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182 Cards in this Set
- Front
- Back
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1) Functional Biology
2) Historical Approach |
1)Why do they do what they do?
2) How and why life is how it is Interconnected to understand underlying reasons for evolution |
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Evolutionary Biology
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mechanisms of change and evolutionary history of an organism
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Anagenesis
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directional change with single lineage
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Cladogenesis
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branched evolution
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Pleisomorphic vs. Apomorphic
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Pleisiomorphic is the ancestral state apomorphic is the derived
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Sympeisiomorphic vs. Synapomorphic
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a group sharing the ancestral (p) or derived (a) traits
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Nomenclature (3)
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1) First word capitalized second lowercase
2) Always underlined or italized 3) only one organism to a name consisting of two words |
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Monophyletic
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when all members in a taxa or group are derived from a common ancestor opposed to a polyphyletic group where they are from different ancestors
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Give an example of a polyphyletic grouping
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Warm blooded- Mammals and birds both warm blooded, not both from common ancestor
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Two ways to classify in figures
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1) Phenogram
2) Cladogram |
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Phenogram
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grouped by similar traits, based on similarity. ignores evolutionary relations and is so not widely used
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Cladogram
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Classification reflects evolutionary relationships, taxa strictly monophyletic, widely used.
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Homology (1), Homoplasy (2), Analogy (3)
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1) Origin
2) look 3) function |
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Teleostei (not Teleostomi)
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Most of todays fish species
200-300 families Extreme level of fecundity (reproductive sucess) Homocircualr tail and mobile premaxillary bone (protrudes mouth) Versatile |
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Major groups of Teleostei (4)
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Osteoglossomorphs
Elopomorphs Clupeomorpha Euteleosts |
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Osteoglossomorphs
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Teleostei
Old- Cretaceous Tropical habitat only 200 species example- Arapaima, the world's largest freshwater fish, plankton strainer, amazon, 4.5 m long |
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Elopomorph
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Teleostei
Have larval forms- Leptocephalis- that disperse widely, adults restricted 800 species Examples- Eels, tarpin, bonefish |
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Clupeomorpha
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Teleostei
360 species marine plankton strainers (small) herring, anchovies, sardines |
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Euteleosts
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teleostei
almost all freshwater fish 98%world's fish posterior fin 5 subgroups |
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5 subgroups of Euteleosts
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Paracanthopterygian
Ostariophysi Protacanthopterygii Scopelomorphs Acanthopterygians |
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Paracanthopterygian
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Euteleost
1200 species marine jaw mobility and flexibility downpointing pectoral fins cod, angular fish |
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Ostariophysi
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Euteleots
6500 species freshwater ostar bones of the wberian apparatus- chain of bones connecting inner ear and swim bladder Carp, Catfish, minnows |
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Weberian apparatus
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a chain of small bones connecting inner ear and swim bladder in ostariophysi fish
enhances hearing of sounds and vibrations underwater |
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Protacanthopterygii
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Euteleosts
polyphyletic ancestral characteristics 300 species "left over" group fusiform pelvic fins walleye, pike, salmon |
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Scopelomorphs
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Euteleosts
800 species gill arch, jaw structure, fins unique photophore organs marine |
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Photophore organ
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derived glands that produce light by chemical reaction in "lantern"fish
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Acanthopterygians
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Euteleosts
13-15 thousand of them shallow marine has two groups |
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2 groups of Acanthopterygians
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1) Atherinomorphs
2) Perciformes |
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Atherinomorphs
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Acanthopterygians
protrudible jaws aquarium fish guppies, swordtails, flying fish, silversides |
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Percifomes
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Acanthopterygians
largest order of fish sunfihs, perch, darters, snappers, barracuda, tuna some have sex reversal |
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Sex reversal
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Perciforme special skill
many begin as little males- females later- males when very very large |
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Sarcopterygians
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Lobe finned fish- opposed to ray finned (most fish alive still)
8 alive fleshy fins with muscle lobes at base enamel on teeth cosmine-- dentine like scales abundant in devonian 3 orders |
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3 Orders of the Sarcopterygians
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1) Actinistians
2) Dipnoi 3) Rhipidstians |
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Actinistians
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Sarcopterygian
"Coelacanths" Deep deep sea Bony swim bladders Move fins in alternating (walking) pattern as they move |
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Dipnoi
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Sacropterygian
lungfish only survive in areas with drought- devonian mimics dependant on air to breath- live in mud pools lack maxilla and premaxilla palatal teeth fused into tooth ridges, mineralized and hard, mullosk crushers cartelage body mostly "walk" along bottom of pools |
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Rhipidistrian
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Sacropterygian
two groups: Potolepiforms and Osterolepiforms (o likely tetrapod ancestor) |
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Habitat at the time of tetrapod evolution
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Devonian
tropical, eqator, shallow fresh and marine waters, stable for long period |
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tetrapod characteristics evolved to be advantageous where?
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in water not on land
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changes for survival on land from water
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water balance
hearing weight bearing |
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Two hypotheses of lobe fin/ tetrapod evolution (the reason why?)
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1) Move from water pool to water pool across land when one dried,not likely- would stay a fish
2) juviniles moved away to find food or escape predators- more likely |
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Limb developement evidence
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unlikely developed in fish for land movement- aestivation(hibrination) more likely
Developed to exploit shallow warm waters more effectively Limbs before the terrestrial forms, terrestrial selection then happened on aquatic tetrapods not fish |
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Evidence for juvinile hypothesis
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shallow= less predators, but also less oxygen- need good lungs
Legs prop up animal in shallow water to breathe easier= better land eyes Juviniles lighter= move in land short time periods for food over time more land forays= terrestrial forms |
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Osteolepiformes eyes
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Eyes moved back in fossils over time- helps on land and in shallow water for ewyes to be looking up
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Tiktaalik rosaea
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late devonian
no operculum "fishapod" sacropterygian Nunavut Canada forelimbs still fins but changed dramatically from fins had been |
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Osteolepiformes
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Rhipidstrian
Had lungs Heavy scales and bodies single nostril each side of head Division between anterior and posterior cranium**- allows head to lift staight up- allows jaws to be more flexible grabbing+ closing weight bearing FINS |
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Labryrinthdontia
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Part of Osteolepiformes
great reduction in tail eyes moved back gulping air doral vental body flattening ribs projected ventrally ancestors to tetrapods |
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True tetrapods of the Devonian (3 examples)
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Acanthostega- fishlike, but had limbs;widespread, eight toes on front (ancestral to five), still had tail
Icthyostega- hind limbs, seven toes Tikaalik- no hind end fossils |
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groups split from Ichtyostega (2)
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Batrachomorpha
Reptilamorphs |
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Batrachomorpha
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important group: Temnospodyles
Ancestral non-amniote tetrapods very sucessful into cretaceous Amphibian ancestor maybe |
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Temnospondyles
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Perhaps ancestors to frogs
short legged, predatory in shallow water crown and base of teeth composed of dentine and were banded with uncalcified fibrous dentine four -five toes |
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Reptilamorphs
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reptile ancestors
very diverse non amniotes but soon amniotic eggs all living reptilamorphs are amniotes terrestrial five fingers domed skull |
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Amphibians true name
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Lissamphibia
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three groups of amphibians
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1)Frogs and Toads
2) Newts and Salamanders 3) Caecilians |
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General points for amphibian
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moist skin acts as respiratory organ
likely branched from batrachomorphas- little fossil evidence all adults are carnivores(limited by mouth gap) "two modes of life" |
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Developement of generalized amphibians
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eggs in water in large numbers
develope into aquatic gilled forms metamorphosis limbs, lungs develope |
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water balance and amphibians
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moist permeable skin water moves freely
90% water can tolerate rapid changes in solute concentration osmoregulation similar to fishes- uses all organs kidneys have no reabsorbtion- flush with water |
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costs and benefits of amphibian skin
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costs- water loss big problem
benefits- obtain oxygen and other gases through skin, one giant lung benefits outweigh costs otherwise would not evolve |
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salamanders (urodela)
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gait similar to early tetrapods (3 feet on gound, one moves/ held out from body)
9 families all in N hemisphere tail and four functional limbs some adults have external gills |
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duty cycle for salamanders
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0.75 spends 3/4 of time on ground
moves diagonally steady body concave in movement allowing limbs to stretch |
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Paedomorphisis
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Salamander trait
juviniles obtain ability to reproduce and adult form never achieved stress conditions produce more juviniles quickly |
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Forgs and Toads (Anura)
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45 families all continents (exc. ANT)
fertilization external herbivore larva vocal males Urostyle- fused posterior vertebrae fro jumping |
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limbs- frog types connection
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long fore long hind= jumper
long fore short hind= jump walker short fore and hind= burrower, toads short fore long hind= swimmer and hoppers |
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locomotion types- frog types
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Hoppers- toads, ranging predators, potent chemical defenses
Jumpers- frogs, ambushers, camoflaged, lack chemcial defenses, leap defense Aquatic- powerful webbed hind feet, swim rapidly |
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Vocality and Auditory among frogs
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most vocal of vertebrates
species, sex, situation specific big male= low freq= old+ sucessful no species freq overlap species hear best at freq they call at |
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Call cost to male frogs
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Energy
increased rate of predation 19% of male frogs a night more calls on darker night= less predation |
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frog fertilization
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external
mostly amplexus- small male on large female males hitch ride until females produce eggs |
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reproductive strategy of a frog
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very diverse
parental care given very diverse lots= small clutch but better survival none= large clutch, ancestral |
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high care strategies (frogs)
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foam nest in tree
floating foam nest males defend nest carrying tadpoles on back gastric brooding frogs |
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Gastric brooding frogs
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tapoles hatch, females swallow them, finsih developing in stomach, vomits up when ready
Australia very rare |
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tadpoles
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can stay up to two years in form
herbivore- avoids competetition with with adults almost every structure changes from tadpole to adult |
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three main stages of metamorphesis
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1) pre metamorphosis: store energy, grows, eats a ton
metamorphesis- incapable of eating- changes occur 2) post metamorphesis: most energy is put into changing not growth 3) metamorphesis climax: tail regresses and tail fat store fuel change |
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Metamorphesis trigger
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Thyroid hormone Throxine
concentration increases as change does |
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Caecilians (Gymnophiona)
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Limbless, segmented, wormlike
aquatic or moist tropical 3 families stout skull small vestigal eyes covered in skin- detect light for timing not vision single lung viviparous burrowers eat insects and small lizards |
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Annuli
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Segments of a Caecilian
corresponds to individual vertebrae |
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Jacobson's organ (Caecilians)
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tentacle on roof of mouth
detects chemicals to taste and smell analogous with snake tongues |
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Amniotes
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Described by amniotic egg
reptiles, birds, mammals waterproof skin- fixes water cost Rib ventiliation- increases air intake TEMPORAL FENESTRA- allows powerful muscle attachment for lower jaw |
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3 membranes of Amniotic egg
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Allantois: hind gut endoderm, stores waste, respiration across
Chorion:outgrowth of body wall, surrounds embryo, creates aquarium Amnion: innermost membrane |
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Amniotic egg evolved only once?
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likely, too complex for more than once
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Outer egg
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Leathery (reptiles), calcified (birds),no shell(mammals)
shell for mechanical protection, but semi-permeable |
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yolk and whites
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white= albulum, what isn't yolk in reptiels/birds
yolk= energy stores, in mammals replaced with energy directly from mother |
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Energy cost of eggs
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Very high
mothers produce few benefits outweigh costs |
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Reptiles
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technically "all amniotes"
320 mya from reptilamorph (more derived than amphibians) waterproof skin jaw attachment points=high power exploited terrestrial environments: Arthropod prey plentiful |
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Synapsids
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one fenestra- the "cheek bone"
early branch gave rise to mammals |
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Diapsids
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Two holes
one in synapsid ploace and one further back birds, snakes, crocs, dinos, etc. |
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Parareptiles (Anapsids)
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no fenestra
turtles |
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Fenestra=
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more muscle attachment and bigger muscles
= power |
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Euryapsids
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Modified diapsid condition
single back fenestra Pleisosaurs and Icthyosaurs |
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Hylonomus
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320mya earliest known reptile
anapsid domed skull, legs underneath small agile insectivore Survived into Permian (long time) |
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Mesosaur
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first to evolved back to aquatic
strainer convergent on crocodile |
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Millerettids
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Replaced hylonomus
legs more upright still small quick insectivores |
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Procelophids
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Late permian to triassic
large and squat grinding teeth= herbivore |
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Pareiasaurs
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Permian
very large herbivores (elk sized) |
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Turtles (Chelonians)
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Anapsids
Shapes and sizes diverse highly derived and unchanged for long time arched shell and beak early turtles non retractable Never stop growing Long lived (100-120 yrs) ancestrally had teeth- now no teeth |
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turtle shell morphology
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domed- more terrestrial
round= tortoises flattened= turtles/ swimmers reduced= snapping turtle- relies on defense |
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Pleurodira
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turtle group
Snake necked turtles- retrack neck horizontally 50 species None in NA Triassic evolution pelvic girdle fused to carapace and plastron |
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Carapace and Plastron
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Carapace= dome of shell
Plastron= flattened belly |
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Cryptodira
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Turtle group
175 species common in NA retract head in vertical s shape pelvic girdle not fused to shell snapping turtles, marine turtles, tortoises, soft shelled turtles, pond turtles |
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Shell Characteristics
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five rows of bony plates
attached to vertebral ribs not formed from ribs or vertebrae Plastron developes from dermal ossification from pectoral girdle outer shell karatin limb gridles support shell inside ribs |
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Slow turtle movement
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tortoises one stride/per 2 second
herbivores- plants dont move very protected live long time slow= low energetic cost |
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turtle heart
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two aortic arches
allows switch between lungs and systemic circuit allows blood to move into system as they warm up limit blood flow while in apnea(head in cant breathe) |
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turtle navigation
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Females and nestlings return to same spot each year
Ascention Island theories: magnetic fields, polarized light, low freq sounds of surf |
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Reproduction turtles
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oviparious that hatch externally
digs hole, lay eggs, covers clutch average 50-100 eggs temperature dependant sex developement: warm=female |
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Two groups of Diapsids
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Archosaurs- birds, dinos, crocs
Lepidisaurs- snakes and lizards |
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Differential Characteristics of Diapsids
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*Embryonic* appearance of Jacobson's organ
Olfactory tract- two attached to brain by a bundle of nervous tissue |
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Diapsid fenestra evolution
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evolved the two only once
ventra continuously lost throughout some species (snakes) where it is lost= flexibility=less power |
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Diapsid dominance
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Most successful group of reptiles
Mesozoic dominated until dinosaur extinction in the Cretaceous |
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Petrolacosaurus
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first sure diapsids
longer limbs very lizardlike big eyes |
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Groups lying outside archosaurs
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Prolacertaforms(lizardlike agile insectivores)
Euparkeria(large bipeds) Rhynchosaurs (rodent like teeth at front of beak) |
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True Archosaurs
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Tend to be bipedal (exceptions)
skull domed diverse- flying, aquatic, terrestrial |
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Phytosaurs
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Archosaurs- Diapsids
aquatic fisheaters looked similar to crocodiles (convergent) triassic nostrils anterior to eyes no secondary palate displaced by croc groups |
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Crocodiles, Aligators, and Caimans
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Archosaurs- Diapsids
Semi Aquatic 21 species today limbs under body- gallop over short distances salt and fresh water temperature dependant sex determination specialized ambushers cretaceous deinosuchus-15m long |
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Pterosaurs
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Archosaurs- Diapsids
most had flight evolved jurassic/cretaceous size varied(sparrow-16m) visual predators large brains fruit,fish,strainers,insect eaters |
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Two groups of Pterosaurs
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1) Rhamphorhynchoids- long tails, more ancestral
2) Pterodactyloids- no tail, more derived, wings skin only, hollow strong bones |
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Dinosaurs
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Archosaurs- Diapsids
dominate terrestial vertebrate group in earth history most bipedal exploited most food sources |
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Reasons dinosaurs dominated
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new movement patterns
limbs underneath them unlike other archosaurs run fast, for longer, energetically cheaper |
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Two dinosaurs groups
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1) Ornithisdians- bird hipped dinos
2)Saurischians- lizard hipped dinos (birds included) |
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Saurischians
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dino-archo-diapsids
Two groups: Sauropods Theropods |
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Sauropods
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Saurischians-dino-archo-diap
quadrapedal herbivores long neck includes largest herbivores to ever live survived until cretaceous |
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two groups of sauropods
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1)Diplodocus
2)Banchiosaurus |
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Diplododocus
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Sauropods-Saurischians-dino
very long necks and tails small enlongated skulls twig eaters- teeth in back only leg structure similar to elephants ex. supersaurus (40m long, 100kilos) |
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Banchiosaurus
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Sauropods-Saurischians-dinos
shorter necks and tails flatter and equal along back chiseled flat teeth- grazers |
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Theropods
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Saurischians-dinos-Archo-dinos
bipeds mostly carnivorous mostly specialized teeth structures to take down prey reduction of forelimb size and increased body size throughout time |
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four groups of theropods
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1)Ceratosaurs
2)Allosaurs 3)Tyrannosaurs 4)Dromeosaurs |
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Tyrannosaurs
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Cretaceous
6m high 15m long short front limbs- couldnt reach mouth birdlike- fused sternum, furcula |
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Dromeosaurs
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ran down prey
much smaller forelimbs longer and good graspers "raptors" some hunted in packs |
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Ornithischians
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dino-arch-diapsids
quadropedal herbivore |
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four groups of ornithischians
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1)Thyreophorans
2)Ornithipods 3)Pachycephalosaurs 4)Ceratopsians |
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Thyreophorans
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Ornithischians-dinos-archo-diap
ex. Stegosaurus,Ankylosaurus armoured, plates, clubbed or spiked tails Jurassic small brains unspecialized teeth- not well digested food "solar panel" plates |
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Ornithipods
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ornithischian-dino-archo
"Iguanodonts"- first dino found 1840's Jurassic smaller bipeds mostly Iguanodonts large grass eaters (serrated flat teeth) Hadrosaurs derived large crested herbivores |
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Pachycephalosaurs
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ornithischians-dinos-archo
bipedal herbivores beak to clip vegatation 25cm thick domed cranium likely similar social interactions to mountain sheep |
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Ceratopsians
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Ornithischians- dinos-archo
quadrapedal horned dinos very derived mid cretaceous horny beak and frill along neck slicing herbivore teeth |
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ceratopsian frills
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protoceratops- early=small frill, likely for jaw attachment
more derived it became for sexual selection= more elaborate also may have been fore defense= protects neck |
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Dinosaur extinction
(what the meteor impact caused) |
Temperature changes
vegatation deaths temperature dependant sex determination |
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Lepidosauromorphs
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Diapsids- reptiles
Most derived group of vertebrates |
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Pleisiosaurs
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Lepidosauromorphs- diapsids
Aquatic Triassic/Jurassic to cretaceous longnecked/small head and short neck/heavy head forms short neck more ancestral |
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Ichtyosaurs
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convergent on porpoises
highly derived lepidosauromorphs moved like tuna today propulsion from tail |
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Lepidosaurs
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Lepidosauromorphs- diapsids
kinetic skulls most insectivores |
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Two groups of lepidosaurs
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1)Sphenodons- Tuatara
2)Squmates- snakes, lizards,amphisbaenians |
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Sphenodons
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Lipidosaurs-Lepidmorphs- Diaps
two species only-tuatara insectivores live in burrows two complete temporal fossa eyesight very good no compulatory organ slow growing, slow reproducing long living(100+) one egg/year very ancestral |
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Squamates
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lipidosaurs-lepidomorphs-diap
copulatory organs highly kinetic skulls variable tooth forms different reproduction modes(parthenogenesis, viviporous, oviparous) |
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Lacetids
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squamates-lipido-lipido-diap
"lizards" most small <20g Jurassic (lost few in extinction) like hot dry places |
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Autotomy
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Dropping the tail as a evasive strategy
natural plane of weakness tails grow back minus vertebrae cost- fat stores, reproductive success |
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four main groups of Lacetids
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1)Iguanids-iguanas and chameleons (stout, long tails)
2)geckonids- geckos (small,short tails,nocturnal,arboreal,hard egg) 3) Scinomorphids- skinks (long,smooth,quick) 4)Angiomorphids- monitor lizards (ancestors to snakes) |
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Amphibaenian
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squamate-lipido-lipido-diapsid
legless for most part fossorial-underground rigid skulls-interlocking bones acute hearing can move in tunnels both ways small prey |
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Ophidia (snakes)
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squamates-lipido-lipido-diap
highly specialized legless lizards highly kinetic skulls- spread jaws completely eye focus by distance evolved from fossoral lizard lateral undulation movement prey death by poison or suffocation |
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3 TYPES of snakes
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1)Scolecophidia- burrowing snakes(small, non venomous)
2)Alethinophidia- boas, pythons, anaconda (heavy constrictors) 3)Colubroidea-includes venomous snakes, sea snakes, garter snakes |
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venom delivery of snakes
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fangs fold down, pop erect when mouth opens
fangs position varies leak out or runs along systems |
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Birds
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Archosaurs-Diapsids
can fly live pole to pole generate power over long periods and for great endurance |
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Endothermy
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regulate body temperature by metabolism
huge energy cost- must eat larger quantities benefits: active in any temperature endothermy needs both increased metabolic rate and insulation |
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small body trouble
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small bodies loss heat quicker than large bodies since volume expands in 3 dimensions and surface area in 2.
endotherm size limit=2g |
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termperature zone limits
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Thermoneutral zone= goldilocks temp, where E used is at its lowest
Upper lethal= body temp goes up and heat is felt, cooling mechanisms kick in Lower lethal= metabolism goes up to generate heat, can be maintained for getter period than heat |
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Torpor
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lowering temperature and sitting still, lowing metabolism right down
ex. poorwill (7 weeks, 5 degrees) some birds do it nightly |
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cooling tricks of endotherms
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drink more
sweat pant gular flapping shading urohydrosis |
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Dromeosaur
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link between birds and dinosaurs
feathered for insulation- hints endothermy not large enough feathers for flight |
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Three defining features of birds
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1)Hollow bones:same mass, but stronger reenforced than mammal bones
2) Furcula: wishbone,stabalizes two wings, allows rapid flapping 3)Feathers problem- dinos had all 3 too |
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Archaeopteryx
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feathered depressions in fossils
feathers asymetrical (flight feathers) had teeth and claws, but also furcula |
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Two theories of flight
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1) trees down:gliding into flapping
2) ground up: open ground predators chasing flying insects |
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flight
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furcula braces pectoral girdle and prevents it from collapsing when muscles contract
pectoralis =downstroke supercoracoideus=upstroke, acts like a pulley around scapula notch |
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Feathers types
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Primaries: outside wing very long, provides thrust
Secondaries: support forearm, shorter, provide lift assymetrical feathers cover body retrices:tail feathers |
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feather makeup
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beta caratin- waterproof, strong
shaft from skin follicle vein runs up middle barbs of shafts branch into barbules:proximal and distal(hooked) that act like velcro preening repairs attachment very strong |
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Wing movement during flight
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see textbook
to complicated to write out |
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Two gaits of flight
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species only use one
1) Slow gait: generate lift and thrust during downstroke only, wavy pattern (circular vortex ring), upstroke for recovery 2) Fast: Continuous vortex ring, generates lift and thrust all the time |
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Drag
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generated by vortexes
lengthening the wing and tapered wing tips reduce drag by changing surface area air hits |
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Classifying bird wings
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by Aspect ratio:
AR=wingspan^2/area and by wing loading: WL= bird weight/ wing area high wing loading means low manouverability high aspect ratio= long wings and usually low manouverability but quick |
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mass reduction in birds
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toothless
no urinary bladders one ovary very small testes avian muscle high power |
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bird lungs
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air sacs
air cycles through to posterior sac across lungs into anterior air sacs then out mouth air flow and blood flow countercurrent very efficient breathers |
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bird song
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air leaves treachea and song is generated, unknown how
syrinx at bottom of trachea is where created-no vocal chords supported by squeezing muscles tempanic membrane stretched across- analagous to vocal chords air sac can be compressed sound may be from vibration of membranes or by vortexes of air as it leaves the bird |
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mammals
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synapsids-reptiles-reptilamorphs
remnants of larger synapsid radiations (majority extinct) late triassic mostly noctunal and small |
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synapsids
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around since late carboniferous
first group of amniotes to radiate widely on land vast majority went extinct in permioan extinction got bigger then smaller (dinos around) then bigger (dinos extinct) |
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synapsid lateral temporal fenestra
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lateral hole in skull behind orbit
bordered byjugal, squasmosal,post orbital dentary bone point of attachment fenestra very important for muscle attachment |
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Pelycosaurs
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Synapsids
earliest known group carboniferous-permian resembled lizards: long tails, legs to the side "sail backs"-Dimetrodon carnivorous |
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Therapsids
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Synapsids
S hemisphere late permian- cretaceous (some survived extinction) legs underneath-could run teeth deversified herbivores and carnivores sense organs improved secondary palate generally reduction of ribs to allow diaphram |
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Cynodonts
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Therapsids-Synapsids
derived therapsids that gave rise to mammals reduction in body size multicusped teeth enlarged dentary bone with reduction of post dentary bones reduction in rib cage, gained diaphram, more efficient breathing, high metabolism, endothermy declined in triassic maxillary turbinates: sinuses, warms air on way to lungs |
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Features in the evolution of endothermy in synapsids
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size of temporal fenestra= increased food eating+ metabolism
lower temporal bar (zygomatic arch)= muscle- side to side chewing as well as up and down Teeth differentiation= food, metabolism Secondary palate= breath and eat at same time Parietal foramen= disappeared in lineage, pelycosaurs, allowed light to hit brain and thermoregulate (didnt need it anymore) limbs, limb girdles, toes= became more efficient to running, to chase down more food |
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Mammal features
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mammary glands, hair, diaphram, tribosphenic molar patterns
hard palate late triassic- cretaceous mammals were very small insignificant |
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Pond hypothesis
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Lactation arose with diphodonty
teeth needed for lactation and mature diet milk evolved for immunity not nutrition |
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Cenozoic mammals three categories
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1) Allotheria: multituberculates, extinct
2) Protheria:monotremes 3)Theria: marsupials and placentals |
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Multituberculates
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mammal-synapids
multicusped molars looked like squirrel with muskrat tail most common mesozoic mammals prehensile tail extinct in eocene brain small |
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Monotremata
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mammal-synapsids
platypus and echidnas lay eggs toothless electomagnetic sensing beak |
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Therians
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mammals-synapsids
radiation while continents drifting apart, effects of isolation Great American Interchange |
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Marsupialia
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therian-mammal-synapsids
high level of convergent evolution with placentals reproductive differences lack auditory bulla larger number of molars and incisors |
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Placental
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therians-mammals-synapsid
grouped into taxa that always change rapid radiation from ancestral stock elephants=aquatic ancestor whales=terrestrial ungulate ancestor |
