Comparative Comparative AnatomyAnatomy
BoneBone
Note Set 7Note Set 7
Chapters 7, 8, & 9Chapters 7, 8, & 9
Bone LegacyBone Legacy
Exoskeleton or dermal skeletonExoskeleton or dermal skeleton Dermal bony armor of ostracodermsDermal bony armor of ostracoderms Bony scales in ancient fishBony scales in ancient fish
Cranial dermal armor arose from Cranial dermal armor arose from neural crest cellsneural crest cells
EndoskeletonEndoskeleton Internal to skinInternal to skin Where once exoskeleton Where once exoskeleton
Ex: clavicle, nasal, frontal, and parietal boneEx: clavicle, nasal, frontal, and parietal bone
Other endoskeletal elements were Other endoskeletal elements were never part of the dermal skeletonnever part of the dermal skeleton Ex: scapula, vertebrae, ribs, sternum, Ex: scapula, vertebrae, ribs, sternum,
brain case, and extremity bonesbrain case, and extremity bones
Bone EvidenceBone Evidence
All bone develops from mesenchymeAll bone develops from mesenchyme Neural crest cellsNeural crest cells Membrane boneMembrane bone- arises from - arises from
mesenchyme without passing through mesenchyme without passing through cartilaginous intermediatecartilaginous intermediate exoskeletonexoskeleton
Replacement boneReplacement bone- arises from - arises from existing cartilageexisting cartilage endoskeletonendoskeleton
Endoskeletal TissuesEndoskeletal Tissues Visceral SkeletonVisceral Skeleton
Jaw cartilages and ear ossiclesJaw cartilages and ear ossicles Weberian ossicles of fish (ear ossicles)Weberian ossicles of fish (ear ossicles)
Derived from transverse processes of Derived from transverse processes of anterior most vertebraeanterior most vertebrae
Somatic SkeletonSomatic Skeleton Remaining internal bones developing Remaining internal bones developing
from mesoderm properfrom mesoderm proper Somite and scleratomeSomite and scleratome
Axial SkeletonAxial Skeleton Appendicular SkeletonAppendicular Skeleton
Vertebrae DevelopmentVertebrae Development
Arise from sclerotome cells of somitesArise from sclerotome cells of somites MorphogenesisMorphogenesis
Sclerotome divides into posterior and Sclerotome divides into posterior and anterior halvesanterior halves
Halves join with segments of adjacent Halves join with segments of adjacent sclerotomessclerotomes
Centrum formed from junction Centrum formed from junction Vertebrae are intersegmentalVertebrae are intersegmental Myotome doesn’t moveMyotome doesn’t move Posterior segment forms costal processPosterior segment forms costal process
Site of rib attachmentSite of rib attachment
Figure 9.2: Developing vertebral column showing intersegmental position.
Figure 9.1: (a) sclerotome divides (b) halves join with adjacent halves of next sclerotome (c) junction forms centrum.
Vertebrae DevelopmentVertebrae Development
Axial Skeleton VertebraeAxial Skeleton Vertebrae
Cartilaginous or bonyCartilaginous or bony From occipital region to tailFrom occipital region to tail Vertebrae types based on centrum Vertebrae types based on centrum
structurestructure Centrum is common feature in all Centrum is common feature in all
vertebraevertebrae
Centrum StructureCentrum Structure
Acelous- flat anterior and posterior surfaceAcelous- flat anterior and posterior surface MammalsMammals
Amphicelous- concavities of anterior and Amphicelous- concavities of anterior and posterior surfacesposterior surfaces
Fish, primitive salamandersFish, primitive salamanders Procelous- concanvity on anterior surfaceProcelous- concanvity on anterior surface
Most reptilesMost reptiles Opisthocelous- concavity of posterior Opisthocelous- concavity of posterior
surfacesurface Most salamandersMost salamanders
Heterocelous- saddle-shapedHeterocelous- saddle-shaped Neck of birds and turtlesNeck of birds and turtles
Figure 9.3: Vertebral types based on articular surface of centra.
Vertebrae EvolutionVertebrae Evolution Transition from Transition from
crossopterygians to crossopterygians to labyrinthodontslabyrinthodonts
Different types of vertebrae Different types of vertebrae came from primitive, came from primitive, rachitomous labyrinthodont rachitomous labyrinthodont vertebraevertebrae
Two pleurocentra and U-Two pleurocentra and U-shaped hypocentrumshaped hypocentrum
Hypocentrum is lost and Hypocentrum is lost and pleurocentrum enlarges and pleurocentrum enlarges and gives rise to centrum of gives rise to centrum of modern amniotemodern amniote
Figure 9.4: Modifications from labyrinthodont to modern amniote vertebrae. Hypocentrum is diagonal lines. Pleurocentrum is red.
Vertebrae Grouping Vertebrae Grouping
Grouped according to body Grouped according to body regionregion
AmphibiansAmphibians First to possess a cervical First to possess a cervical
vertebraevertebrae
Figure 9.5: Single cervical vertebrae of anuran.
Figure 9.6: Regions of vertebral column
Reptile VertebraeReptile Vertebrae
Atlas as 1st and axis Atlas as 1st and axis as 2nd cervicalsas 2nd cervicals
Turtle: 8 cervicals, Turtle: 8 cervicals, 2 sacrals, 10 2 sacrals, 10 dorsals, 16-30 dorsals, 16-30 caudalscaudals
Alligator: 8 Alligator: 8 cervicals, 11 cervicals, 11 thoracic, 5 lumbar, thoracic, 5 lumbar, 2 sacrals, up to 40 2 sacrals, up to 40 caudalscaudals
Figure 9.8: Dorsal view of sacral vertebrae of vertebrates.
Figure 9.7: atlas and axis cervical vertebrae.
Bird VertebraeBird Vertebrae
Possess atlas and axisPossess atlas and axis 13-14 free cervicals, 4 fused 13-14 free cervicals, 4 fused
thoracics, fused synsacrum, free thoracics, fused synsacrum, free caudals, pygostylecaudals, pygostyle
Figure 9.9: Pigeon vertebral column.
SynsacrumSynsacrum Fuses with pelvic Fuses with pelvic
bonebone Reduction in bone Reduction in bone
massmass
Figure 9.11: Synsacrum and pelvic girdle left lateral (a) and ventral (b) views.
Figure 9.10: Pigeon skeleton: trunk, tail, and pectoral girdle.
Mammal VertebraeMammal Vertebrae
most have 7 cervicalsmost have 7 cervicals 12 thoracic and 5 lumbar compose 12 thoracic and 5 lumbar compose
dorsal vertebraedorsal vertebrae ancestral mammals possessed ~ 27 ancestral mammals possessed ~ 27
presacralspresacrals sacrum 2-5 fused vertebrae (ankylosed)sacrum 2-5 fused vertebrae (ankylosed) caudals are variablecaudals are variable
primates have 2-5 fused into coccyxprimates have 2-5 fused into coccyx
Ribs Ribs
Dogfish- develop dorsal ribsDogfish- develop dorsal ribs Most teleost- develop ventral ribsMost teleost- develop ventral ribs Tetrapods- have dorsal and Tetrapods- have dorsal and
ventral ribsventral ribs Dorsal ribs lost, enlargement of head Dorsal ribs lost, enlargement of head
of proximal ribsof proximal ribs 2 portions articulate 2 portions articulate
with vertebraewith vertebrae Tuberculum- dorsal headTuberculum- dorsal head Capitulum- ventral headCapitulum- ventral head
Figure 9.12: Rib types - Dorsal and ventral ribs.
Agnathans- no ribsAgnathans- no ribs Amphibians- ribs Amphibians- ribs
never reach never reach sternumsternum
Birds- flat Birds- flat processes processes extending off ribs extending off ribs posteriorly posteriorly (unicate processes)(unicate processes)
Figure 9.13: Unicate processes of bird.
Figure 9.14: Vertebrae and ribs of alligator.
SternumSternum Tetrapod structureTetrapod structure Amphibians- poorly formedAmphibians- poorly formed Reptiles- cartilaginous platesReptiles- cartilaginous plates
Snakes, legless lizards, turtles have no Snakes, legless lizards, turtles have no sternumsternum
Alligator- extends down bellyAlligator- extends down belly Ribs fused it sternumRibs fused it sternum GastraliaGastralia
Figure 9.15: Ribs and gastralia of alligator.
Birds- unusual, keeled sternum Birds- unusual, keeled sternum in carinatesin carinates
Mammals- well developed Mammals- well developed sternumsternum Rod shapedRod shaped Segments: manubrium, Segments: manubrium,
sternebrae, xiphisternum and sternebrae, xiphisternum and xiphoid processxiphoid process
Figure 9.17: Tetrapod sterna.Figure 9.16: Keeled sternum of bird.
Heterotopic BoneHeterotopic Bone
Develop by endochondral or Develop by endochondral or intramembranous ossification intramembranous ossification
In areas subject to continual stressIn areas subject to continual stress Ex: os cordis, rostral bone, os penis, os Ex: os cordis, rostral bone, os penis, os
clitoridisclitoridis
Os cordis- interventricular Os cordis- interventricular septum in deer heartseptum in deer heart
Rostral bone- snout of pigRostral bone- snout of pig Os penis (baculum)- Os penis (baculum)-
embedded in penis of embedded in penis of lower primateslower primates
Os clitoridis- embedded in Os clitoridis- embedded in clitoris of ottersclitoris of otters
Others include falciform, Others include falciform, sesamoid, patella, sesamoid, patella, pisiformpisiform
Figure 9.18: Heterotopic bones (book figure 7.11).
Skull and Visceral Skull and Visceral SkeletonSkeleton
Two functionally independent Two functionally independent cartilaginous components derived from cartilaginous components derived from replacement bonereplacement bone
1. Neurocranium1. Neurocranium
2. Splanchnocranium2. Splanchnocranium
Figure 9.19: Placoderm skull; neurocranium in blue; splanchnocranium in yellow.
NeurocraniumNeurocranium
Protects brain and anterior part of spinal cordProtects brain and anterior part of spinal cord Sense organ capsulesSense organ capsules Cartilaginous brain case is embryonic Cartilaginous brain case is embryonic
adaptationadaptation Four ossification centersFour ossification centers
Figure 9.20: Development of cartilaginous neurocranium.
Neurocranium Ossification Neurocranium Ossification CentersCenters
Occiptial RegionOcciptial Region Sphenoid Sphenoid
RegionRegion Ethmoid RegionEthmoid Region Otic RegionOtic Region
Figure 9.21: Neurocranium of human skull.
Occipital RegionOccipital Region Basioccipital, 2 exoccipitals, Basioccipital, 2 exoccipitals,
suproccipitalsuproccipital Forms single occipital bone in Forms single occipital bone in
mammalsmammals Sphenoid RegionSphenoid Region
Basisphenoid, orbitosphenoid, Basisphenoid, orbitosphenoid, presphenoid, laterosphenoidpresphenoid, laterosphenoid
Fuse to form one sphenoid Fuse to form one sphenoid
bone in mammalsbone in mammals
Figure 9.22: Sphenoid bone.
Figure 9.23: Human skull (a) cribriform plate (b) crista galli (c) frontal bone (d) sphenoid bone (e) temporal bone (f) sella turcica.
Figure 9.24: Sphenoid bone.
Ethmoid RegionEthmoid Region Anterior to sphenoidAnterior to sphenoid Cribriform plate, olfactory foramina, Cribriform plate, olfactory foramina,
terminals, mesamoid terminals, mesamoid Fuse to form ethmoid in mammalsFuse to form ethmoid in mammals
Otic Region Otic Region Three bones in tetrapodsThree bones in tetrapods
ProoticProotic OpisthoticOpisthotic EpioticEpiotic
Unite to form petrosal bone in birds and Unite to form petrosal bone in birds and mammalsmammals Forms temporal in mammalsForms temporal in mammals
Figure 9.26: Multiple nature of temporal bone of mammals.
Figure 9.25: Temporal bone of human skull.
Figure 9.27: Intramembranous ossification of human skull. Embryonic, cartilaginous neurocranium is black. Neurocranial bones are red. Other is dermal mesenchyme.
SplanchnocraniumSplanchnocranium
Visceral skeletonVisceral skeleton Visceral archesVisceral arches Branchial regionBranchial region
Figure 9.28: Splanchnocranium of human. Skeletal derivatives of 2nd through 5th pharyngeal arches.
1st visceral arch- 1st visceral arch- mandibularmandibular Meckel’s cartilage Meckel’s cartilage
malleusmalleus Pteryoquadrate Pteryoquadrate incus incus
2nd visceral arch- hyoid2nd visceral arch- hyoid hyomandibula hyomandibula columella columella
(stapes)(stapes) ceratohyal ceratohyal styloid styloid
process and anterior horn of process and anterior horn of hyoidhyoid
basihyal basihyal body of hyoid body of hyoidFigure 9.29: Caudal end of Meckel’s cartilage and developing middle ear cavity.
Visceral-Cranial Visceral-Cranial DerivativesDerivatives
Alisphenoid- part of Alisphenoid- part of sphenoidsphenoid
Malleus, incus- 1st archMalleus, incus- 1st arch Stapes- 2nd archStapes- 2nd arch Styloid- 2nd archStyloid- 2nd arch Hyoid- mainly basihyalHyoid- mainly basihyal
Figure 9.30: Derivatives of the human visceral skeleton (red).
Figure 9.31: Skeletal derivatives of pharyngeal arches.
DermatocraniumDermatocranium Membrane bone, not Membrane bone, not
replacement bonereplacement bone Dermal bones of skullDermal bones of skull Upper jaw and face, palates, Upper jaw and face, palates,
mandiblemandible
Figure 9.32: Pattern that tetrapod dermatocrania may have evolved.
Figure 9.34: Endochondral bones (red) of mammalian skull.
Figure 9.33: Dog skull showing dermatocranium (pink), chondrocranium (blue), and splanchnocranium (yellow).
Dermatocranium Dermatocranium (cont.)(cont.)
Dermatocranial ElementsDermatocranial Elements
NasalNasal SquamosalSquamosal Secondary palate- premaxilla, maxilla, Secondary palate- premaxilla, maxilla,
jugaljugal Primary palate- vomer, palatine, Primary palate- vomer, palatine,
pterygoidpterygoid
Neurocranial ElementsNeurocranial Elements
CribriformCribriform EthmoidEthmoid Otic complexOtic complex Temporal boneTemporal bone
Splanchnocranial Splanchnocranial ElementsElements
Maleus, incus, stapesMaleus, incus, stapes Styloid process- hyoidStyloid process- hyoid
Visceral Arches of ManVisceral Arches of Man
Styloid processesStyloid processes Body of hyoidBody of hyoid ThyroidThyroid CricoidCricoid
Middle Ear BonesMiddle Ear Bones
Hammer (malleus_Hammer (malleus_ Anvil (incus)Anvil (incus) Stirrup (stapes)Stirrup (stapes)
Not homologous to weberian ossicles Not homologous to weberian ossicles in teleost fishin teleost fish Modified transverse processes of Modified transverse processes of
anteriormost vertebrae in some fishes.anteriormost vertebrae in some fishes.
Appendicular SkeletonAppendicular Skeleton
Pectoral GirdlePectoral Girdle Pelvic GirdlePelvic Girdle AppendagesAppendages Adaptations for SpeedAdaptations for Speed
Pectoral GirdlePectoral Girdle
2 sets of elements: cartilage 2 sets of elements: cartilage or replacement bone and or replacement bone and membrane bonemembrane bone
Replacement bonesReplacement bones Coracoid, scapula, Coracoid, scapula,
suprascapulasuprascapula Membrane bonesMembrane bones
Clavicle, cleithrum, Clavicle, cleithrum, supracleithrumsupracleithrum
Figure 9.35: Pectoral girdle phylogenetic lines. Dermal bones are red. Replacement bones are black.
Reduction in number Reduction in number of bones through of bones through evolutionevolution
Shark- only cartilagenous Shark- only cartilagenous componentscomponents
Alligator- retains only Alligator- retains only replacement bone replacement bone elements, no dermal boneelements, no dermal bone
Mammals Mammals Scapula of replacement Scapula of replacement
bone bone Clavicle of membrane boneClavicle of membrane bone
Birds- two clavicles fuse Birds- two clavicles fuse to form furcula to form furcula (wishbone)(wishbone)
(a)
(b)
Figure 9.36: Pectoral girdles of (a) Polypterus and (b) shark.. Dermal bones are red. Replacement bones are black..
Pelvic GirdlePelvic Girdle
No dermal elementsNo dermal elements Three replacement Three replacement
bonesbones Ilium, ischium, pubisIlium, ischium, pubis
Triradiate pelvic Triradiate pelvic girdle- alligator and girdle- alligator and dinosaurdinosaur
Figure 9.37: Left halves of pelvic girdles showing parallel evolution.
AppendagesAppendages
Single unit in both fore and hind limbs most Single unit in both fore and hind limbs most medialmedial
Two units in fore and hind limb distal areaTwo units in fore and hind limb distal area
Figure 9.38: Dorsal view of left forelimb or forefin of Devonian tetrapods.
Figure 9.39: Cladogram of lobe-Fin fishes and amphibians.
Figure 9.40: Left pectoral fin of Devonian fish [left] and forelimb of early tetrapod [right].
Small set of bones at wrist Small set of bones at wrist and ankleand ankle
Pentameristic pattern of Pentameristic pattern of phalangesphalanges
Reduction in number and Reduction in number and position of phalangesposition of phalanges
Figure 9.41: Evolution of fins to limbs.
Adaptations for SpeedAdaptations for Speed
PlantigradePlantigrade Flat on the groundFlat on the ground Primates Primates
DigitigradeDigitigrade ElevatedElevated CarnivoresCarnivores
UnguligradeUnguligrade Reduction in digitsReduction in digits Two typesTwo types Figure 9.42: Plantigrade, digitigrade, and
unguligrade feet. Ankle bones are black. Metatarsals are grey.
Unguligrade AdaptationUnguligrade Adaptation Reduction in digitsReduction in digits
PerissodactylsPerissodactyls Odd toedOdd toed Mesaxanic footMesaxanic foot Weight on enlarged Weight on enlarged
middle digitmiddle digit Ex: horseEx: horse
ArtidodactylsArtidodactyls Even toedEven toed Paraxonic footParaxonic foot Weight equally Weight equally
distributed on 3distributed on 3rdrd and and 44thth digits digits
Ex: camelEx: camel
Figure 9.43: Unguligrade adaptations in horse and camel. Bones lost are white.
Locomotion Without Locomotion Without LimbsLimbs
SerpentineSerpentine Lateral undulationLateral undulation Wave motionWave motion Minimum 3 contact Minimum 3 contact
pointspoints RectilinearRectilinear
Straight lineStraight line Scutes on belly liftScutes on belly lift Costocutaneous Costocutaneous
muscles move the skinmuscles move the skinFigure 9.44: Serpentine locomotion (a) and rectilinear locomotion (b & c).
(a)
(b)
(c)
SidewindingSidewinding Minimum 2 contact pointsMinimum 2 contact points Adaptation in sandy Adaptation in sandy
habitats habitats ConcertinaConcertina
Minimum 2 contact pointsMinimum 2 contact points Allows snake to move up Allows snake to move up
guttergutter
Locomotion Without Limbs Locomotion Without Limbs (cont.)(cont.)
(a) (b)
Figure 9.45: Sidewinding locomotion (a) and concertina locomotion (b).
Literature CitedLiterature CitedFigure 9.1- http://www.brown.edu/Courses/BI0032/bone/axial2.htmFigure 9.1- http://www.brown.edu/Courses/BI0032/bone/axial2.htmFigure 9.2, 9.3, 9.4, 9.5, 9.8, 9.9, 9.10, 9.11, 9.12, 9.14, 9.16, 9.17, 9.18, 9.20, 9.21, Figure 9.2, 9.3, 9.4, 9.5, 9.8, 9.9, 9.10, 9.11, 9.12, 9.14, 9.16, 9.17, 9.18, 9.20, 9.21,
9.25, 9.26, 9.27, 9.28, 9.29, 9.30, 9.31, 9.32, 9.34, 9.35, 9.36, 9.37, 9.40, 9.42 & 9.25, 9.26, 9.27, 9.28, 9.29, 9.30, 9.31, 9.32, 9.34, 9.35, 9.36, 9.37, 9.40, 9.42 & 9.43- Kent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9.43- Kent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001.9th ed. McGraw-Hill, 2001.
Figure 9.6- http://www.agrabilityproject.org/assistivetech/tips/tractorseat.cfmFigure 9.6- http://www.agrabilityproject.org/assistivetech/tips/tractorseat.cfmFigure 9.7- http://www.spineuniverse.com/displayarticle.php/article2245.htmlFigure 9.7- http://www.spineuniverse.com/displayarticle.php/article2245.htmlFigure 9.13- Figure 9.13-
http://bioweb.uwlax.edu/zoolab/Table_of_Contents/Lab-9b/Bird_Skeleton_1/http://bioweb.uwlax.edu/zoolab/Table_of_Contents/Lab-9b/Bird_Skeleton_1/Bird_Skeleton_1c/bird_skeleton_1c.htmBird_Skeleton_1c/bird_skeleton_1c.htm
Figure 9.15- http://www.auburn.edu/academic/classes/zy/0301/Topic8/Topic8.htmlFigure 9.15- http://www.auburn.edu/academic/classes/zy/0301/Topic8/Topic8.htmlFigure 9.19-Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution. Figure 9.19-Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution.
McGraw Hill, 2002. McGraw Hill, 2002. Figure 9.22- http://www.mlaphil.org/chronicle/20n3/fall2002.htmFigure 9.22- http://www.mlaphil.org/chronicle/20n3/fall2002.htmFigure 9.23- http://www.staneksoftware.com/anatomy_bowl_content/SkSkull1.htmFigure 9.23- http://www.staneksoftware.com/anatomy_bowl_content/SkSkull1.htmFigure 9.24- http://www.upstate.edu/cdb/grossanat/hnsklatsb.shtmlFigure 9.24- http://www.upstate.edu/cdb/grossanat/hnsklatsb.shtmlFigure 9.33- Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution. Figure 9.33- Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution.
McGraw Hill, 2002. McGraw Hill, 2002. Figure 9.38- http://cas.bellarmine.edu/tietjen/images/subphylum_vertefish.htmFigure 9.38- http://cas.bellarmine.edu/tietjen/images/subphylum_vertefish.htmFigure 9.39- Figure 9.39-
http://bss.sfsu.edu/holzman/courses/Fall%2003%20project/CAtigersalamander.htmhttp://bss.sfsu.edu/holzman/courses/Fall%2003%20project/CAtigersalamander.htmFigure 9.41- http://pharyngula.org/~pzmyers/MyersLab/teaching/Bi104/l02/fins.htmlFigure 9.41- http://pharyngula.org/~pzmyers/MyersLab/teaching/Bi104/l02/fins.htmlFigure 9.44- http://www.worldwidesnakes.com/ri-reptile-basic-anatomy-locomotion.phpFigure 9.44- http://www.worldwidesnakes.com/ri-reptile-basic-anatomy-locomotion.phpFigure 9.45 (a)- http://folio.photosource.com/1120Figure 9.45 (a)- http://folio.photosource.com/1120Figure 9.45 (b)- http://voronoi.sbp.ri.cmu.edu/research/rsch_locomotion.htmlFigure 9.45 (b)- http://voronoi.sbp.ri.cmu.edu/research/rsch_locomotion.html
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