Digestion & Genes Flashcards
Canid vertebral column
Shorter - 13T and 7L vertebrae
More flexible
LUMBAR
shorter transverse processes - shorter gut
FLEXION
dorsoventral flexion great
Equid vertebral column
Long - 18T and 6L vertebrae
Relatively inflexible
Remains straight through all gaits
LUMBAR
long transverse processes support musculature that supports the gut
Equid skull shape
Eyes on the side of the head - look out for predators
Small zygomatic arches - reflects relatively small size of temporalis
Massive mandible - accommodate attachment of huge masseter caudally and house large grinding teeth rostrally
Narrow gape - due to masseter size
Large paramastoid (jugular) process for attachment of large digastricus muscle - opening jaw during grazing
Occlusal surface below TMJ - small gape, lots of forward movement (grinding)
Mandibular fossa wide and flat - range of movements
Canid skull shape
Eyes face forward - depth perception, hunting
Wide zygomatic arches - allow for bulk of temporalis
Relatively small ramus of mandible - masseter less important, little need for transitional movement and it would reduce gape
Large gape - exposes carnassial teeth for slicing meat
Small paramastoid (jugular) process - only occasional jaw opening, strong muscle not needed
Occusal surface level with TMJ - large gape, small forward movement
Equid pupils
Horizontal rectangular pupils, scanning the horizon
Canid pupils
Round pupils, greater visual acuity for hunting
Dentition of equid
[I3/3 C1/1 P3-4/3 M3/3]
Two functional groups:
- insciors, crop grass
- premolars & molars, grinding grass
- canines are vestigial or absent
Hypsodont :
Crowns of teeth long and continue to erupt
Cementum, dentine and enamel = uneven surface
Dentition of canid
[I3/3 C1/1 P4/4 M2/3]
True heterodonts:
- incisors, nibbling
- canines, catch prey
- premolars, slicing
- molars, crushing
Carnassial teeth - UPM1 and LM1
At the widest part of the dental arcade = strong slicers
Brachydont
Teeth have fully erupted
Large anchoring roots esp. canine and carnassial
Enamel
Equid muscles
Small temporalis
Large masseter - largest masticatory muscle, translational movement
Large pterygoids
Canid muscles
Large temporalis - largest masticatory muscle, closes mandible with great force
Medium masseter
Small pterygoids
Equid trunk
Straight, inflexible vertebral column
Long ribcage - 18 ribs
Long transverse processes of L vertebrae
Broad back
Muscles
= cover broad gut
No gall bladder - bile not stored, constantly released
Canid trunk
Flexible vertebral column
13 ribs
Relatively short cranioventrally facing transverse processes
Large gall bladder - bile stored and only released when a meal has been consumed
Limbs - equid and canid
Both cursorial so main adaptations are;
1) all four limbs are weight bearing, lie directly under the body
2) elongated at proximal end of limb - scapula lies laterally, increasing stride length
3) reduced pectoral skeleton - allows more cranial/caudal, clavicle absent/vestigial
4) elongation at distal end of limb - long metacarpals
