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Edwards SV, Cloutier A, Cockburn G, Driver R, Grayson P, Katoh K, Baldwin MW, Sackton TB, Baker AJ. A nuclear genome assembly of an extinct flightless bird, the little bush moa. SCIENCE ADVANCES 2024; 10:eadj6823. [PMID: 38781323 DOI: 10.1126/sciadv.adj6823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 04/17/2024] [Indexed: 05/25/2024]
Abstract
We present a draft genome of the little bush moa (Anomalopteryx didiformis)-one of approximately nine species of extinct flightless birds from Aotearoa, New Zealand-using ancient DNA recovered from a fossil bone from the South Island. We recover a complete mitochondrial genome at 249.9× depth of coverage and almost 900 megabases of a male moa nuclear genome at ~4 to 5× coverage, with sequence contiguity sufficient to identify more than 85% of avian universal single-copy orthologs. We describe a diverse landscape of transposable elements and satellite repeats, estimate a long-term effective population size of ~240,000, identify a diverse suite of olfactory receptor genes and an opsin repertoire with sensitivity in the ultraviolet range, show that the wingless moa phenotype is likely not attributable to gene loss or pseudogenization, and identify potential function-altering coding sequence variants in moa that could be synthesized for future functional assays. This genomic resource should support further studies of avian evolution and morphological divergence.
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Affiliation(s)
- Scott V Edwards
- Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
- Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Alison Cloutier
- Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Glenn Cockburn
- Evolution of Sensory Systems Research Group, Max Planck Institute for Biological Intelligence, 82319 Seewiesen, Germany
| | - Robert Driver
- Department of Biology, East Carolina University, E 5th Street, Greenville, NC 27605, USA
| | - Phil Grayson
- Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
- Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Kazutaka Katoh
- Department of Genome Informatics, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita 565-0871, Japan
| | - Maude W Baldwin
- Evolution of Sensory Systems Research Group, Max Planck Institute for Biological Intelligence, 82319 Seewiesen, Germany
| | - Timothy B Sackton
- Informatics Group, Harvard University, 38 Oxford Street, Cambridge, MA 02138, USA
| | - Allan J Baker
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcox Street, Toronto, ON M5S 3B2, Canada
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, ON M5S 2C6, Canada
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The endocast of the insular and extinct Sylviornis neocaledoniae (Aves, Galliformes), reveals insights into its sensory specializations and its twilight ecology. Sci Rep 2022; 12:21185. [PMID: 36477415 PMCID: PMC9729198 DOI: 10.1038/s41598-022-14829-z] [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: 02/21/2022] [Accepted: 06/13/2022] [Indexed: 12/12/2022] Open
Abstract
Sylviornis neocaledoniae (Galliformes, Sylviornithidae), a recently extinct bird of New-Caledonia (Galliformes, Sylviornithidae) is the largest galliform that ever lived and one of the most enigmatic birds in the world. Herein, for the first time, we analyze its neuroanatomy that sheds light on its lifestyle, its brain shape and patterns being correlated to neurological functions. Using morphometric methods, we quantified the endocranial morphology of S. neocaledoniae and compared it with extinct and extant birds in order to obtain ecological and behavioral information about fossil birds. Sylviornis neocaledoniae exhibited reduced optic lobes, a condition also observed in nocturnal taxa endemic to predator-depauperate islands, such as Elephant birds. Functional interpretations suggest that S. neocaledoniae possessed a well-developed somatosensorial system and a good sense of smell in addition to its specialized visual ability for low light conditions, presumably for locating its food. We interpret these results as evidence for a crepuscular lifestyle in S. neocaledoniae.
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3
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Nakao T, Yamasaki T, Ogihara N, Shimada M. Relationship between flightlessness and brain morphology among Rallidae. J Anat 2022; 241:776-788. [PMID: 35608388 PMCID: PMC9358762 DOI: 10.1111/joa.13690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 05/02/2022] [Accepted: 05/03/2022] [Indexed: 11/30/2022] Open
Abstract
Studies have suggested that the brain morphology and flight ability of Aves are interrelated; however, such a relationship has not been thoroughly investigated. This study aimed to examine whether flight ability, volant or flightless, affects brain morphology (size and shape) in the Rallidae, which has independently evolved to adapt secondary flightlessness multiple times within a single taxonomic group. Brain endocasts were extracted from computed tomography images of the crania, measured by 3D geometric morphometrics, and were analyzed using principal component analysis. The results of phylogenetic ANCOVA showed that flightless rails have brain sizes and shapes that are significantly larger than and different from those of volant rails, even after considering the effects of body mass and brain size respectively. Flightless rails tended to have a wider telencephalon and more inferiorly positioned foramen magnum than volant rails. Although the brain is an organ that requires a large amount of metabolic energy, reduced selective pressure for a lower body weight may have allowed flightless rails to have larger brains. The evolution of flightlessness may have changed the position of the foramen magnum downward, which would have allowed the support of the heavier cranium. The larger brain may have facilitated the acquisition of cognitively advanced behavior, such as tool-using behavior, among rails.
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Affiliation(s)
- Tatsuro Nakao
- Graduate School of Science and EngineeringTeikyo University of ScienceUenoharaJapan
| | | | | | - Masaki Shimada
- Department of Animal SciencesTeikyo University of ScienceUenoharaJapan
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4
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Ströckens F, Neves K, Kirchem S, Schwab C, Herculano-Houzel S, Güntürkün O. High associative neuron numbers could drive cognitive performance in corvid species. J Comp Neurol 2022; 530:1588-1605. [PMID: 34997767 DOI: 10.1002/cne.25298] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 11/19/2021] [Accepted: 01/03/2022] [Indexed: 11/08/2022]
Abstract
Corvids possess cognitive skills, matching those of non-human primates. However, how these species with their small brains achieve such feats remains elusive. Recent studies suggest that cognitive capabilities could be based on the total numbers of telencephalic neurons. Here we extend this hypothesis further and posit that especially high neuron counts in associative pallial areas drive flexible, complex cognition. If true, avian species like corvids should specifically accumulate neurons in the avian associative areas meso- and nidopallium. To test the hypothesis, we analyzed the neuronal composition of telencephalic areas in corvids and non-corvids (chicken, pigeons, and ostriches - the species with the largest bird brain). The overall number of pallial neurons in corvids was much higher than in chicken and pigeons and comparable to those of ostriches. However, neuron numbers in the associative mesopallium and nidopallium were twice as high in corvids and, in correlation with these associative areas, the corvid subpallium also contained high neuron numbers. These findings support our hypothesis that large absolute numbers of associative pallial neurons contribute to cognitive flexibility and complexity and are key to explain why crows are smart. Since meso/nidopallial and subpallial areas scale jointly, it is conceivable that associative pallio-striatal loops play a similar role in executive decision-making as described in primates. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Felix Ströckens
- Department of Psychology, Institute of Cognitive Neuroscience, Biopsychology, Ruhr-University Bochum, Bochum, 44780, Germany.,C. & O. Vogt Institute for Brain Research, University Hospital Düsseldorf, Heinrich-Heine University Düsseldorf, Düsseldorf, 40225, Germany
| | - Kleber Neves
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, CEP 21941-902, Rio de Janeiro, Brazil
| | - Sina Kirchem
- Department of Psychology, Institute of Cognitive Neuroscience, Biopsychology, Ruhr-University Bochum, Bochum, 44780, Germany
| | - Christine Schwab
- Department of Cognitive Biology, University of Vienna, Vienna, 1090, Austria
| | - Suzana Herculano-Houzel
- Department of Psychology, Department of Biological Sciences, Brain Institute, Vanderbilt University, Nashville, TN, 37240, USA
| | - Onur Güntürkün
- Department of Psychology, Institute of Cognitive Neuroscience, Biopsychology, Ruhr-University Bochum, Bochum, 44780, Germany
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5
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Endocranial Anatomy of the Giant Extinct Australian Mihirung Birds (Aves, Dromornithidae). DIVERSITY 2021. [DOI: 10.3390/d13030124] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Dromornithids are an extinct group of large flightless birds from the Cenozoic of Australia. Their record extends from the Eocene to the late Pleistocene. Four genera and eight species are currently recognised, with diversity highest in the Miocene. Dromornithids were once considered ratites, but since the discovery of cranial elements, phylogenetic analyses have placed them near the base of the anseriforms or, most recently, resolved them as stem galliforms. In this study, we use morphometric methods to comprehensively describe dromornithid endocranial morphology for the first time, comparing Ilbandornis woodburnei and three species of Dromornis to one another and to four species of extant basal galloanseres. We reveal that major endocranial reconfiguration was associated with cranial foreshortening in a temporal series along the Dromornis lineage. Five key differences are evident between the brain morphology of Ilbandornis and Dromornis, relating to the medial wulst, the ventral eminence of the caudoventral telencephalon, and morphology of the metencephalon (cerebellum + pons). Additionally, dromornithid brains display distinctive dorsal (rostral position of the wulst), and ventral morphology (form of the maxillomandibular [V2+V3], glossopharyngeal [IX], and vagus [X] cranial nerves), supporting hypotheses that dromornithids are more closely related to basal galliforms than anseriforms. Functional interpretations suggest that dromornithids were specialised herbivores that likely possessed well-developed stereoscopic depth perception, were diurnal and targeted a soft browse trophic niche.
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Hu K, King JL, Romick CA, Dufeau DL, Witmer LM, Stubbs TL, Rayfield EJ, Benton MJ. Ontogenetic endocranial shape change in alligators and ostriches and implications for the development of the non-avian dinosaur endocranium. Anat Rec (Hoboken) 2020; 304:1759-1775. [PMID: 33314780 DOI: 10.1002/ar.24579] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 11/20/2020] [Accepted: 11/27/2020] [Indexed: 01/20/2023]
Abstract
Birds and crocodiles show radically different patterns of brain development, and it is of interest to compare these to determine the pattern of brain growth expected in dinosaurs. Here we provide atlases of 3D brain (endocast) reconstructions for Alligator mississippiensis (alligator) and Struthio camelus (ostrich) through ontogeny, prepared as digital restorations from CT scans of stained head and dry skull specimens. Our morphometric analysis confirms that ostrich brains do not change significantly in shape during postnatal growth, whereas alligator brains unfold from a cramped bird-like shape in the hatchling to an elongate, straight structure in the adult. We confirm that birds exhibit paedomorphic dinosaur endocranial traits such as retaining an enlarged and compact brain shape in the adult, whereas crocodiles show peramorphic traits where the brain elongates with growth as the skull elongates. These atlases of ontogenetic stages of modern bird and crocodilian endocrania provide a basis for comparison of non-avian dinosaur endocasts and consideration of the divergence of the "avian" and "crocodilian" modes of brain development and heterochronic change on phylogenies.
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Affiliation(s)
- Krishna Hu
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - J Logan King
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - Cheyenne A Romick
- Department of Biological Sciences, Ohio University, Athens, Ohio, USA
| | - David L Dufeau
- Department of Biomedical Science, Marian University, Indianapolis, Indiana, USA
| | - Lawrence M Witmer
- Department of Biomedical Science, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
| | - Thomas L Stubbs
- School of Earth Sciences, University of Bristol, Bristol, UK
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7
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Early CM, Iwaniuk AN, Ridgely RC, Witmer LM. Endocast structures are reliable proxies for the sizes of corresponding regions of the brain in extant birds. J Anat 2020; 237:1162-1176. [PMID: 32892372 DOI: 10.1111/joa.13285] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/01/2020] [Accepted: 07/03/2020] [Indexed: 12/15/2022] Open
Abstract
Endocasts are increasingly relied upon to examine avian brain evolution because they can be used across extant and extinct species. The endocasts of birds appear to be relatively faithful representatives of the external morphology of their brains, but it is unclear how well the size of a surface feature visible on endocasts reflects the volume of the underlying brain region. The optic lobe and the Wulst are two endocast structures that are clearly visible on the external surface of avian endocasts. As they overlie two major visual regions of the brain, the optic tectum and hyperpallium, the surface areas of the optic lobe and Wulst, respectively, are often used to infer visual abilities. To determine whether the surface area of these features reflects the volume of the underlying brain regions, we compared the surface areas of the optic lobes and Wulsts from digital endocasts with the volumes of the optic tecta and hyperpallia from the literature or measured from histological series of brains of the same species. Regression analyses revealed strong, statistically significant correlations between the volumes of the brain regions and the surface areas of the overlying endocast structures. In other words, the size of the hyperpallium and optic tectum can be reliably inferred from the surface areas of the Wulst and optic lobe, respectively. This validation opens the possibility of estimating brain-region volumes for extinct species in order to gain better insights in their visual ecology. It also emphasizes the importance of adopting a quantitative approach to the analysis of endocasts in the study of brain evolution.
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Affiliation(s)
- Catherine M Early
- Biology Department, Science Museum of Minnesota, Saint Paul, MN, USA.,Department of Biological Sciences, Ohio University, Athens, OH, USA.,Florida Museum of Natural History, University of Florida, Gainesville, FL, USA
| | - Andrew N Iwaniuk
- Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada
| | - Ryan C Ridgely
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - Lawrence M Witmer
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
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8
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Hogan AVC, Watanabe A, Balanoff AM, Bever GS. Comparative growth in the olfactory system of the developing chick with considerations for evolutionary studies. J Anat 2020; 237:225-240. [PMID: 32314400 PMCID: PMC7369194 DOI: 10.1111/joa.13197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 02/17/2020] [Accepted: 03/10/2020] [Indexed: 12/26/2022] Open
Abstract
Despite the long-held assumption that olfaction plays a relatively minor role in the behavioral ecology of birds, crown-group avians exhibit marked phylogenetic variation in the size and form of the olfactory apparatus. As part of a larger effort to better understand the role of olfaction and olfactory tissues in the evolution and development of the avian skull, we present the first quantitative analysis of ontogenetic scaling between olfactory features [olfactory bulbs (OBs) and olfactory turbinates] and neighboring structures (cerebrum, total brain, respiratory turbinates) based on the model organism Gallus gallus. The OB develops under the predictions of a concerted evolutionary model with rapid early growth that is quickly overcome by the longer, sustained growth of the larger cerebrum. A similar pattern is found in the nasal cavity where the morphologically simple (non-scrolled) olfactory turbinates appear and mature early, with extended growth characterizing the larger and scrolled respiratory turbinates. Pairwise regressions largely recover allometric relationships among the examined structures, with a notable exception being the isometric trajectory of the OB and olfactory turbinate. Their parallel growth suggests a unique regulatory pathway that is likely driven by the morphogenesis of the olfactory nerve, which serves as a structural bridge between the two features. Still, isometry was not necessarily expected given that the olfactory epithelium covers more than just the turbinate. These data illuminate a number of evolutionary hypotheses that, moving forward, should inform tradeoffs and constraints between the olfactory and neighboring systems in the avian head.
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Affiliation(s)
- Aneila V. C. Hogan
- Center for Functional Anatomy and EvolutionJohns Hopkins University School of MedicineBaltimoreMDUSA
| | - Akinobu Watanabe
- Department of AnatomyNew York Institute of Technology College of Osteopathic MedicineNew YorkNYUSA
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkNYUSA
- Life Sciences DepartmentVertebrates DivisionNatural History MuseumLondonUK
| | - Amy M. Balanoff
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkNYUSA
- Department of Psychological and Brain SciencesJohns Hopkins UniversityBaltimoreMDUSA
| | - Gabriel S. Bever
- Center for Functional Anatomy and EvolutionJohns Hopkins University School of MedicineBaltimoreMDUSA
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkNYUSA
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9
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Knoll F, Kawabe S. Avian palaeoneurology: Reflections on the eve of its 200th anniversary. J Anat 2020; 236:965-979. [PMID: 31999834 PMCID: PMC7219626 DOI: 10.1111/joa.13160] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 12/28/2019] [Accepted: 01/07/2020] [Indexed: 12/13/2022] Open
Abstract
In birds, the brain (especially the telencephalon) is remarkably developed, both in relative volume and complexity. Unlike in most early-branching sauropsids, the adults of birds and other archosaurs have a well-ossified neurocranium. In contrast to the situation in most of their reptilian relatives but similar to what can be seen in mammals, the brains of birds fit closely to the endocranial cavity so that their major external features are reflected in the endocasts. This makes birds a highly suitable group for palaeoneurological investigations. The first observation about the brain in a long-extinct bird was made in the first quarter of the 19th century. However, it was not until the 2000s and the application of modern imaging technologies that avian palaeoneurology really took off. Understanding how the mode of life is reflected in the external morphology of the brains of birds is but one of several future directions in which avian palaeoneurological research may extend. Although the number of fossil specimens suitable for palaeoneurological explorations is considerably smaller in birds than in mammals and will very likely remain so, the coming years will certainly witness a momentous strengthening of this rapidly growing field of research at the overlap between ornithology, palaeontology, evolutionary biology and neurosciences.
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Affiliation(s)
- Fabien Knoll
- ARAID‐Fundación Conjunto Paleontológico de Teruel‐DinópolisTeruelSpain
- Departamento de PaleobiologíaMuseo Nacional de Ciencias Naturales‐CSICMadridSpain
| | - Soichiro Kawabe
- Institute of Dinosaur ResearchFukui Prefectural UniversityFukuiJapan
- Fukui Prefectural Dinosaur MuseumFukuiJapan
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10
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Beyond Endocasts: Using Predicted Brain-Structure Volumes of Extinct Birds to Assess Neuroanatomical and Behavioral Inferences. DIVERSITY-BASEL 2020. [DOI: 10.3390/d12010034] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The shape of the brain influences skull morphology in birds, and both traits are driven by phylogenetic and functional constraints. Studies on avian cranial and neuroanatomical evolution are strengthened by data on extinct birds, but complete, 3D-preserved vertebrate brains are not known from the fossil record, so brain endocasts often serve as proxies. Recent work on extant birds shows that the Wulst and optic lobe faithfully represent the size of their underlying brain structures, both of which are involved in avian visual pathways. The endocasts of seven extinct birds were generated from microCT scans of their skulls to add to an existing sample of endocasts of extant birds, and the surface areas of their Wulsts and optic lobes were measured. A phylogenetic prediction method based on Bayesian inference was used to calculate the volumes of the brain structures of these extinct birds based on the surface areas of their overlying endocast structures. This analysis resulted in hyperpallium volumes of five of these extinct birds and optic tectum volumes of all seven extinct birds. Phylogenetic ANCOVA (phyANCOVA) were performed on regressions of the brain-structure volumes and endocast structure surface areas on various brain size metrics to determine if the relative sizes of these structures in any extinct birds were significantly different from those of the extant birds in the sample. Phylogenetic ANCOVA indicated that no extinct birds studied had relative hyperpallial volumes that were significantly different from the extant sample, nor were any of their optic tecta relatively hypertrophied. The optic tectum of Dinornis robustus was significantly smaller relative to brain size than any of the extant birds in our sample. This study provides an analytical framework for testing the hypotheses of potential functional behavioral capabilities of other extinct birds based on their endocasts.
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11
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Torres CR, Clarke JA. Nocturnal giants: evolution of the sensory ecology in elephant birds and other palaeognaths inferred from digital brain reconstructions. Proc Biol Sci 2018; 285:20181540. [PMID: 30381378 PMCID: PMC6235046 DOI: 10.1098/rspb.2018.1540] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 10/10/2018] [Indexed: 11/12/2022] Open
Abstract
The recently extinct Malagasy elephant birds (Palaeognathae, Aepyornithiformes) included the largest birds that ever lived. Elephant bird neuroanatomy is understudied but can shed light on the lifestyle of these enigmatic birds. Palaeoneurological studies can provide clues to the ecologies and behaviours of extinct birds because avian brain shape is correlated with neurological function. We digitally reconstruct endocasts of two elephant bird species, Aepyornis maximus and A. hildebrandti, and compare them with representatives of all major extant and recently extinct palaeognath lineages. Among palaeognaths, we find large olfactory bulbs in taxa generally occupying forested environments where visual cues used in foraging are likely to be limited. We detected variation in olfactory bulb size among elephant bird species, possibly indicating interspecific variation in habitat. Elephant birds exhibited extremely reduced optic lobes, a condition also observed in the nocturnal kiwi. Kiwi, the sister taxon of elephant birds, have effectively replaced their visual systems with hyperdeveloped olfactory, somatosensory and auditory systems useful for foraging. We interpret these results as evidence for nocturnality among elephant birds. Vision was likely deemphasized in the ancestor of elephant birds and kiwi. These results show a previously unreported trend towards decreased visual capacity apparently exclusive to flightless, nocturnal taxa endemic to predator-depauperate islands.
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Affiliation(s)
- Christopher R Torres
- Department of Integrative Biology, University of Texas at Austin, 2415 Speedway, C0930, Austin, TX 78712, USA
| | - Julia A Clarke
- Department of Integrative Biology, University of Texas at Austin, 2415 Speedway, C0930, Austin, TX 78712, USA
- Jackson School of Geosciences, University of Texas at Austin, 2305 Speedway, C1160, Austin, TX 78712, USA
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12
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Proffitt JV, Clarke JA, Scofield RP. Novel insights into early neuroanatomical evolution in penguins from the oldest described penguin brain endocast. J Anat 2016; 229:228-38. [PMID: 26916364 PMCID: PMC4948054 DOI: 10.1111/joa.12447] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2016] [Indexed: 11/29/2022] Open
Abstract
Digital methodologies for rendering the gross morphology of the brain from X-ray computed tomography data have expanded our current understanding of the origin and evolution of avian neuroanatomy and provided new perspectives on the cognition and behavior of birds in deep time. However, fossil skulls germane to extracting digital endocasts from early stem members of extant avian lineages remain exceptionally rare. Data from early-diverging species of major avian subclades provide key information on ancestral morphologies in Aves and shifts in gross neuroanatomical structure that have occurred within those groups. Here we describe data on the gross morphology of the brain from a mid-to-late Paleocene penguin fossil from New Zealand. This most basal and geochronologically earliest-described endocast from the penguin clade indicates that described neuroanatomical features of early stem penguins, such as lower telencephalic lateral expansion, a relatively wider cerebellum, and lack of cerebellar folding, were present far earlier in penguin history than previously inferred. Limited dorsal expansion of the wulst in the new fossil is a feature seen in outgroup waterbird taxa such as Gaviidae (Loons) and diving Procellariiformes (Shearwaters, Diving Petrels, and allies), indicating that loss of flight may not drastically affect neuroanatomy in diving taxa. Wulst enlargement in the penguin lineage is first seen in the late Eocene, at least 25 million years after loss of flight and cooption of the flight stroke for aquatic diving. Similar to the origin of avian flight, major shifts in gross brain morphology follow, but do not appear to evolve quickly after, acquisition of a novel locomotor mode. Enlargement of the wulst shows a complex pattern across waterbirds, and may be linked to sensory modifications related to prey choice and foraging strategy.
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Affiliation(s)
- J. V. Proffitt
- Jackson School of GeosciencesThe University of Texas at AustinAustinTXUSA
| | - J. A. Clarke
- Jackson School of GeosciencesThe University of Texas at AustinAustinTXUSA
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13
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Marugán-Lobón J, Watanabe A, Kawabe S. Studying avian encephalization with geometric morphometrics. J Anat 2016; 229:191-203. [PMID: 27112986 DOI: 10.1111/joa.12476] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/02/2016] [Indexed: 02/02/2023] Open
Abstract
Encephalization is a core concept in comparative neurobiology, aiming to quantify the neurological capacity of organisms. For measuring encephalization, many studies have employed relative brain sizes corrected for expected allometric scaling to body size. Here we highlight the utility of a multivariate geometric morphometric (GM) approach for visualizing and analyzing neuroanatomical shape variation associated with encephalization. GM readily allows the statistical evaluation of covariates, such as size, and many software tools exist for visualizing their effects on shape. Thus far, however, studies using GM have not attempted to translate the meaning of encephalization to shape data. As such, we tested the statistical relationship between size and encephalization quotients (EQs) to brain shape utilizing a broad interspecific sample of avian endocranial data. Although statistically significant, the analyses indicate that allometry accounts for <10% of total neuroanatomical shape variation. Notably, we find that EQs, despite being corrected for allometric scaling based on size, contain size-related neuroanatomical shape changes. In addition, much of what is traditionally considered encephalization comprises clade-specific trends in relative forebrain expansion, particularly driven by landbirds. EQs, therefore, fail to capture 90% of the total neuroanatomical variation after correcting for allometry and shared phylogenetic history. Moving forward, GM techniques provide crucial tools for investigating key drivers of this vast, largely unexplored aspect of avian brain morphology.
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Affiliation(s)
- Jesús Marugán-Lobón
- Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Madrid, Spain.,Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA
| | - Akinobu Watanabe
- Division of Paleontology, American Museum of Natural History, New York, NY, USA.,Richard Gilder Graduate School, American Museum of Natural History, New York, NY, USA
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14
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Corfield JR, Eisthen HL, Iwaniuk AN, Parsons S. Anatomical specializations for enhanced olfactory sensitivity in kiwi, Apteryx mantelli. BRAIN, BEHAVIOR AND EVOLUTION 2014; 84:214-26. [PMID: 25376305 DOI: 10.1159/000365564] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 03/25/2014] [Indexed: 11/19/2022]
Abstract
The ability to function in a nocturnal and ground-dwelling niche requires a unique set of sensory specializations. The New Zealand kiwi has shifted away from vision, instead relying on auditory and tactile stimuli to function in its environment and locate prey. Behavioral evidence suggests that kiwi also rely on their sense of smell, using olfactory cues in foraging and possibly also in communication and social interactions. Anatomical studies appear to support these observations: the olfactory bulbs and tubercles have been suggested to be large in the kiwi relative to other birds, although the extent of this enlargement is poorly understood. In this study, we examine the size of the olfactory bulbs in kiwi and compare them with 55 other bird species, including emus, ostriches, rheas, tinamous, and 2 extinct species of moa (Dinornithiformes). We also examine the cytoarchitecture of the olfactory bulbs and olfactory epithelium to determine if any neural specializations beyond size are present that would increase olfactory acuity. Kiwi were a clear outlier in our analysis, with olfactory bulbs that are proportionately larger than those of any other bird in this study. Emus, close relatives of the kiwi, also had a relative enlargement of the olfactory bulbs, possibly supporting a phylogenetic link to well-developed olfaction. The olfactory bulbs in kiwi are almost in direct contact with the olfactory epithelium, which is indeed well developed and complex, with olfactory receptor cells occupying a large percentage of the epithelium. The anatomy of the kiwi olfactory system supports an enhancement for olfactory sensitivities, which is undoubtedly associated with their unique nocturnal niche.
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Affiliation(s)
- Jeremy R Corfield
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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Kawabe S, Shimokawa T, Miki H, Matsuda S, Endo H. Variation in avian brain shape: relationship with size and orbital shape. J Anat 2013; 223:495-508. [PMID: 24020351 DOI: 10.1111/joa.12109] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2013] [Indexed: 11/29/2022] Open
Abstract
There is wide variation in brain shape among birds. Differences in brain dimensions reflect species-specific sensory capacities and behavioral repertoires that are shaped by environmental and biological factors during evolution. Most previous studies aimed at defining factors impacting brain shape have used volumetric or linear measurements. However, few have explored the quantitative indices of three-dimensional (3D) brain geometry that are absolutely imperative to understanding avian evolutionary history. This study aimed: (i) to explore the relationship between brain shape and overall brain size; and (ii) to assess the relationship between brain shape and orbital shape. Avian brain endocasts were reconstructed from computed tomography images and analyzed using 3D geometric morphometrics. Principal component analysis revealed dominant regional variations in avian brain shape and shape correlations between the telencephalon and cerebellum, between the cerebellum and myelencephalon, and between the diencephalon and optic tectum. Brain shape changes relative to total brain size were determined by multivariate regression analysis. Larger brain size was associated with a relatively slender telencephalon and differences in brain orientation. The correlation between brain shape and orbital shape was assessed by two-block partial least-squares analysis. Relatively round brains with a ventrally flexed brain base were associated with rounder orbits, while narrower brains with a flat brain base were associated with more elongated orbits. The shapes of functionally associated avian brain regions are correlated, and orbital size and shape are dominant factors influencing the overall shape of the avian brain.
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Affiliation(s)
- Soichiro Kawabe
- The University Museum, The University of Tokyo, Tokyo, Japan; Department of Biological Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan; Gifu Prefectural Museum, Gifu, Japan
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Lautenschlager S, Rayfield EJ, Altangerel P, Zanno LE, Witmer LM. The endocranial anatomy of therizinosauria and its implications for sensory and cognitive function. PLoS One 2012; 7:e52289. [PMID: 23284972 PMCID: PMC3526574 DOI: 10.1371/journal.pone.0052289] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 11/14/2012] [Indexed: 11/26/2022] Open
Abstract
Background Therizinosauria is one of the most enigmatic and peculiar clades among theropod dinosaurs, exhibiting an unusual suite of characters, such as lanceolate teeth, a rostral rhamphotheca, long manual claws, and a wide, opisthopubic pelvis. This specialized anatomy has been associated with a shift in dietary preferences and an adaptation to herbivory. Despite a large number of discoveries in recent years, the fossil record for Therizinosauria is still relatively poor, and cranial remains are particularly rare. Methodology/Principal Findings Based on computed tomographic (CT) scanning of the nearly complete and articulated skull of Erlikosaurus andrewsi, as well as partial braincases of two other therizinosaurian taxa, the endocranial anatomy is reconstructed and described. The wider phylogenetic range of the described specimens permits the evaluation of sensory and cognitive capabilities of Therizinosauria in an evolutionary context. The endocranial anatomy reveals a mosaic of plesiomorphic and derived characters in therizinosaurians. The anatomy of the olfactory apparatus and the endosseous labyrinth suggests that olfaction, hearing, and equilibrium were well-developed in therizinosaurians and might have affected or benefited from an enlarged telencephalon. Conclusion/Significance This study presents the first appraisal of the evolution of endocranial anatomy and sensory adaptations in Therizinosauria. Despite their phylogenetically basal position among maniraptoran dinosaurs, therizinosaurians had developed the neural pathways for a well developed sensory repertoire. In particular olfaction and hearing may have played an important role in foraging, predator evasion, and/or social complexity.
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Smith NA, Clarke JA. Endocranial anatomy of the charadriiformes: sensory system variation and the evolution of wing-propelled diving. PLoS One 2012; 7:e49584. [PMID: 23209585 PMCID: PMC3507831 DOI: 10.1371/journal.pone.0049584] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Accepted: 10/15/2012] [Indexed: 11/24/2022] Open
Abstract
Just as skeletal characteristics provide clues regarding behavior of extinct vertebrates, phylogenetically-informed evaluation of endocranial morphology facilitates comparisons among extinct taxa and extant taxa with known behavioral characteristics. Previous research has established that endocranial morphology varies across Aves; however, variation of those systems among closely related species remains largely unexplored. The Charadriiformes (shorebirds and allies) are an ecologically diverse clade with a comparatively rich fossil record, and therefore, are well suited for investigating interspecies variation, and potential links between endocranial morphology, phylogeny, ecology and other life history attributes. Endocranial endocasts were rendered from high resolution X-ray computed tomography data for 17 charadriiforms (15 extant and two flightless extinct species). Evaluation of endocranial character state changes on a phylogeny for Charadriiformes resulted in identification of characters that vary in taxa with distinct feeding and locomotor ecologies. In comparison with all other charadriiforms, stem and crown clade wing-propelled diving Pan-Alcidae displayed compressed semicircular canals, and indistinct occipital sinuses and cerebellar fissures. Flightless wing-propelled divers have relatively smaller brains for their body mass and smaller optic lobes than volant pan-alcids. Observed differences between volant and flightless wing-propelled sister taxa are striking given that flightless pan-alcids continue to rely on the flight stroke for underwater propulsion. Additionally, the brain of the Black Skimmer Rynchops niger, a taxon with a unique feeding ecology that involves continuous forward aerial motion and touch-based prey detection used both at day and night, is discovered to be unlike that of any other sampled charadriiform in having an extremely large wulst as well as a small optic lobe and distinct occipital sinus. Notably, the differences between the Black Skimmer and other charadriiforms are more pronounced than between wing-propelled divers and other charadriiforms. Finally, aspects of endosseous labyrinth morphology are remarkably similar between divers and non-divers, and may deserve further evaluation.
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Affiliation(s)
- N Adam Smith
- Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, USA.
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KSEPKA DANIELT, BALANOFF AMYM, WALSH STIG, REVAN ARIEL, HO AMY. Evolution of the brain and sensory organs in Sphenisciformes: new data from the stem penguin Paraptenodytes antarcticus. Zool J Linn Soc 2012. [DOI: 10.1111/j.1096-3642.2012.00835.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Worthy TH, Scofield RP. Twenty-first century advances in knowledge of the biology of moa (Aves: Dinornithiformes): a new morphological analysis and moa diagnoses revised. NEW ZEALAND JOURNAL OF ZOOLOGY 2012. [DOI: 10.1080/03014223.2012.665060] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Ultraviolet visual sensitivity in three avian lineages: paleognaths, parrots, and passerines. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2012; 198:495-510. [DOI: 10.1007/s00359-012-0724-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 03/02/2012] [Accepted: 04/05/2012] [Indexed: 10/28/2022]
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Corfield JR, Wild JM, Cowan BR, Parsons S, Kubke MF. MRI of postmortem specimens of endangered species for comparative brain anatomy. Nat Protoc 2008; 3:597-605. [DOI: 10.1038/nprot.2008.17] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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