Teratophoneus
Teratophoneus ("monstrous murderer"; Greek: teras, "monster" and phoneus, "murderer") is a genus of tyrannosaurid dinosaur which lived during the late Cretaceous period (late Campanian age, about 77 to 76 million years ago) in what is now Utah, United States, containing a single known species, T. curriei. It is known from an incomplete skull and postcranial skeleton recovered from the Kaiparowits Formation. It was specifically named T. curriei in honor of Philip J. Currie.
Fossils of Teratophoneus were first found in the Kaiparowits 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 the Campanian stage of the Late Cretaceous period. This date means that Teratophoneus lived in the middle of the Campanian stage of the Late Cretaceous.
Several fossils of Teratophoneus have been found. Originally, Teratophoneus was described based on the holotype BYU 8120. More recently, the specimens UMNH VP 16690 and UMNP VP 16691 have been assigned to it.[1] In 2017, a new specimen of Teratophoneus 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. The type and only species was named T. curriei. The generic name is derived from the Greek teras, "monster", and phoneus, "murderer."[4] The specific name honors Philip J. Currie.[5]
The holotype of Teratophoneus consists of a fragmentary skull and parts of the postcranial skeleton. The fossils were originally assigned to four different individuals, but are probably only of a single subadult animal. The specimen of Teratophoneus was not fully grown: according to an estimate by Carr et al. was about 6 meters (20 ft) in length and 667 kg (1,470 lb) in weight.[5] However this is likely an underestimate. In 2016, Gregory S. Paul gave an estimation of 8 meters (26 ft) in length and 2.5 t (2.8 short tons) in body mass for the maximum adult size.[6] In the same year, Molina-Pérez and Larramendi estimated the size of the holotype at 6.4 meters (21.0 ft) in length and 1.15 t (1.27 short tons) in body mass.[7] In 2021, based on the size of the frontal bone (similar to that of Lythronax), Yun moderated the size of the subadult at approximately 6.1 m (20 ft) in length and 1 t (1.1 short tons) in body mass.[8] In the 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 of Teratophoneus was estimated at 8.7 m (29 ft).[3]
Compared to the skull of an Albertosaurus, Teratophoneus is roughly twenty-three percent shorter in proportion between the lacrimal bone of the antorbital fenestra and the tip of the snout. The skull of Teratophoneus 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, increasing the bite force of Teratophoneus.[citation needed]
