TY - JOUR
T1 - The cranial anatomy of the long-snouted tyrannosaurid dinosaur Qianzhousaurus sinensis from the Late Cretaceous of China
AU - Foster, Will
AU - Brusatte, Steve
AU - Carr, Thomas D.
AU - Williamson, Thomas E.
AU - Yi, Laiping
AU - LÜ, Junchang
N1 - Funding Information:
Funding was provided by Natural Science Foundation of China grants (41272022) to J. L., NSF GRF, DDIG (DEB 1110357), the American Museum of Natural History Division of Paleontology, and Columbia University to S. L. Brusatte. S. L. Brusatte thanks his good friend, the late J. Lü for many years of collaboration and camaraderie, and his friends at the Ganzhou Museum for their hospitality and support during his research visit to study Qianzhousaurus with J. Lü in 2014. We thank F. Ma and W. Xuefang for assistance and discussion. We also thank J. Voris and our other reviewers for their insight and assistance.
Publisher Copyright:
© 2022. William Foster, Stephen L. Brusatte, Thomas D. Carr, Thomas E. Williamson, Laiping Yi, and Junchang Lü. Published with license by the Society of Vertebrate Paleontology.
PY - 2022/2/11
Y1 - 2022/2/11
N2 - Tyrannosaurid theropods topped the terrestrial food chain in North America and Asia during the latest Cretaceous. Most tyrannosaurids, exemplified by Tyrannosaurus rex, had deep snouts, thick teeth, and large jaw muscles that could generate high bite forces. They coexisted in Asia with a morphologically divergent group of long-snouted relatives, called alioramins. Qianzhousaurus sinensis, from the Maastrichtian of Ganzhou, China, is the largest alioramin yet discovered, but has only been briefly described. Here we present a detailed osteological description of the holotype cranium and mandible of Qianzhousaurus. We identify several new autapomorphic features of the genus, and new synapomorphies that unite alioramins (Qianzhousaurus, Alioramus altai, Alioramus remotus) as a clade, including a laterally projecting rugosity on the jugal. We clarify that the elongate skull of alioramins involves lengthening of the anterior palate but not the premaxilla, and is reflected by lengthening of the posterior bones of the lower jaw, even though the posterior cranium (orbit and lateral temporal fenestra) are proportionally similar to deep-skulled tyrannosaurids. We show that much of the variation among the alioramin species is consistent with growth trends in other tyrannosaurids, and that A. altai, A. remotus, and Qianzhousaurus represent different ontogenetic stages of progressive maturity, across which the signature nasal rugosites of alioramins became less prominent. We predict that the holotype skull of Qianzhousaurus represents the adult level of maturity for alioramins, and propose that the skull morphology of Qianzhousaurus indicates a much weaker bite than deep-skulled tyrannosaurids, suggestive of differences in prey choice and feeding style.
AB - Tyrannosaurid theropods topped the terrestrial food chain in North America and Asia during the latest Cretaceous. Most tyrannosaurids, exemplified by Tyrannosaurus rex, had deep snouts, thick teeth, and large jaw muscles that could generate high bite forces. They coexisted in Asia with a morphologically divergent group of long-snouted relatives, called alioramins. Qianzhousaurus sinensis, from the Maastrichtian of Ganzhou, China, is the largest alioramin yet discovered, but has only been briefly described. Here we present a detailed osteological description of the holotype cranium and mandible of Qianzhousaurus. We identify several new autapomorphic features of the genus, and new synapomorphies that unite alioramins (Qianzhousaurus, Alioramus altai, Alioramus remotus) as a clade, including a laterally projecting rugosity on the jugal. We clarify that the elongate skull of alioramins involves lengthening of the anterior palate but not the premaxilla, and is reflected by lengthening of the posterior bones of the lower jaw, even though the posterior cranium (orbit and lateral temporal fenestra) are proportionally similar to deep-skulled tyrannosaurids. We show that much of the variation among the alioramin species is consistent with growth trends in other tyrannosaurids, and that A. altai, A. remotus, and Qianzhousaurus represent different ontogenetic stages of progressive maturity, across which the signature nasal rugosites of alioramins became less prominent. We predict that the holotype skull of Qianzhousaurus represents the adult level of maturity for alioramins, and propose that the skull morphology of Qianzhousaurus indicates a much weaker bite than deep-skulled tyrannosaurids, suggestive of differences in prey choice and feeding style.
U2 - 10.1080/02724634.2021.1999251
DO - 10.1080/02724634.2021.1999251
M3 - Article
SN - 0272-4634
VL - 41
JO - Journal of Vertebrate Paleontology
JF - Journal of Vertebrate Paleontology
IS - 4
M1 - e1999251
ER -