| Appalachiosaurus | |
|---|---|
 | |
| Reconstructed skeleton,Tellus Science Museum | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | †Eutyrannosauria |
| Genus: | †Appalachiosaurus Carret al.,2005 |
| Species: | †A. montgomeriensis |
| Binomial name | |
| †Appalachiosaurus montgomeriensis Carret al., 2005 | |
Appalachiosaurus (/ˌæpəˌleɪtʃioʊˈsɔːrəs/AP-ə-LAY-chee-oh-SOR-əs; "Appalachian lizard") is agenus oftyrannosauriantheropoddinosaur from theLate Cretaceous period of what is now easternNorth America. It was a basal member of theEutyrannosauria clade meaning it was rather close in relation to the true tyrannosaurids such asTyrannosaurus. Like most theropods, it was abipedalpredator. Only a juvenile skeleton has been found, representing an animal approximately 6.5 metres (21 ft) long and weighing 623 kilograms (1,373 lb), which indicates an adult would have been significantly larger.
Fossils ofAppalachiosaurus were found in central Alabama'sDemopolis Chalk Formation. This formation dates to the middle of theCampanian age of theLate Cretaceous, around 77million years ago.[1] Fossil material assigned toAppalachiosaurus is also known from theDonoho Creek andTar Heel-Coachman formations ofNorth andSouth Carolina in 2007.[2]
The type specimen was found byAuburn University geologist David King in July 1982.[3] This dinosaur was named after the region of the easternUnited States known asAppalachia, which also gave its name to theancient island continent whereAppalachiosaurus lived. Both are named after theAppalachian Mountains. The generic name also includes theGreek wordsauros ("lizard"), the most common suffix used in dinosaur names. There is one knownspecies,A. montgomeriensis, which is named afterMontgomery County,Alabama. Both the genus and species were named in 2005 bypaleontologistsThomas Carr andThomas Williamson.
The juvenile specimen ofAppalachiosaurus measures approximately 6.5 m (21 ft) long and 623 kg (1,373 lb).[1][4] So far, it is only known from partial remains, including parts of theskull and lower jaw, as well as severalvertebrae, parts of thepelvis, and most of both legs. These remains are housed at theMcWane Science Center inBirmingham, Alabama. There are several opensutures between bones of the skull, indicating that the animal was definitely a juvenile. Several of its bones are crushed, but the specimen is still informative and shows many unique characteristics. Several of these have been identified in the skull and the foot claws show an unusual protrusion on the end closest to the body. A row of six low crests lines the top of the snout, similar to those of theAsianAlioramus, although most tyrannosaur species exhibit ornamentation to varying degrees on top of their snout and brows. The only remains found are from a juvenile, meaning that the size and weight of an adult is unknown.Appalachiosaurus is significantly different and more derived than another eutyrannosaur from eastern North America,Dryptosaurus.
The arms ofAppalachiosaurus are poorly known. Large tyrannosaurids are characterized by proportionally small arms and hands with two functional fingers. Although some reports of ahumerus are ascribed toAppalachiosaurus, no arm material is actually known.[5] Early reconstructions gave it long arms with three large fingers, but they are now thought to have been much shorter and have only two fingers. Museum mounts have been corrected accordingly, though other locations still support the former theory.[6]Appalachiosaurus had a bone-crushing bite force of around 32,500 newtons, or 7,193 pounds per square inch.[7]
The only known specimen ofAppalachiosaurus was complete enough to be included in phylogenetic analyses usingcladistics. The first was performed before the animal had even been named and foundAppalachiosaurus to be a member of theAlbertosaurinae subfamily of Tyrannosauridae, which only includesAlbertosaurus andGorgosaurus.[8] The original description also included a cladistic analysis, findingA. montgomeriensis to be abasal tyrannosauroid outside of Tyrannosauridae.[1] However, Asian tyrannosaurs, likeAlioramus andAlectrosaurus, were excluded, as wasEotyrannus fromEngland. Earlier tyrannosaurs, such asDilong andGuanlong, had not been described at the time this analysis was performed. These exclusions may have a significant effect on the phylogeny.
Below is a cladogram published in 2013 by Loewenet al..[9]
Two vertebrae of the tail were found to be fused together, which is possibly a result of newbone growth following some sort of minor or traumatic injury.[1]
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