Midterm 1 Flashcards
Natural History
The study of animals or plants from an observational point of view rather than experimental. Within the scientific method, reflects the observation sections
how small is the smallest mammal? what is it?
2g - bumblebee bat or Etruscan shrew
What is the largest terrestrial vert?
African elephant
6 tonnes
largest mammal ever?
Blue whale
105-150 tonnes
how many extant orders are is mammalia?
families?
gen?
spp?
28 orders
153 families
genera
>5400 spp
Distinguishing skeletal and skull characteristics of mammals?
1 bone mandible vs > 1 2 occipital condyles vs 1 secondary palate heterodont diphyodont 3 ossicles in middle ear phalangeal 2-3-3-3-3 fused pelvic bones long bones-epiphyses
Distinguishing soft tissue characteristics of mammals
large, complex brain 4 chambered heart vs 3 muscular diaphragm endothermic - high MBR epidermis with hair mammary glands
Many mammalian adaptions were for what ultimate purpose?
Greater capacity for sustained energy production
Endothermic homeothermy
Difference between homeothermy and endothermy?
Homeothermy = ability to maintain a stable body temperate Endothermy = ability to produce heat metabolically
Temporal openings in Anapsids vs Synapsids vs Diapsids
A = no openings S = 1 opening, mammals D = 2 openings, lizards and snakes
What 3 key modifications were made from non-therapsid synapsids to earliest mammals?
what did this allow for?
- skeletal/tooth morphology
- physiology
- ecological habits - foraging and behaviour
increased level of energy intake (MB activity)
Appearance of the first mammals based on old data
- shrew like in size
- small and uninteresting
- oviparous
- mammary glands
- endothermic with coat of fur
Appearance of first mammals based on new data
- medium sized
- quite diverse
- oviparous
- mammary glands
- endothermic with coat of fur
- nocturnal, would have been eaten by dinos
characteristics of Pelycosaurs
When were they present?
did they have increased MBR?
- small and likely insectivorous
- lg’er carnivorous/herbivorous arose later
- sm. temporal openings
- simple cone shaped teeth
- no secondary palate
- sprawling limb posture
- possess lumbar ribs and long, heavy tail
- no evidence for increase MBR
- tail may have been used for behavioural thermoregulation
Results of Permian mass extinction?
- 70% terrestrial vests killed off
- emergence of dinos
- pelycosaurs did not survival mass extinction
- -> descendants = therapsids
Therapsids
when did they appear?
characteristics?
late Permian heavy bodied/stumpy legs enlarged temp fossa enlarged dentary increasingly heterodoxy teeth (with cusps) incomplete 2ndary palate longer slender limbs + upright posture
*modifications suggest increased metabolic capacity
Cynodonts
when did they appear?
characteristics?
late Permian/early Cretaceous - large reduction in size (large dog early --> rabbit size late) -multicusped teeth -ZA -masseter muscle -complete 2ndary palate -nasal turbinate bones -dentary expanded -2 occipital condyles -atlas/axis exec posture
Cynodonts
when did they appear?
characteristics?
late Permian/early Cretaceous
- large reduction in size (large dog early –> rabbit size late)
- multicusped teeth
- ZA
- masseter muscle
- complete 2ndary palate
- nasal turbinate bones
- dentary expanded
- 2 occipital condyles
- atlas/axis
- erect posture
What do anatomical specializations of cynodonts suggest?
- highly efficient feeders
2. developed diaphragm - increased respiratory rate - may have been fully endothermic
in mammals, denture and squamosal adapted to _____ leaving the quadrate and articular to ____
articulate to increase jaw musculature
incorporated to become incus and malleus
Early mammals
when did they arise?
characteristics?
late triassic, just before dinosaurs
- diphyodont
- loss of ancestral jaw joint
- well developed middle ear
- loss/reduction in cervical ribs
- reduced pectoral girdle
What came first, high metabolism or insulation?
Not fully understood yet, by hypothesized that…
Metabolism then insulation quickly after.
what are the 3 phases of endothermy?
- parental care + aerobic capacity
- miniaturization + thermoregulation
- locomotion + adaption to climate change
Were early mammals diurnal or nocturnal, why?
nocturnal - would have been eaten by dinos!
