lab 2 - osteology of sharks, bony fish, and reptiles 2 - osteology... · lab 2 osteology of sharks,...

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G404 Geobiology Fall 2013 Name __________________________________ Lab 2 Osteology of sharks, bony fish, and reptiles Use the materials in this lab to familiarize yourself with the skull and skeleton of living sharks, bony fish, and reptiles. The skulls are complicated and varied, so consider the following tasks as a way to make sense of the material: 1. Identify elements belonging to the chondrocranium (base of the braincase and sense organs), splanchnocranium (gill arches and components of the mandibular and hyoid arches), and dermatocranium (the outer bones, most of which lie not far below the skin). 2. Find the parietal and tabular on all of the skulls (note: not all groups possess both of these bones). 3. Which bones encircle the orbit on each skull? 4. Which bones support teeth? 5. Which bones are involved in the joint between upper and lower jaws? 6. Which taxon has the fewest skull bones? What are some of the extra bones on those with more? 7. What structures are present in the shark skull? Assignment Using the specimens available in lab, begin compiling information about the presence and absence of skeletal characteristics. We will use this information in later labs to perform your own phylogenetic analysis of selected living vertebrates. The kind of information useful at this broad level is the gain and loss of bones or major transformations in homologous bones. Typical examples of phylogenetic characters are “tabular bone (1) present or (2) absent” or “jaw joint (1) between quadrate and articular bones or (2) between dentary and squamosal bones” or “occipital condyle (1) single or (2) double”. For each taxon in your analysis you will eventually need to record the condition of these characters by assigning each variant (state) a number and recording the appropriate number for each taxon. To be useful, the character must vary among taxa being considered. Ideally each variant will be shared by at least two taxa. For this lab, identify at least ten characters that vary among four taxa: shark, bony fish, and amphibian, and reptile. 1. Describe each character and its variants using similar format as above. 2. Record the species name, class name, and specimen number for your four taxa. 3. For each species, record the character state (variant) for each of your ten characters.

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Page 1: Lab 2 - Osteology of sharks, bony fish, and reptiles 2 - Osteology... · Lab 2 Osteology of sharks, bony fish, and reptiles Use the materials in this lab to familiarize yourself with

G404 Geobiology Fall 2013

Name __________________________________

Lab 2 Osteology of sharks, bony f ish, and repti les

Use the materials in this lab to familiarize yourself with the skull and skeleton of living sharks, bony fish, and reptiles. The skulls are complicated and varied, so consider the following tasks as a way to make sense of the material:

1. Identify elements belonging to the chondrocranium (base of the braincase and sense organs), splanchnocranium (gill arches and components of the mandibular and hyoid arches), and dermatocranium (the outer bones, most of which lie not far below the skin).

2. Find the parietal and tabular on all of the skulls (note: not all groups possess both of these bones).

3. Which bones encircle the orbit on each skull? 4. Which bones support teeth? 5. Which bones are involved in the joint between upper and lower jaws? 6. Which taxon has the fewest skull bones? What are some of the extra bones on those

with more? 7. What structures are present in the shark skull?

Assignment

Using the specimens available in lab, begin compiling information about the presence and absence of skeletal characteristics. We will use this information in later labs to perform your own phylogenetic analysis of selected living vertebrates. The kind of information useful at this broad level is the gain and loss of bones or major transformations in homologous bones.

Typical examples of phylogenetic characters are “tabular bone (1) present or (2) absent” or “jaw joint (1) between quadrate and articular bones or (2) between dentary and squamosal bones” or “occipital condyle (1) single or (2) double”. For each taxon in your analysis you will eventually need to record the condition of these characters by assigning each variant (state) a number and recording the appropriate number for each taxon. To be useful, the character must vary among taxa being considered. Ideally each variant will be shared by at least two taxa.

For this lab, identify at least ten characters that vary among four taxa: shark, bony fish, and amphibian, and reptile.

1. Describe each character and its variants using similar format as above. 2. Record the species name, class name, and specimen number for your four taxa. 3. For each species, record the character state (variant) for each of your ten

characters.

Page 2: Lab 2 - Osteology of sharks, bony fish, and reptiles 2 - Osteology... · Lab 2 Osteology of sharks, bony fish, and reptiles Use the materials in this lab to familiarize yourself with

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Shark (Chondrichthyes)

(from Romer and Parsons, 1977, The Vertebrate Body)

(from Walker and Homberger, 1992, Vertebrate Dissection)

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(from Walker and Homberger, 1992, Vertebrate Dissection)

Bony Fish (Osteicthyes)

(from Romer and Parsons, 1977, The Vertebrate Body)

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(from Walker and Homberger, 1992, Vertebrate Dissection)

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Salamander (Amphibia)

(from Trueb, 1993, Patterns of Cranial Diversity among the Lissamphibia)

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Turtle Skull

(from Romer and Parsons, 1977, The Vertebrate Body)

L izard Skull

(from Romer and Parsons, 1977, The Vertebrate Body)

Al l igator Skull

(from Romer and Parsons, 1977, The Vertebrate Body)