| Aviatyrannis | |
|---|---|
 | |
| Diagram of fossils assigned toAviatyrannis | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | Orionides |
| Clade: | Avetheropoda |
| Clade: | Coelurosauria |
| Genus: | †Aviatyrannis Rauhut,2003 |
| Species: | †A. jurassica |
| Binomial name | |
| †Aviatyrannis jurassica Rauhut, 2003 | |
Aviatyrannis is agenus ofcoelurosauriantheropoddinosaur, either atyrannosauroid or anornithomimosaurian, from theOxfordian-Tithonianstages of theLate Jurassic found inPortugal.
In 2000Oliver Walter Mischa Rauhut reported the find of tyrannosauroid material in thelignite coal mine ofGuimarota nearLeiria, which he referred toStokesosaurus.[1] Later concluding the distinctiveness of the material justified a separate genus, Rauhut in 2003 named and described it as thetype speciesAviatyrannis jurassica.[2] Thespecies name was by Rauhut given the intended meaning of "tyrant's grandmother from the Jurassic".[2] The generic name is derived fromLatinavia, "grandmother", andtyrannus, "tyrant", on the presumptiontyrannis would be itsgenitive.[2] Thespecific name means "Jurassic".[2]
Theholotype,IPFUB Gui Th 1, was found in a layer of theAlcobaça Formation dating from the early Kimmeridgian, about 155 million years old. It consists of a rightilium. Rauhut in 2003 referred two other bones toAviatyrannis: IPFUB Gui Th 2, a partial right ilium, and IPFUB Gui Th 3, a rightischium. The referred elements represent slightly larger individuals. Additionally sixteen isolated teeth were referred: IPFUB GUI D 89-91: three teeth of thepremaxilla, and IPFUB GUI D 174-186: thirteen teeth of themaxilla anddentary.[2] These had in 1998 been described byJens Zinke.[3] Rauhut also hypothesised that a number of specimens referred toStokesosaurus might actually belong toAviatyrannis.[2]
Aviatyrannis was a rather small theropod. The holotype specimen IPFUB Gui Th 1, for example, is an ilium only ninety millimeters long. In 2016,Gregory S. Paul estimated its length at 1 m (3.3 ft) and its body mass at 4 kg (8.8 lb); he also suggested that the holotype possibly belongs to a juvenile.[4] The ilium is elongated and low with the typical tyrannosauroid vertical ridge on the outer blade surface above the hip joint.[2] The teeth of the praemaxilla have a D-shaped cross-section. The maxillary and dentary teeth are elongated, only recurving near the top, with perpendicular denticles on both edges. Their bases are circular in cross-section; the top of the tooth crown is more flattened.[3]
Aviatyrannis was in 2003 by Rauhut placed in theTyrannosauroidea, in a basal position.[2] If this placement is correct,Aviatyrannis is one of the oldest tyrannosauroids ever found, the oldest beingProceratosaurus (or, possibly,Iliosuchus).[2] However, a 2023 paper by Hattoriet al. noted that theAviatyrannis ilium is strikingly similar to that of the newly describeddeinocheiridTyrannomimus. The authors argue that, though more detailed study is needed,Aviatyrannis could be the earliest knownornithomimosaur and possibly the earliest known deinocheirid, with one analysis recovering it as a sister taxon ofTyrannomimus and the other recovering it as an ornithomimosaur outside deinocheirids and ornithomimids. The results of theirphylogenetic analyses are displayed in thecladogram below:[5]
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