Test two statsTest two stats

• Mean 65.8

• Median 65Median 65

• Max 100

Mi 24• Min 24

20 30 40 50 60 70 80 90 10020 30 40 50 60 70 80 90 1001 2 6 9 17 12 7 4 1

ArchosauriaArchosauria

Chapter 16

CrocodiliansCrocodilians

• 23 surviving species23 surviving species

• Alligatoridae, Crocodylidae, and Gavialidae• http://wwwyoutube com/watch?v=BTpa9j60Npghttp://www.youtube.com/watch?v=BTpa9j60Npg

AlligatoridaeAlligatoridae

• Caimans (central andCaimans (central and south america)

• Alligator (North• Alligator (North America and China)

CrocodylidaeCrocodylidae

• Tropics worldwideTropics worldwide

• Largest living reptileC d l d d t 7 t– Crocodylus porosus recorded up to 7 meters

GavialidaeGavialidae

• 1 species1 species

• India

i h i li• Fish specialists with long skinny snouts

Crocodilian heartCrocodilian heart

• 4 chambered heart• Some differences from 

other 4 chambered hearts– 2 aortas leaving heart (one g (

from each ventricle) connected by the foramen of panizza

3 diff t tt f• 3 different patterns of blood flow are possible– Resting

A i i– Activity– Thermoregulation

Crocodilian parental careCrocodilian parental care

• build nests which are sometimes gaurdedbuild nests which are sometimes gaurdedsome species even aid the hatching by digging the offspring out and carrying them to waterthe offspring out and carrying them to water

• Have TSD (we talked about this earlier)

DinosaursDinosaurs

• OrnithischiansOrnithischians

• SaurischiansB th h it ith th l di tl d th– Both have a gait with the legs directly under the body (not sprawling as in crocodilians)

Both groups have bipedal forms the Saurischians– Both groups have bipedal forms, the Saurischiansare mostly bipedal and this trend opened new adaptive zones for changes in forelimbs.adaptive zones for changes in forelimbs.

DinosauriaDinosauria

Origin of flightOrigin of flight

• Flight evolved in 2 lineages g gof diapsids– Pterosaurs and birds

BirdsBirds

Birds are derived Theropod dinosaursBirds are derived Theropod dinosaurs

They were called reptiles more than a century ago by Huxley but this was largely ignoredago by Huxley but this was largely ignored until recently

Sh d d i d h i h Th dShared derived characters with TheropodsHollow, pneumatic bones; Elongate, mobile S‐shaped neck; Tridactyl foot; Digitigrade posture; 

Ankle joint forms between tarsal bones rather than tarsals and tibia/fubula; Feather t f th R d d iprecursors or true feathers; Reduced genome size 

DromeosaursDromeosaurs

• A derived group of CoelurosaursA derived group of Coelurosaurs

• Showed character changes that led to flightW i t t t th t ll d th t fl th i t– Wrist structure that allowed them to flex the wrist sideways while rotating them

A more derived dromeosaur have a change in the– A more derived dromeosaur have a change in the shoulder joint.  The glenoid fossa is orientated laterally instead of ventrallylaterally instead of ventrally 

Feathered DinosaursFeathered Dinosaurs

• Most dramatic birdlike character ofMost dramatic birdlike character of dromeosaurs– Simplest types of feathers are single hollow– Simplest types of feathers are single hollow filaments

• Vaned feathers – Caudipteryx and• Vaned feathers – Caudipteryx and Protoarchaeopteryx

Caudipteryx and ProtoarchaeopteryxCaudipteryx and Protoarchaeopteryx

• Had vaned feathers on theHad vaned feathers on the second finger and a tuft on the tail

• Feathers were symmetrical which are used for social displays or insulation

• Asymmetrical feathers appeared with Archaeopteryx 

Origins of flightOrigins of flight

• 2 theories2 theories– “from the trees down”

“from the ground up”– from the ground up

• Trees down says that Archaeopteryx was b l d j d d f t t tarboreal and jumped around from tree to tree 

• http://www.youtube.com/watch?v=FxSGpCOtkSc

From ground upFrom ground up

• Dromeosaurs consisted of bipedal cursorialDromeosaurs consisted of bipedal, cursorial, terrestrial predators.

• Arms (wings) used to aid in the bipedal runningArms (wings) used to aid in the bipedal running for balance, used like a chicken running away from a dog, this later evolved into short flights.from a dog, this later evolved into short flights. (this version dropped)

• Arms used to catch prey by swatting it down, orArms used to catch prey by swatting it down, or for horizontal jumps, more recently modified to include wing assisted incline runningg g

Terrestrial originTerrestrial origin

• Ground up currently seems most consistentGround up currently seems most consistent with evidence– Arm and wrist movements seem to be consistent– Arm and wrist movements seem to be consistent with prey seizing

– Feathered forelimbs seem poorly suited forFeathered forelimbs seem poorly suited for climbing

• Body size also decreased with flight surfaceBody size also decreased with flight, surface area of wings and wing loadings must be in the range of 2 5 gm per cm2the range of 2.5 gm per cm

ArchaeopteryxArchaeopteryx

• Had many characteristics thatHad many characteristics that make us believe that it could flyfly– Wing loadings

– Glenoid fossa

– Furcula

– Rectangular sternum

– Assymetrical flight feathers