Lectures for Test 1 Flashcards
sagittal
any line that divides body into right and left
transverse
any line that divides body into front and back parts
frontal
any line that divides body into top and bottom parts
vertebrates belong to this clade
chordata
largest clade of chordata
craniata
how are groups defined and characterized?
groups defined based on ancestry, traits used to characterize group
chordates + hemichordates =
pharyngotremata
informal name referring to early and non complex craniates
protochordates
5 characters important in vertebrate evolutionary history
pharyngeal slits, notochord, dorsal hollow nerve cord, endotyle, post-anal tail
urochordata means
chordates with tails
example of urochordate
tunicate
what chordate characters does the tunicate have?
pharyngeal slits, endostyle, postanal tail with notochord and nerve chord in larval stage
cephalochordata means
chordates with heads
example of cephalochordate
amphioxus or branchiostoma or lancelet
habitat of amphioxus
in sand, half buried with head poking out
chordate characters present in amphioxus
notochord, dorsal hollow nerve cord, post-anal tail, pharyngeal slits
amphioxus feeding method is called
filter or suspension feeding
difference between amphioxus pharyngeal slits and more derived versions
amphioxus slits are for getting rid of water ingested during feeding not gas exchanged
informal group characterized by lack of jaws
agnathans
groups/species considered agnathans
myxinoidea, petromyzontoidea/hagfish, lamprey
characteristics of agnathans
lack jaws and paired appendages, now represented only by cyclostomes
earlier, diverse group of agnathans (now extinct)
ostracoderms
types of ostracoderms
osteostracans, anapsids, heterostracans
characteristics of cyclostomes
parasitic, no bone, long thin bodies, single median nostril, rasping tongue
lamprey method of feeding
oral cup clings to prey, ingests and filters food from body fluids
hagfish method of feeding
scavenges dead flesh, not a filter feeder
gnathostomes
all vertebrates beyond agnathans, possess jaws, natural group
most basal gnathostomes
placoderms
characteristics of placoderms
external jaws from bony armour that are similar but not the same as later jawed animals, paired fins, extinct
eugnathostomata
natural group, have true jaws
two groups in eugnathostomata
chondricthyes, teleostomi
characteristics of chondricthyes
basal eugnathostomes, cartilaginous fishes, well developed paired fins, two nostrils, usually claspers
3 stages of becoming a vertebrate
prevertebrate, agnathan, gnathostome
characteristics of pre vertebrate stage
suspension feeder, small, poor swimmer, colliery action to produce water movement
characteristics of agnathan stage
muscular bands + cartilaginous bars in pharynx, muscular pump to move water, filter feeder on larger particles, poor swimmer
characteristics of gnathostome stage
efficient movement of water with muscular pump, larger prey, modify pharyngeal slits for gas exchange
two main clades of chondricthyes
elasmobranchii, holocephalia
characteristics of elasmobranchs
typical sharks and rays, movable upper jaw, gills open directly to outside, rapid tooth replacement
characteristics of holocephalians
slow tooth replacement, operculum covering pharyngeal slits, upper jaw fused to brain case, bottom dwelling mollusc eaters
teleostomi
acanthodi and osteichtyes
characteristics of acanthodii
spiny sharks (but not true sharks), heterocercal tail, more than 2 pairs of “odd” paired fins (supported by spine), extinct
natural groups in osteichtyes
actinopterygii, sarcopterygii
characteristics of actinopterygii
99% of all living fish, very diverse, ray finned with poor muscle development in fins, primitively one dorsal fin, ganoid scales, no internal nostrils
characteristics of sarcopterygii
only a few are still alive, ancestors of land vertebrates (tetrapods), fleshy finned with well developed skeletal support, strong fin muscles, cosmic scales, 2 dorsal fins, (some) nasal opening extends to oral cavity
examples of sarcopterygii
lungfishes, coelacanths
3 types of actinopterygians
chondrostei, holostei (not natural group), teleostei
characteristics of chondrostei
early actinopterygians, e.g. sturgeon
characteristics of holosteans
few still living, intermediate forms, freshwater, fast swimming, e.g. gar pikes
morphological trends discussed in chondrostei, holostei, teleostei
body shape and fin form/function, jaws, tail structure
trends from chondrostei to teleostei
elongated fusiform body, long jaws with immobile margin, heterocercal tail»_space;» short deep body, shortened jaws with mobile margin, homocercal tail
limbed vertebrates
stegocephalians
early tetrapod examples
elpistostegid fish, stegocephalians
recently discovered elpistostegid closely related to stegocephalians
tiktaalik
examples of basal stegocephalians
ichthyostega, acanthostega
characteristics of basal stegocephalians
fully formed limbs, skull, and vertebrae that could support weight on land but not well, retained full set of gills
clades of tetrapoda
amphibia, amniota
characteristics of amphibians
intermediate between bony fish and derived tetrapods, distinct mode of reproduction, lay eggs in water and have aquatic larval stage
characteristics of amniotes
extra-embryonic membranes surround and protect embryo, has longer development, gas exchange
living amphibians
lissamphibia
characteristics of lissamphibia
not primitive tetrapods, gas exchange by cutaneous respiration, pedicellate teeth, can have ancient or specialized locomotion
3 groups of lissamphibia
caudata, anura, gymnophiona
example of caudata
salamanders
example of anura
frogs
2 major lineages of amniotes
reptilia, synapsida
4 major skull types in amniotes
anapsid, euryapsid, diapsid, synapsid
characteristics of anapsid skull
no temporal fenestra
characteristics of diapsid skull
two temporal fenestra
characteristics of euryapsid skull
one dorsally positioned fenestra
characteristics of synapsid skull
one ventrally positioned fenestra
2 main subdivisions of reptilia
parareptilia, diapsida
characteristics/examples of parareptilia
anapsid skulls, eg turtles
characteristics/examples of diapsida
diapsid skulls and extinct euryapsid skulls, very large and diverse group
2 main groups of diapsida
arcosauromorpha, lepidosauromorpha
examples of arcosauromorpha
crocodiles, pterosaurs, dinosaurs, birds
examples of euryapsid lepidosauromorpha
ichtyosaurs, plesiosaurs
examples of diapsid lepidosauromorpha
rhyncocephalians, lizards, snakes (lizards non natural group, lizards and snakes in same natural group
2 broad groups of synapsids
“pelycosaurs”, therapsida
characteristics of mammals
mammary glands, hair, muscular diaphragm
useful skeletal elements that help identify specimens as mammals
each mandible formed by 2 dentary bones, 3 middle ear ossicles, jaw joint at squamosal-dentary, complex teeth, non-sprawling posture
reptile-like jaw condition
quadrate-articular
bone that became incus
quadrate
bone that became malleus
articular
bone that became mammalian ectotympanic membrane
angular
2 groups of living mammals
monotremata, theria
2 groups of theria
marsupiala, eutheria (placentals)
species of monotremata and characteristics
platypus, echidnas - have hair, suckle young, endothermic BUT retain cloaca, lack nipples, lay eggs w leathery shells
characteristics of marsupiala
mainly found in SA and australia, pouched mammals, have placenta, most have yolk sac placenta
characteristics of eutheria
all have chorioallantoic placenta
microlecithal
egg with little yolk
mesolecithal
egg with moderate amount of yolk
macrolecithal
egg with a lot of yolk
fertilization»_space;> blastula process in microlecithal egg
protoplasm in animal pole divides twice vertically then horizontally until 1-cell width blastula forms
fertilization»_space;> blastula process in mesolecithal egg
smaller animal pole, cellular divisions less equal, forming several cell width blastula with blastocoele displaced toward animal pole
fertilization»_space;> blastula process in macrolecithal egg
only small cap of protoplasm divides, blastula forms as a plate of cells at animal pole which is separated from yolk by blastocoele
fertilization»_space;> blastula process in mammals
IN UTERUS - continued division produces blastula with outer trophoblast, structure that will be part of placenta
structure of trophoblast
looks like microlecithal blastula but has its own animal pole, the inner cell mass that continues to divide
mammalian embryology post-blastula
gastrulization leading to structural arrangement of 3 basic germ layers
3 basic germ layers
ectoderm, mesoderm, endoderm
gasrulization of amphioxus
blastula vegetal pole folds inward into blastocoele, animal pole cells form ectoderm and vegetal pole cells form endoderm
dorsal middle of ectoderm
neurectoderm
2 kinds of mesoderm
chordamesoderm at dorsal midline, lateral mesoderm on either side
gastrulation results in
elongated gastrula with gastrocoele that opens into the blastopore
ultimately, ectoderm differentiates into
skin and nervous system
ultimately, mesoderm differentiates into
somatic skeleton, muscle, circulatory system
ultimately, endoderm differentiates into
digestive tract and visceral derivatives (muscles and skeleton)
step 1 after gastrula
ectoderm differentiates to also form neurectoderm, mesoderm differentiates into chordamesoderm dorsally and lateral mesoderm that expands laterodistally, endoderm expands dorsomedially
step 2 after gastrula
neurectoderm invaginate while ectoderm expands to cover it forming neural crest cells and neurogenic placodes, mesoderm continues laterodistal expansion while subdividing to form a column on either side, endoderm completely surrounds gastrocoele
step 3 after gastrula
ectoderm covers neural tube, lateral mesoderm subdivides dorsoventrally into epimere, mesomere, hypo mere with enlarging column, endoderm relatively smaller
step 4 after gastrula
neural crest cells begin to migrate, epimere subdivides lateromedially into dermatome, myotome, sclerotome
step 5 after gastrula
further expansion of all mesoderm subdivisions
step 6 after gastrula
dermatome loses segmentation and expands deep into ectoderm, myotome expands dorsally between ectoderm and sclerotome and ventrally between ectoderm and hypo mere, sclerotome surrounds notochord and neural tube
hypomere divides into and becomes
somatic and visceral layers become parietal and visceral serosa, heart and blood vessels, lymph vessels, gonads
mesomere becomes
kedneys, excretory, and reproductive ducts
mesoderm development beyond step 6
dermatome becomes dermis of integument, dermal muscles and dermal skeletal structures, myotome gets divided by horizontal septum into epaxial and hypaxial musculature, sclerotome becomes vertebral column
endoderm development beyond step 6
primitive gut becomes liver, pancreas, lining of lungs, digestive tract, urinary bladder
primary body tissues
epithelial, connective, muscular, nervous
characteristics of epithelial tissue
covers exposed surfaces (internal, no exit - serosa and external, exit - mucosa), forms glands, has apical and basal surfaces, avascular, few to no nervous structures
2 main layers of integument
epidermis and dermis
characteristics of epidermis
superficial, epithelial, derived from ectoderm, usually thin
characteristics of dermis
deep, connective, derived from dermatome, usually thicker than epidermis, sensory receptors
method used by vertebrates to avoid water loss through integument
most superficial layer of epidermis formed by dead hard cells, waterproofed using insoluble proteins like keratins
typical arrangement of integument layers and characteristics
epidermis, dermis, hypodermis - deep to dermis, loose connective tissue and adipose tissue
2 main layers of epidermis
stratum corneum - thin layer of dead cells, stratum basal - mostly keratinocytes, living cells; continually divides to replace lost cells
characteristics of primitive fish skin
epidermis almost all live cells (not keratinized), secrete mucus, in some forms denticles
characteristics of derived fish skin
scales formed of both epidermis and dermis including enamel, dentin, bone
shark skin and scales
placoid scales formed from dentin and capped with enamel
role of dermis in bony fish
forms bony plates of placoderms and ostracoderms, posterior dermal scales in above, forms cosmoid and ganoid scales
cosmoid scale
primitive sarcopterygians, has dentin covering bone
ganoid scale
primitive actinopterygians, has enamel covering bone instead of dentin
teleost scale
derived actinopterygians, divided into cycloid form and ctenoid form
characteristics of amphibian skin
thin stratum corneum, most cells living for cutaneous respiration, have mucous and poison glands
characteristics of reptile skin
extensive keratinization into epidermal scales, may be modified into crests, spines or horns, dermal bone mainly present in gastralia, few glands, mainly scent
keratinized epidermal derivatives in mammals
scales in pangolins, beaver tail, calluses, nails/claws/hooves, hair, horns/antlers, glands
structure of true horns
keratinized sheath supported by unbranched bony core or spike, not shed (cattle, antelope, goats, sheep)
structure of antlers
velvety shin, bone only when mature, tends to be branched, shed annually, usually only males
structure of rhino horn
keratinized epithelium in form of fused hairlike epidermal papillae
structure of giraffe horn
ossified cartilage core covered by skin
types of gland structures
alveolar, tubular/coiled, complex/compound
two important glands found in birds
uropygial - near base of tail, secretes oily substance used in preening
salt gland - on head of some birds, secretes excess salt
glands found in mammals
eccrine - watery secretion
apocrine - viscous secretion (mammary, scent)
monotreme mammary glands
complex glands
marsupial and eutherian mammary glands
teat - complex glands that secrete into a cistern and out the teat through the teat duct
nipple - complex glands that secrete through a concentrated opening
mesenchyme
mainly from epi- and hypo mere, network of cells between outer tube and developing organs, cells capable of amoeboid movement, functions as embryonic CT, differentiates into muscles, circ system, CT
characteristics of bone
mineralized matrix, metabolically active, osteocytes in chambers and stellate lacunae in matrix, vascularized, grows by surface expansion
characteristics of cartilage
more variable than bone, rigid matrix, spherical chondrocytes and isolated lacunae, avascular, not metabolically active, grows by internal and surface expansion
3 broad classes of bone
dermal skeleton, endoskeleton, heterotopic skeletal elements
characteristics of dermal skeleton
forms directly in CT in dermis, never preformed in cartilage superficial position, e.g. bony plates/scales in early fish, osteoderms, crocodilians, turtles, armadillo
characteristics of endoskeleton
endochondral, almost always preformed in cartilage, most bones of the body
subdivisions of endoskeleton
somatic - formed by somites of epaxial mesoderm, axial and appendicular
visceral - associated or derived from branchial arches formed by neurectoderm
characteristics of heterotopic skeletal elements
anything not included as dermal or endoskeleton, similar to dermal but usually not preformed in cartilage
examples of heterotopic skeletal elements
bones that grow in tendon of a muscle - sesamoid bones: patella, os cordis (in septum of cattle heart), baculum (os penis), os clitoridis
shaft of bone
diaphysis
end of bone
epiphysis
separates diaphysis and epiphysis
epiphyseal line
hyaline cartilage layer in young between diaphysis and epiphysis
epiphyseal plate
fibrous CT surrounding element
periosteum
cavity in diaphysis
medullary cavity
CT lining cavity and spaces within bone
medullary cavity
cartilage at joints
articular cartilage
process of endochondral ossification
- formation of bone collar around hyaline cartilage
- perichondral ossification where collar will meet inner oss. centre
- invasion of internal cavities by periosteal bud, spongy bone formation
- formation of medullary cavity, appearance of secondary oss centres in epiphyses
- ossification of epiphyses, cartilage remains only in plates and at articulars
types of vertebrae in fish
trunk, caudal
types of vertebrae in primitive tetrabods
trunk, sacral, caudal
types of vertebrae in advanced tetrapods
cervical, dorsal sacral caudal
types of vertebrae in mammals
cervical, thoracic, lumbar, sacral, caudal
embryological precursor to vertebrae
sclerotome of epimere
arrangement of vertebrae in amniotes
intersegmentally with respect to musculature
development of vertebrae
groups of sclerotome cells form primary sclerotome, migrate medially toward notochord and rearrange, form secondary sclerotome blocks made of 2 adjacent primary sclerotomes
bony fish post cranial skeleton
lots of dermal bone in skin, pectoral girdle formed from dermal (anchor girdle to body) and endoskeletal bone (supports fin)
tetrapod/mammalian post cranial skeleton
endoskeleton expansion, scapula becomes main shoulder element, only clavicle remains of dermal elements and is sometimes reduced to allow more mobile scapula
skull is fusion of
dermal and endoskeletal (endochondral)
3 parts of bony skull
brain case - somatic endochondral, some dermal
palatal complex - dermal, some visceral endochondral
skull roof - dermal
5 groups of skull roof bones
tooth bearing marginal series (rim of roof), midline series (adjacently paired), circumorbital series (surround orbit), temporal series (bw otic notch and midline series), cheek series (behind orbit, below otic notch)
palatal complex
paired bones, mostly dermal some visceral endochondral
bones of palatal complex
dermal: vomer, palatine, ectopterygoid, pterygoid
visceral endochondral: palatoquadrate
2 ossifications along palatoquadrate in tetrapods
quadrate (smaller, posterior), epipterygoid (larger, anterior, art with braincase)
in tetrapods, palatal quadrate articulates with
lower jaw via quadrate, braincase between epipterygoid and basisphenoid
brain case
not all paired bones, mostly somatic endochondral but one dermal bone
dermal bone of braincase
parasphenoid - in skin on roof of oral cavity, ventral brain case, narrow anteriorly wide posteriorly
somaric endochondral bones of braincase
supraoccipital, basiooccipital, paired exooccipitals (surround foramen magnum), opisthotic, prootic (surround canal of inner ear), basisphenoid, sphenethmoid
basisphenoid
median, mostly ventral and anterior to otic region, floor of cranial cavity, covered ventrally by parasphenoid, basipterygoid on either side
sphenethmoid
median ossification in sphenoid and ethmoid regions, trough shaped, contains olfactory nerves
5 skull types (evolutionary progression)
early tetrapod, amniote, early synapsid, non-mammalian therapsid, mammalian
changes from early tetrapod to basal amniote skull
otic notch closed, intertemporals lost, posterior displacement and reduction in other temporal bones, post parietals and tabular fused into occipital, supra temporal lost
changes from early synapsid to non-mammalian therapsid skull
early synapsids developed temporal fenestra, which enlarged to become fossa in non-mammalian therapsid, quadratojugal reduced, squamosal differentiates into zygomatic arch and part of braincase, prefrontals/postfrontals/postorbitals lost
changes from non-mammalian therapsid skull to mammalian
muscles go from outside skull to inside, brain bigger and completely enclosed in bone, development of a secondary palate to differentiate food and air passages, complex fusions of temporal region
role of squamosal in mammalian skull
large flat dermal bone on side of brain
role of petrosal in mammalian skull
braincase, fusion of prootic and opisthotic
role of ectotympanic in mammalian skull
angular dermal bone, old lower jaw
role of entotympanic in mammalian skull
new development in mammals from braincase
precursor to malleus
articular, dermal bone of old lower jaw
precursor to incus
quadrate, endochondral, palatal complex
stapes
hyomandibular, visceral endochondral
