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A collection of over 1,700 small theropod teeth from the Judith River Group (Campanian;˜79.5–74 Ma) allows our understanding of the diversity and variation of small theropods in this assemblage to be refined. In addition to the previously recognized taxa, a series of morphologically distinct groups are recognized that may represent distinct taxa in some cases. Teeth with the Paronychodon-like features of a flat surface with longitudinal ridges on one side are resolved into a few discrete morphotypes. Two of these are included in Paronychodon lacustris and two additional morphotypes are hypothesized to represent distinct taxa, here referred to as ?Dromaeosaurus morphotype A and Genus and species indet. A. The teeth of Paronychodon lacustris and ?Dromaeosaurus morphotype A share a distinctive wear pattern that suggests tooth functioning involved contact between the flat surfaces of opposing teeth. Two species of Richardoestesia, R. gilmorei and R. isosceles, are present in the assemblage. Additionally, bird teeth are identified in the assemblage and are described in this review.Bivariate plots were used to document the variation in the theropod teeth, especially in the features that distinguish between Richardoestesia gilmorei, R. isosceles, Saurornitholestes, and Dromaeosaurus. Considerable overlap is present in all plots, so although the teeth are morphologically distinct, they are not easily distinguished by quantitative means.

This study quantifies the taphonomic context of fossil dinosaur elements in the Late Cretaceous Hell Creek Formation of Montana and North Dakota, USA. A previously published data base consisting of 649 individuals (counted at the family level) was used to establish statistically fundamental associations between the vertebrate faunal elements and the fluvial architectural elements in which they were found. In the Hell Creek, preservation is not equally distributed among the various fluvial architectural elements. Flood-plain and channel deposits preserve the preponderance of the Hell Creek dinosaur fauna. Articulated fossils most commonly occur within floodplain and point-bar deposits. Floodplain and related deposits, however, preserve the highest dinosaur faunal diversities. The dinosaur sample inferred to be most representative of the original dinosaurian assemblage structure, therefore, is obtained from floodplain and genetically related deposits. These yield eight families of dinosaurs represented in the following proportions: Ceratopsidae, 61%; Hadrosauridae, 23%; Ornithomimidae, 5%; Tyrannosauridae, 4%; Hypsilophodontidae, 3%; Dromaeosauridae, 2%; Pachycephalosauridae, 1%; and Troodontidae, 1%. Among these groups, dromaeosaurs and troodontids are represented only by teeth, a circumstance attributed at least in part to thin-walled bones whose potential for preservation in an active fluvial system is jeopardized. Ornithomimids constitute 5% of the total assemblage, which makes them the third most common dinosaur in this study. Their relatively high abundance may suggest a herbivorous dietary preference.

The ‘wishbone’ of birds comprises two clavicles fused into a structure1 known as a furcula. In an influential 1926 book on bird origins by Heilmann2, the furcula's supposed absence in dinosaurs was considered powerful evidence barring them from bird ancestry. A furcula has now been found in several theropod dinosaurs3,4, but its absence in other theropods, and the uncertainty of whether this absence is real or an artefact of preservation, obscures the evolutionary history of this structure5. Here we report the discovery of a furcula in Dromaeosauridae, a group posited to be the closest relative of birds6,7.

The discovery in recent years of additional skull material of the rare carnivorous dinosaur Stenonychosaurus inequalis prompts the first thorough description of this animal. This species, known only from the Upper Cretaceous strata of North America, is closely related to, but distinct from, the two described species of Saurornithoides from Mongolia. A derived characteristic, an inflated parasphenoid capsule, is found in both the saurornithoidids and ornithomimids, strongly suggesting shared ancestry. The middle ear cavity is well defined and is connected to at least two systems of sinuses in the skull bones. Periotic sinuses like these have not been described in theropods, and their presumed absence has been used as evidence against theropod ancestry of birds. Although these and other cranial characteristics of Stenonychosaurus do not prove that birds descended from theropods, they strengthen the claim that small carnivorous dinosaurs are more plausible bird ancestors than either pseudosuchians or crocodiles

The discovery of a new dentary of “Stenonychosaurus inequalis” with six germ teeth prompted a critical examination of all jaws and teeth attributed to Troodon, Stenonychosaurus, and Pectinodon. It is concluded that Troodon is the senior synonym of these genera, and that the name Troodontidae has priority over Saurornithoididae. Troodontid dentaries are unique amongst the Theropoda in that they lack interdental plates. Previous reports that Dromaeosaurus, Deinonychus, and Saurornitholestes do not have interdental plates are erroneous. Premaxillary, maxillary, anterior dentary and dentary teeth can be distinguished from each other. Each troodontid tooth has a constriction between the crown and root that is more comparable with birds and crocodiles than with other theropods.

Three dentaries of small theropod dinosaurs from the Judith River Formation of Alberta are described and their taxonomy is discussed. Two are referable to the Dromaeosauridae (Dromaeosaurus sp.) and the other to the Saurornithoididae. The structural differences seem to support recognition of two distinct families, Dromaeosauridae and Saurornithoididae, as proposed by some authors on the basis of other structural differences.

The skull of the small theropod dinosaurVelociraptor mongoliensis is described in detail, using the holotype from the Djadokhta Formation (Campanian) of Mongolia. A reconstruction of the skull is attempted.Velociraptor is closely related toDeinonychus andDromaeosaurus; however, it is distinguished from all other dromaeosaurids described by its relatively long, low skull and a depressed muzzle. The affinities ofVelociraptor are discussed and the taxonomic status of all other previously described East Asian dromaeosaurids is examined.

A new small theropod dinosaur, documented by an incomplete skeleton and three frontals, is described from the Judith River Formation (Upper Cretaceous: Campanian) of south-central Alberta. It is distinguished from both Stenonychosaurus and Dromaeosaurus by the structure of the frontal and by the marginal dentition. It resembles Stenonychosaurus in the structure of the frontal and the Dromaeosauridae in the shape of the endocranial cavity and other skeletal features. The material is referred to a new genus and species of the Dromaeosauridae.

A fragmentary skeleton of Stenonychosaurus inequalis indicates that this small theropod dinosaur is very closely related to Saurornithoides mongoliensis from the Cretaceous of central Asia. Both forms possessed relatively well developed cerebral hemispheres and large eyes, and were probably fleet bipeds with supple raptorial forelimbs. Their extreme rarity as fossils is attributed to their preference for environments not usually preserved in the stratigraphic record.

Family DROMAEOSAURIDAE Fig. 1 Material: Dentary fragments: UW 13684 (UCMP- V 5003); and UCMP 125238 (UCMP-V73089). Teeth: UCM 39502 (UCMP-V5711) H 1.7 mm, W 2 mm; UCM 45055 (UCMP-V5620) H 2.6 mm, W 2.2 mm; UCMP 124983 (UCMP-V73087) H 2.1 mm, W 2 mm; UCMP 124984 (UCMP-V73087) H 3 mm, W 2.1 mm; and UCMP 124985 (UCMP-V73087) H 2.7 mm, W 2.1 mm. Discussion: The two dentary fragments are much alike and are probably conspecific. UW 13684 is the more complete, measuring 15 mm long and containing the base of two teeth separated by an empty alveolus. UCMP 125238 is 6.5 mm long and contains a nearly complete tooth and a partial alveolus. In both fragments, the alveoli are longer than wide and subrectangular in shape. No interdental plates are present. The inner and outer dental parapets are nearly equal in height. On the external surface the dental foramina are anteroposteriorly elongated and terminate at faint grooves which extend ventrally from the dental border. The preserved parts of the teeth are strongly compressed laterally, and have a shallow sulcus on both sides of the root; this sulcus does not extend onto the crown. The tip of the crown is missing in UCMP 125238; however, the tooth is complete enough to show that it was posteriorly recurved, with well developed serrations on the posterior edge and faint, poorly developed ones on the anterior edge. There are 11 serrations per 2 mm on the posterior edge; those on the anterior edge cannot be counted. Reconstructed, the crown was about as long anteroposteriorly as high. These dentary fragments are similar to Velociraptor in the absence of interdental plates, the subequal height of the inner and outer dental parapets, the long and narrow, subrectangular aveoli, and in the elongated external foramina (see Sues, 1977, P 1. 16). Although these dentary fragments may be those of Velociraptor, they are too fragmentary for positive identification. As will be shown elsewhere (Carpenter and Paul, in preparation), Velociraptor occurs in North America and may differ enough from Dromaeosaurus to warrant its own family. Isolated teeth used in this study are almost as long anteroposteriorly as they are high, strongly compressed laterally, and recurved with serrations well developed along the posterior margin. Development of anterior serrations vary in strength. In these features, these teeth resemble the posterior teeth of Velociraptor mongoliensis (e. g., AMNH 6515). Many of the teeth in the collections show some degree of usage wear, especially at the tip.

Dromaeosaurus is a more robust animal than Saurornitholeates langstoni, and is much rarer (Table 1). The lacrimal slot (Fig. 1e) is well developed. In both AMNH 5356 and NMC 12349, the orbital rim is squared off and rugose, suggesting the presence of an additional bone on the orbital rim, similar to that of Troodon. If this is the case, it may be a palpebral. An examination of Dromaeosaurus teeth from Dinosaur Provincial Park suggests that more than one species was present in Judithian times (Currie, Rigby and Sloan, in preparation). It may be significant then that NMC 12349 is more robust than AMNH 5356, and that the ridge marking the anterior limit of the supratemporal fenestra is more strongly curved. As in tyrannosaurids, the posterodorsal surfaces of the paired frontals separate on the midline for an anteromedial process of the fused parietals (Fig. 1e) in NMC 12349.

Carpenter, Kenneth (1982): Baby dinosaurs from the Late Cretaceous Lance and Hell Creek formations and a description of a new species of theropod. Contributions to Geology, University of Wyoming 20: 123-134, DOI: 10.5281/zenodo.3238510, {"references":["Barsbold, R. , 1974 , Saurornithoididae , a new family of small theropod dinosaurs from central Asia and North America : Results of the Polish-Mongolian Palaeontological Expeditions , Part V , Palaeontologia Polonica, no . 30 , p . 5 -22 .","Behrensmeyer , A . K. , Western , D . , and Boaz , D . E . D. , 1979 , New perspectives in vertebrate paleoecology from a recent bone assemblage : Paleobiology, v . 5 , p . 12 -21 .","Bonaparte , J . F . , and Vince, M. , 1979 , El hallazgo del primer nido de dinosaurios Triasicos (Saurischia, Prosauropoda) , Triasico superior de Patagonia, Argentina : Ameghniana, v . 16 , p . 173- 182 .","Borchert , H . , 1960 , Genesis of marine sedimentary iron ores : Institution of Mining and Metallurgy, Bulletin, v . 64 , p . 261 -279 .","Brown , B. , 1908 , The Ankylosauridae , a new family of armored dinosaurs from the Upper Cretaceous : American Museum of Natural History, Bulletin , v . 24 , p . 187-201 .","Case , T J . , 1978 , Speculations on the growth rate and reproduction of some dinosaurs ; Paleobiology, v . 4 , p . 320-328 .","Chenery , E . , 1954 , Acid sulphate soils in central Africa : 5 th International Congress of Soil Science Transactions , v . 4 , p . 195 .","Clemens , W . A. , 1963 , Fossil mammals of the type Lance Formation , Wyoming : Part 1 . Introduction and Multituberculata : University of California, Publications in Geological Sciences , v . 48 , vi + 105 p","Coleman, J . M. , 1966 , Ecological changes in a massive fresh-water clay sequence : Gulf Coast Association of Geological Societies , Transactions , v . 16 , p . 159- 174 .","Coombs , W . P . , 1971 , The Ankylosauria [PhD thesis] : New York , New York , Columbia University, 487 p","1978, The families of the ornithischian dinosaur Order Ankylosauria: Palaeontology, v . 21 , p . 143- 170 .","1980, Juvenile ceratopsians from Mongoliathe smallest known dinosaur specimens : Nature, v . 283 , p . 380-381 .","Cope, E . D . , 1876 , On some extinct reptiles and Batrachia from the Judith River and Fox Hills Beds of Montana : Academy of Natural Sciences of Philadelphia, Proceedings , v . 28 , p . 340-359 .","Dodson , P . , 1971 , Sedimentology and taphonomy of the Oldman Formation (Campanian) , Dinosaur Provincial Park , Alberta (Canada) : Palaeogeography, Palaeoclimatology, Palaeoecology, v . 10, p . 21 -74 .","The significance of small bones in paleoecological interpretation : Contributions to Geology , University of Wyoming , v . 12 , p . 15- 19 .","Taxonomic implications of relative growth in lambeosaurine hadrosaurs : Systematic Zoology, v . 24 , p . 37 -54 .","Eyre , S . R. , 1968 , Vegetation and soils : London , Edward Arnold Publishers Ltd. , 328 p .","Estes , R . D . , 1964, Fossil vertebrates from the Late Cretaceous Lance Formation , eastern Wyoming : University of California, Publications in Geological Sciences , v . 49 , 180 p .","Fox , R . C . , 1978 , Upper Cretaceous terrestrial vertebrate stratigraphy of the Gobi Desert (Mongolian People's Republic) and western North America, in Stelck , C . R. , and Chatterton , B . D . E . , eds , Western and Arctic Canadian biostratigraphy : Geological Association of Canada, Special Paper 18 , p . 577-594 .","Garrels , R . and Christ , C . L . , 1965 , Solutions , minerals , and equilibria : San Francisco , Freeman , Cooper & Company, 450 p .","Gilmore , C . W. , 1932, A new fossil lizard from the Belly River Formation of Canada : Royal Society of Canada, Transactions , v . 26 , p . 117- 119 .","Glob , P . V. , 1971 , The Bog People : Iron-Age Man preserved : New York , Ballatine Books , 144 p .","Gradzinski , R. , 1970 , Sedimentation of dinosaurbearing Upper Cretaceous deposits of the Nemegt Basin, Gobi Desert : Results of the Polish- Mongolian Palaeontological Expeditions , Part 2, Palaeontologia Polonica v . 21 , p . 148 - 229 .","Hall , T F . , and Penfound , W . T . ,1939a , A phytosociological study of a cypress-gum swamp in southeastern Louisiana : American Midland Naturalist, v . 21 , p . 378 -395 .","1939b, A phytosociological study of a Nyssa biflora consocies in southern Louisiana : ibid. , v . 21 , p . 369 -375","1943, Cypress-gum communities in the Blue Girth Swamp near Selma, Alabama : Ecology v . 24 , p . 208 -217 .","Hatcher , J . B. , Marsh , O . C . , and Lull , R . S . , 1907 , The Ceratopsia : U . S . Geological Survey, Monograph 49 , 198 p .","Horner , J . R. , and Makela, R. , 1979 , Nest of juvenile provides evidence of family structure among dinosaurs : Nature , v . 282 , p . 296 -298 .","Jensen , J . A . , 1966 , Dinosaur eggs from the Upper Cretaceous North Horn Formation of Central Utah : Brigham Young University , Geology Studies , v . 13 , p . 55 -67 .","1970, Fossil eggs in the Lower Cretaceous of Utah : ibid. , v . 17 , p . 51 - 65 .","Fossil eggs in the Lower Cretaceous of Utah : ibid. , v . 17 , p . 51 - 65 .","Jepsen, G . L. , 1931 , Dinosaur egg shell fragments from Montana : Science , v . 73 , p . 12- 13 .","Johnston, D . S . , 1968 , Malayan blackwaters : in Misra, R. , and Gopal , B. , eds , Symposium on recent advances in tropical ecology : Faridad , India , Shri R . K . Jain , Today and Tomorrow's Printers and Publishers , p . 303 - 310 .","Kielan-Jaworowska , Z. , 1975 , Late Cretaceous mammals and dinosaurs from the Gobi Desert : American Scientist , v . 63 , p . 150- 159 .","Kitching , J . , 1979 , Preliminary report on a clutch of six dinosaurian eggs from the Upper Triassic Elliot Formation, northern Orange Free State : Palaeontologica Africana , v . 22 , p . 41 -45 .","Kraemer , J . E. , and Bell, R. , 1980 , Rain-induced mortality of eggs and hatchlings of Loggerhead Sea Turtles (Caretta caretta) on the Georgia coast : Herpetologica, v . 36 , p . 72-77 .","Krauskopf, K . B. , 1967 , Introduction to geochemistry : New York , MCGraw-Hill Book Company, 721 p .","Lambe , L . M. , 1902 , New genera and species from the Belly River Series (Mid-Cretaceous) : Geological Survey of Canada , Contributions to Canadian Paleontology, v . 3 , p . 25 - 81","1917, The Cretaceous theropodous dinosaur Gorgosaurus: Geological Survey of Canada, Memoir 100 , 84 p .","The Cretaceous theropodous dinosaur Gorgosaurus: Geological Survey of Canada, Memoir 100 , 84 p .","Lapparent, A . F. , 1958 , Decouverte d'un gisement d'oeufs de Dinosauriens dans le Cretace superieur du bassin de Tremp (Province de Lerida, Espagne) : Academie des Sciences , Comptes Rendus , v . 247 , p . 1879- 1886 .","Leidy, J. , 1860 , Extinct Vertebrata from the Judith River and Great Lignite Formations of Nebraska : American Philosophical Society, Transactions , new series , v . 11 , p . 139- 154 .","1868, Remarks on a jaw fragment of Megalosaurus: Academy of Natural Sciences of Philadelphia, Proceedings , v . 20 , p . 197-200 .","Remarks on a jaw fragment of Megalosaurus: Academy of Natural Sciences of Philadelphia, Proceedings , v . 20 , p . 197-200 .","Loveless , C . M. , 1959 , A study of the vegetation in the Florida Everglades : Ecology, v . 40 , p . 1 -9 .","Marlier , G. , 1973 , Limnology of the Congo and Amazon rivers , in Meggers , B . J . , Ayensu , E . S . , and Duchworth , W . D. , eds , Tropical Forest Ecosystems in Africa and South America : a comparative review : Washington , D . 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F . , 1905 , Tyrannosaurus and other Cretaceous carnivorous dinosaurs : American Museum of Natural History, Bulletin , v . 21 , p . 259 -265 .","1924, Three new Theropoda, Protoceratops zone , central Mongolia: American Museum Novitates , no . 144 , 12 p .","Ostrom, J . H. , 1969 , Osteology of Deinonychus antirrhopus, an unusual theropod from the Lower Cretaceous of Montana : Peabody Museum of Natural History, Bulletin , no . 30 , 165 p .","Parberry, D . , and Venkatchalam , R. , 1964 , Chemical analysis of South Malayan peat soil : Journal of Tropical Geography, v . 18 , p . 125- 133 .","Richards , P . , 1964 , Tropical rain forest : London , Cambridge University Press , 450 p .","Richmond , N. , 1965 , Perhaps juvenile dinosaurs were always scarce : Journal of Paleontology, v . 39 , p . 503 -505 .","Rolfe , W. , and Brett , D . , 1969 , Fossilization processes , in Eglington, G. , and Murphy, M. , eds , Organic geochemistry: methods and results : New York , Springer-Verlag , p . 213 -244 .","Russell, D . A. , 1969 , A new specimen of Stenonychosaurus from the Oldman Formation (Cretaceous) of Alberta : Canadian Journal of Earth Sciences , v . 6 , p . 595 -612 .","Russell, L . S . , 1948 , The dentary of Troodon , a genus of theropod dinosaurs : Journal of Paleontology, v . 22 , p . 625 -629 .","Sahni , A. , 1972, The vertebrate fauna of the Judith River Formation, Montana : American Museum of Natural History, Bulletin, v . 147 , p . 323 -412 .","Sige, M. , 1968 , Dents de Micromammiferes et fragments de coquilles d'oeufs de Dinosauriens dans la fauna de Vertebres du Cretace superieur de Laguna Umayo (Andes peruviennes) : Academie des Sciences , Comptes Rendus , ser . D , v . 267 , p . 1495- 1498 .","Simpson , G . G. , 1928 , A new mammalian fauna from the Fort Union Formation of southern Montana : American Museum Novitates , no . 297 , 15 p .","Sochava , A . V. , 1969 , Dinosaur eggs from the Upper Cretaceous of the Gobi Desert : Palaeontology Journal, v . 3 , p . 517 -527 .","______1971 , Two types of dinosaur egg shells in the Senonian dinosaurs : ibid. , v . 5 , p . 353 - 361 .","_____1972, The skeleton of an embryo in a dinosaur egg : ibid. , v . 6 , p . 527 -530 .","Sternberg , C . 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Currie, P.J. (1987): Theropods of the Judith River Formation of dinosaur Provincial Park, Alberta, Canada. In: Currie P.J., Koster E.H. (Eds): Fourth Symposium on Mesozoic Terrestrial Ecosystems. Drumheller, Alberta: Tyrrell Museum of Paleontology: 51-60, DOI: http://doi.org/10.5281/zenodo.3676391, {"references":["Bakker, R.I . , Williams , M . and Currie,, P.J. ln preparation . The tyrant dinosaurs--a redefinition of Tyrannosaurus, Albertosaurus, Gorgosaurus, Daspletosaurus, Tarbosaurus , and a new genus of dwarf tyrannosaurine, Clevelanotyrannus; with a discussion of head-neck posture, prey -attacking adaptations and head-butting behaviour . Submitted to Hunteria.","Beland, P. and Russell , D .A . 1978. Paleoecology of Dinosaur Provincial Park (Cretaceous), Alberta, interpreted from the distribution of articulated vertebrate remains. Canadian Journal of Earth Sciences, 15 , pp. 1012- 1024 .","Currie, P.J . 1985. Cranial anatomy of Stenonychosaurus inequalis (Saurischia, Theropoda) and its bearing on the origin of birds. Canadian Journal of Earth Sciences, 22 , pp. 1643-1658.","1986. Dinosaur fauna .In Dinosaur systematics symposium, , field trip guidebook to Dinosaur Provincial Park . Edited by B .G. Naylor. Tyrrell Museum of Palaeontology, Drumheller , Canada , pp. 17-23 .","1987a. Bird-like characteristics of the jaws and teeth of troodontid theropods (Dinosauria, Saurischia) . Journal of Vertebrate Paleontology . 7, pp. 72-81.","1987b. New approaches to studying dinosaurs in Dinosaur Provincial Park . In Dinosaurs Past and Present , Volume II. Edited by S.J. Czerkas and E.C. Olson. Los Angeles County Museum, Los Angeles.","in preparation. Small theropods of the Late Cretaceous of Asia and North America . In International symposium on nonmarine Cretaceous correlations, proceedings. Edited by P.J. Chen and N . Mateer. China Ocean Press, Beijing , China . Submitted 1987.","Currie , P.J., Rigby, J.K . and Sloan , R .E . In preparation . An odontography of theropod teeth.","Currie, P.J . and Russell, D .A . In preparation. Osteology of Chirostenotes pergracilis ( Saurischia, Theropoda) from the Judith River Formation of Alberta, Canada. Submitted to Canadian Journal of Earth Sciences .","Gilmore , C.W . 1924. Contribution of vertebrate palaeontology. Geological Survey of Canada, Bulletin, 38, pp . 1-89.","Matthew, W.D. and Brown. B . 1923 . Preliminary notices of skeletons and skulls of Delnodontidae from the Cretaceous of Alberta. American Museum Novitates, 89, pp . 1-9 .","Russell, D.A. 1970. Tyrannosaurs from the late Cretaceous of western Canada. National Museum of Canada Natural History Publications in Paleontology , 1. pp . 1 -34.","Sues, H.- D. 1987. A new small theropod dinosaur from the Judith River Formation ( Campanian) of Alberta , Canada. Zoological Journal of the Linnean Society, 62 , pp. 381-400 ."]}

Saurornitholestes langstoni (Figs. 1d, 3) is the most common small theropod in the Judith River Formation of Dinosaur Provincial Park, judging from the number o: frontais (Tsble l) and teeth (Currie, Rigby and Sloan, in preparation) recovered. In contrast with Dromaeosaurus, the medial prong of the nasal does not extend as far caudally over the frontal as the more lateral prong. The slot that the lacrimal passes through the frontal to contact the prefrontal. is relatively small (Fig. 1d). The frontal is somewhat bulbous caudally where it curves posteroventrally to meet the parietal. A faint, sigmoidally curved ridge runs rostrolaterally onto the front margin of the postorbital process, and marks the anterior limit of the supratemporal fenestra. Unlike Dromaeosaurus, the portion of the frontal within the supratemporal fenestra is posterodorsally concave, and even forms a deep pit in some specimens (TMP 86.77.57, Fig. 1d)., Published as part of Currie, P. J., 1987, Theropods of the Judith River Formation of dinosaur Provincial Park, Alberta, Canada, pp. 51-60 in Fourth Symposium on Mesozoic Terrestrial Ecosystems, Drumheller, Alberta :Tyrrell Museum of Paleontology on page 54, DOI: 10.5281/zenodo.3676391

ZAPSALIS Cope. The teeth of this genus are intermediate in form between those of Laelaps and Paronychodon. They have one flat and one convex side, whose junctions form the anterior and posterior edges of the crown as in the latter genus; and like the latter, there is, no anterior cutting edge, but instead, a solid angle. But the posterior edge is denticulate as in Laelaps, and the plicae or keels of Paronyclrodon are here only recognizable in low angles. Some light may be cast 0 n the affinities of the latter genus by the discovery of Zapsalis., Published as part of Cope, E. D., 1876, On some extinct reptiles and batrachia from the Judith River and Fox Hills beds of Montana, pp. 340-359 in Proceedings of the Academy of Natural Sciences of Philadelphia 28 on page 344, DOI: 10.5281/zenodo.3368363

Laelaps cristatus Cope, 1877 " ? Dromaeosaurus cristatus, Published as part of Matthew, W. D., & Brown, B., 1922, The family Deinodontidae, with notice of a new genus from the Cretaceous of Alberta., pp. 365-385 in Bulletin of the American Museum of Natural History 56 on page 376, DOI: 10.5281/zenodo.1053799

Coelurus gracilis Marsh, 1888 " " (?)Dromaeosaurus gracilis

1922 Figure 9I Dromaeosaurus albertensis MATTHEW AND BROWN, 1922, p. 383. Laelaps explanatus COPE, 1876a, p. 249. Laelapsfalculus Cope, 1876a, p. 249. Laelaps laevifrons COPE, 1876b, p. 344. Dromaeosaurus albertensis is a small carnivorous dinosaur described from the "Belly River Formation" of Alberta by Matthew and Brown (1922, p. 383). These authors stated that the length of the skull is one-third to one-fourth the linear size of that of Deinodon, and differs from it by "reduced number of teeth, the large premaxillary teeth and the unsymmetric form of the maxillary teeth as well as the light skull construction, large fenestrae and numerous details that might be largely associated with its small size. " Teeth similar to those of Dromaeosaurus have been reported and figured (Russell, 1935, fig. 9) from the Milk River Formation of Alberta. They have also been reported from the Judith River Formation (Matthew and Brown, 1922, p. 378). AMNH 8516 is referable to the genus (fig. 9I). The teeth are usually smaller versions of those of Deinodon, with relatively strongly convex anterior borders. Serrations on the posterior edge of most teeth are coarser than those on the anterior, and in some specimens the anterior crest may be completely unserrated., Published as part of Sahni, Ashok, 1972, The vertebrate Fauna of the Judith River formation, Montana, pp. 319-416 in Bulletin of the American Museum of Natural History 147 (6) on page 359, DOI: 10.5281/zenodo.3382461, {"references":["1876 a. Descriptions of some vertebrate remains from the Fort Union beds of Montana. Proc. Acad. Nat. Sci. Philadelphia, vol. 28, pp. 248 - 261.","1876 b. On some extinct reptiles and batrachians from the Judith River and Fox Hills beds of Montana. Ibid., vol. 28, pp. 340 - 359.","RUSSELL, L. S. 1935. Fauna of the Upper Milk River beds, southern Alberta. Trans. Roy Soc. Canada, ser. 3, sect. 4, vol. 29, pp. 115 - 127, pls. 1 - 5."]}

Zapsalis abradens, sp. nov. This reptile was apparently about the size of the Laelaps laevifrons. The best preserved tooth is that of a probably adult animal, as it displays considerable attrition, especially on the fiat side. Here three worn lines indicate the former existence of as many low longitudinal angles of the surface, of which the median is basal and short. The convex side exhibits four low angles of nearly equal length, all stopping short of the apex. The facets between them, excepting the anterior two, are slightly concave. The denticles are of moderate coarseness, measuring M. 00033., Published as part of Cope, E. D., 1876, On some extinct reptiles and batrachia from the Judith River and Fox Hills beds of Montana, pp. 340-359 in Proceedings of the Academy of Natural Sciences of Philadelphia 28 on page 345, DOI: 10.5281/zenodo.3368363

“ Iaevifrons Cope, 1877 " " Dromaeosaurus laevifrons, Published as part of Matthew, W. D., & Brown, B., 1922, The family Deinodontidae, with notice of a new genus from the Cretaceous of Alberta., pp. 365-385 in Bulletin of the American Museum of Natural History 56 on page 376, DOI: 10.5281/zenodo.1053799

Zapsalis abradens Cope, 1877 " tooth Incertae sedis, cf. Dromaeosaurus, Published as part of Matthew, W. D., & Brown, B., 1922, The family Deinodontidae, with notice of a new genus from the Cretaceous of Alberta., pp. 365-385 in Bulletin of the American Museum of Natural History 56 on page 376, DOI: 10.5281/zenodo.1053799

Matthew, W. D.,, Brown, B. (1922): The family Deinodontidae, with notice of a new genus from the Cretaceous of Alberta. Bulletin of the American Museum of Natural History 56: 365-385, DOI: 10.5281/zenodo.1053799, {"references":["1Gilmore, 1920, U. S. Nat. Mus. Bull. 110.","1Osborn, 1917, Bull. Amer. Mus. Nat. Hist., XXXV, pp. 733-771.","1 Vide discussion in Palmer's 'Index Generum Mammalium.","2Cope, 1866, Proc. Acad. Nat. Sci. Phila., XVIII, p. 279","3Marsh, 1890, Amer. Journ. Sci., XXXIX, p. 424.","4Marsh, 1892, Amer. Journ. Sci., XLIII. p. 451.","5Marsh, 1895, Amer. Journ. Sci 493.","6Proc. Acad. Nat. Sci. Phila. XVIII, p. 317.","l Cope, 1868, Journ. Acad. Nat. Sci. Phila., XIV, p. 100."]}

Dromaeosaurus albertensis , new genus, new species Type.— A. M. No. 5356, skull and lower jaws, and a few foot bones. Horizon and Locality.—Belly River formation, Red Deer River, Alberta. Found by Barnum Brown, Amer. Mus. Exped., 1914. Generic Diagnosis.— Comparable in size with Ornithomimus. Dental formula Pmx.? 3; Max. 9 Den.10 Teeth well developed, asymmetrically oval or compressed, sharp-pointed, recurved, serrate on anterior and posterior border. Premaxillary teeth three or more, not reduced in size, strongly convex antero-extemally but not of fully U-shaped section. Posterior teeth similar but more compressed and blade-like in both upper and lower jaw, the last maxillary tooth small. Jaws elongate, not massive. Orbital fenestra larger proportionately than in Deinodon, not so large as in Struthiomimus. Lateral temporal fenestra of good size, much as in Deinodon, not reduced as in Struthiomimus. Preorbital fenestras at present known only inferiorly, but evidently large. Frontals comparatively long and wide, the nasals overlapping them considerably, especially at the median line. The prefrontal and postfrontal sutures continuous, not separated by an orbital notch. Maxillo-premaxillary suture nearly vertical, the premaxilla large. The top of the skull is fragmentary and the specimen is at present only partly prepared, so that the above diagnosis will be completed and perhaps modified in some details in a later article. The skull is most like that of Deinodon in general proportions, but from a third to a fourth as large lineally, and but little larger than that of Struthiomimus altus. It differs from Deinodon in the reduced number of teeth, the large premaxillary teeth and the unsymmetric form of the maxillary teeth as well as in the light skull construction, large fenestrae and numerous details that might be largely associated with its small size. The foot bones are very different from those of either Deinodon or Struthiomimus, but so fragmentary that they are not positively identifiable, and no generic characters can be based upon them. The distal half of a metapodial, slightly larger than the me. II of Struthiomimus and only a little smaller than me. II of Deinodon (despite the enormous difference in size of the skeleton) has a deeply grooved ginglymoid distal facet, as in Deinodon, but shows a very distinct lateral appression surface. In Struthiomimus there is an appression surface on me. II, but the distal end of the bone is wholly different with a convex condylar facet; it also is of about the same size. Another much smaller metapodial has a less distinctly grooved distal facet and more irregular shaft that may be incomplete proximally. Of the phalanges there are three that fit so closely that they appear to belong with the metapodial first mentioned, but if so it must be the fourth digit, not the second, and may belong to the pes instead of the manus. A fourth phalanx is of similar type but distinct in details from any of the first three. A fifth is a proximal phalanx of size more suited to the smaller metapodial above mentioned, but does not fit it; it is rather short with concave basined head and laterally compressed distal end, apparently a phalanx of the first digit. A sixth phalanx is much larger than the others but only the distal end is preserved, its facet deeply grooved and very similar to the distal facet of the metapodial first noted. Possibly, but not probably, this is a median metapodial. The comparison of these bones with the complete manus and pes of Struthiomimus and of Deinodon shows clearly that Dromaeosaurus differs greatly in the construction of manus or pes, or both, from either of these genera and suggests a less degree of specialization and reduction of the digits in manus or pes. Although provisionally referred to the family Deinodontidae, the differences in the skull, number of teeth, and form of premaxillary teeth, together with the apparent diversity in construction of the foot bones, warrant placing Dromaeosaurus in a distinct subfamily Dromaeosaurinae., Published as part of Matthew, W. D., & Brown, B., 1922, The family Deinodontidae, with notice of a new genus from the Cretaceous of Alberta., pp. 365-385 in Bulletin of the American Museum of Natural History 56 on pages 383-385, DOI: 10.5281/zenodo.1053799

The discovery of dinosaur egg shell fragments from Clambank Hollow in the Judith River Formation unfortunately was made after most of the material had been etched in 10 per cent formic acid. Surprisingly, the external and internal sculpture pattern is well preserved in the etched as well as in the nonetched material. The internal stratification of mineral and organic layers, however, is less clear in radial sections of the acid-treated material, indicating that these substances have been leached out. At least five separate external sculptured patterns can be seen, including all three of the categories devised by Jensen (1966) for distinguishing fossil egg fragments from the North Horn Formation of Utah. According to Jensen's (1966) criteria, the egg shells probably belong to those of dinosaurs, although Jensen's Class A eggs bear certain resemblances to bird eggs. The egg shells described here are all believed to be dinosaurian. The most common egg shell fragments from the Judith River Formation are those that belong to Jensen's Class B. Fragments from Jensen's Class A and Class C are rare in the Judith River Formation. CLASS A: Shells in this class are characterized by a smooth external surface with little or no sculpturing. No color mosaic can be noticed. Pores are distinct and well spaced and their density in AMNH 8544 is about 10/sq. cm. (fig. 9X). The pore openings are either subcircular or pentagonal with straight sides, and do not appear to be elongated parallel to the length of the shell as mentioned by Jensen (1966, p. 61). The internal surface consists of mammillae which reach a maximum diameter of 0.1 mm. The thickness of the shell is 1.0 mm. Stratification, in radial section, is indistinct or, at places, absent. 1 [Palaeoscincus is regarded as a nomen dubium by Walter P. Coombs in his review of the nodosaurs, which is now in an advanced stage of preparation. The specimens referred to Palaeoscincus costatus and to Edmontonia longiceps may all belong to Panoplosaurus Lambe, 1919, fide Coombs (personal commun.).] M. C. McKenna. CLASS B: These shells are ornamented with nodose or linear ridges raised above the general surface of the shell. This, by far, is the most common class in the Judith River Formation. AMNH 8545 is a fairly large fragment (1.5 x 2.0 cm.) with external sculpturing of small, wellspaced nodes (fig. 9P, Q). Pores occur in the valleys between the nodes, are indistinct and few in number. The thickness of the shell is 1.0 mm. The nodes in specimen AMNH 8546 coalesce to form meandering ridges (fig. 9R, S). There is a possibility that this type is identical to the one described above and that the differences are positional in nature. The thickness of the shell is 1.2 mm. Different from the other nodular types is AMNH 8547 (fig. 9V, W). The nodes are not circular in outline but have squared off bases and are relatively more closely spaced. Pores do not occur between the nodes but are deep gutter-like depressions that incompletely encircle the nodes. The thickness of the shell is 1.0 mm. As in some North Horn Formation forms, the internal surface consists of small mammillae with an average diameter of about 0.01 mm. CLASS C: Specimen AMNH 8548 probably belongs to the Class C category ofJensen (1966). The sculpture pattern is impressed into the external layer of the shell and consists of deeply incised grooves and irregular pits (fig. 9T, U). Two distinct shell layers are visible in side view, as well as in radial section. The upper layer is 0.7 mm. thick and appears to be porous and spongy; the lower layer is 1.2 mm. thick, quite dense and extremely hard. No distinct pores are present, and their function must have been carried out by the irregular grooves and pits. On the internal surface, the mammillae are small and relatively well separated. The presence of fragile dinosaur egg shell pieces in the Clambank Hollow Quarry certainly indicates that the eggs were laid quite close to the site of deposition. The variety of the shells also indicates that their discovery at the locality is not a chance occurrence, but that the stream bank was a suitable laying area for a number of different dinosaurs. No generic names have been assigned to the egg shell fragments and as yet little can be said even about the familial affinities of the eggs. The presence of grossly similar types in the Campanian and in the Maestrichtian suggests that similar reptiles existed during the two epochs. Although members of the major groups of dinosaurs were more diverse during the Campanian, all the families persisted into the Maestrichtian. The material from Campanian Clambank Hollow adds yet another locality where eggs of dinosaurs have been found. Eggs and egg shell fragments have been reported from Mongolia (Van Straelen, 1928), Southern China (Young, 1965), India (Sahni, 1957), France and Brazil (Thaler, 1965), and North America (Jepsen, 1931; Jensen, 1966)., Published as part of Sahni, Ashok, 1972, The vertebrate Fauna of the Judith River formation, Montana, pp. 319-416 in Bulletin of the American Museum of Natural History 147 (6) on pages 363-364, DOI: 10.5281/zenodo.3382461, {"references":["JENSEN, J. A. 1966. Dinosaur eggs from the Upper Cretaceous North Horn Formation of Central Utah. Brigham Young Univ., Geol. Studies, vol. 13, pp. 55 - 67, figs. 1, 2, pls. 1 - 4.","VAN STRAELEN, V. 1928. Les oefs de Reptiles fossiles. Palaeobiologica, vol. 1, pp. 295 - 312, pls. 1 - 3.","YOUNG, C. C. 1965. Fossil eggs from Nantsiung, Kwantung and Kanchou, Kiangsi. Vert. PalAsiatica, vol. 9, no. 2, pp. 141 - 170, figs. 1 - 3, pls. 1 - l 9, tables 1 - 7.","SAHNI, M. R. 1957. Recent researches in palaeontology, palaeobotany, and stratigraphy in the Palaeontologic Division, Geological Survey of India. Jour. Palaeont. Soc. India, vol. 2, pp. 29 - 33, fig. 1.","THALER, L. 1965. Les oefs des dinosaures du Midi de la France livrent le secret de leur extinction. Paris, F. Dunod, Sci. Progr. Nat., pp. 41 - 48, figs. 1 - 11.","JEPSEN, G. L. 1931. Dinosaur egg shell fragments from Montana. Science, vol. 73, no. 1879, pp. 12 - 13."]}

THE Lower Cretaceous lithographic limestones from Las Hoyas (province of Cuenca, Spain) have yielded important vertebrate fossil remains. We report here a new specimen, the first ornithomimosaur theropod found in Europe. Pelecanimimus polyodon gen. et sp. nov., has some striking elements preserved, such as the hyoid, sternum and integumentary impressions. The fossil has revealed other unexpected features, including a derived hand in an ancient ornithomimosaur, and a large number of teeth (over 200) with a distinctive morphology. This specimen suggests an alternative evolutionary process towards the toothless condition in Ornithomi-mosauria, which could be explained by an exaptation. Pelecanimimus polyodon stresses the relationship between Troodontidae and Ornithomimosauria.

Over 180 isolated theropod teeth recovered from the Maevarano Formation (Campanian?-Maastrichtian) of the Mahajanga Basin were studied in order to document theropod diversity in the Malagasy insular setting. Tooth morphology and characteristics of the Maevarano teeth were compared to those of known theropod teeth for identification, including the Malagasy non-avian theropods Majungatholus atopus and Masiakasaurus knopfleri. Tooth and denticle morphologies permit the recognition of five tooth morphotypes: three are referable to Majungatholus atopus and one to Masiakasaurus knopfleri. Statistical analyses reveal that the fifth morphotype is similar to dromaeosaurid teeth, suggesting that a yet unknown theropod taxon inhabited Madagascar during the Late Cretaceous. This morphotype support the theory that dromaeosaurids were present throughout Pangea before the break-up of the supercontinent during the Late Jurassic and had colonized Madagascar before its separation from Africa during the Early Cretaceous.

We describe a new dromaeosaurid theropod from the Upper Cretaceous Wulansuhai Formation of Bayan Mandahu, Inner Mongolia. The new taxon, Linheraptor exquisitus gen. et sp. nov., is based on an exceptionally well-preserved, nearly complete skeleton. This specimen represents the fifth dromaeosaurid taxon recovered from the Upper Cretaceous Djadokhta Formation and its laterally equivalent strata, which include the Wulansuhai Formation, and adds to the known diversity of Late Cretaceous dromaeosaurids. Linheraptor exquisitus closely resembles the recently reported Tsaagan mangas. Uniquely among dromaeosaurids, the two taxa share a large, anteriorly located maxillary fenestra and a contact between the jugal and the squamosal that excludes the postorbital from the infratemporal fenestra. These features suggest a sister-taxon relationship between L. exquisitus and T. mangas, which indicates the presence of a unique dromaeosaurid lineage in the Late Cretaceous of Asia. A number of cranial and dental features seen in L. exquisitus and T. mangas, and particularly some postcranial features of L. exquisitus, suggest that these two taxa are probably intermediate in systematic position between known basal and derived dromaeosaurids. The discovery of Linheraptor exquisitus is thus important for understanding the evolution of some salient features seen in the derived dromaeosaurids.