DOCSLIB.ORG

Anatomical Network Analyses Reveal Oppositional Heterochronies in Avian Skull Evolution ✉ Olivia Plateau1 & Christian Foth 1 1234567890():,;

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Anatomical Network Analyses Reveal Oppositional Heterochronies in Avian Skull Evolution ✉ Olivia Plateau1 & Christian Foth 1 1234567890():,; ARTICLE https://doi.org/10.1038/s42003-020-0914-4 OPEN Birds have peramorphic skulls, too: anatomical network analyses reveal oppositional heterochronies in avian skull evolution ✉ Olivia Plateau1 & Christian Foth 1 1234567890():,; In contrast to the vast majority of reptiles, the skulls of adult crown birds are characterized by a high degree of integration due to bone fusion, e.g., an ontogenetic event generating a net reduction in the number of bones. To understand this process in an evolutionary context, we investigate postnatal ontogenetic changes in the skulls of crown bird and non-avian ther- opods using anatomical network analysis (AnNA). Due to the greater number of bones and bone contacts, early juvenile crown birds have less integrated skulls, resembling their non- avian theropod ancestors, including Archaeopteryx lithographica and Ichthyornis dispars. Phy- logenetic comparisons indicate that skull bone fusion and the resulting modular integration represent a peramorphosis (developmental exaggeration of the ancestral adult trait) that evolved late during avialan evolution, at the origin of crown-birds. Succeeding the general paedomorphic shape trend, the occurrence of an additional peramorphosis reflects the mosaic complexity of the avian skull evolution. ✉ 1 Department of Geosciences, University of Fribourg, Chemin du Musée 6, CH-1700 Fribourg, Switzerland. email: [email protected] COMMUNICATIONS BIOLOGY | (2020) 3:195 | https://doi.org/10.1038/s42003-020-0914-4 | www.nature.com/commsbio 1 ARTICLE COMMUNICATIONS BIOLOGY | https://doi.org/10.1038/s42003-020-0914-4 fi fi irds represent highly modi ed reptiles and are the only length (L), quality of identi ed modular partition (Qmax), par- surviving branch of theropod dinosaurs. In contrast to their cellation (P), and number of S-modules (identified using statis- B fi non-avian theropod ancestors, which possess a typical tical signi cance based on a two-sample Wilcoxon rank-sum test) diapsid skull morphology1, adult crown birds have highly apo- and Q-modules (identified based on the cutting of the dendro- morphic skulls, characterized by a toothless beak, enlarged round gram at the optimization function Q), (Fig. 2; Table 1; all para- orbits, an enlarged and highly pneumatized chrondrocranium, meters are defined in the method section). In particular, the the loss and fusion of bones and skull openings, and a complex number of Q-modules ranges from five to eight in non-avian kinetic system that allows the simultaneous motion of both jaws, archosaurs, while adult crown birds possess only two to five skull which magnitude is, however, restricted by the morphology and modules, showing a much higher integration of the skull (see articulation of the quadrate and palate2,3. In contrast, Mesozoic Supplementary Data 2 file). In general, non-avian archosaurs Avialae outside the crown, such as the Late Jurassic Archae- possess a preorbital, suborbital (zygomatic arch), braincase opteryx lithographica or the Late Cretaceous Ichthyornis dispars, (including the skull roof), and a left and right mandibular module still retain numerous ancestral theropod characters4–6. A recent (Fig. 3). In some taxa, however, the suborbital module forms a comparison of ontogenetic series of non-avian theropods and unit with the preorbital (e.g., Archaeopteryx lithographica, Erli- extant crown birds using geometric morphometrics demonstrated kosaurus andrewsi) or braincase module (e.g., Majungasaurus that avian skull shape is the result of a sequence of at least four crenatissimus), while in Allosaurus fragilis and Gallimimus bul- paedomorphic events in the evolution of Eumaniraptora, mean- latus for instance, the suborbital module is expanded, including ing that the shape of adult bird skulls retain juvenile features like the quadrate and squamosal. The palatal bones are either part of the enlarged orbit and associated brain regions7,8. Another recent the preorbital or suborbital module. While the number and dis- application of geometric morphometrics showed that the avian tribution of modules vary between species, the assignment of cranium has extensive variational modularity, consisting of seven single bones to a certain module can vary, too, often showing a to eight semi-independent regions evolving in a mosaic pattern9. left-right asymmetry within a species. In many taxa, for instance, However, when compared to their non-avian theropod ancestors, the premaxilla represents its own module on the one side, while it the number of modules is significantly reduced10. Although less is integrated with the maxilla, nasal and lacrimal into the pre- drastic, a similar relationship was found for the connectivity orbital module on the other side (see Supplementary information; modularity in the skull of the non-avian theropod Tyrannosaurus Supplementary Fig. 1). rex and crown bird Gallus gallus, which based on anatomical In contrast, adult crown birds possess usually a suborbital, network analysis (AnNA)11 (Fig. 1a, b). braincase, and a single mandibular module. The bones forming The cranial and mandibular bone fusion that characterizes the the beak are either integrated into the suborbital or braincase skull of adult crown birds mainly occurs during postnatal module. The suborbital module, however, can be independent development, when existing sutures between neighbouring bones (e.g., Gyps fulvus, Milvus milvus, Ptychoramphus aleuticus, Rhea are fully closed12,13. Consequently, the skull bone configuration of americana) or partly integrated into the braincase module (e.g., extant bird hatchlings resembles, to a certain degree, that of non- Bubulcus ibis, Phoenicopterus ruber). In extreme cases, the skull avian theropods, implying a less integrated skull network with consists of only two modules, one represented by the mandible high connectivity modularity (Fig. 1c). To test this hypothesis, we and the other by the cranium (e.g., Nycticorax nycticorax, Platalea investigated the contact and fusion patterns of skull bones and leucorodia). As in their ancestors, module integration of some their impact on modularity during ontogeny in 41 extant birds crown birds shows a left-right asymmetry, but to a lesser degree and compared them with those of non-avian archosaurs (see Supplementary information). (including 15 adult and two juvenile non-avian dinosaurs and an All three juvenile non-avian archosaurs (Alligator mississip- ontogenetic pair of Alligator mississippiensis; see Supplementary piensis, Tarbosaurus bataar, and Scipionyx samniticus) fall into Data 1 and 2 file), using AnNA and phylogenetic comparative the range of adult non-avian archosaurs, indicating only minor analyses (see the “Methods” section). changes in bone contacts, fusion patterns, and modularity during Our analyses show that early juvenile crown birds have less ontogeny. Interestingly, the early juvenile theropod S. samniticus integrated skulls than adult birds in terms of connectivity due to and the early Avialae A. lithographica show a very similar the greater number of bones and bone contacts, but integration distribution of skull modularity (Fig. 3). Furthermore, T. bataar increases continuously with the net reduction of bones during shows an ontogenetic shift in the module identity of skull roof maturation due to fusion. The skulls of early juvenile crown birds, and temporal bones, which is in concert with the fusion of the however, resemble those of non-avian theropods, including frontal bones and a reduction of the number of modules. Archaeopteryx lithographica and Ichthyornis dispars. In this With the exception of connectivity (C), all network parameters context, phylogenetic comparisons indicate that the highly inte- of juvenile crown bird skulls fall between those of non-avian grated adult bird skull evolved late during avian evolution, at the archosaurs and adult crown birds. Although juveniles differ origin of crown-birds, and are a result of a peramorphosis significantly from the latter two groups (see Table 1), the network (developmental exaggeration of the ancestral adult trait), which parameters correlate significantly with relative skull size, shifting might be related to the origin of cranial kinesis. The sequential towards the adult condition with increasing skull size (see occurrence of oppositional heterochronies (i.e., a trended skull Supplementary Fig. 2). In other words, hatchlings and early shape paedomorphosis within Coelurosauria followed by per- juveniles are closer to non-avian theropods/archosaurs, while amorphic skull bone fusion in the last common ancestor of crown subadults are closer to adult crown birds. As the same parameters birds) reflects the mosaic complexity of avian skull evolution, (except for parameter D) fail to correlate with relative skull size in facilitating shape and ecological diversity. adult crown birds (see Supplementary Fig. 2; Table 2), these correlations represent a true ontogenetic signal. Due to their different ontogenetic growth stages, the modular organization of Results juvenile bird skulls is not uniform. However, some general Anatomical network analysis. The skulls of adult non-avian patterns can be extracted. In many cases, premaxilla, maxilla, archosaurs, including Archaeopteryx and Ichthyornis, differ sig- nasal, lacrimal, and ectethemoid/mesethmoid form a preorbital nificantly from adult crown birds in the number of bones (N) and module, while the skull roof and the temporal bones form a single bone contacts (K), density of connections (D), mean shortest path braincase module. The
Load more

Recommended publications
  • The Phylogenetic Position of Ambiortus: Comparison with Other Mesozoic Birds from Asia1 J
    ISSN 00310301, Paleontological Journal, 2013, Vol. 47, No. 11, pp. 1270–1281. © Pleiades Publishing, Ltd., 2013. The Phylogenetic Position of Ambiortus: Comparison with Other Mesozoic Birds from Asia1 J. K. O’Connora and N. V. Zelenkovb aKey Laboratory of Evolution and Systematics, Institute of Vertebrate Paleontology and Paleoanthropology, 142 Xizhimenwai Dajie, Beijing China 10044 bBorissiak Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya ul. 123, Moscow, 117997 Russia email: [email protected], [email protected] Received August 6, 2012 Abstract—Since the last description of the ornithurine bird Ambiortus dementjevi from Mongolia, a wealth of Early Cretaceous birds have been discovered in China. Here we provide a detailed comparison of the anatomy of Ambiortus relative to other known Early Cretaceous ornithuromorphs from the Chinese Jehol Group and Xiagou Formation. We include new information on Ambiortus from a previously undescribed slab preserving part of the sternum. Ambiortus is superficially similar to Gansus yumenensis from the Aptian Xiagou Forma tion but shares more morphological features with Yixianornis grabaui (Ornithuromorpha: Songlingorni thidae) from the Jiufotang Formation of the Jehol Group. In general, the mosaic pattern of character distri bution among early ornithuromorph taxa does not reveal obvious relationships between taxa. Ambiortus was placed in a large phylogenetic analysis of Mesozoic birds, which confirms morphological observations and places Ambiortus in a polytomy with Yixianornis and Gansus. Keywords: Ornithuromorpha, Ambiortus, osteology, phylogeny, Early Cretaceous, Mongolia DOI: 10.1134/S0031030113110063 1 INTRODUCTION and articulated partial skeleton, preserving several cervi cal and thoracic vertebrae, and parts of the left thoracic Ambiortus dementjevi Kurochkin, 1982 was one of girdle and wing (specimen PIN, nos.
    [Show full text]
  • Fused and Vaulted Nasals of Tyrannosaurid Dinosaurs: Implications for Cranial Strength and Feeding Mechanics
    Fused and vaulted nasals of tyrannosaurid dinosaurs: Implications for cranial strength and feeding mechanics ERIC SNIVELY, DONALD M. HENDERSON, and DOUG S. PHILLIPS Snively, E., Henderson, D.M., and Phillips, D.S. 2006. Fused and vaulted nasals of tyrannosaurid dinosaurs: Implications for cranial strength and feeding mechanics. Acta Palaeontologica Polonica 51 (3): 435–454. Tyrannosaurid theropods display several unusual adaptations of the skulls and teeth. Their nasals are fused and vaulted, suggesting that these elements braced the cranium against high feeding forces. Exceptionally high strengths of maxillary teeth in Tyrannosaurus rex indicate that it could exert relatively greater feeding forces than other tyrannosaurids. Areas and second moments of area of the nasals, calculated from CT cross−sections, show higher nasal strengths for large tyrannosaurids than for Allosaurus fragilis. Cross−sectional geometry of theropod crania reveals high second moments of area in tyrannosaurids, with resulting high strengths in bending and torsion, when compared with the crania of similarly sized theropods. In tyrannosaurids trends of strength increase are positively allomeric and have similar allometric expo− nents, indicating correlated progression towards unusually high strengths of the feeding apparatus. Fused, arched nasals and broad crania of tyrannosaurids are consistent with deep bites that impacted bone and powerful lateral movements of the head for dismembering prey. Key words: Theropoda, Carnosauria, Tyrannosauridae, biomechanics, feeding mechanics, computer modeling, com− puted tomography. Eric Snively [[email protected]], Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada; Donald M. Henderson [[email protected]], Royal Tyrrell Museum of Palaeontology, Box 7500, Drumheller, Alberta T0J 0Y0, Canada; Doug S.
    [Show full text]
  • A Chinese Archaeopterygian, Protarchaeopteryx Gen. Nov
    A Chinese archaeopterygian, Protarchaeopteryx gen. nov. by Qiang Ji and Shu’an Ji Geological Science and Technology (Di Zhi Ke Ji) Volume 238 1997 pp. 38-41 Translated By Will Downs Bilby Research Center Northern Arizona University January, 2001 Introduction* The discoveries of Confuciusornis (Hou and Zhou, 1995; Hou et al, 1995) and Sinornis (Ji and Ji, 1996) have profoundly stimulated ornithologists’ interest globally in the Beipiao region of western Liaoning Province. They have also regenerated optimism toward solving questions of avian origins. In December 1996, the Chinese Geological Museum collected a primitive bird specimen at Beipiao that is comparable to Archaeopteryx (Wellnhofer, 1992). The specimen was excavated from a marl 5.5 m above the sediments that produce Sinornithosaurus and 8-9 m below the sediments that produce Confuciusornis. This is the first documentation of an archaeopterygian outside Germany. As a result, this discovery not only establishes western Liaoning Province as a center of avian origins and evolution, it provides conclusive evidence for the theory that avian evolution occurred in four phases. Specimen description Class Aves Linnaeus, 1758 Subclass Sauriurae Haeckel, 1866 Order Archaeopterygiformes Furbringer, 1888 Family Archaeopterygidae Huxley, 1872 Genus Protarchaeopteryx gen. nov. Genus etymology: Acknowledges that the specimen possesses characters more primitive than those of Archaeopteryx. Diagnosis: A primitive archaeopterygian with claviform and unserrated dentition. Sternum is thin and flat, tail is long, and forelimb resembles Archaeopteryx in morphology with three talons, the second of which is enlarged. Ilium is large and elongated, pubes are robust and distally fused, hind limb is long and robust with digit I reduced and dorsally migrated to lie in opposition to digit III and forming a grasping apparatus.
    [Show full text]
  • A New Troodontid Theropod, Talos Sampsoni Gen. Et Sp. Nov., from the Upper Cretaceous Western Interior Basin of North America
    A New Troodontid Theropod, Talos sampsoni gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America Lindsay E. Zanno1,2*, David J. Varricchio3, Patrick M. O’Connor4,5, Alan L. Titus6, Michael J. Knell3 1 Field Museum of Natural History, Chicago, Illinois, United States of America, 2 Biological Sciences Department, University of Wisconsin-Parkside, Kenosha, Wisconsin, United States of America, 3 Department of Earth Sciences, Montana State University, Bozeman, Montana, United States of America, 4 Department of Biomedical Sciences, Ohio University College of Osteopathic Medicine, Athens, Ohio, United States of America, 5 Ohio Center for Ecology and Evolutionary Studies, Ohio University, Athens, Ohio, United States of America, 6 Grand Staircase-Escalante National Monument, Bureau of Land Management, Kanab, Utah, United States of America Abstract Background: Troodontids are a predominantly small-bodied group of feathered theropod dinosaurs notable for their close evolutionary relationship with Avialae. Despite a diverse Asian representation with remarkable growth in recent years, the North American record of the clade remains poor, with only one controversial species—Troodon formosus—presently known from substantial skeletal remains. Methodology/Principal Findings: Here we report a gracile new troodontid theropod—Talos sampsoni gen. et sp. nov.— from the Upper Cretaceous Kaiparowits Formation, Utah, USA, representing one of the most complete troodontid skeletons described from North America to date. Histological assessment of the holotype specimen indicates that the adult body size of Talos was notably smaller than that of the contemporary genus Troodon. Phylogenetic analysis recovers Talos as a member of a derived, latest Cretaceous subclade, minimally containing Troodon, Saurornithoides, and Zanabazar.
    [Show full text]
  • The-Smartest-Dinosaur.Pdf
    BY “DINO” DON LESSEM ILLUSTRATIONS BY JOHN BINDON a LERNER PUBLICATIONS COMPANY / MINNEAPOLIS To Emily Lessem, my favorite niece Text copyright © 2005 by Dino Don, Inc. Illustrations copyright © 2005 by John Bindon Photographs courtesy of: Dino Don, Inc., p. 12; Dr. Philip Currie, Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta, Canada, p. 13; Photographed by Robert Fillion. Reproduced with permission of the Canadian Museum of Nature, Ottawa, Canada, p. 30; Animals, Animals © OSF/BARTLETT, D&J, p. 31. All rights reserved. International copyright secured. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means—electronic, mechanical, photocopying, recording, or otherwise—without the prior written permission of Lerner Publications Company, except for the inclusion of brief quotations in an acknowledged review. This book is available in two editions: Library binding by Lerner Publications Company, a division of Lerner Publishing Group Soft cover by First Avenue Editions, an imprint of Lerner Publishing Group 241 First Avenue North Minneapolis, MN 55401 U.S.A. Website address: www.lernerbooks.com Library of Congress Cataloging-in-Publication-Data Lessem, Don. The smartest dinosaurs / by Don Lessem ; illustrations by John Bindon. p. cm. — (Meet the dinosaurs) Includes index. eISBN: 0–8225–3285–9 1. Dinosaurs—Juvenile literature. I. Bindon, John, ill. II. Title. III. Series: Lessem, Don. Meet the dinosaurs. QE861.5.L477 2005 567.9—dc22 2004011152 Manufactured in the United States of America 1 2 3 4 5 6 – DP – 10 09 08 07 06 05 MEET THE SMARTEST DINOSAURS . 4 HOW SMART WERE DINOSAURS? .
    [Show full text]
  • A New Raptorial Dinosaur with Exceptionally Long Feathering Provides Insights Into Dromaeosaurid flight Performance
    ARTICLE Received 11 Apr 2014 | Accepted 11 Jun 2014 | Published 15 Jul 2014 DOI: 10.1038/ncomms5382 A new raptorial dinosaur with exceptionally long feathering provides insights into dromaeosaurid flight performance Gang Han1, Luis M. Chiappe2, Shu-An Ji1,3, Michael Habib4, Alan H. Turner5, Anusuya Chinsamy6, Xueling Liu1 & Lizhuo Han1 Microraptorines are a group of predatory dromaeosaurid theropod dinosaurs with aero- dynamic capacity. These close relatives of birds are essential for testing hypotheses explaining the origin and early evolution of avian flight. Here we describe a new ‘four-winged’ microraptorine, Changyuraptor yangi, from the Early Cretaceous Jehol Biota of China. With tail feathers that are nearly 30 cm long, roughly 30% the length of the skeleton, the new fossil possesses the longest known feathers for any non-avian dinosaur. Furthermore, it is the largest theropod with long, pennaceous feathers attached to the lower hind limbs (that is, ‘hindwings’). The lengthy feathered tail of the new fossil provides insight into the flight performance of microraptorines and how they may have maintained aerial competency at larger body sizes. We demonstrate how the low-aspect-ratio tail of the new fossil would have acted as a pitch control structure reducing descent speed and thus playing a key role in landing. 1 Paleontological Center, Bohai University, 19 Keji Road, New Shongshan District, Jinzhou, Liaoning Province 121013, China. 2 Dinosaur Institute, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, California 90007, USA. 3 Institute of Geology, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Road, Beijing 100037, China. 4 University of Southern California, Health Sciences Campus, BMT 403, Mail Code 9112, Los Angeles, California 90089, USA.
    [Show full text]
  • Download Vol. 11, No. 3
    BULLETIN OF THE FLORIDA STATE MUSEUM BIOLOGICAL SCIENCES Volume 11 Number 3 CATALOGUE OF FOSSIL BIRDS: Part 3 (Ralliformes, Ichthyornithiformes, Charadriiformes) Pierce Brodkorb M,4 * . /853 0 UNIVERSITY OF FLORIDA Gainesville 1967 Numbers of the BULLETIN OF THE FLORIDA STATE MUSEUM are pub- lished at irregular intervals. Volumes contain about 800 pages and are not nec- essarily completed in any one calendar year. WALTER AuFFENBERC, Managing Editor OLIVER L. AUSTIN, JA, Editor Consultants for this issue. ~ HILDEGARDE HOWARD ALExANDER WErMORE Communications concerning purchase or exchange of the publication and all manuscripts should be addressed to the Managing Editor of the Bulletin, Florida State Museum, Seagle Building, Gainesville, Florida. 82601 Published June 12, 1967 Price for this issue $2.20 CATALOGUE OF FOSSIL BIRDS: Part 3 ( Ralliformes, Ichthyornithiformes, Charadriiformes) PIERCE BRODKORBl SYNOPSIS: The third installment of the Catalogue of Fossil Birds treats 84 families comprising the orders Ralliformes, Ichthyornithiformes, and Charadriiformes. The species included in this section number 866, of which 215 are paleospecies and 151 are neospecies. With the addenda of 14 paleospecies, the three parts now published treat 1,236 spDcies, of which 771 are paleospecies and 465 are living or recently extinct. The nominal order- Diatrymiformes is reduced in rank to a suborder of the Ralliformes, and several generally recognized families are reduced to subfamily status. These include Geranoididae and Eogruidae (to Gruidae); Bfontornithidae
    [Show full text]
  • Was Dinosaurian Physiology Inherited by Birds? Reconciling Slow Growth in Archaeopteryx
    Was Dinosaurian Physiology Inherited by Birds? Reconciling Slow Growth in Archaeopteryx Gregory M. Erickson1,6*, Oliver W. M. Rauhut2, Zhonghe Zhou3, Alan H. Turner4,6, Brian D. Inouye1, Dongyu Hu5, Mark A. Norell6 1 Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America, 2 Bayerische Staatssammlung fu¨r Pala¨ontologie und Geologie and Department of Earth and Environmental Sciences, LMU Munich, Mu¨nchen, Germany, 3 Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology & Paleoanthropology, Chinese Academy of Science, Beijing, China, 4 Department of Anatomical Sciences, Stony Brook University, Stony Brook, New York, United States of America, 5 Paleontological Institute, Shenyang Normal University, Shenyang, China, 6 Division of Paleontology, American Museum of Natural History, New York, New York, United States of America Abstract Background: Archaeopteryx is the oldest and most primitive known bird (Avialae). It is believed that the growth and energetic physiology of basalmost birds such as Archaeopteryx were inherited in their entirety from non-avialan dinosaurs. This hypothesis predicts that the long bones in these birds formed using rapidly growing, well-vascularized woven tissue typical of non-avialan dinosaurs. Methodology/Principal Findings: We report that Archaeopteryx long bones are composed of nearly avascular parallel- fibered bone. This is among the slowest growing osseous tissues and is common in ectothermic reptiles. These findings dispute the hypothesis that non-avialan dinosaur growth and physiology were inherited in totality by the first birds. Examining these findings in a phylogenetic context required intensive sampling of outgroup dinosaurs and basalmost birds. Our results demonstrate the presence of a scale-dependent maniraptoran histological continuum that Archaeopteryx and other basalmost birds follow.
    [Show full text]
  • PROGRAMME ABSTRACTS AGM Papers
    The Palaeontological Association 63rd Annual Meeting 15th–21st December 2019 University of Valencia, Spain PROGRAMME ABSTRACTS AGM papers Palaeontological Association 6 ANNUAL MEETING ANNUAL MEETING Palaeontological Association 1 The Palaeontological Association 63rd Annual Meeting 15th–21st December 2019 University of Valencia The programme and abstracts for the 63rd Annual Meeting of the Palaeontological Association are provided after the following information and summary of the meeting. An easy-to-navigate pocket guide to the Meeting is also available to delegates. Venue The Annual Meeting will take place in the faculties of Philosophy and Philology on the Blasco Ibañez Campus of the University of Valencia. The Symposium will take place in the Salon Actos Manuel Sanchis Guarner in the Faculty of Philology. The main meeting will take place in this and a nearby lecture theatre (Salon Actos, Faculty of Philosophy). There is a Metro stop just a few metres from the campus that connects with the centre of the city in 5-10 minutes (Line 3-Facultats). Alternatively, the campus is a 20-25 minute walk from the ‘old town’. Registration Registration will be possible before and during the Symposium at the entrance to the Salon Actos in the Faculty of Philosophy. During the main meeting the registration desk will continue to be available in the Faculty of Philosophy. Oral Presentations All speakers (apart from the symposium speakers) have been allocated 15 minutes. It is therefore expected that you prepare to speak for no more than 12 minutes to allow time for questions and switching between presenters. We have a number of parallel sessions in nearby lecture theatres so timing will be especially important.
    [Show full text]
  • A Multifunction Trade-Off Has Contrasting Effects on the Evolution of Form and Function ∗ KATHERINE A
    Syst. Biol. 0():1–13, 2020 © The Author(s) 2020. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For permissions, please email: [email protected] DOI:10.1093/sysbio/syaa091 Downloaded from https://academic.oup.com/sysbio/advance-article/doi/10.1093/sysbio/syaa091/6040745 by University of California, Davis user on 08 January 2021 A Multifunction Trade-Off has Contrasting Effects on the Evolution of Form and Function ∗ KATHERINE A. CORN ,CHRISTOPHER M. MARTINEZ,EDWARD D. BURRESS, AND PETER C. WAINWRIGHT Department of Evolution & Ecology, University of California, Davis, 2320 Storer Hall, 1 Shields Ave, Davis, CA, 95616 USA ∗ Correspondence to be sent to: University of California, Davis, 2320 Storer Hall, 1 Shields Ave, Davis, CA 95618, USA; E-mail: [email protected] Received 27 August 2020; reviews returned 14 November 2020; accepted 19 November 2020 Associate Editor: Benoit Dayrat Abstract.—Trade-offs caused by the use of an anatomical apparatus for more than one function are thought to be an important constraint on evolution. However, whether multifunctionality suppresses diversification of biomechanical systems is challenged by recent literature showing that traits more closely tied to trade-offs evolve more rapidly. We contrast the evolutionary dynamics of feeding mechanics and morphology between fishes that exclusively capture prey with suction and multifunctional species that augment this mechanism with biting behaviors to remove attached benthic prey. Diversification of feeding kinematic traits was, on average, over 13.5 times faster in suction feeders, consistent with constraint on biters due to mechanical trade-offs between biting and suction performance.
    [Show full text]
  • Norntates PUBLISHED by the AMERICAN MUSEUM of NATURAL HISTORY CENTRAL PARK WEST at 79TH STREET, NEW YORK, NY 10024 Number 3265, 36 Pp., 15 Figures May 4, 1999
    AMERICANt MUSEUM Norntates PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024 Number 3265, 36 pp., 15 figures May 4, 1999 An Oviraptorid Skeleton from the Late Cretaceous of Ukhaa Tolgod, Mongolia, Preserved in an Avianlike Brooding Position Over an Oviraptorid Nest JAMES M. CLARK,I MARK A. NORELL,2 AND LUIS M. CHIAPPE3 ABSTRACT The articulated postcranial skeleton of an ovi- presence of a single, ossified ventral segment in raptorid dinosaur (Theropoda, Coelurosauria) each rib as well as ossified uncinate processes from the Late Cretaceous Djadokhta Formation associated with the thoracic ribs. Remnants of of Ukhaa Tolgod, Mongolia, is preserved over- keratinous sheaths are preserved with four of the lying a nest. The eggs are similar in size, shape, manal claws, and the bony and keratinous claws and ornamentation to another egg from this lo- were as strongly curved as the manal claws of cality in which an oviraptorid embryo is pre- Archaeopteryx and the pedal claws of modern served, suggesting that the nest is of the same climbing birds. The skeleton is positioned over species as the adult skeleton overlying it and was the center of the nest, with its limbs arranged parented by the adult. The lack of a skull pre- symmetrically on either side and its arms spread cludes specific identification, but in several fea- out around the nest perimeter. This is one of four tures the specimen is more similar to Oviraptor known oviraptorid skeletons preserved on nests than to other oviraptorids. The ventral part of the of this type of egg, comprising 23.5% of the 17 thorax is exceptionally well preserved and pro- oviraptorid skeletons collected from the Dja- vides evidence for other avian features that were dokhta Formation before 1996.
    [Show full text]
  • Anterior Esthetic Crown-Lengthening Surgery: a Case Report
    C LINICAL P RACTICE Anterior Esthetic Crown-Lengthening Surgery: A Case Report • Jim Yuan Lai, BSc, DMD, MSc (Perio) • • Livia Silvestri, BSc, DDS, MSc (Perio) • • Bruno Girard, DMD, MSc (Perio) • Abstract The theoretical concepts underlying crown-lengthening surgery are reviewed, and a patient who underwent esthetic crown-lengthening surgery is described. An overview of the various indications and contraindications is presented. MeSH Key Words: case report; crown lengthening; periodontium/surgery © J Can Dent Assoc 2001; 67(10):600-3 This article has been peer reviewed. he appearance of the gingival tissues surrounding room for adequate crown preparation and reattachment of the teeth plays an important role in the esthetics of the epithelium and connective tissue.4 Furthermore, by T the anterior maxillary region of the mouth. altering the incisogingival length and mesiodistal width of Abnormalities in symmetry and contour can significantly the periodontal tissues in the anterior maxillary region, the affect the harmonious appearance of the natural or pros- crown-lengthening procedure can build a harmonious thetic dentition. As well nowadays, patients have a greater appearance and improve the symmetry of the tissues. desire for more esthetic results which may influence treat- Good communication between the restoring dentist and ment choice. the periodontist is important to achieve optimal results An ideal anterior appearance necessitates healthy and with crown-lengthening surgery, particularly in esthetically inflammation-free periodontal tissues. Garguilo1 described demanding cases. In addition to establishing the smile line, various components of the periodontium, giving mean the restoring dentist evaluates the anterior and posterior dimensions of 1.07 mm for the connective tissue, 0.97 mm occlusal planes for harmony and balance, as well as the for the epithelial attachment and 0.69 mm for the sulcus anterior and posterior gingival contours.
    [Show full text]