Lab Final General Questions

Question 1

Typical rodent dental formula

Answer 1

1/1, 0/0, 0/0, 3/3 = 16

Question 2

Answer 2

• Left = sciurognathus lower jaw = angular process of dentary is aligned with the jaw
• Right = hystricognathus lower jaw = angular process of dentary is inflected

Question 3

What type of skull is this?

Answer 3

Protrogomorphous (primitive)

Small infraorbital foramen, flat zygomatic arch

Mountain beaver

Question 4

What type of skull is this?

Answer 4

Sciuromorphous (squirrel-like)

Tiny/absent infraorbital foramen, zygomatic plate for lateral masseter attachment

Beaver skull

Question 5

What type of skull is this?

Answer 5

Myomorphous (mouse-like)

Larger infraorbital foramen with lateral plate

Muskrat

Question 6

What type of skull is this?

Answer 6

Hystricomorphous (porcupine-like)

Huge infraorbital foramen for masseter to pass through

New-world porcupine

Question 7

What type of feet do perissodactyls have? What about artiodactyls?

Answer 7

• Perissodactyla = mesaxonic feet (odd-toed)
• Artiodactyla = paraxonic feet (even-toed)
• Have different weight distributions
  
  • Paraxonic weight bearing is mainly divided between 3rd and 4th digits
  • Mesaxonic bear weight on 3rd digit only

Question 8

Describe pronghorn horns

Answer 8

• Horns are composed of bony layer with deciduous keratinous sheath underneath
• New layer grows underneath and old layer is shed each year

Question 9

Describe Cervidae antlers

Answer 9

• Bony antlers grow and are shed each year
• Branched
• Growing antlers are covered in velvet - highly vascularized skin that supplies growing bone tissue with nutrients
• After mating season, bones weaken and distal portion of antler is shed
• Fastest growing tissue other than cancer

Question 10

Describe Bovidae horns

Answer 10

• Surface of keratin
• Inner core of dermal bone (derived from frontal bone of skull) covered by keratinized sheath (derived from epidermis)
• Grow continuously and are never shed

Question 11

What is baleen?

Answer 11

• Composed of keratin
• Plates of keratin hang in comb-like fashion from upper jaw only
• Continuously grows

Question 12

What does rorqual refer to?

Answer 12

• Large mysticetes
• Have longitudinal grooves or pleats on throat and chest that allow for greater expansion of oral cavity as throat fills with water during gulping

Question 13

What are the similarities between cetaceans and artiodactyls?

Answer 13

• Paraxonic limbs
• Extensive lacrimals
• Three bronchi

Question 14

Four ways to estimate age from dentition

Answer 14

• Cementum annuli
• Tooth eruption
• Fluting (muskrats)
• Tooth wear

Question 15

Other ways to determine age

Answer 15

• Epiphyseal sutures
• Saggital crest development
• Cranial suture closures
• Horn annuli
• Eye lens weight
• Baculum length
• Embryonic development
• Molt patterns

Question 16

Locomotion patterns, ground contact, and fused vs. unfused metapodials in suiformes, ruminata, and tylopoda

Answer 16

• Suiformes
  
  • Ambulatory locomotion, plantigrade foot posture, unfused metapodials
• Ruminata
  
  • Cursorial locomotion, unguligrade foot posture, fused metapodials (cannon bone)
• Tylopoda
  
  • Pacing locomotion, digitigrade foot posture, fused metapodials (cannon bone)