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Frog skull parts2/15/2024 Illustrations from Jollie (1962) under CC0 public domain: Ichthyostega reconstruction on right from Wikipedia user Matteo De Stefano/MUSE under CC BY-SA 3.0. Skull of Ichthyostega, a basal tetrapod, in lateral (A), dorsal (B), and ventral (C) views. Illustrations from Jollie (1962) under CC0 public domain Seymouria reconstruction from Wikipedia user Dmitry Bogdanov under CC BY 3.0įigure 3.3. Skull of Seymouria, a reptile-like tetrapod from the Early Permian in lateral (A), dorsal (B), ventral (C), posterior (D) views, and medial view of the right lower jaw (E). Günter Bechly under CC BY-SA 3.0.įigure 3.2. From Jollie (1962) under CC0 public domain Eusthenopteron reconstruction from Wikipedia user Dr. Skull of Eusthenopteron, a prehistoric sarcopterygian fish closely related to tetrapods, lateral view. Eusthenopteron had foot-like fins, Ichthyostega had fin-like feet, and Seymouria probably had the familiar five-toed feet of many modern tetrapods.įigure 3.1. Eusthenopteron, Ichthyostega, and Seymouria are all early branches from the lineage that led to modern tetrapods. With the dependence on lungs, gills were lost and the opercular series was lost with them. The evolution of internal nostrils, or choanae, was a means to pass air from outside the body into the newly evolved lungs for respiration. Many skull bones underwent fusion, and some joints became akinetic. The more derived skulls tend to be longer, due mostly to the elongation of the snout that correlate with differences in feeding. The evolutionary transition from water to land was marked by major changes in the skull and skeleton of the early tetrapods. Checklist of skull bones by region and evolutionary/developmental origin Try to be systematic and creative in your approach to learning skull morphology. Or perhaps you will want to start with the lower jaw and dispense with that before continuing to the cranium. You might look for the nasal bones, follow those to the frontals, and continue from there. Try to develop a consistent approach to any skull that you examine. The dermal bones tend to be faithful to their position relative to the nares, orbits, and fenestrae, and you might start with a focus on those. The table on the following page sorts the bones by cranial region as well as by their location or by the structure to which they contribute. See the terms list here: Terms 3.1–3.6 Strategies for success For a given clade, you only need to know the objects in the pertinent list. The diagrams are organized phylogenetically, and the list of specified objects for a group can be found at the beginning of the section containing the diagram for that group. Bones are lost, fused, and gained throughout evolutionary history, and we have provided separate lists for each taxonomic group. After this lab, you will be able to identify the objects listed below in bold face in the articulated skull, and you will learn to identify the objects with asterisks (*) in isolation. By walking through the evolutionary history of vertebrate skulls, you will learn to recognize morphological differences among taxa based on both their ancestry and their functional demands. Adapting to such large changes in the environment involved major shifts in morphology. The evolutionary transition of vertebrates from water to land was accompanied by large changes in the demands of feeding, gas exchange, and sensation. In this lab, we transition from fish skulls to tetrapod skulls. Observe the differences in morphology among species from different taxonomic groups and under divergent functional demands.Recognize the development origin (endochondral or intramembranous) and cranial region (neurocranium, splanchnocranium, dermatocranium) to which each object belongs.Identify all of the major elements of the non-mammalian tetrapod skull.Vertebra: each of the bones forming the spinal column. Tarsus: each of the bones forming the heel. Metatarsus: each of the bones forming the part of the foot between Phalanges: each of the bones forming the toes. Ischium: one of three bones forming the ilium. Urostyle: adaptation of one or several vertebrae, stretching Metacarpus: each of the bones forming the part of the hand between Occipital lateral: occipital lateral bone.Ĭarpus: each of the bones forming the wrist. Phalange: each of the small bones forming the fingers. Prootic: bones forming the auditory region. Orbital cavity: skull cavity that contains the eye. Visual Dictionary - Copyright © 2005-2016 - All rights reserved.Īnd ponds. Voici le code UBB déjà fait, pour voir cette image sur votre Forum : Voici le code HTML déjà fait, pour voir cette image sur votre site web : Skeleton of a frog - Visual Dictionary - Copyright © 2005-2016 - All rights reserved.
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