Dissecting Dinosaurs: An exercise in
bird anatomy and evolution
What: Students will participate in a dissection of a variety of birds of
different species and ages. We will study internal and external anatomy of
the birds, and learn about what characteristics they share with other
dinosaurs. Students will also participate directly in the scientific process by
collecting data (e.g., molt, stomach contents, reproductive condition) to aid
in a doctoral dissertation research project.
Where: This activity will be schedule to take place in on the University of
California, Berkeley campus in the Valley Life Sciences Building.
Who: Local East Bay high school students will be led in the exercise by UC
Berkeley graduate and undergraduate students.
We provide: Materials to prepare for the activity, specimens and tools for
the dissection, safety gear, and follow-up materials for later use in the
classroom.
Where do the birds come from? All of the birds for this research project
have been donated by wildlife hospitals (such as the Lindsay Wildlife
Museum in Walnut Creek). They are all little guys who simply did not make
it, or had to be anesthetized.
Safety concerns: None of the birds have passed away from a serious
contagious disease, and most have been anesthetized. Additionally, all
specimens have been kept frozen for many weeks, which would kill any
bacteria. And, of course, all participating students will wear appropriate
safety gear; only tweezers and scissors will be used for the dissection (no
scalpel blades).
For any questions, please contact:
Jessie Atterholt ([email protected])
Dissecting Dinosaurs Outline
1) Major themes
a) Birds are living dinosaurs
i) How do we know this? (we’ll be looking at several aspects of anatomy
that birds share with extinct dinosaurs throughout the dissection)
ii) Show cast of Archaeopteryx(?)
b) Birds also have most of the same bones as we do, just in different shapes
and sizes
2) Molt
a) Feathers are one major feature that birds and extinct dinosaurs share
i) Show different feather types on samples skin (if available)
ii) Distinguish and count primaries & secondaries
(1) How many is this taxon supposed to have? Does it have the same #
on the right and the left?
iii) Examine the tail feathers for molt
iv) Mention that we’ll assess body molt later(?)
3) Skull
a) Do birds have teeth?
b) Identify cere and/or external ear opening?
4) Students cut the bird open from vent to throat, and carefully peel back the
skin
5) Throat/neck region
a) Identify larynx and crop
b) Examine trachea/syrinx (possibly sample syrinx)
6) Wings
a) Students cut a slit up the skin of both wings
b) Identify the 3 remaining digits
i) Notice alula on digit I
ii) How does a bird form its wing? Long humerus, very elongate
radius+ulna, long digit II—these are all the same bones we have, just
with some fused up (in the wrist/hand) and some lost (2 digits)
iii) Skin the wings, being very careful not to lose digits I and III
7) Legs
a) Students cut a slit up the skin of both legs
b) Partially remove one of the legs from the body (disarticulate the femur) to
see the perforated acetabulum, another dinosaurian characteristic
c) Notice how the feet are the only scaly parts of the bird, indicating their
reptilian heritage
d) Identify major bones of the leg; how are they the same as what we have?
How are they different?
i) They also are morphologically very similar to the foot of a theropod
dinosaur (show a picture/bring in a cast)
e) Skin the legs, ignoring skin on the feet if it’s too hard to get off
8) Students peel the skin off the back and head, removing it completely
9) Flight apparatus
a) Compare muscle mass on the chest with that on the back. Which is bigger?
Why?
b) Examine pectoral muscles, and supracoracoideus (?); identify triosseal
foramen, if possible
c) Identify furcula; the “wishbone” is another feature birds share with nonavian dinosaurs
10) Viscera
a) Identify and remove the liver
b) Identify and remove the stomach + intestines
i) If possible, examine the differentiated ventriculus and proventriculus
ii) Take notes on stomach contents, possibly collect samples
iii) Examine length of intestines, identify cecae
c) Identify kidneys
d) Identify gonads (if possible)
e) Find and remove heart
f) Collect HLMK tissue sampless
DissectingYourDinosaur
Whatkindofbirdisit?
Examinethebeak.Whatdoyouthinkitisadaptedfor?
Examinethefeet.Whatdoyouthinktheywereusedfor?
Step1:IdentifyingMolt
Birdslosetheirfeathersperiodicallythroughouttheirlives.Whenabirdlosesfeathersand
isgrowingnewones,thisiscalledmolting.
1. Gentlyspreadthewingsofyourbird.Doyouseeanysignsofmolt(feathers
growingit)?
2. Gentlyspreadthetailfeathersofyourbird.Doyouseeanysignsofmolthere?
Primaries attach to
Secondaries attach to
the ____________
the ____________
Primary flight feathers
Secondary flight feathers
Step2:MaketheFirstCut
1. Cuttingintotheskin:pushasidethefeathersonthebreastandstomachareauntil
youseetheskin.Lifttheskinonthebreastwithyourfingersortheforcepsandcuta
holewithyourscissors.
2. Cutopenuptothethroatofthebirdanddowntothecloaca.ITISVERY
IMPORTANTTOMAKESUREYOUAREJUSTCUTTINGTHESKINANDNOTTHE
SKELETONOFTHEABDOMINALWALLOFTHEBIRD.Theskinwillbeathin,
slightlysee‐throughlayerthatcoversabovethemuscleonthebreastmuscleand
downtheabdomen.Whenyouarecutting,ifyouencounteranythingthatishardor
crunchy,STOP,becausethat’sprobablybone.Thesameistrueifyouseeintestines
or“guts.”
3. Don’thesitatetoaskforhelpifyou’rehavingtroublefindingtheskinlayer.
Thesearetheorgansandstructuresyouwillseewhenyoufirstcutopenyourbird.The
heartandlungswillbecoveredbythelarge,bonysternum(breastbone).Donot
removethesternum.Youwillreachintothechestcavitylatertoremovetheheart.
Step3:IdentifyingtheGonads(testesandovaries)
1. Openingtheabdominalwall:cutopenthethinabdominalwallofthebirdto
exposetheintestinesandstomach.
2. Gentlypushthestomachandintestinesasidetotheleft.Lookforgonadsfirston
theright(thebirdsleft).
3. Lookforthegonads,ontopofthekidneys,againstthebodywall.
4. Testes:malebirdswillhavetwotestes.
5. Ovaries:mostfemalebirds(exceptforsomehawks)haveonlyoneovary,ontheleft
handside.
6. Gonadsvarygreatlyinsize,color,andgeneralappearance.Theycanbeverysmall,
andverytrickytofind,solookcarefully.Youmayneedtolookunderamicroscope.
7. AskZachorJessieforhelpifyouneedit,ortoverifythatyouhavefoundthe
gonads.
8. HaveZachorJessietakepicturesofthegonads(orareawheretheyshould
be).
Afteryou’veremovedtheinternalorgansthatwereontoptotaketissuesamplesandcheck
stomachcontents,yourbirdwilllooksomethinglikethis.Nowwecanclearlyseethe
kidneys,andpossiblythegonads(testesorovaries).
Step4:CollectingTissueSamples
1. Labelapapertowel:layoutapapertowel,andwriteonit“HLMK”withthe
letterswidelyspacedapart.Thesestandforheart,liver,muscle,kidney,thefour
tissuesyou’llbecollectingsamplesof.
2. Findthepectoralmuscle:locatethebigflightmuscles(breastmuscles)onthe
sternumofthebird.Usingyourscissorsandtweezers,cutachunkofmuscletissue
andplaceitabovethe“M”onyourlabeledpapertowel.
3. Findandsetasidethestomachandintestines:thegutswillbesittingontopof
theotherviscera,andwereprobablythemostprominentthingwhenyoucutyour
birdopen.Cutopenthestomach.Doyouseeanyinterestingcontents?Whatarethey,
orwhatdotheylooklike?
4. Locatetheliver:theliverconsistsofseverallargelobes,orpieces,alsolocated
prominentlyontopofeverythingelse,slightlyabovethestomach.Cutachunkof
liverandplaceitonyourlabeledpapertowelabove“L.”Removetheliverandsetit
aside.
5. Locatetheheart:Theheartwillbefarupinthechestcavity,easilyreachableafter
theliverisremoved.Pullitout,cutachunkoftissue,andplaceitabovethe“H”on
yourlabeledpapertowel.
6. Findthekidneys:thekidneysaredifficulttospot,buttheyarelocatedagainstthe
backofthebodywall,nearwherewelookedforgonads.Theyaremuchlargethan
thegonads,andwillappearelongateandlobed.Oncelocated,cutatissuesample
andplaceitabove“K”onthelabeledpapertowel.
7. Putthetissuesamplesinthetissuevial:eachgrouphasbeengivenasmalltissue
vial.Placethetissuesinsideofthisvialinthefollowingorder:hear(bottom),liver,
muscle,kidney(top).Youwantsampleslargeenoughtofillmostofthevial.
Step5:TheBirdWing
1. Whilethebirdisonitsback,pulloutoneofthewings.
2. Pushasideanyfeathers,andcutaslituptheskinofthewing.Justlikewhenyou
cutthebodyopen,theskinhereisverythinandmaybealittledifficulttofind.It
willbetheverythin,slightlysee‐throughlayerthatyoucanpinchwithtweezers.
3. Gentlypeelbacktheskintoexposemusclesandbones.
4. Identifythemajorbonesofthebirdwing.Howdoesabirdwingdifferfromthe
wingofotherflyingvertebrates(pterosaursandbats)?
Step6:TheBirdLeg
1. Whilethebirdisonitsback,pulloutoneofthelegs.
2. Pushasideanyfeathers,andcutaslituptheskinoftheleg.Justlikewhenyou
cutthebodyopen,theskinhereisverythinandmaybealittledifficulttofind.It
willbetheverythin,slightlysee‐throughlayerthatyoucanpinchwithtweezers.
Howevertheskinwillbecomeverythickandscalyaroundthefootthiswillbevery
difficulttocutthrough,anddon’tstrugglewithitifitistoohard.
3. Gentlypeelbacktheskintoexposemusclesandbones.
4. Identifythemajorbonesofthebirdleg.Howisitsimilartothelegofadinosaur
likeT.rex?Howisitdifferent?