Vertebrate Zoology 7 - Crocodylia

What are Archosaurs?

Diapsids with two additional skull openings.

What are "thecodont" teeth?

Teeth held in sockets by periodontal ligaments.

What muscle in archosaurs aids jaw movement?

The "Pterygoideus" muscle.

What is the "fourth trochanter"?

A process on the femur shaft for attachment of the powerful caudofemoralis (CFL) muscle.

What type of ankle joint do crocodilians have?

Crurotarsal ankle, where the ankle joint is stitched to the tibia, and the heel bones functions as part of the foot.

What unique feature do crocodilians have in their sinuses?

Paranasal air sacs forming the caviconchal sinus

Gait

• The way an animal walks or moves.

What are the two possible gaits in crocodilians?

High walk and sprawl.

What allows crocodilians to alternate between gaits?

A complex hip joint with a slightly angled, round femoral head.

What is unique about crocodilian respiration?

They use pelvic aspiration, where the diaphragmatic muscle pulls the liver, and the ischiopubic muscle moves the pubis.

What are gastralia in crocodilians?

Dermal bones in the ventral abdomen that stiffen and unify the abdominal wall.

What three skeletal components form a crocodilian's dermal skeleton?

Cranium, gastralia, and osteoderms.

What are osteoderms?

Bony plates within the skin, often with a ridge or keel, for protection and heat exchange.

What is a defining feature of aetosaurs?

They were heavily armored, covered in osteoderms.

How do you distinguish between crocodylidae and alligatoridae?

Crocodylidae have a V-shaped snout with a more slender, elongated head, while Alligatoridae feature a broader, U-shaped snout and their upper jaw overlaps the lower jaw.

What are 2 features of crocodilian eyes?

• Iris, vertical slit by day, widens by night.

• Night vision.

What adaptation helps crocodilians be effective ambush predators?

Eyes, ears, and nostrils are raised above the tip of the snout.

What is twist-feeding in crocodilians?

A method of dismembering large prey by spinning the body.

What is the function of shunting CO₂-rich blood to the stomach?

It aids in digestion by promoting gastric acid production.

How do male crocodilians mate?

They curl their tail under the female while lying to the side.

What is temperature-sensitive sex determination in crocodilians?

The incubation temperature of eggs determines the sex of hatchlings.

What type of airflow do crocodilian lungs exhibit?

Unidirectional airflow.

How do crocodilians excrete nitrogen waste?

As ammonia in freshwater conditions and as uric acid in hyperosmotic conditions.