INVESTIGADORES
TALEVI Marianella
congresos y reuniones científicas
Título:
The ichthyiosaurian eyes: paleobiological information content in the sclerotic ring of Caypullisaurus (Ichthiosauria, Ophthalmosauria) and in other Jurassic ichthyiosaurs
Autor/es:
M. S. FERNÁNDEZ, ., F. ARCHUBY, M. TALEVI Y EBNER R
Reunión:
Congreso; 74 Reunión Anual de la Sociedad Paleontológica Alemana (74. Jahrestagung der Paläontologischen Gesellschaft in Göttingen; 2004
Resumen:
Growth pattern and visual acuity of the Caypullisaurus eye (Ichthyosauria: Ophthalmosauria) M. S. Fernández(1), F. Archuby(2), M. Talevi(3) And R. Ebner(3) 1- Departamento Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque, 1900 La Plata, Argentina, martafer@museo.fcnym.unlp.edu.ar; 2- Institut für Paläontologie der Universität, Pleicherwall 1, D-97070 Würzburg, Germany; 3- Facultad de Ciencias Naturales, Universidad Nacional de La Plata, Calle 60 y 122, 1900 La Plata, Argentina; 4- Unidad de Neurooftalmología, Hospital Británico, Perdriel 74, Buenos Aires, Argentina. 2- Institut für Paläontologie der Universität, Pleicherwall 1, D-97070 Würzburg, Germany; 3- Facultad de Ciencias Naturales, Universidad Nacional de La Plata, Calle 60 y 122, 1900 La Plata, Argentina; 4- Unidad de Neurooftalmología, Hospital Británico, Perdriel 74, Buenos Aires, Argentina. M. S. Fernández(1), F. Archuby(2), M. Talevi(3) And R. Ebner(3) 1- Departamento Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque, 1900 La Plata, Argentina, martafer@museo.fcnym.unlp.edu.ar; 2- Institut für Paläontologie der Universität, Pleicherwall 1, D-97070 Würzburg, Germany; 3- Facultad de Ciencias Naturales, Universidad Nacional de La Plata, Calle 60 y 122, 1900 La Plata, Argentina; 4- Unidad de Neurooftalmología, Hospital Británico, Perdriel 74, Buenos Aires, Argentina. 2- Institut für Paläontologie der Universität, Pleicherwall 1, D-97070 Würzburg, Germany; 3- Facultad de Ciencias Naturales, Universidad Nacional de La Plata, Calle 60 y 122, 1900 La Plata, Argentina; 4- Unidad de Neurooftalmología, Hospital Británico, Perdriel 74, Buenos Aires, Argentina. M. S. Fernández(1), F. Archuby(2), M. Talevi(3) And R. Ebner(3) 1- Departamento Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque, 1900 La Plata, Argentina, martafer@museo.fcnym.unlp.edu.ar; 2- Institut für Paläontologie der Universität, Pleicherwall 1, D-97070 Würzburg, Germany; 3- Facultad de Ciencias Naturales, Universidad Nacional de La Plata, Calle 60 y 122, 1900 La Plata, Argentina; 4- Unidad de Neurooftalmología, Hospital Británico, Perdriel 74, Buenos Aires, Argentina. 2- Institut für Paläontologie der Universität, Pleicherwall 1, D-97070 Würzburg, Germany; 3- Facultad de Ciencias Naturales, Universidad Nacional de La Plata, Calle 60 y 122, 1900 La Plata, Argentina; 4- Unidad de Neurooftalmología, Hospital Británico, Perdriel 74, Buenos Aires, Argentina. Departamento Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque, 1900 La Plata, Argentina, martafer@museo.fcnym.unlp.edu.ar; 2- Institut für Paläontologie der Universität, Pleicherwall 1, D-97070 Würzburg, Germany; 3- Facultad de Ciencias Naturales, Universidad Nacional de La Plata, Calle 60 y 122, 1900 La Plata, Argentina; 4- Unidad de Neurooftalmología, Hospital Británico, Perdriel 74, Buenos Aires, Argentina. In the eyes of many extant reptiles there is an osseous ring embedded within the sclera and around the cornea. This sclerotic ring was well developed and is frequently preserved in ichthyosaurs. Significant information can be drawn from it, such as eyeball diameter and relative size of the cornea. Estimation of these parameters in extinct forms is significant as they are closely related to vision capability. We present here insights into the growth pattern and vision capabilities of some Jurassic ichthyosaurs as inferred from the analysis of the sclerotic rings and orbit sizes. The suggested growth pattern of Caypullisaurus eyes is similar to that of human eyes. Thus, the cornea did not grow as much as the rest of the eye. The relative size of the sclerotic ring and orbits can be used as a complementary criterion for estimating relative age in some ichthyosaurs. In juveniles the aperture of the sclerotic ring represents approximately 20% of the orbital area. This percentage decreases in adults. The most striking property of the parvipelvian ichthyosaur eye is its large absolute size. The absolute size of an eye is very important as it is absolute rather than relative size which determines visual acuity. An increase in the eyeball diameter results in an increase of the resolution of the details of the image. If the simplest way to increase the visual acuity is to have a large eye, then all parvipelvian ichthyosaurs must have had a good visual performance. Previously, it has been suggested that the large eyes allowed Ophthalmosaurus to hunt small, fast-moving prey. This could be also true not only for this genus but for other parvipelvians (like Caypullisaurus), as squid-like cephalopds (belemnites) seem to be an important item in fish-shaped ichthyosaur diet. It is noteworthy that in some belemnites, the presence of an ink sac has been suggested. Animals that fed on them must have had high visual acuity. Also it must be considered that ichthyosaurs were probably intermediate species within a food web, so a good visual performance could be significant not only for prey detection but also for escaping from predators. The most striking property of the parvipelvian ichthyosaur eye is its large absolute size. The absolute size of an eye is very important as it is absolute rather than relative size which determines visual acuity. An increase in the eyeball diameter results in an increase of the resolution of the details of the image. If the simplest way to increase the visual acuity is to have a large eye, then all parvipelvian ichthyosaurs must have had a good visual performance. Previously, it has been suggested that the large eyes allowed Ophthalmosaurus to hunt small, fast-moving prey. This could be also true not only for this genus but for other parvipelvians (like Caypullisaurus), as squid-like cephalopds (belemnites) seem to be an important item in fish-shaped ichthyosaur diet. It is noteworthy that in some belemnites, the presence of an ink sac has been suggested. Animals that fed on them must have had high visual acuity. Also it must be considered that ichthyosaurs were probably intermediate species within a food web, so a good visual performance could be significant not only for prey detection but also for escaping from predators. Caypullisaurus eyes is similar to that of human eyes. Thus, the cornea did not grow as much as the rest of the eye. The relative size of the sclerotic ring and orbits can be used as a complementary criterion for estimating relative age in some ichthyosaurs. In juveniles the aperture of the sclerotic ring represents approximately 20% of the orbital area. This percentage decreases in adults. The most striking property of the parvipelvian ichthyosaur eye is its large absolute size. The absolute size of an eye is very important as it is absolute rather than relative size which determines visual acuity. An increase in the eyeball diameter results in an increase of the resolution of the details of the image. If the simplest way to increase the visual acuity is to have a large eye, then all parvipelvian ichthyosaurs must have had a good visual performance. Previously, it has been suggested that the large eyes allowed Ophthalmosaurus to hunt small, fast-moving prey. This could be also true not only for this genus but for other parvipelvians (like Caypullisaurus), as squid-like cephalopds (belemnites) seem to be an important item in fish-shaped ichthyosaur diet. It is noteworthy that in some belemnites, the presence of an ink sac has been suggested. Animals that fed on them must have had high visual acuity. Also it must be considered that ichthyosaurs were probably intermediate species within a food web, so a good visual performance could be significant not only for prey detection but also for escaping from predators. Ophthalmosaurus to hunt small, fast-moving prey. This could be also true not only for this genus but for other parvipelvians (like Caypullisaurus), as squid-like cephalopds (belemnites) seem to be an important item in fish-shaped ichthyosaur diet. It is noteworthy that in some belemnites, the presence of an ink sac has been suggested. Animals that fed on them must have had high visual acuity. Also it must be considered that ichthyosaurs were probably intermediate species within a food web, so a good visual performance could be significant not only for prey detection but also for escaping from predators.