Aublysodon

Credit: Teratophoneus on DeviantArt.

*Aublysodon* is a dubious genus of tyrannosaurid dinosaurs that lived in Montana during the Late Cretaceous.

## History

Leidy (1856) named the type from 14 teeth collected by Ferdinand Vandeveer Hayden in 1854 and '55 from the Judith River, originally as *Deinodon horridus*. Cope (1866) chose 3 nonserrated teeth as lectotypes, with Leidy naming the lectotypes as *A. mirandus* in 1868. The etymology of this name is uncertain, as he provided no explanation; it is possible that it means "backwards"/"contrariwise"/"to spout"/"to flow" "tooth". The specific epithet means "wonderful" or "strange". Because it was based on the same type, it was originally a junior objective synonym. Cope (1868) had thought that the name *Deinodon* was preoccupied by a snake, *Dinodon*, naming *A. horridus*. However, this was not justified as it was neither preoccupied nor would have been grounds to suppress *Aublysodon* (as it would have taken priority). Perry (1899) corrected Cope's mistake. Marsh further limited the lectotype to one nonserrated premaxillary tooth with a D-shaped cross section (ANSP 9535), making *A. mirandus* valid. The two others, ANSP 9533 and 9534, remained lectotype of *Deinodon* and thus differentiated the names. Some later workers had assumed that it was an ornithomimid before it was discovered to be a toothless family. Lambe (1902) referred the tooth to *Struthiomimus* and Hay (1920) moved *mirandus* to *Ornithomimus*, forgetting that if this were the case, *Aublysodon* would take priority. Today, it is often lumped with juvenile Daspletosaurus. Since the holotype was lost in October 2000 when sent by registered mail from the Academy of Natural Sciences, Philadelphia to the Field Museum of Natural History, Carr no longer considers it valid; a nomen dubium.

## Classification

Cope (1870) initially assigned this taxon to Goniopoda (roughly analogous with theropods), but Marsh (1892) thought their small size, D-shaped cross section and lack of serrations suggested that it was a giant mammal. Typically, it has been assigned to Deinodontidae, which is synonymous with Tyrannosauridae. Paul (1988) used the taxon Aublysodontinae with Aublysodontidae, which were coined by Nopsca (1928). This concept attracted some use with Holtz (2001) creating a taxonomic definition of the clade. He then proposed a node clade definition of tyrannosaurids in 2001 as being all descending taxa from the concester of *Aublysodon* and *Tyrannosaurus*, with the former as the anchor taxon. Sereno also shared that idea, although his definition was not streamlined. Both have been revised without the use of dubious names and Aublysodontidae and -inae have been rejected.

Cope (1876) named *A. lateralis* from AMNH 3956 (tooth), which was synonymized with *Deinodon*. marsh (1892) named *A. amplus* and *A. cristatus* from YPM 296 and YPM 297, respectively, and the latter has been placed into *Deinodon*. They may be juvenile *Tyrannosaurus*, as they are from the Maastrichtian Lance Formation. Hatcher (1903) placed Cope (1876)'s *Laelaps explanatus* as a new species of *Aublysodon*, and is probably actually from *Saurornitholestes*. Von Huene (1932) placed Marsh (1890)'s fragmentary *Ornithomimus grandis* into *A. grandis*, but most consider this synonymous with *Deinodon*. Charig (1967) named *A. lancinator*, *A. novojilovi* and *A. lancensis*: the first two are juvenile *Tarbosaurus*, the latter being what is typically considered *Nanotyrannus* (juvenile *Tyrannosaurus*). The first skeletal material was a partial skull, LACM 28741 (45 centimeters long) from Jordan in 1966 and described by Molnar (1977-1988). First, it was assigned juvenile *Tyrannosaurus* and then to Dromaeosauridae, becoming known as the "Jordan theropod", or *A. molnaris* (*molnari*, as emended in 1990) by Paul (1988). Then, it was separated into *Stygivenator* by Olshevsky (1995); Carr and Williamson (2004) placed it back into *Tyrannosaurus*. OUMNH 10131 is a partial skeleton considered to be a part of this genus, but Carr and Williamson first placed it into *Daspletosaurus* and then *Bistahieversor*. paul (1988) also created *Shanshanosaurus huoyanshanensis*, with Carr and William creating *A. huoyanshanensis*; it is likely the first *Tarbosaurus* specimen.

## Species

### Reassigned Species

* *"A." horridus*
* *"A." lateralis*
* *"A." amplus*
* *"A." cristatus*
* *"A." explanatus*
* *"A." grandis*
* *"A." lancinator*
* *"A." lancensis*
* *"A." novojilhovi*
* *"A." molnaris*/*molnari*
* *"A." huoyanshanensis*