Vertebrates 3 Flashcards
What may the dimetrodon sail have been used for?
- maybe sexual selection, maybe to gain heat
The pelycosaurs gave rise to the …, which gave rise to the …, which gave rise to the mammals
therapsids, cynodonts
In the mammals, the tail has become …, the vertebrae are more …, the anterior pelvic region is …, the … are reduced, the limbs are … the body rather than…
smaller, flexible, reduced, ribs, below, out to the side (allowing faster movement)
The reduction in ribs is thought to coincide with the development of the …
diaphragm
The non-mammalian synapsids are often referred to as the…
mammal-like reptiles
The non-mammalian synapsids are …, meaning all their … are the same
Homodont, teeth
The movement towards mammals changed the articulation of the …, and some of the previously large bones of the jaw have become incorporated into the … …. The teeth became …
dentary, middle ear, heterodont
Mammals have limbs below their body. This means that their movement is less … and their … stays still as they run. Their movement can help … their lungs with changes in volume as they run - making ventilation more efficient
undulatory, thorax, ventilate
It is believed that early mammals were small and …, … laying, … and solitary, with large … bulbs and a strong infant-mother bond
insectivorous, egg, nocturnal, olfactory
The movement of mammals towards a more active lifestyle also suggests a movement towards …
endothermy
What are the key unique features of mammals?
- lactation and suckling
- hairs (may have originally started as a sensory structure, then became insulatory structure)
Most mammals are … (in terms of their teeth) and have precise …
diphyodont (two same sets of teeth), occlusion (teeth fit together)
In mammals the lower jaw is …, allowing sideways movement to process food
narrower
Precise occlusion is not possible in … (found in reptiles, non-mammal synapsids)
polyphyodonty
- therefore diphyodonty preceded precise occlusion
How could diphyodonty have evolved?
- adult didn’t require teeth until later in life once jaw fully formed - fed milk early in life
- -> must have evolved lactation first
How did lactation evolve?
- Mammary glands related to apocrine glands (related to hairs - think monotremes) - originally secreted aggregating pheromones - milk may have been produced to protect eggs from desiccation and microbes - then evolved as nutritious secretion
Males also have mammary glands (except …) - some bats actually …
marsupials, lactate
What is the evolutionary advantage of lactation?
- production of offspring separated from seasonal food supply
- Mother not dependent on paternal care (more potential for male reproduction
- Young can be born at small body size
Lactation helps mammals cope with…
patchy food supplies
Suckling has evolved by the production of … … in the pharynx which prevent fluids from entering the lungs and stomach in an uncontrolled way
tight seals
- because have secondary palate that separates
- can breath and feed at same time
- allows baleen whales to feed in the way that they do
Mammals also have more development of … muscles
facial
- more manipulation of food before it is swallowed
- homologous with neck constrictor muscles in reptiles, which swallow larger bits of prey)
- has meant that mammals can display facial expressions (now used in communication)
Prototheria - ... Theria - ... - ...
monotremes, metatheria (marsupials), eutheria (placentals)
Monotremes have a single …
cloaca
The platypus is rich in … and … receptors
mechanical, electrical
There are … orders of marsupials, four of which occur in …, the others ocurring in the Americas
7, Australasia
What are the unique characteristics of the metatherian mammals when compared to the eutheria?
- usually possess an opposable digit on the hind foot
- generally more incisors and molars but fewer pre-molars
- bifurcated reproductive tract - penis, vagina
- (pouch/marsupium present in 50% of species)
- young more altricial (1% body mass)
- lower body temp and basal metabolic rate
- smaller relative brain size
What does diprotodont mean?
2 procumbent lower incisors
- biggest metatheria order is diprodontia
The marsupial mole is a fantastic example of…
convergence
The marsupials split from the eutherian mammals around … in …
100MYA, Gondwanaland
At the KT extinction, approximately … of all genera became extinct
50%
Australia-Antarctica split occured approx …
45MYA
There is a deep trench in the sea between PNG+Australia and Asia, called the … …, which represents the biogeographical division of the placental and marsupial mammals - the two land masses have never met
Wallace line
Marsupial females:
- 50% have marsupium (pouch)
- Sperm is transferred via paired vaginae
- Birth occurs via a pseudovaginal canal
- Two Uteri
- Few have simple placenta
- Highly altricial young with short gestation
- Flexible reproduction - can have new born attached to nipple, fertilised blastocyst in uterus and young at foot
- Similar oestrus cycle to eutherians (controlled by same hormones
Marsupial males:
- Combined urogenital track - cloaca (both males and females)
- Scrotum in front of split penis (bipartite)
What are the costs of placental mammals?
- can’t offload embryo (long gestation)
- Female structure (and fitness) has to be altered for birth (pelvic girdle)
- Placentals had to develop trophoblast to protect embryo
What are the costs of marsupial mammals?
- Restriction of forelimb development
- Reduced brain size - opportunity to learn by observation rather than work things out
Over … species of marsupial are listed as having some level of concern in Australasia
200
- massive extinctions that may be result of colonisation by aboriginal humans
- accelerated when Europeans reached Australia and South America
- And extinctions during Pliocene when North American Eutherians invaded
+ 2/3 of marsupials are endangered
How has Australia tried to conserve marsupials?
- Introduced herbivores - BAD
- Introduced predators (but more successful hunting marsupials as introduced herbivores had coevolved with predator)
- Changed fire regimes
- Burrowing Boodie now in 4 islands when used to be over majority of Australia
How many primate species are there?
around 250
- restricted to tropical regions for the most part, mostly arboreal
Most primates are general …, whereas some are specialist … eaters with … fermentation
omnivores, leaf, cellulose
How long ago did the earliest true primate exist?
55MYA
What are the four main groups of primates?
- Prosimians (Simoidea) - basal primates - lemurs and bushbabies
- New World Monkeys (Ceboidea) - marmosets, tamarins, spider monkeys
- Old World Monkeys (Cercopithecoidea)- macaques, baboons, langurs
- Apes (Hominoidea) - lesser apes (gibbons and siamang), great apes and humans
What are the characteristics of the primates?
- Opposable thumbs
- 4 Pentadactyl limbs (exceptions)
- Nails on fingers
- Large brain
- Shoulder joint permits movement in all directions + elbow joint permits rotation of forearms
- Reduced snout + reduced no of teeth
- Usually one young per pregnancy
- Retention of clavicle
- Most features are attributed to arboreal lifestyle and large body size
The Strepsirrhini are the “… …”, the tarsiers and prosimians and the Haplorhini are the “… …”, all other primates
wet noses, dry noses
What are the characteristics of the Strepsirrhini?
- Usually small
- Nocturnal
- Long snouted
- Less fusion in skull bones, lack of postorbital closure
- Africa + SE Asia
- Lemurs native to Madagascar, more diverse with large species (cf. apes) in the past
What are the catarrhini?
Narrow nosed primates - old world monkeys and apes
The old world monkeys are more … and …-rich than apes
specialised, species
The catarrhini have two …
premolars in each quarter
What are the old world monkey groups?
- Colobines (fruit eaters, complex fore-stomach, arboreal, stub thumbs, back limbs longer)
- Cercopithecines (omnivorous, increasingly terrestrial - short tail, limbs equal length)
What are the Platyrrhini?
Broad nosed monkeys - a group of new world monkeys - 3 premolars
What are key characteristics of the Hominidea?
- broad thorax and dorsal position of scapula - assist balance in a bipedal pose, centre of gravity near vertebrate column
- Caudal vertebrae reduced (usually no tail)
- Front skull characterised by sinuses
- Five cusps on molars (only for on OWM)
- Critically endangered
Give e.g.s of monogomous primates
gibbons, tamarins, lemurs
Give e.g.s of solitary primates
Bushbabies, orangutans
Give e.g.s of species that show male transfer social systems
Most cercopithecines (male hierarchy system)
Give e.g.s of species that show female transfer social systems
Chimp, gorilla, baboons, colobus (territorial male behaviour, sometimes kinship groups)
Downward nostrils evolved in the..
old world monkeys onwards
The tail is lost in the…
apes (+ some old world such as barbary macaque)
Spider monkeys have a … tail
prehensile
All primates have …-… eyes
forward-facing
Callosities are present in the…
old world monkeys and apes (except humans)
Colobus and spider monkeys only have thumbs…
on their feet
Gibbons are sexually dimorphic in their …. Great apes are sexually dimorphic in their …
colour, size
Lemurs have a … claw
grooming
Orangutans can walk ….
bipedally
Most mammals are …, and along the lineage they improved their night vision by…
nocturnal, losing some colour vision that had evolved before (lost 2 different colour cones and mostly became dichromatic, when ancestral vertebrates where tetrachromatic)
In the primates, colour vision has …
re-evolved
The more opsin pigments you have the more…
colours you can perceive (monochromatic = 1 pigment, dichromatic = 2 pigments etc.)
What are the 3 types of colour vision in primates?
- Dichromacy (red/green colour blind)
- Routine trichromacy (OW + Apes + Howlers) - convergently evolved
- Allelic trichromacy (NW) - polymorphic
Cone cells in the retina contain photopigments called … that “see” colour
opsins
In primates, each cone cell has its own …. The signals are not “pooled” so genetic mutations CAN lead to new colour signals
innovation
The genes for short wavelength (blue) opsin are on chromosome …, whereas the genes for medium (green) and long (red) wavelength opsins are on the … chromosome
7, X
- why 1/12 males are red/green colour blind whereas only 1/200 females
Most new world monkeys are…
dichromatic (red-green colourblind - only have short and long opsins)
Dichromats may be better at distinguishing…
camouflaged predators/prey
Howlers are the most … monkeys in the new world, enforcing their need for routine trichromacy
folivorous
Dichromatic New world monkeys were more frantic with their foraging, touching, sniffing and biting more fruit. Trichromats make fewer mistakes but forage more slowly and measuredly. This suggest..
there may not be an advantage to trichromacy in these polymorphic species
Whilst trichromacy is no doubt advantageous for detecting …, dichromacy may be more effective when detecting…
fruit, the ages of leaves
