Lab Part 2

1
Lab Part 2

• Skeletal parts

2
Marine Mammal Lab Part 2

• Skull Basics
• Temporal Fossa
• Bony Features
• Telescoping
• Sutures
• Nasal and Eye location
• Teeth

3
Skull Basics

• Cranium
• Mandible
• Rostrum (Maxilla, Premaxilla, nasal)
• Sagittal Crest
• Orbit of eye
• Temporal Fossa

4
Temporal Fossa

• A pit, depression or concavity on a bone or
  formed from several bones
• Anapsids (turtle)
• Diapsids (snakes, lizards, birds, dinosaurs)
• Synapsids (mammals)

5
Exercise 1

• On your own face find your temporal fossa
• Sketch your marine mammal skull, identify the
  mandible, orbit, sagittal crest, maxilla, and
  premaxilla

6
Bony Features

• Bony features are landmarks of the skull that are
  formed by one or more bony elements. They reflect
  evolutionary, developmental, and mechanical
  pressures in a visible manner.
• Bony features include Zygomatic Arch, Rostrum,
  Jaw articulation

7
(No Transcript)
8
Exercise 2

• On your sketch draw in the zygomatic arch
• Why would you expect the zygomatic arch of a
  pinniped to be different than a mysticete?

9
Telescoping

• Elongation of rostrum. It creates suture that
  have overlap with adjacent bones. You can see up
  to 4 overlapping bones.
• Telescoping differs for odontocetes and
  mysticetes.

10
Sutures

• Sutures are regions between adjacent bones. They
  are inflexible joints between flat bones. It
  appears as a thin line on the surface of the
  skull.
• Importance of sutures
• determines the muscle attachment to the bones
• determines the size and shape of the nerves and
  sensory capsules
• mechanical attachments for feeding, display,
  locomotion, and social interaction
• used to determine the age of the specimen.

11

• PLA plane (butt) joint
• FOL foliate joint
• SYN synchondrosis
• SER serrate joint
• SQA squamous (scarf) joint

12

• Coronal Suture
• Sagittal Suture

• Exercise 3
• Draw in your sketch the sutures on your skull

13
Nasal and Eye location

• Forward facing orbits
• Laterally facing orbits
• Position of the external nares may reflect
  respiratory adaptations to diving, feeding and
  locomotion

14
Exercise 4

• Where would you expect the external nare of a
  pinniped be located vs. a cetacean, Why?

15
Teeth

• Homodonts 1 type of tooth
• Monophydont 1 set of teeth in a life time
• Brachyodont short crowned teeth found in
  sirenians
• Heterodonts more than 1 type of teeth
• Incisors Used for slicing and chipping
• Canines Used for capturing and piercing
• Premolars molars Used for crushing and
  grinding
• Post Canine (teeth after canines, same as
  premolars and molars)

16
Dental Formula

• Specific Teeth identification
• Superscript number refer to to upper jaw
• Subscript numbers refer to lower jaw
• Dental Formula
• I2/2 C1/1 P3/3 M2/2
• Number of each type of tooth in one side of the
  upper jaw over the corresponding number occurring
  in one side on the lower jaw
• In case of milk teeth, use lower case letters

• I incisors
• C canines
• P premolars
• M molars
• PC post canines

17
Exercise 5

• What specific tooth is this?
• Write the dental formula for the skull you have