Comparative Anatomy Lecture Exam 2

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

features of tetrapod 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

• zygopothesis from one vertebrae overlap the cranial (rostal)

• zygapothesis in another