1
|
Boisvert C, Curtice B, Wedel M, Wilhite R. Description of a new specimen of Haplocanthosaurus from the Dry Mesa Dinosaur Quarry. Anat Rec (Hoboken) 2024. [PMID: 38887924 DOI: 10.1002/ar.25520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 05/29/2024] [Accepted: 05/30/2024] [Indexed: 06/20/2024]
Abstract
A new specimen of Haplocanthosaurus is described based on bones excavated from the Late Jurassic Dry Mesa Dinosaur Quarry near Delta, Colorado. The specimen consists of seven dorsal vertebrae and a right tibia and is identified as Haplocanthosaurus based on the dorsally angled transverse processes, tall neural arch peduncles, low parapophyses relative to the diapophyses in the posterior dorsal vertebrae, and the robustness of the tibia combined with a greatly expanded distal articular surface. The discovery adds to our understanding of the biostratigraphy of Haplocanthosaurus, showing this genus is definitively present in the Brushy Basin Member of the Morrison Formation, and making this individual the geologically youngest Haplocanthosaurus specimen on the Colorado Plateau. The identification of this genus adds to the known diversity of sauropods at Dry Mesa Dinosaur Quarry (DMDQ), which is at least six distinct genera, making DMDQ the most diverse single locality of sauropods in the Morrison Formation and the world.
Collapse
Affiliation(s)
| | - Brian Curtice
- Arizona Museum of Natural History, Mesa, Arizona, USA
| | - Mathew Wedel
- Western University of Health Sciences, Pomona, California, USA
| | | |
Collapse
|
2
|
Grand Pré CA, Thielicke W, Diaz Jr RE, Hedrick BP, Elsey RM, Schachner ER. Validating osteological correlates for the hepatic piston in the American alligator ( Alligator mississippiensis). PeerJ 2023; 11:e16542. [PMID: 38144194 PMCID: PMC10749092 DOI: 10.7717/peerj.16542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 11/08/2023] [Indexed: 12/26/2023] Open
Abstract
Unlike the majority of sauropsids, which breathe primarily through costal and abdominal muscle contractions, extant crocodilians have evolved the hepatic piston pump, a unique additional ventilatory mechanism powered by the diaphragmaticus muscle. This muscle originates from the bony pelvis, wrapping around the abdominal viscera, extending cranially to the liver. The liver then attaches to the caudal margin of the lungs, resulting in a sub-fusiform morphology for the entire "pulmo-hepatic-diaphragmatic" structure. When the diaphragmaticus muscle contracts during inspiration, the liver is pulled caudally, lowering pressure in the thoracolumbar cavity, and inflating the lungs. It has been established that the hepatic piston pump requires the liver to be displaced to ventilate the lungs, but it has not been determined if the lungs are freely mobile or if the pleural tissues stretch ventrally. It has been hypothesized that the lungs are able to slide craniocaudally with the liver due to the smooth internal ceiling of the thoracolumbar cavity. We assess this through ultrasound video and demonstrate quantitatively and qualitatively that the pulmonary tissues are sliding craniocaudally across the interior thoracolumbar ceiling in actively ventilating live juvenile, sub-adult, and adult individuals (n = 7) of the American alligator (Alligator mississippiensis) during both natural and induced ventilation. The hepatic piston is a novel ventilatory mechanism with a relatively unknown evolutionary history. Questions related to when and under what conditions the hepatic piston first evolved have previously been left unanswered due to a lack fossilized evidence for its presence or absence. By functionally correlating specific characters in the axial skeleton to the hepatic piston, these osteological correlates can be applied to fossil taxa to reconstruct the evolution of the hepatic piston in extinct crocodylomorph archosaurs.
Collapse
Affiliation(s)
- Clinton A. Grand Pré
- Cell Biology and Anatomy, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | | | - Raul E. Diaz Jr
- Department of Biological Sciences, California State University Los Angeles, Los Angeles, CA, USA
| | - Brandon P. Hedrick
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, United States of America
| | - Ruth M. Elsey
- Louisiana Department of Wildlife and Fisheries, Grand Chenier, LA, USA
- Murfreesboro, TN, USA
| | - Emma R. Schachner
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| |
Collapse
|
3
|
Laitman JT, Smith HF. Dinosaurs of all ilks bow and pay tribute to Peter Dodson, their intrepid chronicler, in an Anatomical Record Special Issue in his honor. Anat Rec (Hoboken) 2023. [PMID: 37151192 DOI: 10.1002/ar.25233] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 04/18/2023] [Indexed: 05/09/2023]
Affiliation(s)
- Jeffrey T Laitman
- The Anatomical Record, Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Heather F Smith
- The Anatomical Record, Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| |
Collapse
|
4
|
Aureliano T, Ghilardi AM, Müller RT, Kerber L, Pretto FA, Fernandes MA, Ricardi-Branco F, Wedel MJ. The absence of an invasive air sac system in the earliest dinosaurs suggests multiple origins of vertebral pneumaticity. Sci Rep 2022; 12:20844. [PMID: 36494410 PMCID: PMC9734174 DOI: 10.1038/s41598-022-25067-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 11/24/2022] [Indexed: 12/13/2022] Open
Abstract
The origin of the air sac system present in birds has been an enigma for decades. Skeletal pneumaticity related to an air sac system is present in both derived non-avian dinosaurs and pterosaurs. But the question remained open whether this was a shared trait present in the common avemetatarsalian ancestor. We analyzed three taxa from the Late Triassic of South Brazil, which are some of the oldest representatives of this clade (233.23 ± 0.73 Ma), including two sauropodomorphs and one herrerasaurid. All three taxa present shallow lateral fossae in the centra of their presacral vertebrae. Foramina are present in many of the fossae but at diminutive sizes consistent with neurovascular rather than pneumatic origin. Micro-tomography reveals a chaotic architecture of dense apneumatic bone tissue in all three taxa. The early sauropodomorphs showed more complex vascularity, which possibly served as the framework for the future camerate and camellate pneumatic structures of more derived saurischians. Finally, the evidence of the absence of postcranial skeletal pneumaticity in the oldest dinosaurs contradicts the homology hypothesis for an invasive diverticula system and suggests that this trait evolved independently at least 3 times in pterosaurs, theropods, and sauropodomorphs.
Collapse
Affiliation(s)
- Tito Aureliano
- grid.411087.b0000 0001 0723 2494Institute of Geosciences, University of Campinas (Unicamp), Campinas, Brazil ,grid.411233.60000 0000 9687 399XDiversity, Ichnology and Osteohistology Laboratory (DINOlab), Department of Geology, Federal University of Rio Grande Do Norte (URFN), Natal, Brazil ,grid.411247.50000 0001 2163 588XLaboratório de Paleoecologia E Paleoicnologia (LPP), Departamento de Ecologia E Biologia Evolutiva (DEBE), Federal University of São Carlos (UFSCar), São Carlos, Brazil
| | - Aline M. Ghilardi
- grid.411233.60000 0000 9687 399XDiversity, Ichnology and Osteohistology Laboratory (DINOlab), Department of Geology, Federal University of Rio Grande Do Norte (URFN), Natal, Brazil
| | - Rodrigo T. Müller
- grid.411239.c0000 0001 2284 6531Centro de Apoio À Pesquisa Paleontológica da Quarta Colônia (CAPPA), Federal University of Santa Maria (CAPPA/UFSM), São João Do Polêsine, Brazil ,grid.411239.c0000 0001 2284 6531Programa de Pós-Graduação Em Biodiversidade Animal, Federal University of Santa Maria (UFSM), Santa Maria, Brazil
| | - Leonardo Kerber
- grid.411239.c0000 0001 2284 6531Centro de Apoio À Pesquisa Paleontológica da Quarta Colônia (CAPPA), Federal University of Santa Maria (CAPPA/UFSM), São João Do Polêsine, Brazil ,grid.411239.c0000 0001 2284 6531Programa de Pós-Graduação Em Biodiversidade Animal, Federal University of Santa Maria (UFSM), Santa Maria, Brazil
| | - Flávio A. Pretto
- grid.411239.c0000 0001 2284 6531Centro de Apoio À Pesquisa Paleontológica da Quarta Colônia (CAPPA), Federal University of Santa Maria (CAPPA/UFSM), São João Do Polêsine, Brazil ,grid.411239.c0000 0001 2284 6531Programa de Pós-Graduação Em Biodiversidade Animal, Federal University of Santa Maria (UFSM), Santa Maria, Brazil
| | - Marcelo A. Fernandes
- grid.411247.50000 0001 2163 588XLaboratório de Paleoecologia E Paleoicnologia (LPP), Departamento de Ecologia E Biologia Evolutiva (DEBE), Federal University of São Carlos (UFSCar), São Carlos, Brazil
| | - Fresia Ricardi-Branco
- grid.411087.b0000 0001 0723 2494Institute of Geosciences, University of Campinas (Unicamp), Campinas, Brazil
| | - Mathew J. Wedel
- grid.268203.d0000 0004 0455 5679College of Osteopathic Medicine of the Pacific and College of Podiatric Medicine, Western University of Health Sciences, Pomona, USA
| |
Collapse
|
5
|
Cuff AR, Demuth OE, Michel K, Otero A, Pintore R, Polet DT, Wiseman ALA, Hutchinson JR. Walking-and Running and Jumping-with Dinosaurs and Their Cousins, Viewed Through the Lens of Evolutionary Biomechanics. Integr Comp Biol 2022; 62:icac049. [PMID: 35595475 DOI: 10.1093/icb/icac049] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Archosauria diversified throughout the Triassic Period before experiencing two mass extinctions near its end ∼201 Mya, leaving only the crocodile-lineage (Crocodylomorpha) and bird-lineage (Dinosauria) as survivors; along with the pterosaurian flying reptiles. About 50 years ago, the "locomotor superiority hypothesis" (LSH) proposed that dinosaurs ultimately dominated by the Early Jurassic Period because their locomotion was superior to other archosaurs'. This idea has been debated continuously since, with taxonomic and morphological analyses suggesting dinosaurs were "lucky" rather than surviving due to being biologically superior. However, the LSH has never been tested biomechanically. Here we present integration of experimental data from locomotion in extant archosaurs with inverse and predictive simulations of the same behaviours using musculoskeletal models, showing that we can reliably predict how extant archosaurs walk, run and jump. These simulations have been guiding predictive simulations of extinct archosaurs to estimate how they moved, and we show our progress in that endeavour. The musculoskeletal models used in these simulations can also be used for simpler analyses of form and function such as muscle moment arms, which inform us about more basic biomechanical similarities and differences between archosaurs. Placing all these data into an evolutionary and biomechanical context, we take a fresh look at the LSH as part of a critical review of competing hypotheses for why dinosaurs (and a few other archosaur clades) survived the Late Triassic extinctions. Early dinosaurs had some quantifiable differences in locomotor function and performance vs. some other archosaurs, but other derived dinosaurian features (e.g., metabolic or growth rates, ventilatory abilities) are not necessarily mutually exclusive from the LSH; or maybe even an opportunistic replacement hypothesis; in explaining dinosaurs' success.
Collapse
Affiliation(s)
- A R Cuff
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
- Human Anatomy Resource Centre, University of Liverpool, Liverpool, United Kingdom
| | - O E Demuth
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
- Department of Earth Sciences, University of Cambridge, United Kingdom
| | - K Michel
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
| | - A Otero
- CONICET - División Paleontología de Vertebrados, Facultad de Ciencias Naturales y Museo, Anexo Laboratorios, La Plata, Argentina
| | - R Pintore
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
- Mécanismes adaptatifs et évolution (MECADEV) / UMR 7179, CNRS / Muséum National d'Histoire Naturelle, France
| | - D T Polet
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
| | - A L A Wiseman
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
- McDonald Institute for Archaeological Research, University of Cambridge, United Kingdom
| | - J R Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
| |
Collapse
|
6
|
Schachner ER, Diaz RE, Coke R, Echols S, Osborn ML, Hedrick BP. Architecture of the bronchial tree in Cuvier's dwarf caiman (Paleosuchus palpebrosus). Anat Rec (Hoboken) 2022; 305:3037-3054. [PMID: 35377558 DOI: 10.1002/ar.24919] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 02/25/2022] [Accepted: 03/09/2022] [Indexed: 01/16/2023]
Abstract
We imaged the lungs of five Cuvier's dwarf caiman (Paleosuchus palpebrosus) via computed tomography (CT) and micro-computed tomography (μCT) and compared these data to the lungs of the American alligator (Alligator mississippiensis). These data demonstrate anatomical commonalities between the lungs of P. palpebrosus and A. mississippiensis, and a few notable differences. The structural similarities are (a) a proximally narrow, distally widened, hook-shaped primary bronchus; (b) a cervical ventral bronchus that branches of the primary bronchus and immediately makes a hairpin turn toward the apex of the lung; (c) a sequential series of dorsobronchi arising from the primary bronchus caudal to the cervical ventral bronchus; (d) intraspecifically highly variable medial sequence of secondary airways; (e) sac-like laterobronchi; and (f) grossly dead-ended caudal group bronchi in the caudal and ventral aspects of the lung. The primary differences between the two taxa are in the overall number of large bronchi (fewer in P. palpebrosus), and the number of branches that contribute to the cardiac regions. Imaging data of both a live and deceased specimen under varying states (postprandial, fasting, total lung capacity, open to atmosphere) indicate that the caudal margin and position of the lungs shift craniocaudally relative to the vertebral column. These imaging data suggest that the smooth thoracic ceiling may be correlated to visceral movement during ventilation, but this hypothesis warrants validation. These results provide the scaffolding for future comparisons between crocodilians, for generating preliminary reconstructions of the ancestral crocodilian bronchial tree, and establishing new hypotheses of bronchial homology across Archosauria.
Collapse
Affiliation(s)
- Emma R Schachner
- Department of Cell Biology and Anatomy, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Raul E Diaz
- Department of Biological Sciences, California State University Los Angeles, Los Angeles, California, USA
| | - Rob Coke
- San Antonio Zoo, San Antonio, Texas, USA
| | - Scott Echols
- The Medical Center for Birds, Oakley, California, USA
| | - Michelle L Osborn
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Brandon P Hedrick
- Department of Cell Biology and Anatomy, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| |
Collapse
|
7
|
Grigg G, Nowack J, Bicudo JEPW, Bal NC, Woodward HN, Seymour RS. Whole-body endothermy: ancient, homologous and widespread among the ancestors of mammals, birds and crocodylians. Biol Rev Camb Philos Soc 2022; 97:766-801. [PMID: 34894040 PMCID: PMC9300183 DOI: 10.1111/brv.12822] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/25/2021] [Accepted: 11/29/2021] [Indexed: 12/31/2022]
Abstract
The whole-body (tachymetabolic) endothermy seen in modern birds and mammals is long held to have evolved independently in each group, a reasonable assumption when it was believed that its earliest appearances in birds and mammals arose many millions of years apart. That assumption is consistent with current acceptance that the non-shivering thermogenesis (NST) component of regulatory body heat originates differently in each group: from skeletal muscle in birds and from brown adipose tissue (BAT) in mammals. However, BAT is absent in monotremes, marsupials, and many eutherians, all whole-body endotherms. Indeed, recent research implies that BAT-driven NST originated more recently and that the biochemical processes driving muscle NST in birds, many modern mammals and the ancestors of both may be similar, deriving from controlled 'slippage' of Ca2+ from the sarcoplasmic reticulum Ca2+ -ATPase (SERCA) in skeletal muscle, similar to a process seen in some fishes. This similarity prompted our realisation that the capacity for whole-body endothermy could even have pre-dated the divergence of Amniota into Synapsida and Sauropsida, leading us to hypothesise the homology of whole-body endothermy in birds and mammals, in contrast to the current assumption of their independent (convergent) evolution. To explore the extent of similarity between muscle NST in mammals and birds we undertook a detailed review of these processes and their control in each group. We found considerable but not complete similarity between them: in extant mammals the 'slippage' is controlled by the protein sarcolipin (SLN), in birds the SLN is slightly different structurally and its role in NST is not yet proved. However, considering the multi-millions of years since the separation of synapsids and diapsids, we consider that the similarity between NST production in birds and mammals is consistent with their whole-body endothermy being homologous. If so, we should expect to find evidence for it much earlier and more widespread among extinct amniotes than is currently recognised. Accordingly, we conducted an extensive survey of the palaeontological literature using established proxies. Fossil bone histology reveals evidence of sustained rapid growth rates indicating tachymetabolism. Large body size and erect stature indicate high systemic arterial blood pressures and four-chambered hearts, characteristic of tachymetabolism. Large nutrient foramina in long bones are indicative of high bone perfusion for rapid somatic growth and for repair of microfractures caused by intense locomotion. Obligate bipedality appeared early and only in whole-body endotherms. Isotopic profiles of fossil material indicate endothermic levels of body temperature. These proxies led us to compelling evidence for the widespread occurrence of whole-body endothermy among numerous extinct synapsids and sauropsids, and very early in each clade's family tree. These results are consistent with and support our hypothesis that tachymetabolic endothermy is plesiomorphic in Amniota. A hypothetical structure for the heart of the earliest endothermic amniotes is proposed. We conclude that there is strong evidence for whole-body endothermy being ancient and widespread among amniotes and that the similarity of biochemical processes driving muscle NST in extant birds and mammals strengthens the case for its plesiomorphy.
Collapse
Affiliation(s)
- Gordon Grigg
- School of Biological SciencesUniversity of QueenslandBrisbaneQLD4072Australia
| | - Julia Nowack
- School of Biological and Environmental SciencesLiverpool John Moores UniversityJames Parsons Building, Byrom StreetLiverpoolL3 3AFU.K.
| | | | | | - Holly N. Woodward
- Oklahoma State University Center for Health SciencesTulsaOK74107U.S.A.
| | - Roger S. Seymour
- School of Biological SciencesUniversity of AdelaideAdelaideSA5005Australia
| |
Collapse
|
8
|
Radermacher VJ, Fernandez V, Schachner ER, Butler RJ, Bordy EM, Naylor Hudgins M, de Klerk WJ, Chapelle KE, Choiniere JN. A new Heterodontosaurus specimen elucidates the unique ventilatory macroevolution of ornithischian dinosaurs. eLife 2021; 10:66036. [PMID: 34225841 PMCID: PMC8260226 DOI: 10.7554/elife.66036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 05/24/2021] [Indexed: 01/21/2023] Open
Abstract
Ornithischian dinosaurs were ecologically prominent herbivores of the Mesozoic Era that achieved a global distribution by the onset of the Cretaceous. The ornithischian body plan is aberrant relative to other ornithodiran clades, and crucial details of their early evolution remain obscure. We present a new, fully articulated skeleton of the early branching ornithischian Heterodontosaurus tucki. Phase-contrast enhanced synchrotron data of this new specimen reveal a suite of novel postcranial features unknown in any other ornithischian, with implications for the early evolution of the group. These features include a large, anteriorly projecting sternum; bizarre, paddle-shaped sternal ribs; and a full gastral basket – the first recovered in Ornithischia. These unusual anatomical traits provide key information on the evolution of the ornithischian body plan and suggest functional shifts in the ventilatory apparatus occurred close to the base of the clade. We complement these anatomical data with a quantitative analysis of ornithischian pelvic architecture, which allows us to make a specific, stepwise hypothesis for their ventilatory evolution. The fossilised skeletons of long extinct dinosaurs are more than just stones. By comparing these remains to their living relatives such as birds and crocodiles, palaeontologists can reveal how dinosaurs grew, moved, ate and socialised. Previous research indicates that dinosaurs were likely warm-blooded and also more active than modern reptiles. This means they would have required breathing mechanisms capable of supplying enough oxygen to allow these elevated activity levels. So far, much of our insight into dinosaur breathing biology has been biased towards dinosaur species more closely related to modern birds, such as Tyrannosaurus rex, as well as the long-necked sauropods. The group of herbivorous dinosaurs known as ornithischians, which include animals with head ornamentation, spikes and heavy body armour, like that found in Triceratops and Stegosaurus, have often been overlooked. As a result, there are still significant gaps in ornithischian biology, especially in understanding how they breathed. Radermacher et al. used high-powered X-rays to study a new specimen of the most primitive ornithischian dinosaur, Heterodontosaurus tucki, and discovered that this South African dinosaur has bones researchers did not know existed in this species. These include bones that are part of the breathing system of extant reptiles and birds, including toothpick-shaped bones called gastralia, paired sternal bones and sternal ribs shaped like tennis rackets. Together, these new pieces of anatomy form a complicated chest skeleton with a large range of motion that would have allowed the body to expand during breathing cycles. But this increased motion of the chest was only possible in more primitive ornithischians. More advanced species lost much of the anatomy that made this motion possible. Radermacher et al. show that while the chest was simpler in advanced species, their pelvis was more specialised and likely played a role in breathing as it does in modern crocodiles. This new discovery could inform the work of biologists who study the respiratory diversity of both living and extinct species. Differences in breathing strategies might be one of the underlying reasons that some lineages of animals go extinct. It could explain why some species do better than others under stressful conditions, like when the climate is warmer or has less oxygen.
Collapse
Affiliation(s)
- Viktor J Radermacher
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, United States
| | - Vincent Fernandez
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,European Synchrotron Radiation Facility, Grenoble, France.,Natural History Museum, Imaging and Analysis Centre, London, United Kingdom
| | - Emma R Schachner
- Department of Cell Biology & Anatomy, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, United States
| | - Richard J Butler
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Emese M Bordy
- Department of Geological Sciences, University of Cape Town, Cape Town, South Africa
| | | | - William J de Klerk
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Department of Earth Sciences, Albany Museum, Grahamstown, South Africa
| | - Kimberley Ej Chapelle
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Division of Paleontology, American Museum of Natural History, New York, United States
| | - Jonah N Choiniere
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| |
Collapse
|
9
|
Moore AJ. Vertebral pneumaticity is correlated with serial variation in vertebral shape in storks. J Anat 2021; 238:615-625. [PMID: 32981054 PMCID: PMC7855073 DOI: 10.1111/joa.13322] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 08/23/2020] [Accepted: 09/09/2020] [Indexed: 11/29/2022] Open
Abstract
Birds and their ornithodiran ancestors are unique among vertebrates in exhibiting air-filled sinuses in their postcranial bones, a phenomenon called postcranial skeletal pneumaticity. The factors that account for serial and interspecific variation in postcranial skeletal pneumaticity are poorly understood, although body size, ecology, and bone biomechanics have all been implicated as influencing the extent to which pneumatizing epithelia invade the skeleton and induce bone resorption. Here, I use high-resolution computed-tomography to holistically quantify vertebral pneumaticity in members of the neognath family Ciconiidae (storks), with pneumaticity measured as the relative volume of internal air space. These data are used to describe serial variation in extent of pneumaticity and to assess whether and how pneumaticity varies with the size and shape of a vertebra. Pneumaticity increases dramatically from the middle of the neck onwards, contrary to previous predictions that cervical pneumaticity should decrease toward the thorax to maintain structural integrity as the mass and bending moments of the neck increase. Although the largest vertebrae sampled are also the most pneumatic, vertebral size cannot on its own account for serial or interspecific variation in extent of pneumaticity. Vertebral shape, as quantified by three-dimensional geometric morphometrics, is found to be significantly correlated with extent of pneumaticity, with elongate vertebrae being less pneumatic than craniocaudally short and dorsoventrally tall vertebrae. Considered together, the results of this study are consistent with the hypothesis that shape- and position-specific biomechanics influence the amount of bone loss that can be safely tolerated. These results have potentially important implications for the evolution of vertebral morphology in birds and their extinct relatives.
Collapse
Affiliation(s)
- Andrew J. Moore
- Department of Biological SciencesThe George Washington UniversityWashingtonDCUSA,Department of Anatomical SciencesStony Brook UniversityStony BrookNYUSA
| |
Collapse
|
10
|
Schachner ER, Irmis RB, Huttenlocker AK, Sanders K, Cieri RL, Fox M, Nesbitt SJ. Osteology of the Late Triassic Bipedal Archosaur Poposaurus gracilis (Archosauria: Pseudosuchia) from Western North America. Anat Rec (Hoboken) 2020; 303:874-917. [PMID: 31814308 DOI: 10.1002/ar.24298] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 10/10/2019] [Accepted: 10/14/2019] [Indexed: 11/10/2022]
Abstract
Poposaurus gracilis is a bipedal pseudosuchian archosaur that has been poorly understood since the discovery of the holotype fragmentary partial postcranial skeleton in 1915. Poposaurus. gracilis is a member of Poposauroidea, an unusually morphologically divergent clade of pseudosuchians containing taxa that are bipedal, quadrupedal, toothed, edentulous, and some individuals with elongated thoracic neural spines (i.e., sails). In 2003, a well preserved, fully articulated, and nearly complete postcranial skeleton of P. gracilis was discovered with some fragmentary cranial elements from the Upper Triassic Chinle Formation of Grand Staircase-Escalante National Monument of southern Utah, USA. The aim of this work is to describe the osteology of this specimen in detail and compare P. gracilis to other closely related pseudosuchian archosaurs. The open neurocentral sutures throughout the majority of the vertebral column, the small size of this individual, and the presence of seven evenly spaced cyclic growth marks in the histologically sectioned femur indicate that this specimen was a skeletally immature juvenile, or subadult when it died. The pes of P. gracilis contains multiple skeletal adaptations and osteological correlates for soft tissue structures that support a hypothesis of digitigrady for this taxon. When coupled with the numerous postcranial characters associated with cursoriality, and the many anatomical traits convergent with theropod dinosaurs, this animal likely occupied a similar ecological niche with contemporaneous theropods during the Late Triassic Period. Anat Rec, 303:874-917, 2020. © 2019 American Association for Anatomy.
Collapse
Affiliation(s)
- Emma R Schachner
- Department of Cell Biology and Anatomy, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Randall B Irmis
- Natural History Museum of Utah, University of Utah, Salt Lake City, Utah
- Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah
| | - Adam K Huttenlocker
- Department of Integrative Anatomical Sciences, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Kent Sanders
- Department of Diagnostic Imaging, North Canyon Medical Center, Gooding, Idaho
| | - Robert L Cieri
- Department of Biology, University of Utah, Salt Lake City, Utah
| | - Marilyn Fox
- Department of Vertebrate Paleontology, Yale Peabody Museum, Yale University, New Haven, Connecticut
| | | |
Collapse
|
11
|
Roy A, Pittman M, Saitta ET, Kaye TG, Xu X. Recent advances in amniote palaeocolour reconstruction and a framework for future research. Biol Rev Camb Philos Soc 2020; 95:22-50. [PMID: 31538399 PMCID: PMC7004074 DOI: 10.1111/brv.12552] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 08/12/2019] [Accepted: 08/15/2019] [Indexed: 01/24/2023]
Abstract
Preserved melanin pigments have been discovered in fossilised integumentary appendages of several amniote lineages (fishes, frogs, snakes, marine reptiles, non-avialan dinosaurs, birds, and mammals) excavated from lagerstätten across the globe. Melanisation is a leading factor in organic integument preservation in these fossils. Melanin in extant vertebrates is typically stored in rod- to sphere-shaped, lysosome-derived, membrane-bound vesicles called melanosomes. Black, dark brown, and grey colours are produced by eumelanin, and reddish-brown colours are produced by phaeomelanin. Specific morphotypes and nanostructural arrangements of melanosomes and their relation to the keratin matrix in integumentary appendages create the so-called 'structural colours'. Reconstruction of colour patterns in ancient animals has opened an exciting new avenue for studying their life, behaviour and ecology. Modern relationships between the shape, arrangement, and size of avian melanosomes, melanin chemistry, and feather colour have been applied to reconstruct the hues and colour patterns of isolated feathers and plumages of the dinosaurs Anchiornis, Sinosauropteryx, and Microraptor in seminal papers that initiated the field of palaeocolour reconstruction. Since then, further research has identified countershading camouflage patterns, and informed subsequent predictions on the ecology and behaviour of these extinct animals. However, palaeocolour reconstruction remains a nascent field, and current approaches have considerable potential for further refinement, standardisation, and expansion. This includes detailed study of non-melanic pigments that might be preserved in fossilised integuments. A common issue among existing palaeocolour studies is the lack of contextualisation of different lines of evidence and the wide variety of techniques currently employed. To that end, this review focused on fossil amniotes: (i) produces an overarching framework that appropriately reconstructs palaeocolour by accounting for the chemical signatures of various pigments, morphology and local arrangement of pigment-bearing vesicles, pigment concentration, macroscopic colour patterns, and taphonomy; (ii) provides background context for the evolution of colour-producing mechanisms; and (iii) encourages future efforts in palaeocolour reconstructions particularly of less-studied groups such as non-dinosaur archosaurs and non-archosaur amniotes.
Collapse
Affiliation(s)
- Arindam Roy
- Vertebrate Palaeontology Laboratory, Department of Earth SciencesThe University of Hong KongPokfulamHong Kong SARChina
| | - Michael Pittman
- Vertebrate Palaeontology Laboratory, Department of Earth SciencesThe University of Hong KongPokfulamHong Kong SARChina
| | - Evan T. Saitta
- Integrative Research Center, Section of Earth SciencesField Museum of Natural History1400 S. Lake Shore Drive, ChicagoIL60605U.S.A.
| | - Thomas G. Kaye
- Foundation for Scientific Advancement7023 Alhambra Drive, Sierra VistaAZ85650U.S.A.
| | - Xing Xu
- Institute of Vertebrate Paleontology and PaleoanthropologyChinese Academy of Sciences142 Xizhimenwai Street.Beijing100044China
| |
Collapse
|
12
|
Brocklehurst RJ, Schachner ER, Codd JR, Sellers WI. Respiratory evolution in archosaurs. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190140. [PMID: 31928195 PMCID: PMC7017431 DOI: 10.1098/rstb.2019.0140] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Archosauria are a highly successful group of vertebrates, and their evolution is marked by the appearance of diverse respiratory and metabolic strategies. This review examines respiratory function in living and fossil archosaurs, focusing on the anatomy and biomechanics of the respiratory system, and their physiological consequences. The first archosaurs shared a heterogeneously partitioned parabronchial lung with unidirectional air flow; from this common ancestral lung morphology, we trace the diverging respiratory designs of bird- and crocodilian-line archosaurs. We review the latest evidence of osteological correlates for lung structure and the presence and distribution of accessory air sacs, with a focus on the evolution of the avian lung-air sac system and the functional separation of gas exchange and ventilation. In addition, we discuss the evolution of ventilation mechanics across archosaurs, citing new biomechanical data from extant taxa and how this informs our reconstructions of fossils. This improved understanding of respiratory form and function should help to reconstruct key physiological parameters in fossil taxa. We highlight key events in archosaur evolution where respiratory physiology likely played a major role, such as their radiation at a time of relative hypoxia following the Permo-Triassic mass extinction, and their evolution of elevated metabolic rates. This article is part of the theme issue ‘Vertebrate palaeophysiology’.
Collapse
Affiliation(s)
- Robert J Brocklehurst
- School of Earth and Environmental Sciences, University of Manchester, Manchester, UK
| | - Emma R Schachner
- Department of Cell Biology and Anatomy, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Jonathan R Codd
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - William I Sellers
- School of Earth and Environmental Sciences, University of Manchester, Manchester, UK
| |
Collapse
|
13
|
Paul G. Comment on Brocklehurst et al. ROYAL SOCIETY OPEN SCIENCE 2019; 6:181872. [PMID: 30891298 PMCID: PMC6408402 DOI: 10.1098/rsos.181872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 02/07/2019] [Indexed: 06/09/2023]
|
14
|
Capano JG, Moritz S, Cieri RL, Reveret L, Brainerd EL. Rib Motions Don't Completely Hinge on Joint Design: Costal Joint Anatomy and Ventilatory Kinematics in a Teiid Lizard, Salvator merianae. Integr Org Biol 2019; 1:oby004. [PMID: 33791512 PMCID: PMC7780499 DOI: 10.1093/iob/oby004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Rib rotations contribute to lung ventilation in most extant amniotes. These rotations are typically described as bucket-handle rotation about a dorsoventral axis, caliper rotation about a craniocaudal axis, and pump-handle rotation about a mediolateral axis. A synapomorphy for Lepidosauria is single-headed costovertebral articulations derived from the ancestral double-headed articulations of most amniotes. With a single articular surface, the costovertebral joints of squamates have the potential to rotate with three degrees-of-freedom (DOFs), but considerable variation exists in joint shape. We compared the costovertebral morphology of the Argentine black and white tegu, Salvator merianae, with the green iguana, Iguana iguana, and found that the costovertebral articulations of I. iguana were hemispherical, while those of S. merianae were dorsoventrally elongated and hemiellipsoidal. We predicted that the elongate joints in S. merianae would permit bucket-handle rotations while restricting caliper and pump-handle rotations, relative to the rounded joints of I. iguana. We used X-ray reconstruction of moving morphology to quantify rib rotations during breathing in S. merianae for comparison with prior work in I. iguana. Consistent with our hypothesis, we found less caliper motion in S. merianae than in I. iguana, but unexpectedly found similar pump-handle magnitudes in each species. The dorsoventrally elongate costovertebral morphology of S. merianae may provide passive rib support to reduce the conflict between locomotion and ventilation. Moreover, the observation of multiple DOFs during rib rotations in both species suggests that permissive costovertebral morphology may be more related to the biological roles of ribs outside of ventilation and help explain the evolution of this trait.
Collapse
Affiliation(s)
- J G Capano
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02906, USA
| | - S Moritz
- Department of Biology, Community College of Rhode Island, Warwick, RI 02886, USA
| | - R L Cieri
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - L Reveret
- Inria Grenoble Rhone Alpes, 655 Avenue de l'Europe, 38330 Montbonnot-Saint-Martin, France
| | - E L Brainerd
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02906, USA
| |
Collapse
|
15
|
Brocklehurst RJ, Schachner ER, Sellers WI. Vertebral morphometrics and lung structure in non-avian dinosaurs. ROYAL SOCIETY OPEN SCIENCE 2018; 5:180983. [PMID: 30473845 PMCID: PMC6227937 DOI: 10.1098/rsos.180983] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 09/24/2018] [Indexed: 06/09/2023]
Abstract
The lung-air sac system of modern birds is unique among vertebrates. However, debate surrounds whether an avian-style lung is restricted to birds or first appeared in their dinosaurian ancestors, as common osteological correlates for the respiratory system offer limited information on the lungs themselves. Here, we shed light on these issues by using axial morphology as a direct osteological correlate of lung structure, and quantifying vertebral shape using geometric morphometrics in birds, crocodilians and a wide range of dinosaurian taxa. Although fully avian lungs were a rather late innovation, we quantitatively show that non-avian dinosaurs and basal dinosauriforms possessed bird-like costovertebral joints and a furrowed thoracic ceiling. This would have immobilized the lung's dorsal surface, a structural prerequisite for a thinned blood-gas barrier and increased gas exchange potential. This could have permitted high levels of aerobic and metabolic activity in dinosaurs, even in the hypoxic conditions of the Mesozoic, contributing to their successful radiation.
Collapse
Affiliation(s)
| | - Emma R. Schachner
- Department of Cell Biology and Anatomy, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - William I. Sellers
- School of Earth and Environmental Sciences, University of Manchester, Manchester, UK
| |
Collapse
|
16
|
Brocklehurst RJ, Moritz S, Codd J, Sellers WI, Brainerd EL. Rib kinematics during lung ventilation in the American alligator ( Alligator mississippiensis): an XROMM analysis. ACTA ACUST UNITED AC 2018; 220:3181-3190. [PMID: 28855323 PMCID: PMC5612015 DOI: 10.1242/jeb.156166] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 06/15/2017] [Indexed: 11/20/2022]
Abstract
The current hypothesis regarding the mechanics of breathing in crocodylians is that the double-headed ribs, with both a capitulum and tuberculum, rotate about a constrained axis passing through the two articulations; moreover, this axis shifts in the caudal thoracic ribs, as the vertebral parapophysis moves from the centrum to the transverse process. Additionally, the ventral ribcage in crocodylians is thought to possess additional degrees of freedom through mobile intermediate ribs. In this study, X-ray reconstruction of moving morphology (XROMM) was used to quantify rib rotation during breathing in American alligators. Whilst costovertebral joint anatomy predicted overall patterns of motion across the ribcage (decreased bucket handle motion and increased calliper motion), there were significant deviations: anatomical axes overestimated pump handle motion and, generally, ribs in vivo rotate about all three body axes more equally than predicted. The intermediate ribs are mobile, with a high degree of rotation measured about the dorsal intracostal joints, especially in the more caudal ribs. Motion of the sternal ribs became increasingly complex caudally, owing to a combination of the movements of the vertebral and intermediate segments. As the crocodylian ribcage is sometimes used as a model for the ancestral archosaur, these results have important implications for how rib motion is reconstructed in fossil taxa, and illustrate the difficulties in reconstructing rib movement based on osteology alone. Summary: Using XROMM to test how well joint anatomy predicts rib motion during breathing in crocodylians, our best living model for the earliest archosaurs.
Collapse
Affiliation(s)
- Robert J Brocklehurst
- School of Earth and Environmental Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Sabine Moritz
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA
| | - Jonathan Codd
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - William I Sellers
- School of Earth and Environmental Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Elizabeth L Brainerd
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA
| |
Collapse
|
17
|
Schachner ER, Sedlmayr JC, Schott R, Lyson TR, Sanders RK, Lambertz M. Pulmonary anatomy and a case of unilateral aplasia in a common snapping turtle (Chelydra serpentina): developmental perspectives on cryptodiran lungs. J Anat 2017; 231:835-848. [PMID: 29063595 DOI: 10.1111/joa.12722] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2017] [Indexed: 01/07/2023] Open
Abstract
The common snapping turtle (Chelydra serpentina) is a well studied and broadly distributed member of Testudines; however, very little is known concerning developmental anomalies and soft tissue pathologies of turtles and other reptiles. Here, we present an unusual case of unilateral pulmonary aplasia, asymmetrical carapacial kyphosis, and mild scoliosis in a live adult C. serpentina. The detailed three-dimensional (3D) anatomy of the respiratory system in both the pathological and normal adult C. serpentina, and a hatchling are visualized using computed tomography (CT), microCT, and 3D digital anatomical models. In the pathological turtle, the right lung consists of an extrapulmonary bronchus that terminates in a blind stump with no lung present. The left lung is hyperinflated relative to the normal adult, occupying the extra coelomic space facilitated by the unusual mid-carapacial kyphotic bulge. The bronchial tree of the left lung retains the overall bauplan of the normal specimens, with some minor downstream variation in the number of secondary airways. The primary difference between the internal pulmonary structure of the pathological individual and that of a normal adult is a marked increase in the surface area and density of the parenchymal tissue originating from the secondary airways, a 14.3% increase in the surface area to volume ratio. Despite this, the aplasia has not had an impact upon the ability of the turtle to survive; however, it did interfere with aquatic locomotion and buoyancy control under water. This turtle represents a striking example of a non-fatal congenital defect and compensatory visceral hypertrophy.
Collapse
Affiliation(s)
- E R Schachner
- Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - J C Sedlmayr
- Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - R Schott
- Wildlife Rehabilitation Center of Minnesota, Roseville, MN, USA
| | - T R Lyson
- Department of Earth Sciences, Denver Museum of Nature and Science, Denver, CO, USA
| | - R K Sanders
- Department of Diagnostic Imaging, North Canyon Medical Center, Gooding, ID, USA
| | - M Lambertz
- Institut für Zoologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany.,Sektion Herpetologie, Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany
| |
Collapse
|
18
|
Lambertz M. Recent advances on the functional and evolutionary morphology of the amniote respiratory apparatus. Ann N Y Acad Sci 2016; 1365:100-13. [PMID: 27037667 DOI: 10.1111/nyas.13022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 01/14/2016] [Accepted: 01/19/2016] [Indexed: 12/30/2022]
Abstract
Increased organismic complexity in metazoans was achieved via the specialization of certain parts of the body involved in different faculties (structure-function complexes). One of the most basic metabolic demands of animals in general is a sufficient supply of all tissues with oxygen. Specialized structures for gas exchange (and transport) consequently evolved many times and in great variety among bilaterians. This review focuses on some of the latest advancements that morphological research has added to our understanding of how the respiratory apparatus of the primarily terrestrial vertebrates (amniotes) works and how it evolved. Two main components of the respiratory apparatus, the lungs as the "exchanger" and the ventilatory apparatus as the "active pump," are the focus of this paper. Specific questions related to the exchanger concern the structure of the lungs of the first amniotes and the efficiency of structurally simple snake lungs in health and disease, as well as secondary functions of the lungs in heat exchange during the evolution of sauropod dinosaurs. With regard to the active pump, I discuss how the unique ventilatory mechanism of turtles evolved and how understanding the avian ventilatory strategy affects animal welfare issues in the poultry industry.
Collapse
Affiliation(s)
- Markus Lambertz
- Institut für Zoologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| |
Collapse
|
19
|
Pittman M, Pei R, Tan Q, Xu X. The first dromaeosaurid (Dinosauria: Theropoda) from the Lower Cretaceous Bayan Gobi Formation of Nei Mongol, China. PeerJ 2015; 3:e1480. [PMID: 26664809 PMCID: PMC4675113 DOI: 10.7717/peerj.1480] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 11/16/2015] [Indexed: 11/30/2022] Open
Abstract
The first dromaeosaurid theropod from the Lower Cretaceous Bayan Gobi Formation is identified based on an incompletely preserved partially-articulated left leg, increasing the known diversity of its understudied ecosystem. The leg belongs to specimen IVPP V22530 and includes a typical deinonychosaurian pedal phalanx II-2 with a distinct constriction between the enlarged proximal end and the distal condyle as well as a typical deinonychosaurian enlarged pedal phalanx II-3. It possesses a symmetric metatarsus and a slender and long MT V that together suggest it is a dromaeosaurid. Two anatomical traits suggest the leg is microraptorine-like, but a more precise taxonomic referral was not possible: metatarsals II, III and IV are closely appressed distally and the ventral margin of the medial ligament pit of phalanx II-2 is close to the centre of the rounded distal condyle. This taxonomic status invites future efforts to discover additional specimens at the study locality because—whether it is a microraptorine or a close relative—this animal is expected to make important contributions to our understanding of dromaeosaurid evolution and biology. IVPP V22530 also comprises of an isolated dromaeosaurid manual ungual, a proximal portion of a right theropod anterior dorsal rib and an indeterminate bone mass that includes a collection of ribs. Neither the rib fragment nor the bone mass can be confidently referred to Dromaeosauridae, although they may very well belong to the same individual to whom the left leg belongs.
Collapse
Affiliation(s)
- Michael Pittman
- Vertebrate Palaeontology Laboratory, Department of Earth Sciences, The University of Hong Kong , Pokfulam , Hong Kong, China
| | - Rui Pei
- Vertebrate Palaeontology Laboratory, Department of Earth Sciences, The University of Hong Kong , Pokfulam , Hong Kong, China
| | - Qingwei Tan
- Long Hao Institute of Geology and Paleontology , Hohhot, Nei Mongol , China
| | - Xing Xu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology & Paleoanthropology, Chinese Academy of Sciences , Beijing , China
| |
Collapse
|
20
|
Evers SW, Rauhut OWM, Milner AC, McFeeters B, Allain R. A reappraisal of the morphology and systematic position of the theropod dinosaur Sigilmassasaurus from the "middle" Cretaceous of Morocco. PeerJ 2015; 3:e1323. [PMID: 26500829 PMCID: PMC4614847 DOI: 10.7717/peerj.1323] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 09/24/2015] [Indexed: 11/20/2022] Open
Abstract
Sigilmassasaurus brevicollis is an enigmatic theropod dinosaur from the early Late Cretaceous (Cenomanian) of Morocco, originally based on a few isolated cervical vertebrae. Ever since its original description, both its taxonomic validity and systematic affinities were contentious. Originally considered to represent its own family, Sigilmassasauridae, the genus has variously been suggested to represent a carcharodontosaurid, an ornithischian, and, more recently, a spinosaurid. Here we describe new remains referrable to this taxon and re-evaluate its taxonomic status and systematic affinities. Based on the new remains, a re-evaluation of the original materials, and comparisons with other spinosaurids, the holotype of Sigilmassasaurus brevicollis is identified as an anterior dorsal, rather than a cervical vertebra, and differences between elements referred to this taxon can be explained by different positions of the elements in question within the vertebral column. Many characters used previously to diagnose the genus and species are found to be more widespread among basal tetanurans, and specifically spinosaurids. However, the taxon shows several autapomorphies that support its validity, including the presence of a strongly rugose, ventrally offset triangular platform that is confluent with a ventral keel anteriorly in the mid-cervical vertebral centra and a strongly reduced lateral neural arch lamination, with no or an incomplete distinction between anterior and posterior centrodiapophyseal laminae in the posterior cervical and anterior dorsal vertebrae. We argue furthermore that Spinosaurus maroccanus, also described on the basis of isolated cervical vertebrae from the same stratigraphic unit and in the same paper as Sigilmassasaurus brevicollis, is a subjective synonym of the latter. Both a detailed comparison of this taxon with other theropods and a formal phylogenetic analysis support spinosaurid affintities for Sigilmassasaurus. However, we reject the recently proposed synonymy of both Spinosaurus maroccanus and Sigilmassasurus brevicollis with Spinosaurus aegyptiacus from the Cenomanian of Egypt, as there are clear differences between the vertebrae of these taxa, and they do not share any derived character that is not found in other spinosaurids. Together with a comparison with other spinosaurid vertebral material from the Kem Kem, this suggests that more than one taxon of spinosaurid was present in the Kem Kem assemblage of Morocco, so the referral of non-overlapping material from this unit to a single taxon should be regarded with caution.
Collapse
Affiliation(s)
- Serjoscha W Evers
- Department of Earth Sciences, University of Oxford , Oxford , United Kingdom ; Department für Geo- und Umweltwissenschaften, Ludwig-Maximilians-Universität München , Munich , Germany
| | - Oliver W M Rauhut
- Bayerische Staatssammlung für Paläontologie und Geologie, Staatliche Naturwissenschaftliche Sammlungen Bayerns (SNSB) , Munich , Germany ; Department für Geo- und Umweltwissenschaften and GeoBioCenter, Ludwig-Maximilians-University , Munich , Germany
| | - Angela C Milner
- Department of Earth Sciences, Natural History Museum , London , United Kingdom
| | | | - Ronan Allain
- Département Histoire de la Terre, Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements (CR2P), Muséum National d'Histoire Naturelle, Université Pierre et Marie Curie , Paris , France
| |
Collapse
|
21
|
Bourke JM, Porter WMR, Ridgely RC, Lyson TR, Schachner ER, Bell PR, Witmer LM. Breathing life into dinosaurs: tackling challenges of soft-tissue restoration and nasal airflow in extinct species. Anat Rec (Hoboken) 2015; 297:2148-86. [PMID: 25312371 DOI: 10.1002/ar.23046] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 06/25/2014] [Indexed: 11/10/2022]
Abstract
The nasal region plays a key role in sensory, thermal, and respiratory physiology, but exploring its evolution is hampered by a lack of preservation of soft-tissue structures in extinct vertebrates. As a test case, we investigated members of the "bony-headed" ornithischian dinosaur clade Pachycephalosauridae (particularly Stegoceras validum) because of their small body size (which mitigated allometric concerns) and their tendency to preserve nasal soft tissues within their hypermineralized skulls. Hypermineralization directly preserved portions of the olfactory turbinates along with an internal nasal ridge that we regard as potentially an osteological correlate for respiratory conchae. Fossil specimens were CT-scanned, and nasal cavities were segmented and restored. Soft-tissue reconstruction of the nasal capsule was functionally tested in a virtual environment using computational fluid dynamics by running air through multiple models differing in nasal soft-tissue conformation: a bony-bounded model (i.e., skull without soft tissue) and then models with soft tissues added, such as a paranasal septum, a scrolled concha, a branched concha, and a model combining the paranasal septum with a concha. Deviations in fluid flow in comparison to a phylogenetically constrained sample of extant diapsids were used as indicators of missing soft tissue. Models that restored aspects of airflow found in extant diapsids, such as appreciable airflow in the olfactory chamber, were judged as more likely. The model with a branched concha produced airflow patterns closest to those of extant diapsids. These results from both paleontological observation and airflow modeling indicate that S. validum and other pachycephalosaurids could have had both olfactory and respiratory conchae. Although respiratory conchae have been linked to endothermy, such conclusions require caution in that our re-evaluation of the reptilian nasal apparatus indicates that respiratory conchae may be more widespread than originally thought, and other functions, such as selective brain temperature regulation, could be important.
Collapse
Affiliation(s)
- Jason M Bourke
- Department of Biological Sciences, Ohio University, Athens, Ohio
| | | | | | | | | | | | | |
Collapse
|
22
|
Zhang Z, Chen D, Zhang H, Hou L. A large enantiornithine bird from the Lower Cretaceous of China and its implication for lung ventilation. Biol J Linn Soc Lond 2014. [DOI: 10.1111/bij.12330] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zihui Zhang
- College of Life Sciences; Capital Normal University; Beijing 100048 China
| | - Defeng Chen
- School of Mathematical Sciences; Capital Normal University; Beijing 100048 China
| | - Huitao Zhang
- School of Mathematical Sciences; Capital Normal University; Beijing 100048 China
| | - Lianhai Hou
- College of Life Sciences; Capital Normal University; Beijing 100048 China
- Institute of Vertebrate Paleontology and Paleoanthropology; Chinese Academy of Sciences; Beijing 100044 China
| |
Collapse
|
23
|
Chen XH, Motani R, Cheng L, Jiang DY, Rieppel O. A carapace-like bony 'body tube' in an early triassic marine reptile and the onset of marine tetrapod predation. PLoS One 2014; 9:e94396. [PMID: 24718682 PMCID: PMC3981804 DOI: 10.1371/journal.pone.0094396] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 03/13/2014] [Indexed: 11/25/2022] Open
Abstract
Parahupehsuchus longus is a new species of marine reptile from the Lower Triassic of Yuan’an County, Hubei Province, China. It is unique among vertebrates for having a body wall that is completely surrounded by a bony tube, about 50 cm long and 6.5 cm deep, comprising overlapping ribs and gastralia. This tube and bony ossicles on the back are best interpreted as anti-predatory features, suggesting that there was predation pressure upon marine tetrapods in the Early Triassic. There is at least one sauropterygian that is sufficiently large to feed on Parahupehsuchus in the Nanzhang-Yuan’an fauna, together with six more species of potential prey marine reptiles with various degrees of body protection. Modern predators of marine tetrapods belong to the highest trophic levels in the marine ecosystem but such predators did not always exist through geologic time. The indication of marine-tetrapod feeding in the Nanzhang-Yuan’an fauna suggests that such a trophic level emerged for the first time in the Early Triassic. The recovery from the end-Permian extinction probably proceeded faster than traditionally thought for marine predators. Parahupehsuchus has superficially turtle-like features, namely expanded ribs without intercostal space, very short transverse processes, and a dorsal outgrowth from the neural spine. However, these features are structurally different from their turtle counterparts. Phylogeny suggests that they are convergent with the condition in turtles, which has a fundamentally different body plan that involves the folding of the body wall. Expanded ribs without intercostal space evolved at least twice and probably even more among reptiles.
Collapse
Affiliation(s)
- Xiao-hong Chen
- Wuhan Center of China Geological Survey, Wuhan, Hubei, P. R. China
| | - Ryosuke Motani
- Department of Earth and Planetary Sciences, University of California Davis, Davis, California, United States of America
| | - Long Cheng
- Wuhan Center of China Geological Survey, Wuhan, Hubei, P. R. China
| | - Da-yong Jiang
- Laboratory of Orogenic Belt and Crustal Evolution, Ministry of Education, Department of Geology and Geological Museum, Peking University, Beijing, P.R. China
| | - Olivier Rieppel
- Center of Integrative Research, The Field Museum, Chicago, Illinois, United States of America
| |
Collapse
|
24
|
Geist NR, Hillenius WJ, Frey E, Jones TD, Elgin RA. Breathing in a box: constraints on lung ventilation in giant pterosaurs. Anat Rec (Hoboken) 2013; 297:2233-53. [PMID: 24357452 DOI: 10.1002/ar.22839] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 08/08/2013] [Indexed: 11/05/2022]
Abstract
Pterosaurs were the first vertebrates to achieve active flight, with some derived forms reaching enormous size. Accumulating fossil evidence confirms earlier indications that selection for large size in these flying forms resulted in a light, yet strong skeleton characterized by fusion of many bones of the trunk. However, this process also added mechanical constraints on the mobility of the thorax of large pterosaurs that likely limited the options available for lung ventilation. We present an alternative hypothesis to recent suggestions of an avian-like mechanism of costosternal pumping as the primary means of aspiration. An analysis of the joints among the vertebrae, ribs, sternum, and pectoral girdle of large pterosaurs indicates limited mobility of the ribcage and sternum. Comparisons with modes of lung ventilation in extant amniotes suggests that the stiffened thorax, coupled with mobile gastralia and prepubic bones, may be most consistent with an extracostal mechanism for lung ventilation in large pterodactyloids, perhaps similar to a crocodile-like visceral displacement system.
Collapse
Affiliation(s)
- Nicholas R Geist
- Department of Biology, Sonoma State University, Rohnert Park, California
| | | | | | | | | |
Collapse
|
25
|
The alligator gut microbiome and implications for archosaur symbioses. Sci Rep 2013; 3:2877. [PMID: 24096888 PMCID: PMC3791443 DOI: 10.1038/srep02877] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 09/20/2013] [Indexed: 02/07/2023] Open
Abstract
Among vertebrate gastrointestinal microbiome studies, complete representation of taxa is limited, particularly among reptiles. Here, we provide evidence for previously unrecognized host-microbiome associations along the gastrointestinal tract from the American alligator, a crown archosaur with shared ancestry to extinct taxa, including dinosaurs. Microbiome compositional variations reveal that the digestive system consists of multiple, longitudinally heterogeneous microbiomes that strongly correlate to specific gastrointestinal tract organs, regardless of rearing histories or feeding status. A core alligator gut microbiome comprised of Fusobacteria, but depleted in Bacteroidetes and Proteobacteria common to mammalians, is compositionally unique from other vertebrate gut microbiomes, including other reptiles, fish, and herbivorous and carnivorous mammals. As such, modern alligator gut microbiomes advance our understanding of archosaur gut microbiome evolution, particularly if conserved host ecology has retained archosaur-specific symbioses over geologic time.
Collapse
|
26
|
Schachner ER, Hutchinson JR, Farmer C. Pulmonary anatomy in the Nile crocodile and the evolution of unidirectional airflow in Archosauria. PeerJ 2013; 1:e60. [PMID: 23638399 PMCID: PMC3628916 DOI: 10.7717/peerj.60] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 03/10/2013] [Indexed: 11/20/2022] Open
Abstract
The lungs of birds have long been known to move air in only one direction during both inspiration and expiration through most of the tubular gas-exchanging bronchi (parabronchi). Recently a similar pattern of airflow has been observed in American alligators, a sister taxon to birds. The pattern of flow appears to be due to the arrangement of the primary and secondary bronchi, which, via their branching angles, generate inspiratory and expiratory aerodynamic valves. Both the anatomical similarity of the avian and alligator lung and the similarity in the patterns of airflow raise the possibility that these features are plesiomorphic for Archosauria and therefore did not evolve in response to selection for flapping flight or an endothermic metabolism, as has been generally assumed. To further test the hypothesis that unidirectional airflow is ancestral for Archosauria, we measured airflow in the lungs of the Nile crocodile (Crocodylus niloticus). As in birds and alligators, air flows cranially to caudally in the cervical ventral bronchus, and caudally to cranially in the dorsobronchi in the lungs of Nile crocodiles. We also visualized the gross anatomy of the primary, secondary and tertiary pulmonary bronchi of C. niloticus using computed tomography (CT) and microCT. The cervical ventral bronchus, cranial dorsobronchi and cranial medial bronchi display similar characteristics to their proposed homologues in the alligator, while there is considerable variation in the tertiary and caudal group bronchi. Our data indicate that the aspects of the crocodilian bronchial tree that maintain the aerodynamic valves and thus generate unidirectional airflow, are ancestral for Archosauria.
Collapse
Affiliation(s)
- Emma R Schachner
- Department of Biology, University of Utah , Salt Lake City, UT , USA
| | | | | |
Collapse
|
27
|
Butler RJ, Barrett PM, Gower DJ. Reassessment of the evidence for postcranial skeletal pneumaticity in Triassic archosaurs, and the early evolution of the avian respiratory system. PLoS One 2012; 7:e34094. [PMID: 22470520 PMCID: PMC3314707 DOI: 10.1371/journal.pone.0034094] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 02/21/2012] [Indexed: 11/19/2022] Open
Abstract
Uniquely among extant vertebrates, birds possess complex respiratory systems characterised by the combination of small, rigid lungs, extensive pulmonary air sacs that possess diverticula that invade (pneumatise) the postcranial skeleton, unidirectional ventilation of the lungs, and efficient crosscurrent gas exchange. Crocodilians, the only other living archosaurs, also possess unidirectional lung ventilation, but lack true air sacs and postcranial skeletal pneumaticity (PSP). PSP can be used to infer the presence of avian-like pulmonary air sacs in several extinct archosaur clades (non-avian theropod dinosaurs, sauropod dinosaurs and pterosaurs). However, the evolution of respiratory systems in other archosaurs, especially in the lineage leading to crocodilians, is poorly documented. Here, we use µCT-scanning to investigate the vertebral anatomy of Triassic archosaur taxa, from both the avian and crocodilian lineages as well as non-archosaurian diapsid outgroups. Our results confirm previous suggestions that unambiguous evidence of PSP (presence of internal pneumatic cavities linked to the exterior by foramina) is found only in bird-line (ornithodiran) archosaurs. We propose that pulmonary air sacs were present in the common ancestor of Ornithodira and may have been subsequently lost or reduced in some members of the clade (notably in ornithischian dinosaurs). The development of these avian-like respiratory features might have been linked to inferred increases in activity levels among ornithodirans. By contrast, no crocodile-line archosaur (pseudosuchian) exhibits evidence for unambiguous PSP, but many of these taxa possess the complex array of vertebral laminae and fossae that always accompany the presence of air sacs in ornithodirans. These laminae and fossae are likely homologous with those in ornithodirans, which suggests the need for further investigation of the hypothesis that a reduced, or non-invasive, system of pulmonary air sacs may be have been present in these taxa (and secondarily lost in extant crocodilians) and was potentially primitive for Archosauria as a whole.
Collapse
Affiliation(s)
- Richard J Butler
- GeoBio-Center, Ludwig-Maximilians-Universität München, Munich, Germany.
| | | | | |
Collapse
|