Archosaurs were the dominant land vertebrates during the Mesozoic era. They tended towards bipedalism with reduced forelimbs and hindlimbs that bore most of the weight. Their skulls were diapsid with an additional opening called the antorbital fenestra. Thecodonts gave rise to later archosaurs including pterosaurs, the first vertebrates to evolve powered flight, and dinosaurs, one of the most successful animal groups in terms of longevity. Dinosaurs included the saurischians with reptilian pelvises and predatory carnivores, and the ornithischians with avian pelvises, herbivorous diets, and one small bipedal group

1. ARCHOSAURS

2. Dominant land vertebrates
during the Mesozoic
Display a trend towards
bipedalism – 2 footed locomotion
Forelimbs tend to be reduced
and hindlimbs are drawn under
the body to become the major
weight bearing and locomotor
appendages

3. Skull is diapsid
There is an additional
fenestra – antorbital
fenestra – large
mandibular foramen
opening in the skull in
front of the eye that
distinguishes archosaurs

4. THECODONT
 Gave rise to all later archosaurs
 Named because their teeth are set in deep
sockets
 Stem archosaurs

5. PTEROSAURIA
The Winged Reptile

6. PTEROSAURS!
More commonly known as
PTERODACTYLS
First vertebrate to evolve
powered flight
ACTIVE AERIAL
LOCOMOTION
 Pterosaurs, birds and bats

7. RHAMPHORHYNCHOIDS
 Long tails and teeth

8. LATER PTERODACTYLOIDS
 Lacked a tail and teeth. Had projecting crest at
the back of the head.

9. TWO TEMPORAL FOSSAE/POST
ORBITAL FENESTRAE

10. I BELIEVE I CAN FLY 
Like birds, Pterosaurs had
pneumatic bones
Wings were more bat-like
Supported by an elongated 4th
finger
Long, hollow bones
Convergent evolution

12. DINOSAURS
RAAWRRR!

13. DINOSAURS!
 One of the most successful groups of
animals (in terms of longevity) that
have ever lived, evolved into many
diverse sizes and shapes, with many
equally diverse modes of living.
 Contains two major groups of
dinosaurs: the Ornithischia, or
"bird-hipped" dinosaurs, and the
Saurischia, or "lizard-hipped"
dinosaurs.

15. SAURISCHIA
Reptilian pelvis
Swift predatory carnivores
The three bones of the pelvis
– ilium, ischium, pubis–
radiate outward from the
center of the pelvis

18. ORNITHISCHIANS
 Pelvis similar of that of birds
 Herbivores. Lack teeth
 Some had horny beaks
 Some small unidentified bipedal
ornithischian is thought to have
given rise to birds
 The ischium and part of the pubis lie
parallel and project backward
toward the tail