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 RegionSphenoid Region 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 process styloid process

and anterior horn of hyoidand anterior horn of hyoid basihyal basihyal body of hyoid body of hyoid Figure 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