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Maleevosaurus n. g. Etymology: For the late Eugene Alexandrovich Maleev who first studied the tyrannosaurids of the Mongolian People’s Republic., Published as part of Carpenter, K., 1992, Tyrannosaurids (Dinosauria) of Asia and North America, pp. 250-268 in Aspects of Nonmarine Cretaceous Geology, Beijing :China Ocean Press on page 256, DOI: 10.5281/zenodo.1038212

Albertosaurus sarcophagus Osborn 1905 Figs. 2 D, 5 D = Laelaps incrassatus Cope 1892 = Dryptosaurus incrassatus (Cope) 1892 = Albertosaurus arctunguis Parks 1928 Holotype: NMC 5600 nearly complete skull from the Horseshoe Canyon Formation, Alberta, Canada. (Cranial) premaxilla anteroposteriorly very short and broad so that littie of it is visible in lateral view; pro-maxillary fenestra set well in advance of maxillary fenestra,and visible in lateral'view;maxillary fenestra taller than long,and separated from antorbital fenestra by a thin bar of the maxillary; lacrymal horn moderately developed;surangular foramen small for tyrannosaurid. (Postcranial) Body appears to be shorter than in A. libratus; distal end of scapular blade strongly inflected forward; tibia more gracile than in A. libratus. Stratigraphic and Palaeobiogeographic Distribution: Horseshoe Canyon Formation, Alberta, Canada., Published as part of Carpenter, K., 1992, Tyrannosaurids (Dinosauria) of Asia and North America, pp. 250-268 in Aspects of Nonmarine Cretaceous Geology, Beijing :China Ocean Press on pages 257-258, DOI: 10.5281/zenodo.1038212, {"references":["Osborn, H., 1905, Tyrannosaurus and other Cretaceous carnivorous dinosaurs: American Museum of Natural History Bulletin 21, pp. 259 - 265.","Cope, E., 1892, On the skull of Laelaps incrassatus, Cope: American Philosophical Society Proceedings, v. 30, p. 240 - 245","Parks, W., 1928, Albertosaurus arctunguis, a new species of theropodous dinosaur from the Edmonton Formation of Alberta: University of Toronto Studies, Geological Series, v. 25, p. 1 - 42."]}

Skulls Six partial and complete skulls are now known for Tyrannosaurus rex, including the holotype CM 9380 (formerly AMNH 973), AMNH 5027, LACM 23844, MOR 009, SDSM 12047, and TMP 81.6.1. Two additional specimens, AMNH 5029 and AMNH 5117, are braincases (Osborn 1912). Five of the skulls are shown in Figure 10.1. As may be seen, there is a considerable amount of variation in the size and shape of all the cranial openings (e.g., orbit and lateral temporal fenestra), as well as all the individual elements, including the lacrimal, postorbital, quadratojugal, jugal, and surangular. In fact, no two specimens are identical. Seven maxillae were available for comparison. Five of these were overlain in Figure 10.2A using the anterior-most margins of the maxilla and maxillary fenestra as standard lengths. Most of the maxillae resemble one another, except for TMM 41436-1, the specimen reported from the Tornillo Formation by Lawson (1976). Variation can be seen in the depth of the maxilla, size and shape of the maxillary and antorbital fenestrae, position of the lacrimal processes, and the position and shape of the jugal process (Fig. 10.2A). Differences in the depth of the maxilla affect the position of the lacrimal process, which in tum influences the height and shape of the antorbital fenestra. There is also a considerable amount of variation in position of the jugal process that forms the lower rim of the antorbital fenestra, but this does not seem to correlate with the size of the antorbital process. The shape of the maxillary fenestra ranges from almost oval (CM 9380) to subtriangular (LACM 23844 and TMP 81.6.1) to almost square (AMNH 5012). There is little or no difference in the position of the largest teeth and therefore this feature is not affected by the depth of the maxilla or the shape of the antorbital fenestra. Even the left and right maxilla of the same skull show variation (Figs. 10.2B,C). The maxilla from the Tornillo Formation lacks the anterior-most margin and was scaled to the other maxilla using height and the anterior margin of the maxillary fenestra (Fig. 10.2A). The nasal, or dorsal, margin of the maxilla arcs sharply down suggesting a face considerably shorter than in T. rex. Other differences include a slightly larger maxillary fenestra in proportion to the size of the maxilla and a much deeper jugal process. The antorbital fenestra appears to be smaller, but the lacrimal process is too incomplete to be certain. These differences are great enough to suggest that TMM 41436-1 falls outside the range of individual variation for Tyrannosaurus rex. It may belong to a new genus, but no name should be proposed until additional material is available. Because it is unusual, it is excluded from discussions on variation. Variation in the dentary is demonstrated by six specimens (Fig. 10.3). The distance between the anterior tip and the highest part of the dentary were used for the standard length. The greatest difference is the depth of the posteroventral margin of the dentary. It is relatively shallowest in SDSM 12047 and deepest in AMNH 5027 (Fig. 10.3). However, AMNH 5027 also has a tooth row that curves more ventrally than the others and this may have had an influence on the posteroventral margin. The posterior margin of the dentary is thin and easily damaged, although three of the dentaries have complete margins (CM 9380, AMNH 5027, and TMP 81.6.1). The shape of the anterior portion of the external mandibular fossa (expressed as a notch at the lower edge of the posterior margin, see Fig. 10.1) is variable. The teeth seem to show more variation in positional size, but this may be due to how the dentaries were overlain. Cervicals Complete cervical series are known for only two specimens, AMNH 5027 and BM(NH) R7994. There is a considerable amount of variation in the shape of the neural spines. Similar variation appears to be present in the tyrannosaur Albertosaurus libratus, so the use of neural spine shape in the diagnosis of the tyrannosaur Daspletosaurus torosus (Russell 1970) is suspect. The neck is more robust in BM(NH) R7994 than in AMNH 5027 (Fig. 10.4). This is especially evident in the atlas and its intercentrum, and in the neural spines of cervicals two and three. Asymmetrical co-ossification of the last cervical and first dorsal in AMNH 5027 has not been observed in any other specimen, and is probably pathological. Ischiae Three ischia were available for comparison. Length was standardized and the articular surface of the iliac peduncle was used to determine orientation in Fig. 10.5. Points of variation include the relative size of the iliac peduncle, the relative size and position of the pubic peduncle, the position and size of the obturator process, and the development of the insertion scar for the M. flexor tibialis internus part 3. This scar is best developed in CM 9380 where it forms a prominent ridge. Of the two types of ischia, one (Fig. 10.5A) is oriented more ventrally from the horizontal articular surface of the iliac peduncle. I suspect that CM 9380 and TMP 81.6.1 are females because the greater angle between the sacral vertebrae and distal end of the ischium would permit the passage of eggs (or live young) more readily than that of AMNH 5027. The more divergent ischia are associated with robust skeletons, whereas the less divergent ischium is from a gracile skeleton., Published as part of Carpenter, Kenneth, 1990, Variation in Tyrannosaurus rex, pp. 141-145 in Dinosaur Systematics: Perspectives and Approaches, Cambridge :Cambridge University Press on pages 141-144, DOI: 10.5281/zenodo.3676505, {"references":["1912. Crania of Tyrannosaurus and Allosaurus. American Museum of Natural History Memoirs, new series 1: 1 - 30.","Lawson, D. 1976. Tyrannosaurus and Torosaurus, Maestrichtian dinosaurs from Trans-Pecos, Texas. Journal of Paleontology 50: 158 - 164.","1906. Tyrannosaurus, Upper Cretaceous carnivorous dinosaur. American Museum of Natural History Bulletin 22: 281 - 296.","Russell, D. 1970. Tyrannosaurs from the Late Cretaceous of western Canada. National Museums of Canada, National Museum of Natural History, Publications in Palaeontology 1: 1 - 34."]}

Tyrannosaurus bataarMaleev 1995a Figs. 2B, 4, 5B = Tarbosaurus efremovi Maleev 1955b = Gorgosaurus lancinator Maleev 1955b = Tarbosaurus bataar (Maleev) 1955 b Holotype: PIN 551-1 partial skull from the Nemegt Formation, Mongolian People’s Republic. Diagnosis: Angular terminates anterior to the surangular fenestra;surangular fenestra proportionally smaller than in Tyrannosaurus rex; surangular fenestra proportionally smaller than in T. rex. Stratigraphic and Paleobiogeographic Distribution: Nemegt Formation and Upper White Beds of Khermeen Tsav, Mongolian People’s Republic; possibly the Subashi Formation,Xinjiang,People’s Republic of China. Discussion: Maleev (1955a,b; 1974) recognized three genera and four species of tyrannosaurids from Mongolia: Tyrannosaurus bataar, Tarbosaurus efremovi, Gorgosaurus lancinator and Gorgosaurus novojilovi. Rozhdestvensky (1965),however,argued that most of the differences cited by Maleev were ontogenetic, and that only a single species was represented. Rozhdestvensky also argued that this single species was intermediate between Albertosaurus and Tyrannosaurus and, thus, represented a distinct genus for which the name Tarbosaurus was available. Accordingly, Rozhdestvensky referred all Mongolian tyrannosaurid to Tarbosaurus bataar. Re-examination of Maleev’s figures (Maleev, 1955a, 1955 b; 1974),as well as photographs of these specimens and of those collected by the Polish palaeontological expeditions to Mongolia, reveal that Rozhdestvensky erred in a number of points in his analysis. The quadratojugal process of the jugal in T. bataar reaches the posterior rim of the lateral temporal fenestra as it does in T. rex. The tetragonal-shaped ascending process of the jugal in T. rex,this observation is based on AMNH 5027 (Osborn, 1912). A new skull of T. rex, LACM 23844,has a tapering ascending process as in PIN 551-3, thus showing the shape of this bone is variable. Development of the ascending process into the orbit is variable as indicated by the holotype T. bataar, PIN 551-1, which shows a slight development of the jugal within the orbint. This makes it intermediate in shape between AMNH 5027 and PIN 551-3. Another taxonomical difference Rozhdestvensky stated was the smaller size of the Mongolian tyrannosaurid. However,the holotype skull, PIN 551-1,has premaxillary to occipital condyle length of 1220 mm (Maleev, 1955a, 1974). This compares to 1210 mm for AMNH 5027, T. rex (Osborn, 1912). Thus,contrary to Rozhdestvensky’s(1965) claims, T. bataar is not intermediate between Albertosaurus and Tyrannosaurus, but is generically indistinguishable from Tyrannosaurus. It is remarkable that of the five skulls of T. rex known all are adults (however see below). This is not the case with T. bataar. Figure 4 shows a growth series of skulls from the smallest with a premaxillary-occipital condyle length of 825 mm to the largest with a premaxillary-occipital condyle length of 1220mm. The general ontogenetic trend is a deepening of the skull, shortening of the muzzle,and an increase in the rugosity of the region dorsal to the orbit. As may be seen, the smaller skulls resemble that of Albertosaurus (compare Figs. 4 C, D with Fig. 2 E),especially because of the longer muzzle. Thus,it is understandable that Maleev referred these skulls to Gorgosaurus (= Albertosaurus). However,the well-developed stereoscopic vision (due to the differentiation of the muzzle from the cranium) separates these skulls from Albertosaurus. Variation in the skulls is apparent in the posterior portion of the lateral temporal fenestra where the squamosal may butt against the quadratojugal (Fig. 4 B and D) or there may be an overlap (Fig. 4 C). A similar pattern is seen in T. rex as well (Carpenter,in press). There has been some confusion about the astragulus in Tyrannosaurus. Welles and Long (1974) figured an element associated with AMNH 5827 that they ascribed as a Tyrannosaurus astragulus. This element, however, is unlike any theropod astragulus known,and is certainly very different from the astragulus associated with MOR 009, Tyrannosaurus rex. This astragulus resembles that of Albertosaurus as would be expected. Comparison of the original drawings by Christman of the element figured by Welles and Long show that it is,in fact,a medial and dorsal view of the right quadrate of AMNH 5027 (Fig. 3). At this time the specific differences between the postcrania of T. rew and T, bataar have not been established. This is due to the considerable amount of variation among the T. rex specimens (Carpenter,in press). Some of the differences may be individual, but most appear to be sexual. Until the range of this variation can be determined, it is not certain what postcranial characters separate T. rex from T. bataar. With regard to the maxilla from the Tornillo Formation of Texas ascribed by Lawson (1976) to T. rex,it does not belong to Tyrannosaurus (Carpenter,in press), but another short-faced theropod. A description of the postcrania of Tyrannosaurus is in preparation., Published as part of Carpenter, K., 1992, Tyrannosaurids (Dinosauria) of Asia and North America, pp. 250-268 in Aspects of Nonmarine Cretaceous Geology, Beijing :China Ocean Press on pages 254-256, DOI: 10.5281/zenodo.1038212, {"references":["------, 1955 b, New carnivorous dinosaurs from the Upper Cretaceous of Mongolia: Dokladi Akademii Nauk S. S. S. R., v. 104, p. 779 - 782.","Maleev, E., 1955 a, Gigantic carnivorous dinosaurs of Mongolia: Dokladi Akademii Nauk S. S. S. R., v. 104, p. 634 - 637.","------, 1974, Giant carnosaurs of the family Tyrannosauridae, in Mesozoic and Cenozoic faunas and biostratigraphy of Mongolia: Transactions of the Joint Soviet-Mongolian Palaeontological Expedition, v. l, p. 132 - 190.","Rozhdestvensky, A., 1965, Growth changes in Asian dinosaurs and some problems of their taxonomy. paleontologicheskii Zhurnal, p. 95 - 109.","------, 1912, Crania of Tyrannosaurus and Allosaurus: American Museum of Natural History Memoirs, new series v. 1, p. 1 - 30.","Carpenter, K., in press, Examples of variation in Tyrannosaurus rex: in Currie, P. and Carpenter, K., eds., Dinosaur Systematics: Cambridge, Cambridge University Press","Welles, S. and Long, R., 1974, The tarsus of theropod dinosaurs: Annals of the South African Museum, v. 64, p. 191 - 218.","Lawson, D., 1976, Tyrannosaurus and Torosaurus, Maestrichtian dinosaurs from Trans-Pecos, Texas: Journal of Paleontology 50, p. 158 - 164."]}

Carpenter, K. (1992): Tyrannosaurids (Dinosauria) of Asia and North America. In: Mateer, N.J., Chen, P.-J. (Eds): Aspects of Nonmarine Cretaceous Geology. Beijing: China Ocean Press: 250-268, DOI: 10.5281/zenodo.1038212, {"references":["Barsbold,R., 1983, Carnivorous dinosaurs from the Cretaceous of Mongolia: Transactions of the Joint Soviet-Mongolian Palaeontological Expedition,v. 19,p. 1-117.","Bonaparte,J.,1985,A horned Cretaceous carnosaur from Patagonia: National Geographic Research, vol. l,p. 149-151.","Brown, B. and Schlaikjer, E., 1940, The structure and relationships of Protoceratops: New York Academy of Sciences Annals,v. 40,p. 133-266.","Carpenter, K.,in press, Examples of variation in Tyrannosaurus rex: in Currie, P. and Carpenter, K.,eds., Dinosaur Systematics: Cambridge, Cambridge University Press","Cope,E.,1892,On the skull of Laelaps incrassatus, Cope: American Philosophical Society Proceedings, v. 30,p. 240-245","Fox,R.,1978,Upper Cretaceous terrestrial vertebrate stratigraphy of the Gobi Desert (Mongolian People's Republic) and Western North America: in Stelck,C.,and Chatterton, B., eds, Western and Arctic Canadian Biostratigraphy, Geological Association of Canada Special Paper 18, p. 577- 594.","Gilomre,C.,1920,Osteology of the carnivorous Dinosauria in the United States National Museum, United States National Museum Bulletin,v. 110,p. 1-159.","------1946, A new carnivorous dinosaur from the Lance Formation of Montana: Smithsonian Miscellaneous Collections, v. 106,p. 1-19.","Gradzinski,R., Kielan-Jaworowska,Z. and Maryanska,T.,1977,Upper Cretaceous Djadokhta, Barun Goyot and Nemegt formations of Mongolia, including remarks on previous subdivisions: Acta Geologica Polonica,v. 27,p. 281-317.","Kielan-Jaworowska,Z. and Dovchin,N., 1968,Narrative of the Polish-Mongolian Palaeontological Expeditions 1963-1965: Palaeontologia Polonica,v. 19,p. 7-30.","Kielan-Jaworowska,Z. and Barsbold,R., 1972,Narrative of the Polish-Mongolian Palaeontological Expeditions 1967-1971: Palaeantologia Polonica,v. 27,p. 5-13.","Lambe,L.,19 14a,On the fore-limb of a carnivorous dinosaur from the Belly River Formation of Alberta, an a new genus of Ceratopsia from the same horizon, with remarks on the integument of some Cretaceous herbivorous dinosaurs: Ottawa Naturalist,v. 27,p. 129-135","------,19 14b,On a new genus and species of carnivorous dinosaur from the Belly River Formation of Alberta, with a description of the skull of Stephanosaurus marginatus from the same horizon: Ottawa Naturalist,v. 28,p. 13-20","------, 1917,The Cretaceous theropodous dinosaur Gorgosaurus: Geological Survey of Canada Memoir 100, p. 1-84.","Lawson, D., 1976, Tyrannosaurus and Torosaurus, Maestrichtian dinosaurs from Trans-Pecos, Texas: Journal of Paleontology 50,p. 158-164.","Leidy,J., 1857,Notices of remains of extinct reptiles and fishes,discovered by Dr. F. V. Hayden in the badlands of the Judith River,Nebraska Territory: Academy of Natural Sciences of Philadelphia Proceedings,v. 8. p. 72-73.","Maleev,E., 1955a,Gigantic carnivorous dinosaurs of Mongolia: Dokladi Akademii Nauk S. S. S. R., v. 104,p. 634-637.","------,1955b,New carnivorous dinosaurs from the Upper Cretaceous of Mongolia: Dokladi Akademii Nauk S. S. S. R.,v. 104,p. 779-782.","------,1974,Giant carnosaurs of the family Tyrannosauridae,in Mesozoic and Cenozoic faunas and biostratigraphy of Mongolia: Transactions of the Joint Soviet-Mongolian Palaeontological Expedition, v. l,p. 132-190.","Matthew,W. and Brown,B., 1922,The family Deinodontidae,with notice of a new genus from the Cretaceous of Alberta: American Museum of Natural History Bulletin 46,p. 367-385.","------,1923 Preliminary notices of skeletons and skulls of Deinodontidae from the Cretaceous of Alberta: American Museum of Natural History Bulletin 48,p. 1-9.","Molnar,R.,1973, The cranial morphology and mechanics of Tyrannosaurus rex(Reptilia: Saurischia): Ph. D. thesis,Los Angeles University of California, 451.","------,1980,An albertosaur from the Hell Creek Formation of Montana, Journal of Paleontology,v. 54, p. 102-108.","Newman, B.,1970, Stance and gait in the flesh-eating dinosaur Tyrannosaurus: Biological Journal of the Linnean Society,v. 2,p. 119-123.","Osborn,H.,1905,Tyrannosaurus and other Cretaceous carnivorous dinosaurs: American Museum of Natural History Bulletin 21,pp. 259-265.","------, 1906, Upper Cretaceous carnivorous dinosaur (second communication): American Museum of Natural History Bulletin 22,p. 281-296.","------,1912,Crania of Tyrannosaurus and Allosaurus: American Museum of Natural History Memoirs, new series v. 1,p. 1-30.","------,1913, Tyrannosaurus, restoration and model of the skeleton: American Museum of Natural History Bulletin 32,p. 91-92.","------, 1917, Skeletal adaptations of Ornitholestes, Struthiomimus, Tyrannosaurus: American Museum of Natural History Bulletin 35,p. 733-771.","Osmolska, H. , 1980, The Late Cretaceous vertebrate assemblages of the Gobi Desert, Mongolia. Memoires de la Societe de Geologique de France,v. 139,p. 145-150.","Parks, W., 1928, Albertosaurus arctunguis,a new species of theropodous dinosaur from the Edmonton Formation of Alberta: University of Toronto Studies, Geological Series,v. 25,p. 1-42.","Raath,M.,1977, The anatomy of the Triassic theropod Syntarsus rhodesiensis (Saurischia: Podokesauridae) and a consideration of its biology: Ph. D. thesis, Grahamstown, South Africa, Rhodes University 233 p.","Rozhdestvensky, A.,1965,Growth changes in Asian dinosaurs and some problems of their taxonomy .paleontologicheskii Zhurnal,p. 95-109.","Russell,D., 1970,Tyrannosaurs from the Late Cretaceous of Western Canada: National Museums of Canada Publication in Palaeontology,v. l,p. 1-34.","Welles,S. and Long,R.,1974,The tarsus of theropod dinosaurs: Annals of the South African Museum, v. 64,p. 191-218."]}

Albertosaurus libratus (Lambe) 1914 Figs. 2E, 5E = Gorgosaurus libratus Lambe 1914 Holotype: NMC 2120 nearly complete skeleton from the Judith River Formation, Alberta, Canada. Diagnosis: (Cranial) pro-maxillary fenestra close to the maxillary fenestra; maxillary fenestra oval in shape and separated from the antorbital fenestra by a wide bar of maxillary; lacrymal horn very well developed; surangular very large. (Postcranial) distal end of scapula gradually broadens; acromion process of the scapula very deep; tibia more robust than in A. sarcophagus. Stratigraphic and Palaeobiogeographic Distribution: Judith River Formation of Alberta, Canada, and Montana, U. S. A.. Also possibly the Horseshoe Canyon Formation of Alberta, the Two Medicine Formation of Montana, Fruitland Formation of New Mexico,and the Morreville Chalk of Alabama,U.S.A., Published as part of Carpenter, K., 1992, Tyrannosaurids (Dinosauria) of Asia and North America, pp. 250-268 in Aspects of Nonmarine Cretaceous Geology, Beijing :China Ocean Press on page 258, DOI: 10.5281/zenodo.1038212, {"references":["Lambe, L., 19 14 a, On the fore-limb of a carnivorous dinosaur from the Belly River Formation of Alberta, an a new genus of Ceratopsia from the same horizon, with remarks on the integument of some Cretaceous herbivorous dinosaurs: Ottawa Naturalist, v. 27, p. 129 - 135"]}

Daspletosaurus torosus Russell 1970 Figs. 2G, 5F NMC 8506,skeleton lacking hind legs from the Judith River Formation of Alberta. Diagnosis: (Cranial) Premaxilla does not contact nasals under external nares; lacrymal horn well developed; postorbital rugose, although less that Tyrannosaurus; pro-maxillary fenestra very small; surangular foramen very large. (Postcranial) Postacetabular blade of ilium very long; ischium straight; scapula broadens gradually posteriorly; acromion process of scapula forms a continuous arc with the coracoid. Stratigraphic and Palaeobiogeographic Distribution: Judith River and Horseshoe Canyon formations of Alberta,Canada;Judith River Formation of Montana. Discussion: As Russell (1970) has pointed out, adult Daspletosaurus the same length as an adult Albertosaurus is heavier and more powerfully built. This gives it the appearance of Tyrannosaurus, but this resemblance is superficial. Numerous differences between the two animals, such as the lack of the postorbital extending into the orbit and no contact between the nasal and premaxilla below the external nares, indicate that Daspletosaurus is distinct from Tyrannosaurus (see also Russell, 1970). As yet, Daspletosaurus is too poorly represented with skulls and skeletons to determine the full range of variation, including individual, sexual and ontogenetic. The largest individual (CM 9401)is represented by a nearly complete right lacrymal larger than that of the holotype of T. rex (CM 9380). This is suggests a skull with a premaxillary-occipital condyle length of over 1200 mm. A detailed osteology of Daspletosaurus is in preparation., Published as part of Carpenter, K., 1992, Tyrannosaurids (Dinosauria) of Asia and North America, pp. 250-268 in Aspects of Nonmarine Cretaceous Geology, Beijing :China Ocean Press on pages 260-261, DOI: 10.5281/zenodo.1038212, {"references":["Russell, D., 1970, Tyrannosaurs from the Late Cretaceous of Western Canada: National Museums of Canada Publication in Palaeontology, v. l, p. 1 - 34."]}

Maleevosaurus novojilovi (Maleev) 1955 b Figs. 2C, 5C = Gorgosaurus novojilovi Maleev 1955b PIN 552-2 partial skull and skeleton. Diagnosis: (Cranial) Maxillary fenestra small; pro-maxillary fenestra not visible laterally; antorbital fenestra proportionally very large,and much longer than high; lacrymal horn moderately developed, not rugose; postorbital not very rugose; lower ramus of maxilla low and slender; jugal slender resulting in a very large orbit; dentary slender. (Postcranial) Cervical neural spines tall, not as reduced as in other tyrannosaurids. Acromion process of scapula virtually non-existant. Ischium has a very pronounced spur-like obturator process, and distally, the shaft curves downward. Metatarsal IV does not overlap metatarsal III at midshaft, nor does metatarsal III have much of an overlap of metatarsal II at midshaft. Stratigraphic and Palaeobiogeographic Distribution: Nemegt Formation,Mongolian People’s Republic. Discussion: That Maleevosaurus is a tyrannosaurid is indicated by the slightly opisthocoelous cervical centra, didactyl manus, anteroposteriorly compressed, broad cervicals,well developed anterior foot of the pubis,and broad and tall ascending process of the astragulus. Originally, the holotype of Maleevosaurus was one of four species of tyrannosaurid named by Maleev from Mongolia. He had named it Gorgosaurus novojilovi (Maleev, 1955b),but because of its small size (femur length 560 mm), Rozhdestvensky (1965) considered it a juvenile Tarbosaurus (= Tyrannosaurus) bataar. Gradzinski and others (1977) and Osmolska (1980) noted that the third metatarsal was considerably more slender than in T. bataar,and doubted that this was a juvenile character. They referred to the specimen as ’Gorgosaurus’ novojilovi. In order to determine if ’Gorgosaurus’ novojilovi is a juvenile T. bataar, comparisons were made to the similarities and differences between an adult and juvenile Albertosaurus libratus. These were AMNH 5458,with a femur length of 1025 mm,and AMNH 5664, with a femur length of 700 mm. Comparisons were also made to a growth series of skulls of T. bataar (Fig. 4). In the juvenile Albertosaurus, the lacrymal horn is already well developed and the jugal proportionally large. In T. bataar, there is also no change in development of the lacrymal horn and in size of the jugal. Therefore, the moderately developed lacrymal horn and the slenderness of the jugal in ‘ G.’ novojilovi are not considered juvenile features. Furthermore, no change occurs in the relative size of the antorbital fenestra in T. bataar from juvenile to adult, indicating that the large size of the antorbital fenestra in ‘ G.’ novojilovi is also not a juvenile feature. However, contrary to Gradzinski and others (1977) and Osmolska (1980),it is possible that the slenderness of the third metatarsal is a juvenile character,as this metatarsal is considerably more slender in the juvenile Albertosaurus than in the adult. It is possible, however, that this is not the case in the Tyrannosaurus specimens available to Gradzinski and others and Osmolska,but their observations have not yet been published. It is clear from the above analysis, that except for possibly the slenderness of the third metatarsal, ‘ G. ’novojilovi is not a juvenile T. bataar. Furthermore, ‘G. ’novojilovi cannot be referred to the genus Albertosaurus (= Gorgosaurus),nor to any other known genus of tyrannosaurid because of the large size of the antorbital fenestra, slenderness of the jugal, the very well developed obturator process, and sharply downward curved ischium. For this reason,it is best to assign ‘Gorgosaurus’ novojilovi to a new genus, Maleevosaurus. Although it is possible that the holotype of Maleevosaurus novojilovi is a juvenile, based on its small size, the neural arches are fused to their centra, and the calcaneum to the astragulus. This suggests that Maleevosaurus is a small tyrannosaurid., Published as part of Carpenter, K., 1992, Tyrannosaurids (Dinosauria) of Asia and North America, pp. 250-268 in Aspects of Nonmarine Cretaceous Geology, Beijing :China Ocean Press on pages 256-257, DOI: 10.5281/zenodo.1038212, {"references":["Maleev, E., 1955 a, Gigantic carnivorous dinosaurs of Mongolia: Dokladi Akademii Nauk S. S. S. R., v. 104, p. 634 - 637.","------, 1955 b, New carnivorous dinosaurs from the Upper Cretaceous of Mongolia: Dokladi Akademii Nauk S. S. S. R., v. 104, p. 779 - 782.","Rozhdestvensky, A., 1965, Growth changes in Asian dinosaurs and some problems of their taxonomy. paleontologicheskii Zhurnal, p. 95 - 109.","Gradzinski, R., Kielan-Jaworowska, Z. and Maryanska, T., 1977, Upper Cretaceous Djadokhta, Barun Goyot and Nemegt formations of Mongolia, including remarks on previous subdivisions: Acta Geologica Polonica, v. 27, p. 281 - 317.","Osmolska, H., 1980, The Late Cretaceous vertebrate assemblages of the Gobi Desert, Mongolia. Memoires de la Societe de Geologique de France, v. 139, p. 145 - 150."]}

Albertosaurus Osborn 1905 = Laelaps (in part) = Dryptosaurus (in part) = Deinodon (in part) = Gorgosaurus Lambe 1914 Diagnosis: (Cranial) Premaxillary contacts nasal below external nares;lacrymal horn often better developed than in Tyrannosaurus, and the postorbital considerably smoother; posterior part of the dentary not as deep as in Tyrannosaurus. (Postcranial) Wrist composed of five elements. Postacetabular blade of ilium deep,and pubic shaft straight., Published as part of Carpenter, K., 1992, Tyrannosaurids (Dinosauria) of Asia and North America, pp. 250-268 in Aspects of Nonmarine Cretaceous Geology, Beijing :China Ocean Press on page 257, DOI: 10.5281/zenodo.1038212, {"references":["Osborn, H., 1905, Tyrannosaurus and other Cretaceous carnivorous dinosaurs: American Museum of Natural History Bulletin 21, pp. 259 - 265.","Lambe, L., 19 14 a, On the fore-limb of a carnivorous dinosaur from the Belly River Formation of Alberta, an a new genus of Ceratopsia from the same horizon, with remarks on the integument of some Cretaceous herbivorous dinosaurs: Ottawa Naturalist, v. 27, p. 129 - 135"]}

Tyrannosaurus Osborn, 1905 = Dynamosaurus Osborn 1905 = Tarbosaurus Maleev 1955a = Gorgosaurus (in part) Diagnosis; (Cranial) Viewed dorsally,muzzle well-differentiated from cranium so that stereoscopic vision well-developed; descending process of postorbital extends into orbit; premaxillary contacts nasal below external nares and medial to maxilla (not visible in lateral profile); lacrymal horn not developed,but is rugose, as is the dorsal part of the postorbital; pro-maxillary fenestra not visible when the skull is viewed in lateral profile; prefrontal forms a wedge between lacrymal and fused frontals; ectopterygoids are swollen and have a very large sinus opening. (Postcranial) Ilium with a well developed notch along the front margin of the preacetabular blade; postacetabular blade of ilium slender; wrist composed of a single element; pubic shaft has a pronounced curve., Published as part of Carpenter, K., 1992, Tyrannosaurids (Dinosauria) of Asia and North America, pp. 250-268 in Aspects of Nonmarine Cretaceous Geology, Beijing :China Ocean Press on page 253, DOI: 10.5281/zenodo.1038212, {"references":["Osborn, H., 1905, Tyrannosaurus and other Cretaceous carnivorous dinosaurs: American Museum of Natural History Bulletin 21, pp. 259 - 265.","Maleev, E., 1955 a, Gigantic carnivorous dinosaurs of Mongolia: Dokladi Akademii Nauk S. S. S. R., v. 104, p. 634 - 637."]}