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Figueroa RT, Weinschütz LC, Giles S, Friedman M. Soft-tissue fossilization illuminates the stepwise evolution of the ray-finned fish brain. Curr Biol 2024; 34:2831-2840.e2. [PMID: 38866006 DOI: 10.1016/j.cub.2024.05.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 04/12/2024] [Accepted: 05/14/2024] [Indexed: 06/14/2024]
Abstract
A complex brain is central to the success of backboned animals. However, direct evidence bearing on vertebrate brain evolution comes almost exclusively from extant species, leaving substantial knowledge gaps. Although rare, soft-tissue preservation in fossils can yield unique insights on patterns of neuroanatomical evolution. Paleontological evidence from an exceptionally preserved Pennsylvanian (∼318 Ma) actinopterygian, Coccocephalus, calls into question prior interpretations of ancestral actinopterygian brain conditions. However, the ordering and timing of major evolutionary innovations, such as an everted telencephalon, modified meningeal tissues, and hypothalamic inferior lobes, remain unclear. Here, we report two distinct actinopterygian morphotypes from the latest Carboniferous-earliest Permian (∼299 Ma) of Brazil that show extensive soft-tissue preservation of brains, cranial nerves, eyes, and potential cardiovascular tissues. These fossils corroborate inferences drawn from ✝Coccocephalus, while adding new information about neuroanatomical evolution. Skeletal features indicate that one of these Brazilian morphotypes is more closely related to living actinopterygians than the other, which is also reflected in soft-tissue features. Significantly, the more crownward morphotype shows a key neuroanatomical feature of extant actinopterygians-an everted telencephalon-that is absent in the other morphotype and ✝Coccocephalus. All preserved Paleozoic actinopterygian brains show broad similarities, including an invaginated cerebellum, hypothalamus inferior lobes, and a small forebrain. In each case, preserved brains are substantially smaller than the enclosing cranial chamber. The neuroanatomical similarities shared by this grade of Permo-Carboniferous actinopterygians reflect probable primitive conditions for actinopterygians, providing a revised model for interpreting brain evolution in a major branch of the vertebrate tree of life.
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Affiliation(s)
- Rodrigo T Figueroa
- Department of Earth and Environmental Sciences, University of Michigan, North University Building, 1100 North University Avenue, Ann Arbor, MI 48109, USA; Museum of Paleontology, University of Michigan, Biological Sciences Building, 1105 North University Avenue, Ann Arbor, MI 48109, USA.
| | - Luiz Carlos Weinschütz
- Centro Paleontologico da Universidade do Contestado, CENPALEO, Av. Presidente Nereu Ramos 1071, Jardim Moinho, Mafra 89806-076, Santa Catarina, Brazil
| | - Sam Giles
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Matt Friedman
- Department of Earth and Environmental Sciences, University of Michigan, North University Building, 1100 North University Avenue, Ann Arbor, MI 48109, USA; Museum of Paleontology, University of Michigan, Biological Sciences Building, 1105 North University Avenue, Ann Arbor, MI 48109, USA
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Ristevski J. Neuroanatomy of the mekosuchine crocodylian Trilophosuchus rackhami Willis, 1993. J Anat 2022; 241:981-1013. [PMID: 36037801 PMCID: PMC9482699 DOI: 10.1111/joa.13732] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 07/15/2022] [Accepted: 07/17/2022] [Indexed: 12/03/2022] Open
Abstract
Although our knowledge on crocodylomorph palaeoneurology has experienced considerable growth in recent years, the neuroanatomy of many crocodylomorph taxa has yet to be studied. This is true for Australian taxa, where thus far only two crocodylian crocodylomorphs have had aspects of their neuroanatomy explored. Here, the neuroanatomy of the Australian mekosuchine crocodylian Trilophosuchus rackhami is described for the first time, which significantly increases our understanding on the palaeoneurology of Australian crocodylians. The palaeoneurological description is based on the taxon's holotype specimen (QMF16856), which was subjected to a μCT scan. Because of the exceptional preservation of QMF16856, most neuroanatomical elements could be digitally reconstructed and described in detail. Therefore, the palaeoneurological assessment presented here is hitherto the most in‐depth study of this kind for an extinct Australian crocodylomorph. Trilophosuchus rackhami has a brain endocast with a distinctive morphology that is characterized by an acute dural peak over the hindbrain region. While the overall morphology of the brain endocast is unique to T. rackhami, it does share certain similarities with the notosuchian crocodyliforms Araripesuchus wegeneri and Sebecus icaeorhinus. The endosseous labyrinth displays a morphology that is typical for crocodylians, although a stand‐out feature is the unusually tall common crus. Indeed, the common crus of T. rackhami has one of the greatest height ratios among crocodylomorphs with currently known endosseous labyrinths. The paratympanic pneumatic system of T. rackhami is greatly developed and most similar to those of the extant crocodylians Osteolaemus tetraspis and Paleosuchus palpebrosus. The observations on the neuroanatomy of T. rackhami are also discussed in the context of Crocodylomorpha. The comparative palaeoneurology reinforces previous evaluations that the neuroanatomy of crocodylomorphs is complex and diverse among species, and T. rackhami has a peculiar neuromorphology, particularly among eusuchian crocodyliforms.
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Affiliation(s)
- Jorgo Ristevski
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
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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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Dumont MV, Santucci RM, de Andrade MB, de Oliveira CEM. Paleoneurology of Baurusuchus (Crocodyliformes: Baurusuchidae), ontogenetic variation, brain size, and sensorial implications. Anat Rec (Hoboken) 2020; 305:2670-2694. [PMID: 33211405 DOI: 10.1002/ar.24567] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 09/18/2020] [Accepted: 10/18/2020] [Indexed: 12/23/2022]
Abstract
Knowledge on crocodyliform paleoneurology has significantly improved with development of computed tomography. However, studies so far have been able to reconstruct brain endocasts based only on single specimens for each taxon. Here for the first time, we reconstructed brain endocasts for multiple fossil specimens of the same crocodyliform taxon (Baurusuchus), consisting of complete skulls of two medium sized specimens, one large adult, and a late juvenile. In addition, we were able to reconstruct the inner ear anatomy of a fragmentary skull using microtomography. We present estimates of brain size using simple models, based on modern Crocodylia, able to adapt brain to endocranial cavity ratios to expected ontogenetic variation instead of using fixed ratios. We also analyzed relative brain sizes, olfactory ratios, facial sensation, alert head posture, best hearing frequencies, and hearing range. The calculated endocranial volumes showed that they can be greatly altered by taphonomic processes, altering both total and partial endocranial volumes. Reconstructed endocasts are compatible with different degrees of occupation along the endocranial cavity and some of their characteristics might be useful as phylogenetic characters. The relative brain size of Baurusuchus seems to be small in comparison to modern crocodilians. Sensorial abilities were somewhat similar to modern crocodilians and hearing ranges and best mean frequencies remarkably similar to modern taxa, whereas olfactory ratio values are a little higher. Differing from its modern relatives, Baurusuchus hypothesized alert head posture is compatible with a terrestrial habit.
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Affiliation(s)
- Marcos V Dumont
- Federal Institute of Brasília, Brasília, Brazil.,University of Brasília, Brasília, Brazil
| | | | - Marco Brandalise de Andrade
- Pontifical Catholic University of Rio Grande do Sul, PUCRS, School of Health and Life Sciences, Porto Alegre, Brazil
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Voeten DFAE, Reich T, Araújo R, Scheyer TM. Synchrotron microtomography of a Nothosaurus marchicus skull informs on nothosaurian physiology and neurosensory adaptations in early Sauropterygia. PLoS One 2018; 13:e0188509. [PMID: 29298295 PMCID: PMC5751976 DOI: 10.1371/journal.pone.0188509] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 11/08/2017] [Indexed: 02/06/2023] Open
Abstract
Nothosaurs form a subclade of the secondarily marine Sauropterygia that was well represented in late Early to early Late Triassic marine ecosystems. Here we present and discuss the internal skull anatomy of the small piscivorous nothosaur Nothosaurus marchicus from coastal to shallow marine Lower Muschelkalk deposits (Anisian) of Winterswijk, The Netherlands, which represents the oldest sauropterygian endocast visualized to date. The cranial endocast is only partially encapsulated by ossified braincase elements. Cranial flattening and lateral constriction by hypertrophied temporal musculature grant the brain a straight, tubular geometry that lacks particularly well-developed cerebral lobes but does potentially involve distinguishable optic lobes, suggesting vision may have represented an important sense during life. Despite large orbit size, the circuitous muscular pathway linking the basisphenoidal and orbital regions indicates poor oculomotor performance. This suggests a rather fixed ocular orientation, although eye placement and neck manoeuvrability could have enabled binocular if not stereoscopic vision. The proportionally large dorsal projection of the braincase endocast towards the well-developed pineal foramen advocates substantial dependence on the corresponding pineal system in vivo. Structures corroborating keen olfactory or acoustic senses were not identified. The likely atrophied vomeronasal organ argues against the presence of a forked tongue in Nothosaurus, and the relative positioning of external and internal nares contrasts respiratory configurations proposed for pistosauroid sauropterygians. The antorbital domain furthermore accommodates a putative rostral sensory plexus and pronounced lateral nasal glands that were likely exapted as salt glands. Previously proposed nothosaurian 'foramina eustachii' arose from architectural constraints on braincase development rather than representing functional foramina. Several modifications to brain shape and accessory organs were achieved through heterochronic development of the cranium, particularly the braincase. In summary, the cranium of Nothosaurus marchicus reflects important physiological and neurosensory adaptations that enabled the group's explosive invasion of shallow marine habitats in the late Early Triassic.
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Affiliation(s)
- Dennis F. A. E. Voeten
- European Synchrotron Radiation Facility, Grenoble, France
- Department of Zoology and Laboratory of Ornithology, Palacký University, Olomouc, Czech Republic
| | - Tobias Reich
- University of Zurich, Palaeontological Institute and Museum, Zurich, Switzerland
| | - Ricardo Araújo
- Institute for Plasma Research and Nuclear Fusion, Technical University of Lisbon, Lisbon, Portugal
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
- Institute of Evolutionary Sciences, University of Montpellier 2, Montpellier, France
| | - Torsten M. Scheyer
- University of Zurich, Palaeontological Institute and Museum, Zurich, Switzerland
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Pandya S. The two Drs. Edinger who deserve greater recognition. Neurol India 2018; 66:914-918. [DOI: 10.4103/0028-3886.236982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Raghanti MA, Todd N, Hof PR. Probing the proboscidea: Lessons from the past. J Comp Neurol 2015; 523:2321-5. [PMID: 26184071 DOI: 10.1002/cne.23824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 06/11/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Mary Ann Raghanti
- Department of Anthropology and School of Biomedical Sciences, Kent State University, Kent, Ohio, 44242
| | - Nancy Todd
- Biology and Environmental Studies, Manhattanville College, Purchase, New York, 10577
| | - Patrick R Hof
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, 10029.,New York Consortium in Evolutionary Primatology, New York, New York, 10029
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Carabajal AP, Sterli J, Müller J, Hilger A. Neuroanatomy of the marine Jurassic turtle Plesiochelys etalloni (Testudinata, Plesiochelyidae). PLoS One 2013; 8:e69264. [PMID: 23844257 PMCID: PMC3699497 DOI: 10.1371/journal.pone.0069264] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 06/06/2013] [Indexed: 11/19/2022] Open
Abstract
Turtles are one of the least explored clades regarding endocranial anatomy with few available descriptions of the brain and inner ear of extant representatives. In addition, the paleoneurology of extinct turtles is poorly known and based on only a few natural cranial endocasts. The main goal of this study is to provide for the first time a detailed description of the neuroanatomy of an extinct turtle, the Late Jurassic Plesiochelysetalloni, including internal carotid circulation, cranial endocast and inner ear, based on the first digital 3D reconstruction using micro CT scans. The general shape of the cranial endocast of P. etalloni is tubular, with poorly marked cephalic and pontine flexures. Anteriorly, the olfactory bulbs are clearly differentiated suggesting larger bulbs than in any other described extinct or extant turtle, and indicating a higher capacity of olfaction in this taxon. The morphology of the inner ear of P. etalloni is comparable to that of extant turtles and resembles those of slow-moving terrestrial vertebrates, with markedly low, short and robust semicircular canals, and a reduced lagena. In P. etalloni the arterial pattern is similar to that found in extant cryptodires, where all the internal carotid branches are protected by bone. As the knowledge of paleoneurology in turtles is scarce and the application of modern techniques such as 3D reconstructions based on CT scans is almost unexplored in this clade, we hope this paper will trigger similar investigations of this type in other turtle taxa.
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Affiliation(s)
- Ariana Paulina Carabajal
- Consejo Nacional de Investigaciones Científicas y Técnicas-Museo Carmen Funes, Neuquén, Argentina.
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Lautenschlager S, Hübner T. Ontogenetic trajectories in the ornithischian endocranium. J Evol Biol 2013; 26:2044-50. [DOI: 10.1111/jeb.12181] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 04/05/2013] [Accepted: 04/09/2013] [Indexed: 11/30/2022]
Affiliation(s)
| | - T. Hübner
- Bayerische Staatssammlung für Paläontologie und Geobiology; Munich Germany
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Prithishkumar IJ. Ludwig Edinger (1855-1918): founder of modern neuroanatomy. Clin Anat 2011; 25:155-7. [PMID: 21800368 DOI: 10.1002/ca.21224] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 05/19/2011] [Accepted: 05/23/2011] [Indexed: 11/12/2022]
Abstract
Ludwig Edinger, a German neurologist is considered as one of the founders of modern neuroanatomy. He was conferred the degree of Doctor of Medicine at the University of Strassburg. His observation of small living organisms under a microscope at an early age led him to study medicine. Edinger had many discoveries to his credit. He was the first to describe the ventral and dorsal spinocerebellar tracts, to distinguish between paleo-encephalon and neo-encephalon, and between paleo-cerebellum and neo-cerebellum. He coined the terms "gnosis" and "praxis," which were later adopted in psychological descriptions of agnosia and apraxia. He identified the Edinger-Westphal nucleus in 1885 and was the first to describe the syndrome of thalamic pain. Edinger worked with renowned clinicians and published a large number of papers. He founded the Neurological Institute at the Goethe University in Frankfurt, which is the oldest neurological Institute in Germany. Edinger was a rare combination of a profound scientist, a brilliant teacher, a fine artist, and a noted hypnotist. While at the height of his career, he underwent a surgery and died a few hours later. It was his last will that his brain should be dissected in his own institute. It showed extraordinarily well-developed occipital lobes as well as other unusual features.
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Macrini TE, Rowe T, Vandeberg JL. Cranial endocasts from a growth series ofMonodelphis domestica (Didelphidae, Marsupialia): A study of individual and ontogenetic variation. J Morphol 2007; 268:844-65. [PMID: 17626259 DOI: 10.1002/jmor.10556] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Intraspecific variation (e.g., ontogenetic, individual, sexual dimorphic) is rarely examined among cranial endocasts (infillings of the braincase cavity) because of the difficulty in obtaining multiple specimens of a species, particularly fossil taxa. We extracted digital cranial endocasts from CT scans of a growth series of skulls of Monodelphis domestica, the gray short-tailed opossum, as a preliminary assessment of the amount of intraspecific variation in mammalian endocranial morphology. The goals of this study were 1) to provide an anatomical description to document developmental changes in endocranial morphology of M. domestica and 2) to examine ontogenetic and individual variation with respect to phylogenetic characters of endocranial cavities that are known to be variable between different mammalian taxa. In this study, "ontogenetic variation" refers to variation between specimens of different ages whereas "individual variation" (i.e., polymorphism) is restricted to variation between specimens of comparable age. Aside from size, changes in shape account for the greatest amount of morphological variation between the endocasts of different ages. Endocast length, width, and volume increase with age for the growth series. Relative olfactory bulb cast size increases with age in the growth series, but the relative size of the parafloccular casts shows a slight negative allometric trend through ontogeny. More than one-third of the phylogenetic characters of the endocranial cavity we examined showed some sort of variation (ontogenetic, individual, or both). This suggests that although endocasts are potentially informative for systematics, both ontogenetic and individual variation affect how endocranial characters are scored for phylogenetic analysis. Further studies such as this are necessary to determine the taxonomic extent of significant intraspecific variation of these endocranial characters.
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Affiliation(s)
- Thomas E Macrini
- Department of Mammalogy, American Museum of Natural History, New York, New York 10024, USA.
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Abstract
Although brain studies began in ancient Egypt, speculations on vertebrate brain evolution occurred only much later, after the publication of Darwin's Origin of Species in 1859. Subsequently, views of brain evolution have been shaped by a complex interplay of theory and technique. Darwin's theory allowed the variation in brain size and complexity to be re-interpreted within an evolutionary context, albeit an erroneous pre-Darwinian context based on scala naturae. With the development of histological techniques, research shifted to descriptions of cellular structure, cellular aggregates and their putative interconnections. In spite of these technical advances, brain evolution continued to be viewed within the context of scala naturae. Following the publication of The Comparative Anatomy of the Nervous System of Vertebrates by Ariëns Kappers, Huber, and Crosby in 1936, there followed a period of stasis, after which biological views of evolution were radically altered by the confluence of genetics, paleontology, and systematics, termed the Evolutionary Synthesis. Against this background, the development of new experimental techniques for establishing neural connections resulted in a new flowering of comparative neuroanatomy. While comparative descriptive and experimental studies of brain organization continue, the rapprochement of embryology and genetics is fueling a new renaissance that promises to increase our understanding of brain evolution and its genetic basis.
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Affiliation(s)
- R G Northcutt
- Neurobiology Unit, Scripps Institution of Oceanography and Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, CA, USA.
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BUCHHOLTZ EMILYA, SEYFARTH ERNSTAUGUST. The Study of “Fossil Brains”: Tilly Edinger (1897–1967) and the Beginnings of Paleoneurology. Bioscience 2001. [DOI: 10.1641/0006-3568(2001)051[0674:tsofbt]2.0.co;2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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