| Coloborhynchus Fossil range: Early Cretaceous | |
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 Coloborhynchus piscator, a pterodactyloid. | |
| Scientific classification
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Ornithocheiridae | |
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See text. | |
Coloborhynchus is a genus in the pterosaur family Ornithocheiridae, and is known from the Lower Cretaceous of Europe, North America, and South America.
History and classification[]
In 1874 Richard Owen, rejecting the creation by Harry Govier Seeley of the genus Ornithocheirus, named a species Coloborhynchus clavirostris based on holotype BMNH 1822, a partial snout from the Cambridge Greensand. The genus name means "maimed beak", a reference to the damaged and eroded condition of the fossil; the specific name means "key snout", referring to its form in cross-section. Owen considered the defining trait of the genus to be the location of the front tooth pairs high on the side of the upper jaws. However, in 1913 Reginald Walter Hooley concluded that this location was an artefact of the erosion and that the genus was indistinguishable from Criorhynchus, the second genus Owen erected in 1874. Most later researchers assigned both forms to Ornithocheirus.
This changed in 1994 when Yuaong-Nam Lee named Coloborhynchus wadleighi for a snout found in 1992 in Texas. The revival of the genus implied that of several related species, in the meantime assigned to other genera, it had to be determined whether they belonged to Coloborhynchus. No consensus has developed on this matter, especially as the most complete material is from to be renamed forms as Anhanguera, whereas the type species and C. wadleighi are known from very fragmentary remains. Paleontologists David Unwin and André Veldmeijer have named several new Coloborhynchus species, whereas Brazilian researcher Alexander Kellner opposes their position. Species include:
- C. clavirostris (Owen, 1874), the type species.
- C. sedgwicki (Owen 1874) = Pterodactylus sedgwickii (Owen 1859) = Ornithocheirus sedgwicki (Newton 1888)
- C. araripensis (Veldmeijer 2003) = Santanadactylus araripensis (Wellnhofer 1985) from Brazil. Its wingspan is in excess of three metres.
- C. wadleighi (Lee 1993) from Texas. In 2009 it has been given the name Uktenadactylus by Kellner.
- C. spielbergi (Veldmeijer 2003) from Brazil. It has an estimated wingspan of six metres; the specific name honours Steven Spielberg.
- C. piscator (Veldmeijer 2003) = originally Anhanguera piscator (Kellner & Tomida 2000)
Description[]
The type specimen of Coloborhynchus is known only from a partial upper jaw. Therefore, according to Rodrigues and Kellner's 2008 re-evaluation on Coloborhynchus clavirostris, it can only be differentiated from its relatives based on its unique combination of tooth socket positions. In Coloborhynchus, the two front teeth pointed forward and were higher on the jaw than the other teeth, while the next three pairs of teeth pointed to the sides. The final two (preserved) pairs of teeth pointed downward. Finally, a unique oval depression was located below the first pair of teeth.
Like the related Anhanguera and Uktenadactylus, the tip of the snout flared out into a wider rosette, in contrast to the narrow posterior jaws. However, whereas the rosettes of species typically assigned to Anhanguera were rounded and spoon-shaped, those of Coloborhynchus were robust and box-shaped.
Also like its close relatives, Coloborhynchus had a keel-shaped crest on the front of its jaws, though it was broad and thinned from base to top, rather than the uniformly thin crests of its relatives. This kind of thickened crest is also seen in Siroccopteryx moroccensis, which may be its closest relative or a member of the same genus. It also had a straight, rather than curved, front margin, unlike its relatives, and begins at the tip of the snout, rather than further back as in other species.
A second specimen showing all of these same unique features was reported to Brazilian paleontologist Alexander Kellner by Darren Naish in 2007, and likely represents a second specimen of C. clavirostris, though it has not yet been described.
The possible species Coloborhynchus capito represents the second largest known ornithocheirid (after a Tropeognathus specimen), and indeed the largest toothed pterosaur known. A referred specimen from the Cambridge Greensand of England described in 2011 consists of a very large upper jaw tip which displays the tooth characteristics that distinguish C. capito from other species. The jaw tip is nearly 10 cm tall and 5.6 cm wide, with teeth up to 1.3 cm in base diameter. If the proportions of this specimen were consistent with other known species of Coloborhynchus, the total skull length could have been up to 75 cm, leading to an estimated wingspan of 7 metres (23 ft). However, this species may belong to a different genus.
A rostrum fragment diagnostic to Coloborhynchus sp. is known from the Wessex Formation of England.
Classification[]
A topology made by Andres and Myers in 2013 placed the species Coloborhynchus clavirostris and C. wadleighi (now generally considered as Uktenadactylus) within the family Ornithocheiridae as sister taxa to Ornithocheirus simus, and the family itself is placed within the more inclusive clade Ornithocheirae. Later, in 2019, Pentland et al. recovered a similar result to the one by Andres and Myers in 2013 where Coloborhynchus is the sister taxon of Ornithocheirus. Their cladogram is shown on the left. In 2018, Jacobs et al. also recovered a similar cladogram compared to Andres and Myers (2013), where both Coloborhynchus and Siroccopteryx were assigned to the Ornithocheiridae, however, unlike the study made by Andres and Myers, they used the name Uktenadactylus wadleighi to refer to C. wadleighi in their analysis. They published their conclusion in 2019. However, many subsequent analyses made in 2019 and 2020 have recovered Coloborhynchus within the family Anhangueridae, more specifically within the subfamily Coloborhynchinae. The cladogram on the left shows a phylogenetic analysis made by Borja Holgado and Rodrigo Pêgas in 2020.
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Topology 1: Pentland et al. (2019).[1]
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Topology 2: Holgado & Pêgas (2020).[2]
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Paleobiology[]
See also[]
References[]
The Pterosaur Database (multiple species, scroll down)
