1
|
Cerio DG, Witmer LM. Orbital soft tissues, bones, and allometry: Implications for the size and position of crocodylian eyes. Anat Rec (Hoboken) 2023; 306:2537-2561. [PMID: 36508325 DOI: 10.1002/ar.25133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 09/14/2022] [Accepted: 10/25/2022] [Indexed: 12/14/2022]
Abstract
Although the visual system of crocodylians has attracted interest regarding optical parameters and retinal anatomy, fundamental questions remain about the allometry of the eyeball and whether such scaling is the same across all crown groups of crocodylians. In addition, anatomy and identities of adnexal soft tissues that interact with the visual system are not well understood in many cases. We used contrast-enhancing iodine stain and high-resolution micro-computed tomography to assess the anatomy of orbital soft tissues, including extraocular muscles and glands, in crocodylians. We also used regression analysis to estimate the allometric relationship between the bony orbit and eyeball across Alligator mississippiensis and Crocodylus niloticus for the first time. Results revealed tight, negatively allometric relationships between the bony orbit and eyeball. Notably, the eyes of C. niloticus were larger for a given orbit size than the eyes of A. mississippiensis, although the slope of the relationship was no different between these two crown crocodylian groups. Among the findings from our anatomical study, new details were uncovered about the homologies of muscles of the abducens complex. In particular, M. rectus lateralis of crocodylians is revealed to have a more complex form than previously appreciated, being adhered to the tendon of the nictitating membrane, which may be apomorphic for Crocodylia. Our calculation of the orbit-eyeball allometric relationship and study of the adnexal soft tissues of the crocodylian visual system, in combination with previous work by other teams in other crown saurian clades, is a critical, formerly missing, piece in the Extant Phylogenetic Bracket for restoring the visual apparatus of extinct crocodyliforms and other archosauriform groups.
Collapse
Affiliation(s)
- Donald Greene Cerio
- Department of Biological Sciences, Ohio University, Athens, Ohio, USA
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, Ohio, USA
- Ohio Center for Ecology and Evolutionary Studies, Ohio University, Athens, Ohio, USA
| | - Lawrence M Witmer
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, Ohio, USA
- Ohio Center for Ecology and Evolutionary Studies, Ohio University, Athens, Ohio, USA
| |
Collapse
|
2
|
Holliday CM, Schachner ER. Dispatches from the age of crocodiles: New discoveries from ancient lineages. Anat Rec (Hoboken) 2022; 305:2343-2352. [PMID: 35912969 DOI: 10.1002/ar.25043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 01/19/2023]
Abstract
Crocodilians inspire researchers and the public alike with their explosive hunting methodologies, distinct craniofacial and dental morphology, and resplendent fossil record. This special issue highlights recent advances in the biology and paleontology of this fascinating lineage of vertebrates. The authors in this volume bring crocodylians and their extinct ancestors to life using a variety of approaches including fieldwork, imaging, 3D modeling, developmental biology, physiological monitoring, dissection, and a host of other comparative methods. Our journey begins with early crocodylomorphs from the Triassic, carries us through the radiation of crocodyliforms during the rest of the Mesozoic Era, and finally celebrates the diversification development and biology of extant crocodylians. Crocodyliform science has grown appreciably the past few decades. New fossil species and genetic evidence continue to keep phylogenies and our understanding of relationships wavering in key places of the tree such as the relationships of the extinct marine thalattosuchians as well as still living species like gharials. The application of imaging approaches and 3D modeling to both preserved tissues as well as living specimens is now revealing patterns in brain and lung evolution and function, growth strategies, and feeding and locomotor behaviors across the lineage. Comparative anatomical studies are offering new data on genitals, cephalic venous drainage and thoracoabdominal pressures. The new discoveries found here only reveal there is far more work to be done to understand the biology and behavior responsible for the great radiation extinct suchians and their crocodylian descendants experienced during their conquest of Mesozoic and Tertiary ecosystems.
Collapse
Affiliation(s)
- Casey M Holliday
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Emma R Schachner
- Department of Cell Biology and Anatomy, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| |
Collapse
|
3
|
Holliday CM, Sellers KC, Lessner EJ, Middleton KM, Cranor C, Verhulst CD, Lautenschlager S, Bader K, Brown MA, Colbert MW. New frontiers in imaging, anatomy, and mechanics of crocodylian jaw muscles. Anat Rec (Hoboken) 2022; 305:3016-3030. [PMID: 35723491 DOI: 10.1002/ar.25011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 05/16/2022] [Accepted: 05/21/2022] [Indexed: 12/12/2022]
Abstract
New imaging and biomechanical approaches have heralded a renaissance in our understanding of crocodylian anatomy. Here, we review a series of approaches in the preparation, imaging, and functional analysis of the jaw muscles of crocodylians. Iodine-contrast microCT approaches are enabling new insights into the anatomy of muscles, nerves, and other soft tissues of embryonic as well as adult specimens of alligators. These imaging data and other muscle modeling methods offer increased accuracy of muscle sizes and attachments without destructive methods like dissection. 3D modeling approaches and imaging data together now enable us to see and reconstruct 3D muscle architecture which then allows us to estimate 3D muscle resultants, but also measurements of pennation in ways not seen before. These methods have already revealed new information on the ontogeny, diversity, and function of jaw muscles and the heads of alligators and other crocodylians. Such approaches will lead to enhanced and accurate analyses of form, function, and evolution of crocodylians, their fossil ancestors and vertebrates in general.
Collapse
Affiliation(s)
- Casey M Holliday
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Kaleb C Sellers
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Emily J Lessner
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Kevin M Middleton
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Corrine Cranor
- Department of Geology and Geologic Engineering, South Dakota School of Mines and Technology, Rapid City, South Dakota, USA
| | - Conner D Verhulst
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Stephan Lautenschlager
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
| | - Kenneth Bader
- Texas Vertebrate Paleontology Collection, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA
| | - Matthew A Brown
- Texas Vertebrate Paleontology Collection, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA
| | - Matthew W Colbert
- Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA
| |
Collapse
|
4
|
Schwab JA, Young MT, Walsh SA, Witmer LM, Herrera Y, Brochu CA, Butler IB, Brusatte SL. Ontogenetic variation in the crocodylian vestibular system. J Anat 2022; 240:821-832. [PMID: 34841534 PMCID: PMC9005688 DOI: 10.1111/joa.13601] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 10/29/2021] [Accepted: 11/19/2021] [Indexed: 01/20/2023] Open
Abstract
Crocodylians today live in tropical to subtropical environments, occupying mostly shallow waters. Their body size changes drastically during ontogeny, as do their skull dimensions and bite forces, which are associated with changes in prey preferences. Endocranial neurosensory structures have also shown to change ontogenetically, but less is known about the vestibular system of the inner ear. Here we use 30 high-resolution computed tomography (CT) scans and three-dimensional geometric morphometrics to investigate the size and shape changes of crocodylian endosseous labyrinths throughout ontogeny, across four stages (hatchling, juvenile, subadult and adult). We find two major patterns of ontogenetic change. First, the labyrinth increases in size during ontogeny, with negative allometry in relation to skull size. Second, labyrinth shape changes significantly, with hatchlings having shorter semicircular canal radii, with thicker diameters and an overall dorsoventrally shorter labyrinth than those of more mature individuals. We argue that the modification of the labyrinth during crocodylian ontogeny is related to constraints imposed by skull growth, due to fundamental changes in the crocodylian braincase during ontogeny (e.g. verticalisation of the basicranium), rather than changes in locomotion, diet, or other biological functions or behaviours.
Collapse
Affiliation(s)
- Julia A. Schwab
- School of GeoSciencesGrant InstituteUniversity of EdinburghEdinburghUK
| | - Mark T. Young
- School of GeoSciencesGrant InstituteUniversity of EdinburghEdinburghUK
| | - Stig A. Walsh
- School of GeoSciencesGrant InstituteUniversity of EdinburghEdinburghUK
- National Museum of ScotlandEdinburghUK
| | - Lawrence M. Witmer
- Department of Biomedical SciencesHeritage College of Osteopathic MedicineOhio Center for Ecology and Evolutionary StudiesOhio UniversityAthensOhioUSA
| | - Yanina Herrera
- CONICET. División Paleontología VertebradosMuseo de La Plata, FCNyMUNLPLa PlataArgentina
| | | | - Ian B. Butler
- School of GeoSciencesGrant InstituteUniversity of EdinburghEdinburghUK
| | | |
Collapse
|
5
|
Iijima M, Qiao Y, Lin W, Peng Y, Yoneda M, Liu J. An intermediate crocodylian linking two extant gharials from the Bronze Age of China and its human-induced extinction. Proc Biol Sci 2022; 289:20220085. [PMID: 35259993 PMCID: PMC8905159 DOI: 10.1098/rspb.2022.0085] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
A solid phylogenetic framework is the basis of biological studies, yet higher level relationships are still unresolved in some major vertebrate lineages. One such group is Crocodylia, where the branching pattern of three major families (Alligatoridae, Crocodylidae and Gavialidae) has been disputed over decades due to the uncertain relationship of two slender-snouted lineages, gavialines and tomistomines. Here, we report a bizarre crocodylian from the Bronze Age of China, which shows a mosaic of gavialine and tomistomine features across the skeleton, rendering support to their sister taxon relationship as molecular works have consistently postulated. Gavialine characters of the new Chinese crocodylian include a novel configuration of the pterygoid bulla, a vocal structure known in mature male Indian gharials. Extinct gavialines have repeatedly evolved potentially male-only acoustic apparatus of various shapes, illuminating the deep history of sexual selection on acoustic signalling in a slender-snouted group of crocodylians. Lastly, a cutmark analysis combined with accelerator mass spectrometry (AMS) radiocarbon dating of bone remains demonstrated that two individuals from Shang and Zhou dynasties in Guangdong, China, suffered head injuries and decapitation. Archaeological evidence together with historical accounts suggests the human-induced extinction of this unique crocodylian only a few hundred years ago.
Collapse
Affiliation(s)
- Masaya Iijima
- School of Resource and Environmental Engineering, Hefei University of Technology, 193 Tunxi Road, Baohe, Hefei, Anhui 230009, People's Republic of China,Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA,Nagoya University Museum, Furocho, Chikusa-Ku, Nagoya, Aichi 464-8601, Japan
| | - Yu Qiao
- School of Resource and Environmental Engineering, Hefei University of Technology, 193 Tunxi Road, Baohe, Hefei, Anhui 230009, People's Republic of China
| | - Wenbin Lin
- Xinhui Museum, 12 Gongyuan Road, Xinhui, Jiangmen, Guangdong 529199, People's Republic of China
| | - Youjie Peng
- Shunde Museum, Bishui Road, Shunde, Foshan, Guangdong 528300, People's Republic of China
| | - Minoru Yoneda
- The University Museum, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan
| | - Jun Liu
- School of Resource and Environmental Engineering, Hefei University of Technology, 193 Tunxi Road, Baohe, Hefei, Anhui 230009, People's Republic of China
| |
Collapse
|
6
|
Schwab JA, Young MT, Walsh SA, Witmer LM, Herrera Y, Timmons ZL, Butler IB, Brusatte SL. 'Ear stones' in crocodylians: a cross-species comparative and ontogenetic survey of otolith structures. R Soc Open Sci 2022; 9:211633. [PMID: 35345438 PMCID: PMC8941411 DOI: 10.1098/rsos.211633] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 02/25/2022] [Indexed: 05/03/2023]
Abstract
The vestibular system of the inner ear is a crucial sensory organ, involved in the sensation of balance and equilibrium. It consists of three semicircular canals that sense angular rotations of the head and the vestibule that detects linear acceleration and gravity. The vestibule often contains structures, known as the otoliths or 'ear stones'. Otoliths are present in many vertebrates and are particularly well known from the fossil record of fish, but surprisingly have not been described in detail in most tetrapods, living or extinct. Here, we present for the first time a survey of the otoliths of a broad sample of extant crocodylian species, based on computed tomography scans. We find that otoliths are present in numerous crocodylian species of different growth stages, and they continue to increase in size during ontogeny, with positive allometry compared to skull length. Our results confirm that otoliths are a common component of the crocodylian vestibular system, and suggest they play an important role in sensory detection. Otoliths are likely common, but overlooked, constituents of the inner ear in tetrapods, and a broader study of their size, shape and distribution promises insight into sensory abilities.
Collapse
Affiliation(s)
- Julia A. Schwab
- School of GeoSciences, Grant Institute, University of Edinburgh, James Hutton Road, The King's Buildings, Edinburgh EH9 3FE, UK
| | - Mark T. Young
- School of GeoSciences, Grant Institute, University of Edinburgh, James Hutton Road, The King's Buildings, Edinburgh EH9 3FE, UK
| | - Stig A. Walsh
- School of GeoSciences, Grant Institute, University of Edinburgh, James Hutton Road, The King's Buildings, Edinburgh EH9 3FE, UK
- National Museum of Scotland, Chambers Street, Edinburgh EH 1 1JF, UK
| | - Lawrence M. Witmer
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH 45701, USA
| | - Yanina Herrera
- CONICET. División Paleontología Vertebrados, Museo de La Plata, FCNyM, UNLP, La Plata, Argentina
| | - Zena L. Timmons
- National Museum of Scotland, Chambers Street, Edinburgh EH 1 1JF, UK
| | - Ian B. Butler
- School of GeoSciences, Grant Institute, University of Edinburgh, James Hutton Road, The King's Buildings, Edinburgh EH9 3FE, UK
| | - Stephen L. Brusatte
- School of GeoSciences, Grant Institute, University of Edinburgh, James Hutton Road, The King's Buildings, Edinburgh EH9 3FE, UK
- National Museum of Scotland, Chambers Street, Edinburgh EH 1 1JF, UK
| |
Collapse
|