| Choyrodon | |
|---|---|
 | |
| Skull of MPC-D 100/801, drawing and physical reconstruction | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Clade: | †Ornithopoda |
| Clade: | †Hadrosauriformes |
| Superfamily: | †Hadrosauroidea |
| Genus: | †Choyrodon |
| Species: | †C. barsboldi |
| Binomial name | |
| †Choyrodon barsboldi Gateset al.,2018 | |
Choyrodon is agenus ofhadrosauroiddinosaur from theEarly CretaceousAlbian-ageKhuren Dukh Formation ofMongolia. Thetype and only species isChoyrodon barsboldi. The generic name is derived from the city ofChoyr, and-odon, fromLatin for tooth; the specific namebarsboldi honourspaleontologistRinchen Barsbold. The material consists of aholotype partial skull and cervical ribs, with two other partial skulls both with associated postcranial material. It was found to be thesister taxon ofEolambia.
Three specimens of a newiguanodontian were discovered in theKhuren Dukh Formation ofMongolia by an expedition led by Mongolian paleontologistRinchen Barsbold. These three specimens, stored in theMongolian Natural History Museum, were found within the same sediments that had yielded the iguanodontianAltirhinus, but comparisons showed that they represented different taxa and so in2018 American paleontologist Terry Gates and colleagues named themChoyrodon barsboldi. The genus name is derived from the nearby city ofChoyr and theLatin word for "tooth",don, while the species name is in honour of Barsbold and his contributions to Mongolian paleontology.[1]
Three specimens ofChoyrodon are known, each from a different locality of the lower member of the Khuren Dukh Formation. Theholotype is MPC-D 100/801, and includes a partial but mostly complete disarticulated skull, while the referred specimens, MPC-D 100/800 and MPC-D 100/803, preserve another partial skull and fragmentary skeleton, and a fragmentary skull and partial skeleton, respectively. The quarry the holotype was found in is a thick brown-blacksiltstone at the Khuren Dukh locality of the formation, with an age of approximately middle to lateAlbian based onpalynology.[1]
Gates and colleagues assessed the position ofChoyrodonphylogenetically when describing the taxon, under two varying conditions.Choyrodon displays an openantorbital fenestra, which clearly distinguishes it from coexistingAltirhinus, but this feature can vary during growth so they assessed the impact of treating the fenestra as present or absent in an adult would alter relationships. They found that the presence or absence of an antorbital fenestra in adults did not significantly change the relationships ofChoyrodon, with it either as the sister taxon ofEolambia or an intermediate earlyhadrosauroid. There was not support for interpretingChoyrodon as a juvenileAltirhinus, despite their similar anatomy, age, and location.[1]
