Raptorex
From Latin raptor ('robber') and rex ('king')
Raptorex is a controversial genus of tyrannosaurid dinosaur. Its fossil remains consist of a single juvenile specimen probably uncovered in Mongolia, or possibly northeastern China. The type species is R. kriegsteini, described in 2009 by Sereno and colleagues. The genus name is derived from Latin raptor, "robber", and rex, "king". The specific name honors Roman Kriegstein, a survivor of the Holocaust, whose son Henry Kriegstein donated the specimen to the University of Chicago for scientific study.
Under dispute
Raptorex kriegsteini was named by Sereno and colleagues (2009) from a single small skeleton (holotype LH PV18) they interpreted as a subadult from the Lower Cretaceous of China. Fowler and colleagues (2011) reassessed LH PV18 as a probable juvenile of currently unknown provenance, rejecting the Lower Cretaceous China origin, and argued it more likely represents a juvenile of a larger Late Cretaceous Mongolian tyrannosaurid — possibly Tarbosaurus, as in its original sale description — concluding that Raptorex should be regarded as a nomen dubium pending stronger evidence. Loewen and colleagues (2013) nonetheless recover it as a distinct taxon, morphologically separable from Alioramus and Tarbosaurus whatever its age, and Carr (2023), restudying the holotype, agrees it is a juvenile but finds it a valid taxon and lists features separating it from other tyrannosaurids.
Diagnosis
- Narrow accessory pneumatic fossa within antorbital fossa dorsal to maxillary fenestra
- Jugal suborbital ramus of particularly narrow depth (transverse width approximately 60% of vertical depth)
- Absence of vertical crest on iliac blade dorsal to acetabulum
- Proportionately large skull measuring approximately 40% of trunk length
- Enlarged olfactory bulbs approximately 60% of maximum cerebral hemispheres width
- Diminutive forelimb with humeral length 29% that of femur
Species
Raptorex kriegsteini Sereno et al., 2009 Disputed
Type species
Honors Roman Kriegstein, a Holocaust survivor, whose son Henry Kriegstein donated the specimen to the University of Chicago for study
- Holotype
- LH PV18 , Long Hao Institute of Geology and Palaeontology
- Material
- Partially articulated skeleton with most of skull and postcranial skeleton, lacking portions of forelimb and distal half of tail.
- Horizon
- Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
References
-
Sereno, P. C.; Tan, L.; Brusatte, S. L.; Kriegstein, H. J.; Zhao, X.; Cloward, K. (2009). Tyrannosaurid Skeletal Design First Evolved at Small Body Size. Science 326(5951): 418-422. American Association for the Advancement of Science (AAAS). doi:10.1126/science.1177428
Erected Raptorex kriegsteini on holotype LH PV18, interpreted as a subadult tyrannosauroid from the Lower Cretaceous of China.
sereno2009a -
Fowler, D. W.; Woodward, H. N.; Freedman, E. A.; Larson, P. L.; Horner, J. R. (2011). Reanalysis of "Raptorex kriegsteini": a juvenile tyrannosaurid dinosaur from Mongolia. PLoS ONE 6(6): e21376. doi:10.1371/journal.pone.0021376
Reanalyzed LH PV18 as a probable juvenile of unknown provenance; argues it is likely a juvenile Late Cretaceous Mongolian tyrannosaurid (possibly Tarbosaurus), rendering Raptorex a nomen dubium.
fowler2011b -
Loewen, M. A.; Irmis, R. B.; Sertich, J. J. W.; Currie, P. J.; Sampson, S. D. (2013). Tyrant Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans. PLoS ONE 8(11): e79420. Public Library of Science (PLoS). doi:10.1371/journal.pone.0079420
Recognizes Raptorex as a distinct taxon, morphologically separable from Alioramus and Tarbosaurus regardless of its ontogenetic status.
loewen2013a -
Carr, T. D. (2023). A reappraisal of tyrannosauroid fossils from the Iren Dabasu Formation (Coniacian–Campanian), Inner Mongolia, People's Republic of China. Journal of Vertebrate Paleontology 42(5): e2199817. doi:10.1080/02724634.2023.2199817
Restudies the holotype, agrees it is a juvenile, and finds it a valid taxon distinct from other tyrannosaurids.
carr2023a