Friday, April 28, 2017

Teratophoneus and Kosmoceratops by atrox1

Teratophoneus is a genus of carnivorous tyrannosaurid theropod 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. It is known from an incomplete skull and postcranial skeleton recovered from the Kaiparowits Formation. The Teratophoneus or “monstrous murderer” (Greek: teras, “monster” and phoneus, “murderer”) was specifically named T. curriei in honor of Philip J. Currie.

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 metres (20 ft) in length and 667 kg in weight.

Compared to the skull of an AlbertosaurusTeratophoneus is roughly twenty-three percent shorter in proportion between the lacrimal bone of the orbital 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.

Teratophoneus curriei skeleton in Japan. Author ★Kumiko★

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. Three different fossils of Teratophoneus have been found. Originally, Teratophoneus was described based on the holotype UMNH VP 16690. More recently, the specimens UMNP VP 16691 and BYU 8120 have been assigned to it.

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”. The specific name honors Philip J. Currie.

Restored skull and fossils Skull reconstructions and selected cranial elements of Teratophoneus curriei. These stippled reconstructions (A) are based on all available material. Some of the preserved elements of the referred specimen T. curriei (UMNH VP 16690) including: (B) left maxilla in lateral view, (C) both lacrimals superimposed and in lateral view; (D) photoreversed postorbital in lateral view; (E) frontals, parietals, and laterosphenoids in lateral and dorsal views; (F) braincase in caudal and lateral view; (G) squamosal in lateral and dorsal views; (H) quadratojugal in lateral view; (I) quadrate in lateral and caudal views; (J) left palatine in lateral view; (K) prearticular in left lateral view; (L) angular in left lateral view; (M) surangular in lateral view. Element recovery maps (N) of T. curriei (UMNH VP 16690) from which the reconstruction in A are derrived. Other Kaiparowits T. curriei specimens include two right jugals (UMNH VP 16691 & BYU 8120) and a left dentary from BYU 8120. Abbreviations: bpt, basipterygoid process; bt, basal tubera; bsr, basisphenoid recess; cb, cornual boss; fpc, frontoparietal midsagittal crest; jf, jugal flange of the quadrate; ls, laterosphenoid; lva, lacrimal vacuity; mf, maxillary fenestra; nc, nuchal crest; oc, occipital condyle; p, parietal; pop, paroccipital process; qc, quadrate cotylus; qf, quadrate foramen; sf, surangular foramen; so, supraoccipital; sof, suborbital flange; sog, supraorbital groove. All scale bars represent 10 cm except N which represents 50 cm.

Loewen et al. (2013) conducted a phylogenetic analysis and confirmed the assignment of Teratophoneus to the theropod sub-family tyrannosaurinae. Teratophoneus was closely related but more primitive than the large theropods Tarbosaurus and Tyrannosaurus, but more derived than Daspletosaurus.

Tyrannosauridae by Teratophoneus

The only known specimens of Teratophoneus were recovered at the Kaiparowits Formation, in southern Utah. Argon-argon radiometric dating indicates that the fossils were buried during the Campanian stage of the Late Cretaceous period. During the Late Cretaceous period, the site within the Kaiparowits Formation was located on Laramidia near its eastern shore on the Western Interior Seaway, a large inland sea that split North America into two landmasses, the other being Appalachia to the east. The plateau where dinosaurs lived was an ancient floodplain dominated by large channels and an abundance of wetland peat swamps, ponds and lakes, and was bordered by highlands. The climate was wet and humid, and supported an array of different and diverse groups of organisms. This formation contains one of the best and most continuous records of Late Cretaceous terrestrial life in the world.

Teratophoneus shared its paleoenvironment with theropods such as dromaeosaurids, the troodontid Talos sampsoni, ornithomimids like Ornithomimus velox, the tyrannosaurid Albertosaurus, armored ankylosaurids, the duckbilled hadrosaurs Parasaurolophus cyrtocristatus and Gryposaurus monumentensis, the ceratopsians Utahceratops gettyiNasutoceratops titusi and Kosmoceratops richardsoni and the oviraptorosaurian Hagryphus giganteus. Paleofauna present in the Kaiparowits Formation included chondrichthyans (sharks and rays), frogs, salamanders, turtles, lizards and crocodilians. A variety of early mammals were present including multituberculates, marsupials, and insectivorans.

Teratophoneus vs Kosmoceratops by PaleoGuy.deviantart.com