Order Testudines

Question 1

Order Testudines

Answer 1

• The turtles
• 200 mya
• Fossils appear in the Upper Triassic
• 360+ spp.
• Synapomorphies:
  1. Diapsid (2 holes) secondarily evolved to an Anapsid (no holes) skull form
  2. Carapace & Plastron (belly)

Question 2

Turtle Shell

Answer 2

• The shell consists of a dorsal *carapace and ventral *plastron
  - Outer layer of *keratin and inner layer of *bone
• Fusion of flat ribs and vertebrae
• Unique: limb girdles deep within rib cage
• No teeth: keratinized beak
• Rigid shell -> turtle cannot expand its chest to breathe

Question 3

Turtle Breathing

Answer 3

Cannot expand chest to breathe
Lungs attached to carapace
- most must breathe inside “box” via contraction of muscle “sling” under ventral viscera
- use abdominal and pectoral muscles as a “diaphragm”
- *inhalation by contraction of limp flank muscles, increasing abdominal cavity volume
- *exhalation by drawing back the shoulder girdle to compress the vicera

Question 4

Turtle Reproduction

Answer 4

• All internally fertilize via copulation
• All oviparous & lay eggs in ground
• <27.7C = male; >31C = females (sea turtles)
• No parental care