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Scleral Ring

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intense changes in pressure in the air and in the water. Additionally, scleral rings may help the eye adjust to different viewing differences, also known as visual accommodation. Muscles are used to adjust the shape of the eye for accommodation, and the rings provide attachment sites for these muscles. In aquatic animals, the lens is squeezed in a different way to compensate for differences in
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Scleral rings may help support inner structures of the eye, especially in animals that do not have round eyes. Animals that move rapidly, including both fast flying birds and fast swimming fish have the most robust scleral rings, indicating that these thick rings are used to protect the eye during
93:), or often a combination of both, that comes together to form a ring. The arrangement, size, shape, and number of ossicles vary by group. They are believed to have a role in supporting the eye, especially in animals whose eyes are not spherical, or which live underwater. 229:
Teleost fish typically have only one or two ossicles per ring, and fish with no ossicles still retain cartilage. Most teleosts do not have ossicles, but this can vary even within groups. As a general trend, more basal groups (such as
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had scleral rings, so the trait was lost over time. Scleral rings of varying lengths, curvatures, numbers of ossicles, and thickness are found in all birds. Birds typically have 12-18 ossicles, with 14 being the most common number.
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A combination of scleral cartilage and ossicles are present, in which the cartilage acts as a cup around the posterior (rear) position of the eye and ossicles at the anterior (front) position of the eye form the ring.
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lifestyle or lack of limbs, indicating a possible correlation among these traits and loss of the scleral ring. Lizards typically have 14 ossicles in the ring, though this can vary.
78:", an unrelated medical condition), recent authors have urged avoiding the use of this term, to avoid confusion and to increase the utility of character comparisons. 256: 754: 326: 193:, crocodilians, and relatives), only birds and turtles retain the scleral rings. Fossil evidence shows that extinct marine crocodiles living in the 350: 635:"The anatomical relationships between the avian eye, orbit and sclerotic ring: implications for inferring activity patterns in extinct birds" 586: 308: 418: 1034: 245:
More active fish are more likely to have scleral rings, indicating that the rings help keep the eye stable during rapid swimming.
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fish are the only family to retain scleral rings, with the rings being absent in the more basal clades
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underwater, and so the shape of the ring can be different than those in terrestrial animals.
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lack scleral rings. The ring is in the fibrous outer layer of the eye, called the
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The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
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The vertebrate eye and its adaptive radiation [by] Gordon Lynn Walls
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Parentheses denote bones that receive a different name in particular clades
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Italics denote neomorphic bones present only in particular clades
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Atkins, Jade B.; Franz-Odendaal, Tamara A. (October 2016).
170:, which are both legless lizard families. All of these 1880: 1808: 1770: 1747: 1716: 1707: 1698: 1663: 1630: 1553: 1488: 1479: 1451: 1403: 1394: 1362: 1296: 1287: 1221: 1156: 1054: 1009: 943: 922: 803: 794: 34:is a hardened ring of plates, often derived from 748: 697:Franz-Odendaal, Tamara A. (22 January 2008). 457:Franz-Odendaal, Tamara Anne (December 2018). 8: 421:. UC Museum of Paleontology. Archived from 1713: 1704: 1695: 1550: 1485: 1476: 1400: 1293: 1284: 1273: 1019:(Supraoccipital+Exoccipital+Basioccipital) 1006: 919: 800: 791: 778: 755: 741: 733: 666: 540: 530: 474: 97:scleral rings are known for a variety of 174:that lack a scleral ring share either a 406: 294:Virtually complete scleral ring of the 252: 206:While all fish have scleral cartilage, 70:often implies pathology of the sclera ( 412: 410: 158:, or snakes, and two families within 7: 1822:) (Tibiale+Intermedium+Centrale 3+4) 692: 690: 688: 686: 508: 506: 504: 502: 452: 450: 448: 446: 444: 442: 440: 417:Motani, Ryosuke (15 November 2001). 25: 1043:(Squamosal+Petrosal+Ectotympanic) 651:10.1111/j.1469-7580.2008.00897.x 589:. Natural History Museum, London 391: 377: 349: 325: 307: 287: 271: 255: 633:Hall, Margaret I. (June 2008). 113:, but are often not preserved. 27:Ring of bone supporting the eye 332:Skull and scleral ring of the 282:, showing large scleral rings. 266:, showing large scleral rings. 1: 81:Scleral rings can be made of 566:"Re: Sclerotic ring in eyes" 1031:(Parasphenoid+Basisphenoid) 1985: 1927: 1845: 1599: 1283: 1272: 1112: 790: 777: 608:Walls, Gordon L. (1942). 280:satanic leaf-tailed gecko 1025:(Exoccipital+Opisthotic) 314:Partial scleral ring of 38:, that is found in the 1786:Intermediate cuneiform 932:(Postparietal+Tabular) 620:10.5962/bhl.title.7369 419:"Eyes of Ichthyosaurs" 463:The Anatomical Record 278:A skull of an extant 262:A skull of an extant 46:in several groups of 1278:Postcranial skeleton 1037:(Prootic+Opisthotic) 356:Scleral ring of the 89:) or bony material ( 1834:(Distal tarsal 4+5) 425:on 17 December 2001 385:Paleontology portal 101:animals, including 1954:Vertebrate anatomy 1316:Cervical vertebrae 639:Journal of Anatomy 519:Journal of Anatomy 50:. Some species of 1941: 1940: 1923: 1922: 1919: 1918: 1876: 1875: 1872: 1871: 1868: 1867: 1841: 1840: 1809:Composite tarsals 1793:Lateral cuneiform 1791:Distal tarsal 3 ( 1784:Distal tarsal 2 ( 1777:Distal tarsal 1 ( 1626: 1625: 1622: 1621: 1595: 1594: 1581:Distal carpal 4 ( 1574:Distal carpal 3 ( 1567:Distal carpal 2 ( 1560:Distal carpal 1 ( 1390: 1389: 1268: 1267: 1264: 1263: 1152: 1151: 1050: 1049: 939: 938: 532:10.1111/joa.12498 236:Osteoglossomorpha 87:scleral cartilage 16:(Redirected from 1976: 1959:Dinosaur anatomy 1779:Medial cuneiform 1717:Proximal tarsals 1714: 1705: 1696: 1551: 1523:Lateral centrale 1486: 1477: 1401: 1331:Caudal vertebrae 1321:Dorsal vertebrae 1294: 1285: 1274: 1029:Parabasisphenoid 1007: 920: 801: 792: 779: 757: 750: 743: 734: 727: 726: 715:10.1002/ar.20639 694: 681: 680: 670: 630: 624: 623: 605: 599: 598: 596: 594: 585:Milner, Angela. 582: 576: 575: 573: 572: 561: 555: 554: 544: 534: 510: 497: 496: 478: 476:10.1002/ar.24043 454: 435: 434: 432: 430: 414: 401: 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Retrieved 580: 569:. Retrieved 559: 522: 518: 466: 462: 427:. Retrieved 423:the original 360: 341:Viatkogorgon 339: 334:gorgonopsian 315: 298: 244: 228: 205: 180: 137: 133: 115: 103:ichthyosaurs 90: 86: 80: 71: 67: 60:crocodilians 32:scleral ring 31: 29: 1729:Intermedium 1518:Intermedium 1236:Ceratohyoid 1071:Alisphenoid 1023:Otoccipital 966:Exoccipital 867:Postorbital 862:Postfrontal 296:ichthyosaur 240:Percomorpha 232:Elopomorpha 216:Chondrostei 168:Rhineuridae 160:Anguimorpha 140:Lepidosaurs 48:vertebrates 1948:Categories 1911:Osteoderms 1850:Metatarsal 1816:Astragalus 1763:Centrale 4 1760:Centrale 3 1757:Centrale 2 1754:Centrale 1 1604:Metacarpal 1512:Triquetral 1382:Caudal rib 1377:Dorsal rib 1251:Thyrohyoid 1246:Stylohyoid 1213:Surangular 1202:Predentary 976:Opisthotic 882:Premaxilla 877:Prefrontal 819:Internasal 805:Skull roof 593:15 October 571:2007-07-06 429:15 October 371:References 317:Mosasaurus 224:Amiiformes 107:pterosaurs 85:material ( 56:amphibians 1901:Gastralia 1895:Baubellum 1855:Phalanges 1826:Navicular 1748:Centralia 1738:Calcaneum 1609:Phalanges 1569:Trapezoid 1562:Trapezium 1423:Cleithrum 1345:Pygostyle 1298:Vertebrae 1231:Basihyoid 1176:Articular 1117:Columella 1089:Pterygoid 1017:Occipital 944:Braincase 904:Squamosal 836:Zygomatic 659:0021-8782 485:1932-8486 358:hadrosaur 337:therapsid 212:Cladistia 176:burrowing 164:Dibamidae 156:Serpentes 111:dinosaurs 76:sclerosis 68:sclerotic 1734:Fibulare 1665:Hindlimb 1576:Capitate 1538:Pisiform 1502:Scaphoid 1453:Forelimb 1428:Coracoid 1413:Clavicle 1241:Epihyoid 1208:Splenial 1186:Coronoid 1158:Mandible 1094:Quadrate 1083:Prevomer 1077:Palatine 1041:Temporal 1035:Petrosal 857:Parietal 842:Lacrimal 771:skeleton 768:tetrapod 723:18213703 677:18510506 551:27240556 493:30548203 195:Mesozoic 130:Reptiles 42:of many 1889:Baculum 1724:Tibiale 1689:Patella 1640:Ischium 1544:Pteroid 1498:Radiale 1461:Humerus 1443:Sternum 1438:Scapula 1417:Furcula 1191:Dentary 1180:Malleus 1166:Angular 991:Prootic 961:Ethmoid 914:Tabular 893:Rostral 847:Maxilla 813:Frontal 796:Cranium 766:in the 668:2423400 542:5013065 249:Gallery 208:Teleost 187:turtles 181:Within 152:tuatara 148:lizards 138:Within 99:extinct 52:mammals 44:animals 1860:Ungual 1832:Cuboid 1709:Tarsus 1683:Fibula 1614:Ungual 1583:Hamate 1527:Lunate 1508:Ulnare 1490:Carpus 1338:Coccyx 1326:Sacrum 1121:Stapes 1055:Palate 721:  675:  665:  657:  549:  539:  491:  483:  222:, and 172:clades 144:snakes 95:Fossil 64:sclera 58:, and 1969:Skull 1820:Talus 1678:Tibia 1673:Femur 1650:Pubis 1645:Ilium 1481:Manus 1306:Atlas 1289:Axial 1223:Hyoid 1104:Vomer 1098:Incus 852:Nasal 832:Jugal 784:Skull 764:Bones 191:birds 1471:Ulna 1364:Ribs 1311:Axis 719:PMID 673:PMID 655:ISSN 595:2013 547:PMID 489:PMID 481:ISSN 431:2013 234:and 202:Fish 166:and 40:eyes 36:bone 30:The 1964:Eye 1700:Pes 711:doi 707:291 663:PMC 647:doi 643:212 616:doi 537:PMC 527:doi 523:229 471:doi 467:303 72:see 1950:: 717:. 705:. 701:. 685:^ 671:. 661:. 653:. 641:. 637:. 545:. 535:. 521:. 517:. 501:^ 487:. 479:. 465:. 461:. 439:^ 409:^ 226:. 218:, 214:, 189:, 162:: 150:, 146:, 105:, 54:, 1892:/ 1818:( 1795:) 1788:) 1781:) 1740:) 1736:( 1585:) 1578:) 1571:) 1564:) 1529:) 1525:( 1514:) 1510:( 1504:) 1500:( 1419:) 1415:( 1182:) 1178:( 1172:) 1168:( 1123:) 1119:( 1100:) 1096:( 1073:) 1069:( 838:) 834:( 756:e 749:t 742:v 725:. 713:: 679:. 649:: 622:. 618:: 597:. 574:. 553:. 529:: 495:. 473:: 433:. 365:. 344:. 320:. 185:( 142:( 74:" 20:)

Index

Sclerotic rings
bone
eyes
animals
vertebrates
mammals
amphibians
crocodilians
sclera
sclerosis
cartilaginous
Fossil
extinct
ichthyosaurs
pterosaurs
dinosaurs
light refraction
Lepidosaurs
snakes
lizards
tuatara
Serpentes
Anguimorpha
Dibamidae
Rhineuridae
clades
burrowing
Archelosauria
turtles
birds

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