Class Aves. Archaeopteryx 150 MYA Archaeopteryx Skeleton

Class Aves

Archaeopteryx

150 MYA

Archaeopteryx Skeleton

Avian Skeleton

Major Bird Groups

• Paleognathae– Mostly flightless– Usually ratite sternum (flat)

• Neognathae– Mostly flying birds with carinate sternum (keeled)

Is It A Bird?

• Wings• Feathers• Beak• Oviparous

Placode Specification

Placode Growth

Barb & Barbule Development

Down feather development

Pennacous feather development

Mature FeatherPennaceous

Plumulaceous

Feathers or Scales

Inhibition of BMP4 signaling in chick hindlimb causes dorsal scales (scutes) to develop as feathers and prevents apoptosis of interdigit webbing

Does a Chicken have Lips?

Figure 1   A "hen's tooth" formed by the combination of chick pharyngeal (presumptive jaw) ectoderm and mouse molar mesenchyme. (From Kollar and Fisher, 1980; courtesy of E. J. Kollar.)

Adaptations for Flight

Unique Pulmonary Structures

Bird Brained

A Bird's Eye View

Optic nerve

Wing Forms

Migration

Navigation

• Birds can sense Earth’s magnetic field

• Orient relative to field• Calibration of internal

compass– Twilight cues– Nocturnal celestial cues– Daylight cues

Parenting

Juvenile Forms

Reproductive System

Largest Bird

Largest Flying BirdAlbatross – 11ft wing-span

Smallest Flying Bird