Browsing by Author "Pol, Diego."
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ItemAnatomy of Mahakala omnogovae (Theropoda, Dromaeosauridae), Tögrögiin Shiree, Mongolia. (American Museum novitates, no. 3722)(American Museum of Natural History., 2011-10-05) Turner, Alan H. (Alan Hamilton); Pol, Diego.; Norell, Mark.; Mongolian-American Museum Paleontological Project.; Mongolyn Shinzhlėkh Ukhaany Akademi.The dromaeosaurid Mahakala omnogovae is known from a unique specimen from the late Cretaceous deposits of the Djadokhta Formation at Tögrögiin Shiree, Ömnögov Aimag, Mongolia. The holotype specimen is comprised of a well-preserved but partial skull and a nearly complete postcranial skeleton. Mahakala omnogovae is included in a comprehensive phylogenetic analysis of Coelurosauria using a dataset, which reflects a greatly expanded character set and taxon-sampling regime. Several interesting features of Mahakala omnogovae have implications for deinonychosaurian and avialan character evolution and for understanding patterns of size variation and size change within paravian theropods. These morphologies include the shape of the iliac blade, the triangular obturator process of the ischium, and the evolution of the subarctometatarsalian condition. We present an expanded diagnosis of Mahakala omnogovae which included following unique combination of characters (autapomorphies noted by *): a ledgelike depression at the confluence of metotic strut and posterior tympanic recess on the anterior face of the paroccipital process*, a posteriorly tapering scapula; a shortened forelimb (humerus 50% femur length); a strongly compressed and anteroposteriorly broad ulna tapering posteriorly to a narrow edge*; elongate lateral crest on the posterodistal femur*; anterior caudal vertebrae with subhorizontal, laterally directed prezygapophyses*; a prominent supratrochanteric process; and the absence of a cuppedicus fossa. ItemMorphology of the late Cretaceous crocodylomorph Shamosuchus djadochtaensis and a discussion of neosuchian phylogeny as related to the origin of Eusuchia. (Bulletin of the American Museum of Natural History, no. 324)(2009) Pol, Diego.; Turner, Alan H. (Alan Hamilton); Norell, Mark.We describe a new specimen of the fossil crocodyliform taxon Shamosuchus djadochtaensis from the late Cretaceous Djadokhta Formation. The new specimen consists of an almost complete skull found in association with postcranial material. Because it is considerably more complete than the holotype, the new specimen permits proper diagnosis of Shamosuchus djadochtaensis and offers new information for exploring its phylogenetic relationships. The phylogenetic analysis conducted here improves taxon sampling of neosuchian crocodyliforms with respect to previous approaches to crocodyliform systematics and reveals that Shamosuchus djadochtaensis bears important information toward an understanding of the relationships of advanced neosuchians and the evolutionary origin of Eusuchia. Shamosuchus djadochtaensis is found to be the sister group of Rugosuchus nonganensis, comprising an Asian clade diagnosed by the presence of a sagittal ridge on the dorsal surface of the frontal, confluent openings for the exit of cranial nerves IX-XI, a posterior region of the palatine bar between suborbital fenestra that is flared posteriorly, and a longitudinal ridge on the lateral surface of the angular. This clade is inferred to be the sister group of Eusuchia, to the exclusion of Bernissartia fagesii and the Glen Rose form, based on the absence of an acute anterior tip of the frontal that wedges between the nasals, the presence of rodlike neural spines in the posterior cervical vertebrae, procoelous cervical vertebrae, and the presence of hypapophyses in the three anteriormost dorsal vertebrae. Incorporating the new information into the phylogenetic analysis indicates the decoupled nature of the evolutionary history of procoely in different regions of the vertebral column and the eusuchian type of palate, both traditionally considered as diagnostic of Eusuchia. All these features have complex evolutionary histories with several cases of convergences and reversals. Finally, a review of all the available evidence on the diversity of advanced neosuchians suggests this group achieved a worldwide distribution and a remarkable morphological diversity, pushing their evolutionary origins back to the Jurassic. ItemNew Araripesuchus remains from the early late Cretaceous (Cenomanian-Turonian) of Patagonia. American Museum novitates ; no. 3490(New York, NY : American Museum of Natural History, 2005) Pol, Diego.; Apesteguia, SebastianTwo new crocodyliform specimens found in a recently discovered locality from the late Cretaceous of Patagonia (Argentina) are described herein. One of them comprises an almost complete skull found in articulation with the lower jaws, while the other consists of the anterior region of the lower jaws and fragmentary remains of the palate. These two specimens differ in the morphology of their lower jaws (e.g., height of mandibular symphysis, pattern of ornamentation on ventral surface of mandibular ramus, concavity of medial surface of splenials, shape of splenial-dentary suture on ventral surface of mandibular symphysis) and probably belong to different taxa. The more complete specimen is considered to be a new taxon, Araripesuchus buitreraensis, diagnosed by the combination of the following characters (autapomorphic characters are indicated with an asterisk): long and acute anterior process of frontals extending anteriorly between the nasals; frontals extending into supratemporal fenestra; narrow parietal dorsal surface between supratemporal fossa; anterior palpebral remarkably broad; large siphoneal foramen in otic recess; T-shaped choanal septum that completely divides the internal nares, having its anterior end as broad as the midregion of the septum*; pterygoid flanges pneumatic and poorly expanded at its lateral end*; transversely elongated depression on ventral surface of pterygoid flanges close to the posterior margin of suborbital fenestra*; longitudinal groove on flat lateral surface of dentaries below toothrow. The second, more fragmentary specimen might represent a different new taxon, although more material is needed in order to make a justified taxonomic decision. The phylogenetic relationships of both specimens are analyzed through a comprehensive cladistic analysis including 50 crocodylomorph taxa. All the most parsimonious hypotheses depict both specimens as closely related to the previously known South American species of Araripesuchus (A. gomesii and A. patagonicus). This group is depicted as the most basal clade of notosuchians, the most diverse group of Cretaceous mesoeucrocodylians from Gondwana. ItemA new crocodyliform from Zos Canyon, Mongolia. American Museum novitates ; no. 3445(New York, NY : American Museum of Natural History, 2004) Pol, Diego.; Norell, Mark.; Mongolian-American Museum Paleontological Project.; Mongolyn Shinzhlėkh Ukhaany Akademi.Here we report on a new fossil crocodyliform from Cretaceous Redbeds in the Zos Canyon, Gobi Desert, Mongolia. This new taxon, Zosuchus davidsoni, is described based on the information provided by five specimens collected during expeditions of the Mongolian Academy of Sciences-American Museum of Natural History. Zosuchus davidsoni is identifiable by numerous characters, including a posteriorly extensive secondary palate that opens through a secondary choana bordered by the palatines and pterygoids near the posterior edge of the skull, and a lacrimal-premaxillary contact on the dorsal surface of the snout. The phylogenetic relationships of Zosuchus davidsoni are shown through a parsimony analysis in the context of Crocodyliformes. This new form is found to be a late-appearing basal crocodyliform, forming a monophyletic group with two other taxa from the early Cretaceous of China. Because of the basal position of Zosuchus within Crocodyliformes, the marked posterior extension of the secondary palate is most parsimoniously interpreted as a convergence with the derived condition of neosuchian crocodyliforms. ItemA new gobiosuchid crocodyliform taxon from the Cretaceous of Mongolia. American Museum novitates ; no. 3458(New York, NY : American Museum of Natural History, 2004) Pol, Diego.; Norell, Mark.; Mongolian-American Museum Paleontological Project.; Mongolyn Shinzhlėkh Ukhaany Akademi.We describe a new fossil crocodyliform, Zaraasuchus shepardi, found in the Cretaceous Red Beds of Zos Canyon (Gobi Desert, Mongolia). Z. shepardi shares numerous derived characters with Gobiosuchus kielanae, also known from the late Cretaceous of Mongolia (Bayn Dzak locality). However, it is distinguished from the latter by the presence of a moderately large infratemporal fenestra, anterior margin of infratemporal fenestra almost completely formed by the postorbital, retroarticular process with a well-developed ornamented posterolateral pointed process, and extremely well-developed keels on dorsal and lateral cervical osteoderms (the heights of which are approximately as long as the lateromedial extension of the dorsal osteoderms). A phylogenetic analysis indicated that these two taxa form a monophyletic group located basally among crocodyliforms. This clade is diagnosed by 14 synapomorphies (e.g., anterior and posterior palpebrals sutured to each other and to the frontal, excluding it from the orbital margin, external surface of ascending process of jugal exposed posterolaterally, dorsal surface of posterolateral process of squamosal ornamented with three longitudinal ridges, dorsal surface of osteoderms ornamented with anterolaterally and anteromedially directed ridges, cervical region surrounded by lateral and ventral osteoderms sutured to the dorsal elements, and closed supratemporal fenestra). 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. 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)'