Lab 8 Flashcards
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\\\\\\\\\\nbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbFoot postures in mammals
Plantigrade
Digitigrade
Unguligrade
Plantigrade
The entire foot is in contact with the ground
Plesiomorphic condition among mammals
Allows for good weight distribution and stability
Digitigrade
Only the fingers and toes and tips of the metacarpals/metatarsals (palm or sole) are in contact with the ground
Common in carnivorans like cats/dogs
Unguligrade
Only the hoof is in contact while walking
Allows for further lengthening of the limbs and an even greater stride length than digitigrade
Rabbit saltation (jumping or hopping) trait
Hind limb greatly enlarged with fore limb normal or reduced
Ricochetal
More extreme type of saltatory locomotion
Kangaroo ricochetal locomotion traits
Bipedal stance
Long tail to control balance
Enlarged tendons of the lower hind limb store energy as they stretch under the weight of the animal
The energy stored is released when they jump
Cursorial locomotion
Running/galloping
Cursorial adaptations (cat and deer)
Ribcage is narrow and deep- allows movement of the limbs beside the ribs without compressing lungs
Reduction in the lumbar (lower back) ribs enables greater flexibility of that region of the spine
The limbs are elongated-
Spinal column as a springe
Semi-fossorial
Spending some of their time underground
Fully fossorial
Spending most their lives underground
General fossorial adaptations (ground squirrel, armadillo)
Enlarged claws for digging
Body shape usually narrow
Chisel like teeth often employed in digging
Reduction in external body projections
Fully fossorial adaptations
(European mole, golden mole, marsupial mole)
Greatly enlarge forefeet and claws
Further reduction of external body projections including the tail, external ears, limbs and neck
Body shape often flattened
Increased development of pectoral and forelimb musculature
Arboreal locomotion
Movement along trees
Scansorial
Running along branches
Prime locomotion
Swinging and leaping from branches
Tree squirrel scansorial adaptations
Sharp, strong claws on all four feet provide grip and allow the lightweight squirrels to climb vertical surfaces
Large, long tails help provide balance
Have a patagium or sheet of skin connecting the fore and hind limbs
Allows for gliding
Primate adaptations related to leaping and swinging
Long limbs and a strong flexible back
Long hands and feet modified for grasping with opposable digits and nails instead of claws
Long tails often prehensile for grasping branches
Phalanges (bones of the digits) curved to better conform to branches
Eyes facing forward- increased depth perception aids in judging distance when leaping from branch of branch
Bat flight adaptations
Digits 2 through 5 of the forelimb greatly elongated forming the wing skeleton in combination with other bones of the limb
Patagium
Uropatagium
Flight is powered by both breast and back
Compact body with a short neck region helps position the center of gravity between the wings
Patagium
A sheet of skin stretched between digits 2-5 of the forelimb creates a membranous wing with a very large surface area relative to the body
Uropatagium
A sheet of skin stretched between the hindlimbs and tail created additional surface area and can contribute lift as well as steering during flight
Secondarily aquatic
Aquatic vertebrae has evolved from a terrestrial ancestor
Adaptations of secondarily aquatic organisms
Increased surface area to a varying degree
Feet may be webbed or modified into flippers
Modifications to fur to reduce friction (viscous drag) and trap a layer of air against skin
The tail may take a role of propulsion. With gravity no longer a force on the spinal column, the zygopophyses are reduced or lost, allowing greater flexibility of the spine in order to undulate the modified tail fluke
Dolphins (secondary aquatic mammals), sharks (primarily aquatic fish), and extinct Ichthyosaurs (secondarily aquatic diapsid reptiles) show a great amount of
Convergent evolution
General mammalian feeding adaptations
Synapsid skull
Jaw articulation
Heterodonty
Diphyodonty
Muscular tongue
Secondary palate
Muscular lips
Synapsid skull
The temporal opening permits greater surface area for jaw muscle attachment
Jaw articulation
Articulate between the dentary and squamosal
High jaw flexibility is associated with chewing
Heterodonty
Variability of teeth
Diphyodonty
Do not replace teeth but have two sets of teeth which are a result of differences between juveniles and adults
Muscular tongue
Oral food processing increases with a highly muscular and mobile tongue
Secondary palate
As endotherms, the metabolic requirements mean they spend a large amount of time processing food
Allows respiration to occur while feeding
Muscular lips
Only mammals have lips that are muscular and capable of manipulating food
Mammalian teeth types
Incisors
Canine
Premolars
Molars
Incisors
The anterior- most teeth of the upper and lower jaws
Typically rectangular
Slicing or nipping
Canine
Posterior to the incisors, more conical , pointed and frequently longer than other teeth
Piercing or gripping food
Premolars
Typically have two tips (or cusps) premolars reside beside the canine
Molars
Found at the back of tooth row, molars are usually the largest teeth in the jaw
Crushing food
Brachydont
Teeth with a proportionately low crown relative to the root
When the jaws are closed, the cusps of brachydont teeth interlock tightly
This provides for both piercing and crushing food
Three types of brachydont
Bunodont
Sectorial
Carnassial pair
Bunodont
Molars of omnivores are usually bunodont, having low rounded cusps for grinding a variety of food
Sectorial
Premolars and molars of carnivores are usually sectorial, providing many piercing or slicing occlusal surfaces
Carnassial pair
Highly derived sectorial teeth of some carnivores
Act like blades of scissors
Includes the fourth upper premolar and first lower molar
Hypsodont
Teeth with a high crown relative to the root
Herbivores that masticate (chew) highly durable or abrasive foods like grasses or branches to wear off occlusal surface
Types of hypsodont teeth
Selenodont
Lophodont
Selenodont
Highly crowned teeth with crescent shaped wear patterns in line with the jaw
Lophodont
High crowned teeth with transverse (perpendicular to jaw axis) oriented wear patterns
Ever growing incisors
Teeth that have evolved to endure extreme wear and continuously grow throughout one’s life
Some rodents have iron in the enamel of their incisors, increasing durability and giving it a orange appearance
Diastema
A gap in the tooth row
Mammals that chew food for long periods often have a conspicuous gap between the incisors and premolars
Used to store food for short periods or to roll food into a ball to be moistened by saliva
Pig tusks
Used in defense, aggression, foraging and display
Enlarged, ever growing canines
Elephant tusks
Like pig tusks, elephant tusks are ever growing but are formed from incisors rather than canines
social dominance, defense, and foraging
Walrus tusks
Enlarged, ever-growing canines
Display, defense, aggression, foraging and even locomotion
Narwhal tusk
Sensory organ
The teeth of harbor porpoise
Reduced and of uniform shape
Whales typically use water to aid in moving food into the esophagus and use their teeth only for prey capture
Post-canine teeth of seals
Form a row of uniform triangular shapes with deep grooves along their margins
Allows water to be pushed out while retaining food when mouth is closed
Baleen whales teeth
Have lost teeth altogether
Developed baleen
Filter organisms out of seawater
