Mammalogy 1, biology
Terms
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- 11 soft anatomy characteristics of mammals
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1. lactogenic
2. viviparous
3. hair
4. sweat and sabaceous glands
5. endothermic
6. four-chambered heart
7. anucleate red blood cells
8. separate renal artery
9. muscularized diaphragm
10. facial muscles
11. expanded cerebrum expanded from dorsal pallium - lactogenic
- -nourish young with milk produced by mammary glands
- viviparous
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-give birth to live young which are nourished in the uterus
-exception of egg-laying monotremes - three layers of hair
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-medulla - insulation
-cortex - pigment
-cuticle - scales (pattern species-specific) - sebaceous glands
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-associated with hair follicles
-produce oils that condition hair - significance of four-chambered heart
- -separates pulmonary from systemic circulation
- renal artery
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-blood flowing into kidneys is supplied by renal artery from aorta
-vs. renal portal system - muscularized diaphragm
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-separates abdominal cavity from thoracic cavity
-expands rib cage during inhalation - facial muscles all derived from what?
- -constrictor colli (throat muscle)
- 8 cranial characters of mammals
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-double occipital condyle
-modified atlas/axis complex
-tympanic bone
-3 ear ossicles
-single pair of bones in mandible
-single nares
-secondary palate
-respiratory turbinates - double occipital condyle
- -point on skull that articulates with first cervical vertebra
- atlas/axis complex in mammals
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-first and second cervical vertebrae
-atlas reduced to simple ring that stays fixed when skull moves up and down
-axis has post that goes through hole, on which skull rotates - tympanic bone
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-supports tympanum (eardrum)
-forms auditory bulla in many mammals
-non-mammals have angular bone in lower jaw - 3 ear ossicles and their ancestral homologs
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-malleus - articular
-incus - quadrate
-stapes - stapes - secondary palate
- -separates nasal from oral cavities
- two points to respiratory turbinates
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-olfactory turbinates support epithelium for scent
-large surface area for recovery of exhaled water vapor, therefore required for endothermy - 5 characteristics of mammalian teeth
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-restricted to margins of the jaw
-diphyodont
-thecodont
-heterodont
-multi-cuspate - diphyodont
- -two growths (baby and adult teeth)
- thecodont
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-socketed (tooth anchored)
-contrasts: acrodont (on jaw, not socketed) and pleurodont (on shelf, not socketed) - heterodont
- -different shapes for different functions
- multi-cuspate
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-many bumps
-especially cheek teeth
-upper teeth acclue with lower teeth - 2 characteristics of mammalian axial skeleton
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-extreme regionalization of vertebral column
-rib distribution restricted to thoracic vertebrae - 5 regions of vertebral column in mammals
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-cervical (7 bones in neck)
-thoracic (13 bones in chest)
-lumbar (varied # in lower back)
-sacral (varied # in pelvic area)
-caudal (varied # in tail area) - four characteristics in appendicular skeleton in mammals
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-epiphyses
-calcaneum
-limb orientation
-reduction in bones of limb girdles - characteristics of mammalian axial skeleton
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-extreme regionalization of vertebral column
--cervical
--thoracic
--lumbar
--sacral
--caudal
-Rib distribution - restricted to thoracic vertebrae - characteristics of mammalian appendicular skeleton
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-epiphyses - bony caps at tips of limb bones (permits stress at joints)
-calcaneum (allows calf musculature)
-limb orientation - rotated under body (most of weight supported by skeleton vs. musculature)
-reduction of bones in limb girdles - mammal pectoral girdle
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-scapula and clavicle
-vs. anterior and posterior coracoids and interclavicle
-monotremes still possess the latter - mammal pelvic girdle
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-fusion of three ancestral elements into single pelvic bone: illium, ishium, and pubis
-remain unfused in monotremes - captorhinomorphs
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-carboniferous period
-temporal region- solid shield of bone
-jaw closing muscles attach onto ventral surface of solid shield of bone - synapsid
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-"together arch" - arch of bone formed by opening of fenestra
-fenestra - below suture of postorbital and squamosal, much of musculature passes through and anchors on dorsal surface of skull - modified synapsid condition
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-temporal fenestra expands
-brain case expands - pelycosaurs
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-non-therapsid synapsids
-early permian - 320 mya
-ex. Dimetrodon - Dimetrodon
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-3 m long
-small temporal fenestra
-weakly heterodont
-small dentary with post dentary bones (articular and angular)
-quadrate articular jaw joint
-lacked secondary palate
-single occipital condyle - therapsids
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-advanced synapsids
-mammal-like reptiles
-became dominant by 265 mya
-all large (up to 5m) and very active
-cynodonts evolved from therapsids in the late Permian - what happened at the end of the Permian?
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-mass extinction - 90% of all species, including nearly all therapsids
-cynodonts survived - cynodonts
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-"dog teeth"
-strongly heterodont dentition
-gradual evolution of mammalian characters
-gradual evolution of secondary palate
-double occipital condyle
-expansion of dentary in posterior direction, postdentary bones shrinking
-expansion of temporal fenestra and brain case - key character approach
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-used jaw joint - mammals have joint between squamosal and dentary
-vs. quadrate and articular
-approach confused by Probainognathus and Diarthragnathus, perfect transitional forms (possessed both types of jaw joints) - suite of characters approach
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-jaw joint - dentary/squamosal articulation
-strongly heterodont dentition
-precision of acclusion
-alternate side chewing
-well-developed inner ear region (expanded petrosal, which houses inner ear)
-small size (rat-sized or smaller)
-axial flexes (dorso-ventral in mammals, lateral in non-mammals) - grade-based approaches
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key character and suite of character approaches
-problematic
-based on some perceived level of organization - requirements of classifications
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-must reflect evolutionary history - monophyletic groups (allow us to make better predictions about unknown groups)
-stable to the largest degree possible - implications for endothermy
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-energy requirements
-increased efficiency of cardio/pulmonary activities
-behavior implications - energy requirements for endothermy
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-10 times more energy than ectotherm
-increased efficiency of food gathering and processing
--complex, specialized dentition and precise acclusion
--specialized jaw musculature (masseter)
--secondary palate (allow animal to eat and breathe simulataneously) - increased efficiency of cardio/pulmonary activities
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-extrusion of nuclei from red blood cells
-separation of pulmonary from systemic circulation, four chambered heart
-restriction of ribs to thoracic region
-muscularized diaphragm - behavioral implications for endothermy
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-permits nocturnal behavior
-hair for insulation
-increased auditory capacity
-increased olfactory capabilites - lineage of mammals
- -synapsida - therapsida - cynodontia - mammalia
- morganucodontids - morganucodon
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-small size
-large nasal cavity, respiratory turbinates, well developed ear region
-dentary expanded (D/S jaw joint, articular still present)
-no tympanic bone (angular still present)
-3-cusped teeth, labial off-set lingually
-alternate side chewing
-shearing teeth (insectivorous)
-diphyodont (infer lactation)
-ancestral condition of pectoral girdle
-possessed vibrissae
-infer endothermy - triconodonts
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-3 cusped teeth, linear
-ex Jeholedens in China - Jeholedens
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-large nasal cavities
-well-developed inner ear
-limb bones lacked epiphygeal plates
-has derived mammalian pectoral girdle
-pectoral limb not rotated under body
-pelvic girdle retained ancestral condition - multituberculates
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-"rodents of the mesozoic)
-coexisted with modern mammals
-chisel-like incisors
-large diastema (char. of herbivores)
-complex cheek teeth (many cusps)
-diversified simultaneously with angiosperms
-some arboreal, some may have been gliding - Pantotheres
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-multiple lineages - non-monophyletic
-progressively more "therian"
-bifunctional teeth
--single tooth with two functions
--tribosphenic molars - newly discovered fossils
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-Ausktribosphenos (closely related to monotremes)
-Hadrocodium (oldest known mammalian fossil - 195 mya)
-Eomaia (verl well-preserved Eutheriam mammal - 125 mya)