Lecture 14 Flashcards
Carnivorous Pelycosurs (Sail and Posture)
- Sail used in intra-specific communication or as a solar collector
- Sprawling posture
Herbivorous Pelycosaurs (teeth and rib cage):
- Blunt teeth organized as a crushing plate
- Laterally expanded rib cage suggesting a large gut used in fermentation of plant material
Features of Dinocephalians:
- Heavy skulls (used for intraspecific head-butting
- Begin a trend toward more erect limbs
Features of Cynodonts:
- Mammal-like reptiles
- Evolved changes in jaw musculature that allowed chewing
Features of Cynodonts (Cranium structure):
- Evolved changes in jaw musculature that allowed chewing
- Adductor differentiates into masseter and temporalis muscles, expand and invade larger areas of the skull roof bones
Pelycosaurs Characteristics:
- One occipital condyle (like reptiles)
- Sprawled posture beings a medially directed force toward the shoulder girdle
Cynodonts Characteristics:
- Double occipital condyles (like mammals… Greater mobility of neck
- Limbs brought underbody, forces directed less toward the midline and more in a vertical direction… Greater stride length
Mammalian Characteristics (4):
- Feed young milk secreted from mammary glands
- Extended parental care of young
- Large brain/body size ratio
- Hair (integumentary derivative)
Fossil Mammals: Skeletal Characteristics (Cervical):
Lack of reduction of ribs, seven cervical vertebrae
1. two condyles
2. best atlas-axis rotation
Fossil Mammals: Skeletal Characteristics (Thoracic)
Ribs
Fossil Mammals: Skeletal Characteristics (Lumbar)
No ribs
Fossil Mammals: Skeletal Characteristics (Sarcal)
Articulate with pelvic girdle
Fossil Mammals: Skeletal Characteristics (Caudal)
Presence of hemal arch
Fossil Mammals: Middle Ear Bones (3)
- Incus
- Malleus
- Stapes
Fossil Mammals: Jaw Evolution (3)
- Lower jaw is now made up of a single bone, the dentary
- Jaw joint is now between dentary and squamosal
- Quadrate and articular are now part of the middle ear
Types of Fossil Mammals Teeth (4):
- Incisors
- Canines
- Premolars
- Molars