1. What Makes a Dinosaur?
Ralph E. Chapman
Eryops Consulting
LAVA Technologies
2. What is a Dinosaur?
dinosaur = member of a very specific group of animals
• lived during a restricted period of time
• had diagnostic anatomical features
dinosaur ≠ fossil
dinosaur ≠ extinct animal
7. ichthyosaurs
plesiosaurs
lizards &
snakes
crocodylians
diapsids pterosaurs
archosaurs
The Origin of Dinosaurs
dinosaurs &
birds
8.
9. The Origin of Dinosaurs
“protodinosaurs”
crocodylians
dinosaurs &
pterosaurs
other
birds
archosaurs
other
archosaurs
other
archosaurs
archosaurs
10. The Origin of Dinosaurs
“protodinosaurs”
Middle
Triassic
Marasuchus
small
carnivorous
facultative bipeds
11. What Makes a Dinosaur?
Definition of the Dinosauria: most
recent common ancestor of
Triceratops and neornitheans
(modern birds) and all of its
Diagnosis of the Dinosauria:
• 3 or more sacral vertebrae
• glenoid faces caudally
• acetabulum completely open medially
• femur with ball-shaped head on proximal end
12. What Makes a Dinosaur?
• 3 or more sacral vertebrae
Plateosaurus
lateral view
dorsal view
13. What Makes a Dinosaur?
• glenoid faces caudally Acrocanthosaurus
dorsal
cranial
ventral
Allosaurus
14. What Makes a Dinosaur?
• acetabulum completely open medially dorsal
cranial
dorsal
ventral
cranial
ventral
Euparkeria
Allosaurus
15. What Makes a Dinosaur?
• femur with ball-shaped head on proximal end
Postosuchus Apatosaurus
Tyrannosaurus