Comparative Anatomy Lecture Final ?

#tibula

describe what morphology is

the use of morphological characteristics to compare evolutionary relationships between organisms

Jean Bapsitste de Lamark

• believed in progressive change of characteristics dictated by use and disuse

• believed evolution happened each generation

describe what morphology is

the use of morphological characteristics to compare evolutionary relationships between organisms

Jean Bapsitste de Lamark

• believed in progressive change of characteristics dictated by use and disuse

• believed evolution happened each generation

Carolus Linnaeus

• used morphology to group organisms

• taxonomic classification founder

Charles Darwin

• survival of the fittest

• tree of life

George Curvier

• believed organisms exhibit ideal forms

• father of comparative anatomy

Richard Owen

• ancestral forms and homology

  • did not believe in evolution

• named dinosaurs

ontogeny

an animals individual development from fertilization to death

• gives us clues as to why form and function have changed in particular ways

invagination

one example of ontogeny: “how do we solve the surface area to volume ratio”

• the respiratory and digestive system in surface are in relation to our mass → think villi

synapomorphy

shared derived characteristic

autoapomorphy

unique characteristics

pleisomorphy

ancestral characteristics

monophyly

common ancestor and all descendants

paraphyly

common ancestor and some descendants united by some characteristic

chordata characteristics

1. dorsal hollow nerve

2. endostyle

3. notocord

4. post-anal tail

5. pharyngeal gill slits

compare and contrast homology VS homoplasy

similarities: similar structures in different animals

differences: homology is when structures have morphological resemblance to each each other due to a shared common ancestor (forelimbs of mammals). homoplasy is when structures resemble one another but develop independently potentially due to the environment (wings of birds, bats, and reptiles).

vertebrata characteristics

1. backbone

2. inner ear specialization

3. radial fin muscles

compared and contrast Protostome VS Deuterostome

similarities: they are both the first major division between organisms

differences: in protostomes the blastula develops a mouth first, has spiral cleavage and develops the coelom via schizocoely AKA the mesoderm splits to form the coelom. ex) crab

in deuterostomes the blastula develops a mouth second, has radial cleavage, and the coelom develops via enterocoely AKA the coelom buds off of the archenteron via enterocoelic pouches ex) fish

hemichordate characteristics

1. tripartite body (proboscis, collar, trunk)

2. link between invertebrates and vertebrates

3. have a stomochord

cephalochordate characteristics

1. myomeres (segmented muscles)

2. nervous system innervates muscles

3. “head” enclosed brain

4. locomotion!

craniate characteristics

1. “head” with tripartite brain

2. paired sense organs

3. neural crest cells (form when dorsal hollow nerve cord is developed)

4. neurogenic places (sense organ precursors)

5. muscularized hypomeres (contract the gills)

chordates VS craniates

chordates are filter feeders, craniates are pharynx feeders

Paedomorphism

vertebrate origins hypothesis: retention in adults of the larval form - child form

• keep the overall larval form and specialize it

• locomotion and different rate of development in reproductive organs drives this hypothesis

ex) axolotl

“new head” hypothesis

vertebrate origins hypothesis: Organisms centralized many structures in their head region (brain, eyes, ears) as well as changing feeding (muscular pharynx) means which makes you a better predator.

Gnathostome characterisitcs

• vertebrates with jaws

• paired nostrils

• fill gill slits + visceral gill arches

chrondrichthyes characteristics

• cartilaginous fish

  • cartilage skeleton strengthened by calcification

    • NOT BONES

Osteichthyes characteristics

• bony fish aka teleosts

• calcified bones

• swim bladders

Sarcoptyergian characteristics

• fleshy fish

• fins are monobasic (have a humerus + femur)

tetrapod characteristics

• limbs have digits

• develop articulations (shoulder + hips bear weight now)

• specialized sacral vertebra and sacral ribs

• lose connection between skull and pectoral girdle

embryogenesis

make an embryo

morphogenesis

making of the morphology (how you make an organ)

two types of development

indirect = metamorphosis phase

• (tadpole → frog)

direct = no intermediate stage

stages of development

1. fertilization

   • when sperm meets egg

2. cleavage

   • cell division without growth

3. gastrulation

   • formation of the three germ layers

three germ layers

1. ectoderm = outer skin

2. mesoderm = middle skin

3. endoderm = inner skin

ectoderm turns into….

epidermis

endoderm turns into…..

liver

mesoderm turns into….

notochord

neurulation

creation of the dorsal hollow nerve cord and neural crest cells

mesoderm differentiation

Created from enterocoelic pouches that bud off of the archenteron (gut) and form mesodermal segments called somites

• 1. Paraxial mesoderm:

  • segmented somites lateral to neural tube

  2. Lateral plate mesoderm:

  • broad, unsegmented somite that lies ventral between archenteron and ectoderm

  3. Intermediate mesoderm:

  • lies between the other two mesoderm layers

Paraxial mesoderm regions

1. sclerotome

   • forms vertebrate + occipital region of skull

2. myotome

   • forms voluntary + skeletal muscle

3. dermatome

   • forms the dermis

what does the meckel’s cartilage become

articular

what does the palatoquadrate become

quadrate

what are the two regions of the mandibular arch

1. palatoquadrate

2. mandible (meckel’s cartilage)

branchiomere

term used for embryonic development

• refers to the segmentation of the gill region

evolution of chordates feeding style

filter feeds → pharyngeal feeders

region between each branchiomere (arch)

pharyngeal pouch

how many branchiomeres

7 total arches

branchiomere - arch I

mandibular

• innervated by the trigeminal nerve (IV)

branchiomere - arch II

hyoid

• innervated by byfacial (VII)

branchiomere - arch III

glossopharyngeal

• innervated by glossopharyngeal (IX)

branchiomere - arches IV-VII

vagal 1, 2, 3, 4

• innervated by vagus (X)

characteristics of the skeletal system

• support / protection

  • attachment of muscles, tendons, and ligaments (locomotion)

  • framework of overall body shape

  • protection of internal organs

• hemopoeitic

  • produce blood cells in the bone marrow

• dynamic system

  • bimechanical strain, regulation of blood calcium levels, growth

why study bones?

• easy to study since they preserve well (fossilization)

• provides lots of information

  • can see where soft tissue attaches

  • predict locomotion

  • information about sense organs

  • diet of organisms (teeth shape)

3 classifications as bones

1. dermal VS endoskeleton

2. somatic VS visceral

3. cranial VS post-cranial

dermal VS endoskeleton

dermal = more superficial and develops as a membranous origin, consists of bony scales or large bony plates

endoskeleton = deeper and composed of cartilage then replaced by bones, ossification

2 types of ossification

1. intramembranous

2. endochondral

intramembranous ossification

formation of flat bones with mesenchymal cells that invade fibrous connective tissue, no cartilage model is present, flat bones are produced this way, this is the way bones heal after they are broken

endochondral ossification

bones are created through ossification of cartilage model, long bones are formed this way

somatic VS visceral

somatic = skeleton is associated with outer tube (mesoderm and ectoderm), most of the skeleton we think of

visceral = skeleton is associated with inner tube (endoderm), cartilage in the pharynx or gills

cranial VS post-cranial

head VS rest of the body

cranial skeleton regions

1. chondrocranium

   • protection of brain, neural crest cells derived

2. splanchnocranium

   • visceral skeleton, neural crest cells derived

3. dermatocranium

   • roofing bones, dermal bones, both mesoderm and neural crest cells derived

post-cranial skeletal regions

1. axial

   • notochord, vertebral column, ribs, fins, sternum

2. appendicular

   • appendages and associated girdles

cranial skeleton jobs

• protect soft tissue (brain + sense organs)

• involved in food gathering

• passage for respiratory flow of water and air

• major evolutionary changes occurred in the skull

chondrocranium jobs

• protects brain and sense organs

• most conserved evolutionarily

  • any change is done by fusion

splanchnocranium jobs

• jaws and gill arches

• primarily feeding and respiration

• contains the mandibular arch

splanchnocranium evolutionary trends

• loss of arches (associated with air breathing)

• incorporation of bones into the head

• jaw articulation changes

dermatocranium jobs

• primarily superficial dermal bones that cover the other two regions

  • roofing bones

  • palatal series (roof of mouth)

  • encase mandibular cartilage

  • opercular series

  • ventral gills

evolution of jaw suspension and jaw articulation is driven by …..

predation

three places jaws attach to on the palatoquadrate

1. ethmoid process

2. basiethmoid

3. otic process

three ways jaws are suspended

1. Amphistylic

2. Hyostylic

3. Autostylic

Amphistylic

• palatoquadrate anchored to chondrocranium and hyomandibular extends from otic capsule

• EX] bony fish

Hyostylic

• palatoquadrate is stabalized only the Hyomandibular

• EX] great white

Autostylic

• palatoquadrate fused to chondrocranium, frees up hyomandibular

• EX] cat

adaptation VS exaptation

adaptation = trait which makes an animal better suited for their environment

exapataion = adaptation with a change in function (palatoquadrate + meckel’s cartilage articulation)

what does the hyomandibula become in amphibians

columella

• transmits sound

• connects the tympanic membranes in frogs

what does the quadrate-articular become in mammals

denture-squamosal articulation

• increase in bite force

what does the quadrate become in mammals

incus

what does the articular become in mammals

malleus

what does they hyomadibular become in mammals

stapes

axial skeleton

portion of the skeleton that lies in the longitudinal axis of body

• cranial skeleton, notochord, vertebral column, medial finds, ribs and sternum

post cranial skeleton

axial skeleton and appendicular without skull

• give stability, rigidity, connection point for girdles

vertebrae common components

1. neural arches

2. hermal arches

3. neural and hemal spines

4. vertebral foramina

5. centrum

which craniates do not have vertebrae

• Hagfish only have a notocord

• lamprey have arcualia

Different types of vertebral columns

1. Amphicoelous

2. Procoelous

3. Opisthocoelous

4. Acoelous

5. Heterocoelus

amphicoelous vertebrae

both side of centra are concave, intervertebral pads present (derived from notochord), fishes

procoelous vertebrae

concave on cranial side, reduced chance of dislocation, intervertebral pads of ossified notochord, amphibians

opishocoelous vertebrae

convince caudal side, amphibians

acoelous vertebrae

flat surface, intervertebral disks present, mammals

heterocoelus vertebrae

saddle shaped centra, high mobility, bird necks

list the rib articulations

1. Basapothesis

2. Parapothesis

3. Diapothesis

Basapothesis rib articulation

vertebral rib attachment

Parapothesis rib articulation

small process for head of rib

Diapothesis rib articulation

transverse process for rib tuberculum

types of skeletogenous septum

1. dorsal

2. lateral

3. ventral

4. horizontal

tetrapod vertebrae evolution

1. centrum have become larger and well developed

2. increase in articulation sites

3. evolved ‘neck’ region

   • atlas + axis

4. regionalization of vertebrae

type of apotheoses: Zygapotheses

extend from neural arch and caudal

type of apotheoses: zygopothesis

from one vertebrae overlap the cranial (rostal)

type of apotheoses: zygapothesis

another type that helps with stability

what are the 2 major challenges which shape the axial skeleton over the years?

1. the type of environment the organism lives in

2. the type of locomotion the organism exhibits

hagfish vertebrae evolution

no true vertebrae

lamprey vertebrae evolution

1. have arcualia

   • not q true vertebrae but gives stability to notochord