus conandoylei Frey & Martill 1994FMB03 |--BarbosaniaW13 |--Yixianopterus jingangshanensisW13, RK13 |--GuidracoW13 |--Aetodactylus halliW13, RK13 |--MythungaW13 |--*Aussiedraco molnariRK13, W13, RK13 |--OrnithocheirusRK13 |--Araripesaurus Price 1971W91 | |--A. castilhoi Price 1971U03 | `--A. dehmiW91 `--Santanadactylus Buisonjé 1980W91 |--S. brasilensis Buisonjé 1980U03 `--S. pricei Wellnhofer 1985U03
*Cimoliopterus cuvieri (Bowerbank 1851) [=Pterodactylus cuvieri, Anhanguera cuvieri, Coloborhynchus cuvieri, Ornithocheirus cuvieri, Ornithochirus (l. c.) cuvieri, Ptenodactylus cuvieri]RK13
*Lonchodraco giganteus (Bowerbank 1846) [=Pterodactylus giganteus, Lonchodectes giganteus, Ornithocheirus giganteus, Ornithochirus (l. c.) giganteus, Ornithodesmus giganteus, Pterodactylus conirostris Owen in Dixon 1850]RK13
Lonchodraco machaerorhynchus (Seeley 1870) [=Ornithocheirus machaerorhynchus, Lonchodectes machaerorhynchus, Lonchodectes machaeorhynchus (l. c.), Ptenodactylus machaerorhynchus Seeley 1869 (n. n.)]RK13
Lonchodraco microdon (Seeley 1870) [=Ornithocheirus microdon, Lonchodectes microdon, Ptenodactylus microdon Seeley 1869 (n. n.); incl. Ornithocheirus oweni Seeley 1870, Lonchodectes oweni, Ptenodactylus oweni Seeley 1869 (n. n.)]RK13
Osteornis diomedeus Gervais 1844 (n. d.) [=Cimoliornis diomedeus, C. diomedaeus (l. c.), Ornithocheirus diomedius (l. c.), Ornithochirus diomedius (l. c.)]RK13
Pteranodon occidentalis (Marsh 1872) [=Pterodactylus occidentalis, Pterodactylus oweni Marsh 1871 non Ornithocheirus oweni Seeley 1870]W91
Pterodactyloidea [Euornithocheira, Eupterodactyloidea, Lophocratia, Germanodactylidae, Ornithocheira, Ornithocheiroidea, Pterodactylida, Pterodactyloidei, Tapejaroidea]
*Type species of generic name indicated
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[RK13] Rodrigues, T., & A. W. A. Kellner. 2013. Taxonomic review of the Ornithocheirus complex (Pterosauria) from the Cretaceous of England. ZooKeys 308: 1–112.
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[W91] Wellnhofer, P. 1991. The Illustrated Encyclopedia of Pterosaurs. Salamander Books: London (reprinted in: Norman, D., & P. Wellnhofer. 2000. The Illustrated Encyclopedia of Dinosaurs. Salamander Books).
[W13] Witton, M. P. 2013. Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press: Princeton (New Jersey).