Genus of lonchodraconid pterosaur from the Early Cretaceous
Ikrandraco ("Ikran [a flying creature from "Avatar" with a crest on the lower jaw] dragon") is a genus of lonchodraconid pterodactyloid pterosaur known from the Lower Cretaceous Jiufotang Formation of northeastern China, and the Cambridge Greensand of England. It is notable for its unusual skull, which features a crest on the lower jaw.
Discovery and naming.
The type species, "Ikrandraco avatar" is based on specimen IVPP V18199, a partial skeleton including the skull and jaws, several neck vertebrae, a partial sternal plate, parts of both wings, and part of a foot. A second specimen, IVPP 18406, has also been assigned to "Ikrandraco"; it consists of a skull and jaws and the first three neck vertebrae. Both specimens come from the Aptian-age Lower Cretaceous Jiufotang Formation of Liaoning, with an estimated date of 120 million years ago. The type species is I. avatar, a second reference to James Cameron’s “Avatar”. It was described in 2014 by Wang Xiaolin and colleagues, but was not properly named according to ICZN rules until 2020.
In 1869, British paleontologist Harry Govier Seeley assigned remains he found to a new species of pterosaur called "Ptenodactylus machaerorhynchus", at the same time disclaiming the name which makes it invalid by modern standards. In 1870, Seeley had realized that the generic name "Ptenodactylus" had been preoccupied and renamed the species into "Ornithocheirus machaerorhynchus". The specific name means "sabre snout" in Greek. In 1914, Hooley renamed it into "Lonchodectes machaerorhynchus". Its holotype, CAMSM B54855, was found near Cambridge, in a layer of the Cambridge Greensand dating from the Cenomanian but containing reworked fossils from the Albian. It consists of the rear end of a symphysis of the lower jaws.
Also in 1869, Seeley informally named "Ptenodactylus microdon". In 1870, he formally named it "Ornithocheirus microdon", "small tooth", Hooley (1914) transferred this species to "Lonchodectes" to form the new combination "Lonchodectes microdon". Its holotype, CAMSM B54486, has its provenance in the Cambridge Greensand and consists of the front of a snout. The type specimen of the species "Ornithocheirus oweni", CAMSM B 54439, initially described by Seeley in 1864 as "Pterodactylus oweni", was synonymized with "microdon" by Unwin in 2001, and later in 2013, Rodrigues &amp; Kellner agreed with this synonymy.
In 2013, paleontologists Taissa Rodrigues and Alexander Kellner made an extensive review of the species of "Ornithocheirus", and stated that the generic name "Lonchodectes" would have been a "nomen dubium", and therefore reassigned both "Lonchodectes machaerorhynchus" and "L. microdon" into the genus "Lonchodraco", creating "Lonchodraco machaerorhynchus" and "L. microdon".
In his review of Lonchodectidae, Alexander Averianov reassigned "Lonchodraco machaerorhynchus" to "Ikrandraco", and also declared "Lonchodraco microdon" (including "O. oweni") a junior synonym of "machaerorhynchus".
Description.
"Ikrandraco avatar" is notable for having a very long, low skull (the height of the back of the skull, at the quadrates, is less than 19% the length of the skull), with a prominent blade-like crest on the underside of the lower jaw and no corresponding crest on the tip of the upper jaw, a crest combination not seen in other pterosaurs to date. The posterior edge of the crest also has a hook-like process. Each side of the upper jaw has at least 21 small cylindrical teeth, and each side of the lower jaw has at least 19. The skull of the type specimen is long, and the skull of the second specimen is at least long.
Rodrigues &amp; Kellner established four autapomorphies of "Ikrandraco machaerorhynchus" (then "Lonchodraco"). A deep crest is present at the underside of the lower jaws. To the rear, the profile of this crest turns upwards. Behind this crest a depression is present at the underside of the jaws. The midline groove at the top of the lower jaws symphysis is deep. Furthermore, there is a density of 4.5 teeth per three centimeters of jaw edge.
Classification.
Wang "et al." performed a phylogenetic analysis including "Ikrandraco" and found it to be a basal pteranodontoid, more derived than "Pteranodon" but not as derived as the istiodactylids, anhanguerids, and other pteranodontoids. The portion of their results dealing with Pteranodontoidea is shown below.
The cladogram below is a topology recovered by Pêgas "et al." (2019). In the analyses, they recovered "Ikrandraco" as a member of the family Lonchodraconidae, and the sister taxon of "Lonchodraco".
Paleobiology.
Wang "et al." interpreted the crest as a possible adaptation for skim fishing, although they did not regard this as the animal's main method of foraging. The hook on the crest may have been an attachment point for a throat pouch for storing food, akin to a pelican. "Ikrandraco" was an approximate contemporary of the distantly related anhanguerians "Liaoningopterus gui" and "Guidraco venator", and all three are regarded as piscivores, but "Ikrandraco" differed from them in its much smaller and less robust teeth, indicating it had a different niche.
References.
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