| Teratophoneus | |
|---|---|
 | |
| Reconstructed adult and juvenile skeletons,Natural History Museum of Utah | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Superfamily: | †Tyrannosauroidea |
| Family: | †Tyrannosauridae |
| Subfamily: | †Tyrannosaurinae |
| Tribe: | †Teratophoneini |
| Genus: | †Teratophoneus Carr et al.,2011 |
| Type species | |
| †Teratophoneus curriei Carr et al., 2011 | |
Teratophoneus ("monstrous murderer"; Greek:teras, "monster" andphoneus, "murderer") is agenus oftyrannosaurinetheropoddinosaur that lived during the lateCampanian age of theLate Cretaceous period, (about 76.5 to 75.5 million years ago) in what is nowUtah. It contains a single known species,T. curriei, named in honor of paleontologistPhilip J. Currie. It is known from an incompleteskull and postcranialskeleton recovered from theKaiparowits Formation.
Fossils ofTeratophoneus were first found in theKaiparowits Formation of southern Utah. Later, fossils from the same formation were discovered and identified as the genus.Argon-argon radiometric dating indicates that the Kaiparowits Formation was deposited between 76.1 and 74.0 million years ago, during theCampanian age of theLate Cretaceous period. This date means thatTeratophoneus lived in the middle of the Campanian age.
Several fossils ofTeratophoneus have been found. Originally,Teratophoneus was described based on the holotype specimen BYU 8120. More recently, the specimens UMNH VP 16690 and UMNP VP 16691 have been assigned to it.[1] In 2017, a new specimen ofTeratophoneus was discovered in the Grand Staircase-Escalante National Monument and airlifted to the Natural History Museum of Utah in Salt Lake City.[2] Later, in 2021, fossils belonging to 4 or 5 individuals were described in the same study.[3]
Teratophoneus was named by Thomas D. Carr, Thomas E. Williamson, Brooks B. Britt, and Ken Stadtman in 2011. Thetype and onlyspecies was namedT. curriei. Thegeneric name is derived from the Greek wordsteras, meaning "monster", andphoneus, meaning "murderer."[4] Thespecific name honorsPhilip J. Currie.[5]
Theholotype ofTeratophoneus consists of a fragmentary skull and parts of a postcranial skeleton. The fossils were originally assigned to four different individuals, but are probably only of a single subadult animal. The specimen ofTeratophoneus was not fully grown. According to an estimate by Carr et al., it was about 6 meters (20 ft) long and 667 kg (1,470 lb).[5] However, this is likely an underestimate. In 2016,Gregory S. Paul gave an estimation of 8 meters (26 ft) long and 2.5 t (2.8 short tons) for the maximum adult size.[6] That same year, Molina-Pérez and Larramendi estimated the size of the holotype at 6.4 meters (21.0 ft) long and 1.15 t (1.27 short tons).[7] In 2021, based on the size of the frontal bone (similar to that ofLythronax), Yun moderated the size of the subadult at approximately 6.1 m (20 ft) long and 1 t (1.1 short tons).[8] That same year, the length of the only known articulated specimen, UMNH VP 21100, was measured at 7.6 m (25 ft) and the maximum adult length ofTeratophoneus was estimated at 8.7 m (29 ft).[3]
Compared to the skull ofAlbertosaurus,Teratophoneus is roughly twenty-three percent shorter in proportion between the lacrimal bone of theantorbital fenestra and the tip of the snout. The skull ofTeratophoneus is also comparably deeper. It is unclear if there was a specific reason for these differences, but the extra depth may have allowed for stronger jaw muscles, thus increasing the bite force ofTeratophoneus.[9]
Loewen et al. (2013) conducted a phylogenetic analysis of the familyTyrannosauridae and confirmed the assignment ofTeratophoneus to the tyrannosaurid subfamilyTyrannosaurinae. They concluded thatTeratophoneus was closely related to bothTarbosaurus andTyrannosaurus, but placed it in a more basal position within the family, though it was more derived thanDaspletosaurus.[1]
Below is the cladogram based on thephylogenetic analysis conducted by Loewen et al. in 2013.[1]
In 2020, when describing the genusThanatotheristes, Voris et al., 2020 foundTeratophoneus to be in a subclade alongsideDynamoterror andLythronax.[10] This clade was named theTeratophoneini in 2024.[11]
A bone bed of fossils from the Rainbows and Unicorns Quarry in Southern Utah's Kaiparowits Formation described in 2021 attributed toTeratophoneus suggests that the genus may have been a social pack-hunter. The fossils, consisting of four or possibly five animals ranging from 4–22 years of age, suggest a mass mortality event, possibly caused by flooding or less likely by cyanobacterial toxicosis, fire, or drought. The fact that all of the animals preserved died within a short time period further strengthens the argument for gregarious behavior in tyrannosaurids, with bone beds ofTeratophoneus,Albertosaurus, andDaspletosaurus showcasing the potential behavior may have been widespread amongst tyrannosaurs in general.[3][12]
The holotype ofTeratophoneus was recovered at the Kaiparowits Formation in southern Utah. Argon-argon radiometric dating indicates that the fossils were buried during the Campanian age of the Late Cretaceous period.[13][14] During the Late Cretaceous, the site within the Kaiparowits Formation was located onLaramidia near its eastern shore on theWestern Interior Seaway, a large inland sea that split North America into two island landmasses, the other one beingAppalachia in the east. The plateau where dinosaurs lived was an ancient floodplain dominated by large channels and an abundance of wetlandpeat swamps, ponds, and lakes and was bordered by highlands. The climate was wet and humid, supporting an array of different and diverse groups of organisms.[15] This formation contains one of the best and most continuous records of Late Cretaceous terrestrial life in the world.[16]
Teratophoneus curriei shared itspaleoenvironment with othertheropods, such asdromaeosaurids, thetroodontidTalos sampsoni,ornithomimids likeOrnithomimus velox, and thecaenagnathidHagryphus giganteus. Non-theropod dinosaurs included the ankylosaurAkainacephalus johnsoni, thehadrosaursParasaurolophus cyrtocristatus andGryposaurus monumentensis, and theceratopsiansUtahceratops gettyi,Nasutoceratops titusi, andKosmoceratops richardsoni.[17] Other paleofauna present in the Kaiparowits Formation includedchondrichthyans (sharks and rays),frogs,salamanders,turtles,lizards, andcrocodilians, withDeinosuchus being theapex predator.[18] A variety of earlymammals were present, includingmultituberculates,marsupials, andinsectivorans.[19]
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