Vertebrate Zoology Lab VI- Amniota & Synapsida

We will be examining representative of some amniotes. Both the ancestors to the mammals evolved very early in amniote evolution. (The other major lineage of amniotes will be examined in the next two labs). Therefore, we will focus on them. Information for this lab is in Lab 8 of Gergus and Schuett.

 

1) Look at the preserved specimens and note the characteristics of the class and orders. Notice the diversity in body/skull morphology. Based on what you observe, what can you reasonably deduce about the ecology of these organisms?

 

2) From lab 1, use the diagrams of the cat and identify the major bones in these animals.

 

3) Identify the Orbit and the Jugal, Squamosal, and Parietal Bones. Find the Foramen Magnum and note the number of occipital condyles. How many bones form the lower jaw (look at one side only)?

 4) Mammals have what is called HETERODONT dentition. That is they have different kinds of teeth (for a comparison, look at the fish skull). Be able to identify the various kinds of teeth (i.e., incisors, canines, premolars, and molars). What is the function of each type of tooth? Look at the various skulls and, based on the teeth, try to determine their diet.

 

5) Examine the casts of the fossilized horse teeth (NB: most are a complete series of teeth in the jaw but several are either single or just a few of the teeth). What do these fossils tell you? What kinds of trends do you notice in the evolution of dentition in these organisms?

 

6) Look at the pictures in the book "Prehistoric Life" by David Norman (appropriate pages marked by yellow paper). These show artists reconstruction of some the ancient relatives/ancestors to mammals (a group called the Synapsida). Notice their overall size and shape. Please remember that these animals (e.g., Dimetrodon ) are NOT dinosaurs!

 

Know Figures 7.1, 8.1

Mammalia, Monotremata, Marsupialia, Placentalia,

Know the following structures: Frontal, parietal, occipital, temporal, zygomatic, maxilla, dentary, incisors, canines, premolars, molars,

Answer: Q3, Q13, Q16,

 

Skip: Fig 8.3 pp. 234-237 (Respiratory & Circulatory); pp. 244-245.