Browsing by Author "Makovicky, Peter J."
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ItemAnatomy and phylogenetic relationships of the theropod dinosaur Microvenator celer from the Lower Cretaceous of Montana. American Museum novitates ; no. 3240(New York, NY : American Museum of Natural History, 1998) Makovicky, Peter J.; Sues, Hans-Dieter, 1956-"The holotype of Microvenator celer Ostrom, 1970 (AMNH 3041) is a partial skeleton of a small maniraptoran theropod from the Lower Cretaceous Cloverly Formation of Montana. We present a detailed redescription of this specimen, emphasizing those features that are of interest for discovering the phylogenetic relationships of Microvenator. Based on several postcranial features, especially the lack of fusion of the neurocentral sutures, we consider AMNH 3041 a juvenile individual. Reexamination of the holotype revealed the presence of several autapomorphies that provide the basis for a revised diagnosis of Microvenator celer. Diagnostic characters include posterior dorsal and caudal vertebrae that are wider than high, the presence of a deep depression on the proximomedial part of the pubis, and an accessory trochanteric ridge below the lesser femoral trochanter. Phylogenetic analysis places Microvenator either among Oviraptorosauria, or as the sister group to the Oviraptorosauria. Among the characters diagnostic for the Oviraptorosauria, anteriorly concave pubes, a proximodorsal tubercle on the manual unguals, and possibly an edentulous dentary with a pronounced symphysis are present in Microvenator. M. celer is the earliest known oviraptorosaurian or oviraptorosaur-like theropod represented by diagnostic skeletal remains"--P. . ItemAn early ostrich dinosaur and implications for ornithomimosaur phylogeny. American Museum novitates ; no. 3420(New York, NY : American Museum of Natural History, 2003) Ji, Qiang.; Norell, Mark.; Makovicky, Peter J.; Gao, Keqin, 1955-; Ji, Shu'an.; Yuan, Chongxi.A new ornithomimosaur from the Yixian Formation of Liaoning Province Peoples Republic of China is described. These beds are near the Jurassic-Cretaceous boundary. This specimen is interesting because it has several primitive characters for ornithomimosaurs such as teeth and a short first metacarpal. This taxon is placed in a phylogenetic analysis of Coelurosauria and shown to be near the base of the ornithomimosaur clade. Using this phylogeny we comment on the biogeographic history of this group. ItemImportant features of the dromaeosaur skeleton : information from a new specimen. American Museum novitates ; no. 3215(New York, N.Y. : American Museum of Natural History, 1997) Norell, Mark.; Makovicky, Peter J.; Mongolian-American Museum Paleontological Project.; Mongolyn Shinzhlėkh Ukhaany Akademi. ItemImportant features of the dromaeosaurid skeleton. 2, Information from newly collected specimens of Velociraptor mongoliensis. American Museum novitates ; no. 3282(New York, NY : American Museum of Natural History, 1999) Norell, Mark.; Makovicky, Peter J.; Mongolian-American Museum Paleontological Project.; Mongolyn Shinzhlėkh Ukhaany Akademi.The postcranial anatomy of several new specimens of Velociraptor mongoliensis is described. This description concentrates on poorly known aspects of the skeleton of Velociraptor mongoliensis, including several features that are extremely similar to characters found in basal avialans like Archaeopteryx lithographica. Among these the pelvis and shoulder girdle display several characters such as a reduced antiliac shelf, a furcula, a scapula lying in a subhorizontal position relative to the dorsal column, and sternal plates that articulate with the coracoids. Some problematic features and conditions such as the hypopubic cup and the degree of opisthopuby are also discussed in relation to claims made about these features in regard to the origin of Avialae. Comparisons are made between Velociraptor mongoliensis and the enigmatic maniraptoran Unenlagia comahuensis"--P. . ItemA new dromaeosaurid theropod from Ukhaa Tolgod (Ömnögov, Mongolia) ; American Museum novitates, no. 3545(New York, NY : American Museum of Natural History, 2006) Norell, Mark.; Clark, James Matthew, 1956-; Turner, Alan H. (Alan Hamilton); Makovicky, Peter J.; Barsbold, Rinchin.; Rowe, Timothy, 1953-We describe a new dromaeosaurid theropod from the Upper Cretaceous Djadokhta Formation of Ukhaa Tolgod, Mongolia. The new taxon, Tsaagan mangas, consists of a well-preserved skull and cervical series. This specimen marks only the second dromaeosaurid taxon from a formation that has otherwise yielded numerous specimens of Velociraptor mongoliensis, and Tsaagan mangas is the only dromaeosaurid known from Ukhaa Tolgod beyond sporadic occurrences of isolated teeth. Tsaagan mangas differs from other dromaeosaurids in the possession of a straight, untwisted, and pendulous paroccipital process, a large and anteriorly located maxillary fenestra, and a jugal-squamosal contact that excludes the postorbital from the margin of the infratemporal fenestra. The phylogenetic affinities of Tsaagan mangas are determined through a comprehensive phylogenetic analysis of Coelurosauria, confirming its position within Dromaeosauridae. This new specimen, coupled with CT imaging, provides new information on the skull and braincase anatomy of dromaeosaurids. ItemOsteology and relationships of Byronosaurus jaffei (Theropoda, Troodontidae). American Museum novitates ; no. 3402(New York, NY : American Museum of Natural History, 2003) Makovicky, Peter J.; Norell, Mark.; Clark, James Matthew, 1956-; Rowe, Timothy, 1953-; Mongolian-American Museum Paleontological Project.; Mongolyn Shinzhlėkh Ukhaany Akademi.The troodontid Byronosaurus jaffei is known from two specimens from adjacent localities in the Nemegt basin, Omnögov Aimag, Mongolia. These specimens are composed of well-preserved cranial material and fragmentary postcrania. All of these elements are described here. Byronosaurus jaffei is included in a comprehensive phylogenetic analysis of Coelurosauria to ascertain its relationships. Several interesting characters of Byronosaurus jaffei have implications both for theropod relationships and for understanding patterns of variation within coelurosaurian theropods. These include the position of a foramen that marks the exit of the supra-alveolar canal (which we suggest is homologous with the subnarial foramen), the flattened internarial bar, the unusual interfenestral bar, and the unserrated teeth. Additionally, the well-preserved braincase allows detailed comparison with other troodontid taxa. ItemA partial ornithomimid braincase from Ukhaa Tolgod (Upper Cretaceous, Mongolia). American Museum novitates ; no. 3247(New York, NY : American Museum of Natural History, 1998) Makovicky, Peter J.; Norell, Mark.; Mongolian-American Museum Paleontological Project.; Mongolyn Shinzhlėkh Ukhaany Akademi."Among the dinosaurian remains recently discovered by the Mongolian Academy of Sciences-American Museum of Natural History expeditions at the Ukhaa Tolgod locality (Southeastern Gobi Desert, Mongolia) are a partial braincase and cervical vertebrae of an ornithomimid dinosaur (IGM 100/987). This specimen represents the first record of an ornithomimid from this rich locality, as well as the first discovery of such an animal in Djadokhta-like beds. Although broken and slightly distorted, the preserved portion of the braincase reveals new information on the anatomy of ornithomimids. The middle ear region is enlarged and is connected to three expansive tympanic pneumatic systems as in other advanced theropods. The hypoglossal nerve (cranial nerve XII) is divided into three branches, a feature otherwise known among nonavialan coelurosaurs only in Troodon formosus. Several autapomorphies of the Ornithomimidae are preserved in IGM 100/987, including expansive pneumatization of the basioccipital-exoccipital region dorsal to the basal tubera and a large depression of the posterior face of the quadrate shaft. IGM 100/987 displays subtle differences from North American ornithomimid taxa and Gallimimus bullatus, but a more definite taxonomic assessment must await a thorough revision of ornithomimid phylogeny"--P. . ItemPennaraptoran theropod dinosaurs : past progress and new frontiers. (Bulletin of the American Museum of Natural History, no. 440)(American Museum of Natural History., 2020-08-21) Pittman, Michael, 1985-; Xu, Xing, 1969-; O'Connor, Jingmai.; Field, Daniel J.; Turner, Alan H. (Alan Hamilton); Ma, Waisum.; Makovicky, Peter J.; Tse, Edison.; Norell, Mark.; Pei, Rui.; Pol, Diego.; Goloboff, Pablo A.; Ding, Anyang.; Upchurch, Paul.; Berv, Jacob S.; Hsiang, Allison Y.; Landis, Michael J.; Dornburg, Alex.; Nebreda, Sergio M.; Navalón, Guillermo.; Menéndez, Iris.; Sigurdsen, Trond.; Chiappe, Luis M.; Marugán-Lobón, Jesús.; Wang, Shuo.; Stiegler, Josef.; Wu, Ping.; Zhong, Zhengming.; Lautenschlager, Stephan.; Meade, Luke E.; Roy, Arindam.; Rogers, Christopher S.; Clements, Thomas.; Habimana, Olivier.; Martin, Peter.; Heers, Ashley M.; Serrano, Francisco J.; Habib, Michael B.; Dececchi, T. Alexander.; Kaye, Thomas G.; Larsson, Hans C.E.; Wang, Xiaoli.; Zheng, Xiaoting.; Novas, Fernando E.; Agnolín, Federico L.; Egli, Federico Brisson.; Lo Coco, Gastón E.Introduction / Michael Pittman and Xing Xu -- Section 1. Systematics, fossil record, and biogeography -- Chapter 1. Pennaraptoran systematics / Michael Pittman, Jingmai O’Connor, Daniel J. Field, Alan H. Turner, Waisum Ma, Peter Makovicky, and Xing Xu -- Chapter 2. The fossil record of Mesozoic and Paleocene pennaraptorans / Michael Pittman, Jingmai O’Connor, Edison Tse, Peter Makovicky, Daniel J. Field, Waisum Ma, Alan H. Turner, Mark A. Norell, Rui Pei, and Xing Xu -- Chapter 3. The impact of unstable taxa in coelurosaurian phylogeny and resampling support measures for parsimony analyses / Diego Pol and Pablo A. Goloboff -- Chapter 4. The biogeography of coelurosaurian theropods and its impact on their evolutionary history / Anyang Ding, Michael Pittman, Paul Upchurch, Jingmai O’Connor, Daniel J. Field, and Xing Xu -- Chapter 5. Timing the extant avian radiation : the rise of modern birds, and the importance of modeling molecular rate variation / Daniel J. Field, Jacob S. Berv, Allison Y. Hsiang, Robert Lanfear, Michael J. Landis, and Alex Dornburg -- Section 2. Anatomical frontiers -- Chapter 6. Disparity and macroevolutionary transformation of the maniraptoran manus / Sergio M. Nebreda, Guillermo Navalón, Iris Menéndez, Trond Sigurdsen, Luis M. Chiappe, and Jesús Marugán-Lobón -- Chapter 7. Tooth vs. beak : the evolutionary developmental control of the avian feeding apparatus / Shuo Wang, Josef Stiegler, Ping Wu, and Cheng-ming Chuong -- Chapter 8. Functional morphology of the oviraptorosaurian and scansoriopterygid skull / Waisum Ma, Michael Pittman, Stephan Lautenschlager, Luke E. Meade, and Xing Xu -- Chapter 9. Fossil microbodies are melanosomes : evaluating and rejecting the ‘fossilised decay-associated microbes’ hypothesis / Arindam Roy, Christopher S. Rogers, Thomas Clements, Michael Pittman, Olivier Habimana, Peter Martin, and Jakob Vinther -- Section 3. Early-flight study : methods, status, and frontiers -- Chapter 10. Methods of studying early theropod flight / Michael Pittman, Ashley M. Heers, Francisco J. Serrano, Daniel J. Field, Michael B. Habib, T. Alexander Dececchi, Thomas G. Kaye, and Hans C.E. Larsson -- Chapter 11. High flyer or high fashion? A comparison of flight potential among small-bodied paravians / T. Alexander Dececchi, Hans C.E. Larsson, Michael Pittman, and Michael B. Habib -- Chapter 12. Navigating functional landscapes : a bird’s eye view of the evolution of avialan flight / Hans C.E. Larsson, Michael B. Habib, and T. Alexander Dececchi -- Chapter 13. Laser-stimulated fluorescence refines flight modeling of the Early Cretaceous bird Sapeornis / Francisco J. Serrano, Michael Pittman, Thomas G. Kaye, Xiaoli Wang, Xiaoting Zheng, and Luis M. Chiappe -- Chapter 14. Pectoral girdle morphology in early-diverging paravians and living ratites : implications for the origin of flight / Fernando E. Novas, Federico L. Agnolín, Federico Brisson Egli, and Gastón E. Lo Coco. ItemA review of dromaeosaurid systematics and paravian phylogeny. (Bulletin of the American Museum of Natural History, no. 371)(American Museum of Natural History., 2012-08-17) Turner, Alan H. (Alan Hamilton); Makovicky, Peter J.; Norell, Mark.Coelurosauria is the most diverse clade of theropod dinosaurs. Much of this diversity is present in Paraves--the clade of dinosaurs containing dromaeosaurids, troodontids, and avialans. Paraves has over 160 million years of evolutionary history that continues to the present day. The clade represents the most diverse living tetrapod group (there are over 9000 extant species of Aves--a word used here as synonomous with "bird"), and it is at the root of the paravian radiation, when dromaeosaurids, troodontids, and avialans were diverging from one another, that we find the morphology and soft tissue changes associated with the origin of modern avian flight. Within the first 15 million years of known paravian evolutionary history members of this clade exhibited a difference of nearly four orders of magnitude in body size, a value that is similar to the extreme body size disparity present today in mammalian carnivorans, avians, and varanoid squamates. In this respect, Paraves is an important case study in characterizing the patterns, processes, and dynamics of evolutionary size change. This last point is of particular interest because of the historical significance placed on the role of body size reduction in the origin of powered avian flight. Our study reviews and revises the membership of Dromaeosauridae and provides an apomorphy-based diagnosis for all valid taxa. Of the currently 31 named dromaeosaurid species, we found 26 to be valid. We provide the most detailed and comprehensive phylogenetic analysis of paravians to date in order to explore the phylogenetic history of dromaeosaurid taxa. The general pattern of paravian relationships is explored within the broader context of Coelurosauria with an emphasis on sampling basal avialans, because of their importance for character optimizations at the base of Paraves. A large dataset was constructed by merging two datasets, one examining coelurosaur relationships broadly (based on previous TWiG datasets) and the other examining avialan relationships specifically (Clarke et al., 2006). This merged dataset was then significantly revised and supplemented with novel character analysis focusing on paravian taxa. During character analysis, particular attention was given to basal members of Dromaeosauridae, enigmatic basal paravians such as Jinfengopteryx elegans and Anchiornis huxleyi, and the incorporation of new morphological information from two undescribed troodontid species from the late Cretaceous of Mongolia. A final dataset of 474 characters scored for 111 taxa was used to address paravian evolution. This dataset is important in that it bridges a phylogenetic gap that had persisted between studies on birds and studies on all other coelurosaurs. Most scorings in this matrix were based on the direct observation of specimens. All most parsimonious trees recovered in the cladistic analysis support the monophyly of Paraves, Troodontidae, Dromaeosauridae, and Deinonychosauria. A new clade of basal troodontids is discovered including two undescribed Mongolian troodontids and Jinfengopteryx elegans. Xiaotingia and Anchiornis form a clade at the base of Troodontidae. Recently proposed relationships within Dromaeosauridae are further supported and a succession of clades from Gondwana and Asia form sister taxa to a clade of Laurasian dromaeosaurids. Avialan monophyly is strongly supported with Archaeopteryx, Sapeornis, Jeholornis, and Jixiangornis forming the successive sister taxa to the Confuciusornis node. This topology supports a more basal position for Sapeornis than previous phylogenetic analyses and indicates a progressive acquisition of a fully "avian" shoulder morphology. ItemA review of the Mongolian Cretaceous dinosaur Saurornithoides (Troodontidae, Theropoda). (American Museum novitates, no. 3654)(2009) Norell, Mark.; Makovicky, Peter J.; Bever, Gabe S.; Balanoff, Amy M.; Clark, James Matthew, 1956-; Barsbold, Rinchin.; Rowe, Timothy, 1953-We review the morphology, taxonomy, and phylogenetic relationships of the Upper Cretaceous Mongolian troodontid Saurornithoides. Saurornithoides mongoliensis is known only by the holotype from Bayan Zag, Djadokhta Formation. This specimen includes a nearly complete, but weathered, skull and mandibles, a series of dorsal, sacral, and caudal vertebrae, and a partial pelvic girdle and hind limb. Saurornithoides junior, here referred to Zanabazar, also is known only by the holotype from Bugiin Tsav, Nemegt Formation. This specimen consists of a skull and partial mandible, a series of sacral and caudal vertebrae, a partial pelvic girdle, and the distal part of the right hind limb. Saurornithoides + Zanabazar is one of the few Mongolian taxa known from both the Djadokhta and Nemegt formations. The monophyly of Saurornithoides + Zanabazar has not been seriously questioned historically, yet empirical support for this clade is currently tenuous. A privileged phylogenetic relationship between Saurornithoides, Zanabazar, and the North American troodontid Troodon formosus is supported by numerous characters including the presence of a subotic recess, lateroventrally projecting and hollow basipterygoid processes, a lacrimal whose anterior process is significantly longer than its posterior process, a highly pneumatized parasphenoid rostrum, a constricted neck of the occipital condyle, a symphyseal region of the dentary that is slightly recurved medially, and an obturator process located near the middle of the ischiadic shaft. CT data for the skulls of both species facilitated a description of the endocranial anatomy of Saurornithoides mongoliensis and Zanabazar junior, including a reconstruction of the endocranial space of Zanabazar junior. Despite being the largest of the known troodontid species, the endocranial volume of Zanabazar junior is considerably smaller than that estimated for Troodon formosus, suggesting that the extremely high encephalization quotient of Troodon formosus may be autapomorphic among troodontids. ItemSupplemental Material for 'Pennaraptoran theropod dinosaurs : past progress and new frontiers. (Bulletin of the American Museum of Natural History, no. 440)'(American Museum of Natural History., 2020-08-21) Pittman, Michael, 1985-; Xu, Xing, 1969-; O'Connor, Jingmai.; Field, Daniel J.; Turner, Alan H. (Alan Hamilton); Ma, Waisum.; Makovicky, Peter J.; Tse, Edison.; Norell, Mark.; Pei, Rui.; Pol, Diego.; Goloboff, Pablo A.; Ding, Anyang.; Upchurch, Paul.; Berv, Jacob S.; Hsiang, Allison Y.; Landis, Michael J.; Dornburg, Alex.; Nebreda, Sergio M.; Navalón, Guillermo.; Menéndez, Iris.; Sigurdsen, Trond; Chiappe, Luis M.; Marugán-Lobón, Jesús.; Wang, Shuo.; Stiegler, Josef.; Wu, Ping.; Zhong, Zhengming.; Lautenschlager, Stephan.; Meade, Luke E.; Roy, Arindam.; Rogers, Christopher S.; Clements, Thomas.; Habimana, Olivier.; Martin, Peter.; Heers, Ashley M.; Serrano, Francisco J.; Habib, Michael B.; Dececchi, T. Alexander.; Kaye, Thomas G.; Larsson, Hans C.E.; Wang, Xiaoli.; Zheng, Xiaoting.; Novas, Fernando E.; Agnolín, Federico L.; Egli, Federico Brisson.; Lo Coco, Gastón E.Supplemental Material for 'Pennaraptoran theropod dinosaurs : past progress and new frontiers. (Bulletin of the American Museum of Natural History, no. 440)' ItemYamaceratops dorngobiensis, a new primitive ceratopsian (Dinosauria, Ornithischia) from the Cretaceous of Mongolia ; American Museum novitates, no. 3530(New York, NY : American Museum of Natural History, 2006) Makovicky, Peter J.; Norell, Mark.; Mongolian-American Museum Paleontological Project.; Mongolyn Shinzhlçekh Ukhaany Akademi.A new basal neoceratopsian taxon from the eastern Gobi Desert is described. Yamaceratops dorngobiensis, tax. nov., is probably of late Early Cretaceous age, and occupies a phylogenetic position intermediate between Liaoceratops and Archaeoceratops. It is the most basal taxon to display a number of traditional neoceratopsian synapomorphies concentrated in the cheek region and mandible. These include presence of an epijugal, lateral displacement of the coronoid process, a lateral ridge on the surangular for insertion of the jaw adductors, and a lateral wall to the mandibular glenoid. Yamaceratops shares two synapomorphies (tubercles on the ventral edge of the angular and shape of the jugal) with Liaoceratops, indicating that the transient presence of derived characters may be prevalent in the early evolutionary history of Ceratopsia. Yamaceratops shares aspects of frill morphology with Liaoceratops and Leptoceratops that suggest a function unrelated to display for this anatomical structure in basal neoceratopsians, and hints at a more complex evolutionary history for ceratopsian frills. Considerations of patristic distances and mosaic evolution among basal neoceratopsian taxa indicate that a greater diversity of these animals remains undiscovered.