Appalachiosaurus

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Extinct genus of dinosaurs

title: "Appalachiosaurus" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["tyrannosauroidea", "dinosaur-genera", "campanian-dinosaurs", "demopolis-chalk", "dinosaurs-of-the-united-states", "fossil-taxa-described-in-2005"] description: "Extinct genus of dinosaurs" topic_path: "geography/united-states" source: "https://en.wikipedia.org/wiki/Appalachiosaurus" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Extinct genus of dinosaurs ::

| fossil_range = Late Cretaceous, | image = Tellus Appalachiosaurus.jpg | image_caption = Reconstructed skeleton, Tellus Science Museum | display_parents = 2 | genus = Appalachiosaurus | parent_authority = Carr et al., 2005 | species = montgomeriensis | authority = Carr et al., 2005

Appalachiosaurus ( ; "Appalachian lizard") is a genus of tyrannosauroid theropod dinosaur from the Late Cretaceous period of what is now eastern North America. It was a basal member of the clade Eutyrannosauria, meaning it was rather close in relation to the true tyrannosaurids such as Tyrannosaurus. Like most theropods, it was a bipedal predator. Only a juvenile skeleton has been found, representing an animal approximately 6.5 m long and weighing 623 kg, which indicates an adult would have been significantly larger.

Fossils of Appalachiosaurus were found in central Alabama's Demopolis Chalk Formation. This formation dates to the middle of the Campanian age of the Late Cretaceous, around 77 million years ago. Fossil material assigned to Appalachiosaurus is also known from the Donoho Creek and Tar Heel/Coachman formations of South and North Carolina respectively in 2007, as well as the Ripley Formation in the Hannahatchee Creek in Georgia.

Discovery and naming

The type specimen was found by Auburn University geologist David King in July 1982. This dinosaur was named after the region of the eastern United States known as Appalachia, which also gave its name to the ancient island continent where Appalachiosaurus lived. Both are named after the Appalachian Mountains. The generic name also includes the Greek word sauros ("lizard"), the most common suffix used in dinosaur names. There is one known species, A. montgomeriensis, which is named after Montgomery County, Alabama. Both the genus and species were named in 2005 by paleontologists Thomas Carr and Thomas Williamson.

Description

::figure[src="https://upload.wikimedia.org/wikipedia/commons/d/d6/Appalachiosaurus_Scale.svg" caption="Size comparison"] ::

The juvenile specimen of Appalachiosaurus measures approximately 6.5 m long and 623 kg. So far, it is only known from partial remains, including parts of the skull and lower jaw, as well as several vertebrae, parts of the pelvis, and most of both legs. These remains are housed at the McWane Science Center in Birmingham, Alabama. There are several open sutures 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 the Asian Alioramus, 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.

::figure[src="https://upload.wikimedia.org/wikipedia/commons/a/ab/Appalachiosaurus_montgomeriensis.jpg" caption="[[Life restoration"] ::

The arms of Appalachiosaurus are poorly known. Large tyrannosaurids are characterized by proportionally small arms and hands with two functional fingers. Although some reports of a humerus are ascribed to Appalachiosaurus, no arm material is actually known. 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.

Classification

::figure[src="https://upload.wikimedia.org/wikipedia/commons/2/23/Appalachiosaurus_arms.jpg" caption="Outdated skeletal reconstruction with large, three-fingered forelimbs, based on a [[pubic bone]] earlier thought to have been a [[humerus]] upper arm bone."] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/b1/Appalachiosaurus_humerus,_Tellus_Science_Museum.jpg" caption="Pubic bone mislabelled as a humerus, Tellus Science Museum"] ::

The only known specimen of Appalachiosaurus was complete enough to be included in phylogenetic analyses using cladistics. The first was performed before the animal had even been named and found Appalachiosaurus to be a member of the Albertosaurinae subfamily of Tyrannosauridae, which only includes Albertosaurus and Gorgosaurus. The original description also included a cladistic analysis, finding A. montgomeriensis to be a basal tyrannosauroid outside of Tyrannosauridae. However, Asian tyrannosaurs, like Alioramus and Alectrosaurus, were excluded, as was Eotyrannus from England. Earlier tyrannosaurs, such as Dilong and Guanlong, 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 Loewen et al..

|1={{clade |1=Dilong paradoxus |2={{clade |1=Eotyrannus lengi |2={{clade |1=Bagaraatan ostromi |2={{clade |1=Raptorex kriegsteini |2={{clade |1=Dryptosaurus aquilunguis |2={{clade |1={{clade |1=Alectrosaurus olseni |2=Xiongguanlong baimoensis }} |2={{clade |1=Appalachiosaurus montgomeriensis |2={{clade |1={{clade |1=Alioramus altai |2=Alioramus remotus }} |2=Tyrannosauridae }} }} }} }} }} }} }} }} }} In their 2025 paper, Zanno and Napoli conducted two phylogenetic analyses using an extensive novel dataset focused on sampling tyrannosauroids. The first, a maximum parsimony analysis (shown below as Topology A) recovered Appalachiosaurus outside of Eutyrannosauria as sister taxon to a clade containing the Mongolian species Alectrosaurus olseni and Khankhuuluu mongoliensis. The second, a Bayesian inference analysis implementing a fossilized birth–death (BI-FBD) model (shown below as Topology B), placed the Appalachian tyrannosauroids Appalachiosaurus and Dryptosaurus as the successive earliest-divering branches within the Nanotyrannidae. The authors noted that further testing and more data would be required to support the results of one analysis over the other.

Topology A: Maximum parsimony tree (K = 12) |{{clade |1=Proceratosauridae [[File:Sinotyrannus kazuoensis.png|65px]] |label2= |2={{clade |1={{clade |1=Dilong paradoxus [[File:Dilong scratching 02.png|65px]] |2=Eotyrannus lengi [[File:Eotyrannus 2 NT.jpg|65px]] }} |3={{clade |1=Suskityrannus hazelae [[File:Suskityrannus.png|65px]] |2={{clade |1=Xiongguanlong baimoensis [[File:Xiongguanlong baimoensis.png|65px]] |2={{clade |1=Timurlengia euotica [[File:Timurlengia.jpg|65px]] |2={{clade |1={{clade |1=Appalachiosaurus montgomeriensis [[File:Appalachiosaurus TD.png|65px]] |2={{clade |1=Alectrosaurus olseni [[File:Alectrosaurus flipped.png|65px]] |2=Khankhuuluu mongoliensis [[File:Khankhuuluu mongoliensis.png|65px]] }} }} |label3= |3={{clade |1=Dryptosaurus aquilunguis [[File:Dryptosaurus TD.png|65px]] |2={{clade |label1=Nanotyrannidae |1={{clade |1={{clade |1=Moros intrepidus [[File:Moros TD.png|65px]] |2=N. lethaeus (BMRP 2002.4.1) [[File:Nanotyrannus lethaeus.png|65px]]|barbegin2=crimson }} |label3=N. lancensis |3={{clade |1=BMRP 2006.4.4 |bar1=crimson |2=CMNH 7541 (N. lancensis holotype) [[File:Nanotyrannus lancensis.png|65px]]|bar2=crimson |3=NCSM 40000 ("Bloody Mary") |bar3=crimson |4=KUVP 156375 |barend4=crimson }} }} |grouplabel1=

|label5=Tyrannosauridae |5={{clade |label1=Albertosaurinae |1={{clade hidden |id=1 |1={{clade |1=Bistahieversor sealeyi [[File:Bistahieversor sealeyi life restoration.jpg|65px]] |2=UMNH VP 16690 }} |3={{clade |1=Jinbeisaurus wangi |2={{clade |1=TCMI 2001.81.1 |2={{clade |1=Teratophoneus curriei [[File:Teratophoneus curriei by PaleoGeek.png|65px]] |2={{clade |1=UALVP 52981 |2={{clade |1=Gorgosaurus sp. nov |2={{clade |1=Gorgosaurus libratus [[File:Gorgosaurus flipped.png|65px]] |2={{clade |1=Albertosaurus sarcophagus [[File:Albertosaurus TD.png|65px]] |2=Albertosaurus sp. nov }} }} }} }} }} }} }} }} |label3=Tyrannosaurinae |3={{clade |label1=Alioramini |1={{clade hidden |id=2 |1=Alioramus altai [[File:Alioramus_altai.jpg|65px]] |2=Qianzhousaurus sinensis [[File:Qianzhousaurus sinensis by PaleoGeek.png|65px]] }} |3={{clade |1=Asiatyrannus xui [[File:Asiatyrannus xui.png|65px]] |2={{clade |1=Thanatotheristes degrootorum |2={{clade |label1=Daspletosaurus |1={{clade hidden |id=3 |1=Daspletosaurus wilsoni |2={{clade |1=Daspletosaurus horneri |2=Daspletosaurus torosus [[File:Daspletosaurus torosus steveoc flipped.jpg|65px]] }} }} |label3=Tyrannosaurini |3={{clade hidden |id=4 |1=Lythronax argestes [[File:Lythronax TD.png|65px]] |2={{clade |1=Zhuchengtyrannus magnus [[File:Zhuchengtyrannus magnus reconstruction.jpg|65px]] |2={{clade |1=Tarbosaurus bataar [[File:Tarbosaurus TD.png|65px]] |2={{clade |1=Tyrannosaurus mcraeensis [[File:Tyrannosaurus mcraeensis.png|65px]] |2=Tyrannosaurus rex [[File:Tyrannosaurus TD.png|65px]]

Topology B: BI-FBD tree |{{clade |1=Proceratosauridae [[File:Sinotyrannus kazuoensis.png|65px]] |label2= |2={{clade |1={{clade |1=Dilong paradoxus [[File:Dilong scratching 02.png|65px]] |2=Eotyrannus lengi [[File:Eotyrannus 2 NT.jpg|65px]] }} |3={{clade |1=Xiongguanlong baimoensis [[File:Xiongguanlong baimoensis.png|65px]] |2={{clade |1={{clade |1=Suskityrannus hazelae [[File:Suskityrannus.png|65px]] |2={{clade |1=Alectrosaurus olseni [[File:Alectrosaurus flipped.png|65px]] |2=Khankhuuluu mongoliensis [[File:Khankhuuluu mongoliensis.png|65px]] }} }} |3={{clade |1={{clade |1=Moros intrepidus [[File:Moros TD.png|65px]] |2=Timurlengia euotica [[File:Timurlengia.jpg|65px]] }} |label3= |3={{clade |label1=Nanotyrannidae |1={{clade |1=Appalachiosaurus montgomeriensis [[File:Appalachiosaurus TD.png|65px]] |2={{clade |1=Dryptosaurus aquilunguis [[File:Dryptosaurus TD.png|65px]] |2={{clade |1=N. lethaeus (BMRP 2002.4.1) [[File:Nanotyrannus lethaeus.png|65px]]|barbegin1=crimson |label3=N. lancensis |3={{clade |1=BMRP 2006.4.4 |bar1=crimson |2={{clade |1=CMNH 7541 (N. lancensis holotype) [[File:Nanotyrannus lancensis.png|65px]]|bar1=crimson |2={{clade |1=KUVP 156375 |bar1=crimson |2=NCSM 40000 ("Bloody Mary") |barend2=crimson }} }} }} }} }} }} |grouplabel1=

|label3=Tyrannosauridae |3={{clade |label1=Albertosaurinae |1={{clade hidden |id=1 |1={{clade |1=Bistahieversor sealeyi [[File:Bistahieversor sealeyi life restoration.jpg|65px]] |2=Jinbeisaurus wangi }} |3={{clade |1=UALVP 52981 |2={{clade |1={{clade |1=TCMI 2001.81.1 |2=Gorgosaurus sp. nov }} |3={{clade |1=Gorgosaurus libratus [[File:Gorgosaurus flipped.png|65px]] |2={{clade |1=Albertosaurus sarcophagus [[File:Albertosaurus TD.png|65px]] |2=Albertosaurus sp. nov }} }} }} }} }} |label3=Tyrannosaurinae |3={{clade |1={{clade |1=Lythronax argestes [[File:Lythronax TD.png|65px]] |2={{clade |1=Teratophoneus curriei [[File:Teratophoneus curriei by PaleoGeek.png|65px]] |2=UMNH VP 16690 }} }} |3={{clade |label1=Alioramini |1={{clade hidden |id=2 |1=Asiatyrannus xui [[File:Asiatyrannus xui.png|65px]] |2={{clade |1=Alioramus altai [[File:Alioramus_altai.jpg|65px]] |2=Qianzhousaurus sinensis [[File:Qianzhousaurus sinensis by PaleoGeek.png|65px]] }} }} |3={{clade |1=Thanatotheristes degrootorum |2={{clade |label1=Daspletosaurus |1={{clade hidden |id=3 |1=Daspletosaurus horneri |2={{clade |1=Daspletosaurus torosus [[File:Daspletosaurus torosus steveoc flipped.jpg|65px]] |2=Daspletosaurus wilsoni }} }} |label3=Tyrannosaurini |3={{clade hidden |id=4 |1=Zhuchengtyrannus magnus [[File:Zhuchengtyrannus magnus reconstruction.jpg|65px]] |2={{clade |1=Tarbosaurus bataar [[File:Tarbosaurus TD.png|65px]] |2={{clade |1=Tyrannosaurus mcraeensis [[File:Tyrannosaurus mcraeensis.png|65px]] |2=Tyrannosaurus rex [[File:Tyrannosaurus TD.png|65px]]

Paleobiology

::figure[src="https://upload.wikimedia.org/wikipedia/commons/0/0d/Appalachiosaurus.jpg" caption="Reconstructed skull"] ::

Appalachiosaurus had a bone-crushing bite force of around 32,500 newtons, or 7,193 pounds per square inch.

Paleopathology

Two vertebrae of the tail were found to be fused together, which is possibly a result of new bone growth following some sort of minor or traumatic injury.

References

References

  1. (2005). "A new genus and species of tyrannosauroid from the Late Cretaceous (middle Campanian) Demopolis Formation of Alabama". Journal of Vertebrate Paleontology.
  2. Brownstein, Chase D.. (2018-02-08). "The biogeography and ecology of the Cretaceous non-avian dinosaurs of Appalachia". Palaeontologia Electronica.
  3. "Appalachiosaurus montgomeriensis - Australian Museum".
  4. (2009). "First large tyrannosauroid theropod from the Early Cretaceous Jehol Biota in northeastern China". Geological Bulletin of China.
  5. (2012). "Comparison of the Functional Morphology of ''Appalachiosaurus'' and ''Albertosaurus''". The Open Geology Journal.
  6. "The Daily Tribune News - Tellus Appalachiosaurus to receive shorter arms Friday".
  7. Holtz, T.R. (2004). "Tyrannosauroidea." In: Weishampel, D.A., Dodson, P., & Osmolska, H. (Eds.). ''The Dinosauria'' (2nd Edition). Berkeley: University of California Press. Pp. 111–136.
  8. (2013). "Tyrant Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans". [[PLoS ONE]].
  9. (September 2012). "Comparison of the Functional Morphology of Appalachiosaurus and Albertosaurus". The Open Geology Journal.

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tyrannosauroideadinosaur-generacampanian-dinosaursdemopolis-chalkdinosaurs-of-the-united-statesfossil-taxa-described-in-2005