Early Bird-like Forms

VERTEBRATE ZOOLOGY (VZ Lecture22 – Spring 2012 Althoff - reference PJH Chapter 16)

Model of Microraptor (Dromaeosaurid)

(American Museum of Natural History)

Archaeopteryx

• Found in South America—primarily Brazil

_______________ (Opisthocomus hoazin)

• Opisthocomus comes from the Greek meaning "wearing long hair behind"

• Nicknames include: __________ (because of their crocodilian odor

& harsh monotonous call)__________ (because of it's clumsiness in the

air and unusual diet)

• Nestlings have the ________ (2 per wing). When freightened they fall out of the nest (which is usually over water) and they use the claws to climb back up to the nest

• Has a diet of leaves…which means it has to have a way to breakdown cellulose “______________” stomach

___________________

__________ (Opisthocomus hoazin)

• Skeleton modified to accommodate large crop – fermentation vat housing bacteria that help it breakdown cellulose to obtain “the good stuff” (proteins/sugars) in the plant material

(not unlike what ungulates do)

• _________ bird species that has the “foregut fermentation” approach to handling plant material containing cellulose

• Rests on a _____________ while lengthy digestion takes place. The callosity is an elliptical, horny patch of skin lying over the rear tip of the sternum

• Feeds chicks _______________ mush of leaves

• Emu also has claws…3 per wing

Hoatzin

ArchaeopteryxLate Jurassic (155-150 MYA) Germany

reptilian

reptilian

reptilianavian

• Feathers had much more differentiated feathers than either Caudipteryx and Protoarchaeopteryx—two species which appeared “after” Archaeopteryx

• Wing feathers differentiated into primaries and secondaries—nearly identical to extant birds

• ___________________ flight feathers—which enhances aerodynamics forces on the wing

• After finding the 7th specimen, revealed a rectangular sternum which would add surface area for flight muscle attachment…further evidence it probably could fly. Probably took off by running and flapping wings. Modern day “__________” equivalent would be roadrunner…a ground dwelling, cursorial predator that takes to the air to escape a predator

Archaeopteryx …. features

Fig. 16-25, p427 PJH

Archaeopteryx Neornithes

TERRESTRIAL ARBOREAL

12

34

56

Grasping arms, swivel wrist joint, _________ directed pubis

Symmetrical vane feathers on wings and tail, down-like feathers on body, long tail

Asymmetrical wing and tail feathers, longer arms, reduced tail

Evolution of Derived Characters (Fig. 16-25)

Early archosaur

RIGHT LATERAL VIEWS OF PELVIS1

Ornithischia

Saurischia

PUBUS

ORIENTED

POSTERIORLY

Fig. 16-2, p391 PJH

ARCHOSAURS LEPIDOSAURS

Ornithischia

BIRDS

Archosauromorphs Lepidosauromorphs

Saurischia

Pubis oriented posteriorly

Strut-like coracoid, fused pelvis, pygostyle, reduced foot claws

Increased skeletal fusion, deeper sternum, alula, shorter tail

Shorter back and tail, deeper sternum AND keel, more compact back and hip

Evolution of Derived Characters (Fig. 16-25)

Strut-like coracoid4

Fused pelvis

(dorsal view)

4

Pygostule fused caudal vertebrae

(laternal view)

Alula – feathers attached to “thumb”

that help with aerodynamics of flight…

especially with slowing down without stalling

5

Deeper sternum with keel6

Arctic puffin