III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- climate:
Dry; low sea levels; one large supercontinent
beginning to break up
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- inverts:
- marine communities - gastropods and molluscs begin to dominate in these initially depauperate faunas... the 'modern marine fauna', including modern reef-builders
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Plants:
- recovery from the mass extinction is slow; lycopsids
dominate early, but soil formation is very slow...
- dry climate selects for seed plants with pollen;
the Gymnosperms...
Petrified Forest N. P.
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- Medium sized therapsids dominate early... like Lystrosaurus
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- Medium sized therapsids dominate early... like Lystrosaurus
- Temnospondyls resurgent (Mastodonosaurus - 6m)
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- radiation of the diapsids, but only Ichthyosaurs abundant early
Diapsida
Younginiformes
Ichthyosaurs
Lepidosaurs: Lizards, Snakes, Sphenodonts, Plesiosaurs)
Archosaurs: Dinosaurs, Pterosaurs, Crocodilians, Birds
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- the opening of the shallow Tethys Sea between Laurasia and Gondwanaland created a very productive marine environment, which was exploited by a diverse group of evolving marine reptiles in the three major diapsid groups:
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- marine reptiles:
Ichthyosaurs
Placodonts
Archeosaurs:
Tanystropheus
Lepidosaurs:
Nothosaurus
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- marine reptiles:
Lepidosaurs:
Nothosaurus
Shonisaurus - 21m
(Blue Whale = 33m, 110 ft)
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- As the Triassic proceeds, the Archosaurs displace the Therapsids.
Crocodylomorphs
(Ornithosuchans and Phytosaurs)
Pterosaurs
Dinosaurs
crucrotarsi
Ornithodira
(Marasuchas)
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- As the Triassic proceeds, the Archosaurs displace the Therapsids.
- Crocodylomorphs:
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- As the Triassic proceeds, the Archosaurs displace the Therapsids.
- In the late Triassic, the first Dinosaur radiations occur.
Ornithichians
Prosauropods
Sauropods
Theropods
Saurichians
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- As the Triassic proceeds, the Archosaurs displace the Therapsids.
- In the late Triassic, the first Dinosaur radiations occur.
Ornithichians
Prosauropods
Sauropods
Theropods
Ornithischians
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- As the Triassic proceeds, the Archosaurs displace the Therapsids.
- In the late Triassic, the first Dinosaur radiations occur.
Ornithichians
Prosauropods
Sauropods
Theropods
Saurischians
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- As the Triassic proceeds, the Archosaurs displace the Therapsids.
- In the late Triassic, the first Dinosaur radiations occur.
Oldest Dinosaurs are the Theropod-like Eoraptor
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- As the Triassic proceeds, the Archosaurs displace the Therapsids.
- In the late Triassic, the first Dinosaur radiations occur.
The first radiation of large dinosaurs were the herbivorous Prosauropods
By the late Triassic, all large herbivores were Sauropodomorphs.
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
- Verts:
- the first mammaliforms... Morganucodontids
III. Mesozoic Era
B. Jurassic (200-146 mya)
- Climate:
A global greenhouse - lush tropical habitats and rich shallow seas lead to the period of maximum Dinosaur domination.
III. Mesozoic Era
B. Jurassic (200-146 mya)
- Marine Reptiles:
but now joined by Plesiosaurs and Pliosaurs (both Lepidosaurs)
III. Mesozoic Era
B. Jurassic (200-146 mya)
- Herbivores:
Sauropods - the first of the real giants
1, small head and peg-like teeth (and elongated cervical vertebrae)
2, addition of extra cervical vertebrae to the neck
3, apron-like pubis
4, fore limbs as long as or longer than hind limbs, making the back slope posteriorly
5, teeth restricted to front of mouth 6, armor.
III. Mesozoic Era
B. Jurassic (200-146 mya)
- Herbivores:
Sauropods - the first of the real giants
Ultrasaurus (maybe a Brachiosaurus) stood 98 ft long, 140 tons
III. Mesozoic Era
B. Jurassic (200-146 mya)
- Herbivores:
Sauropods - the first of the real giants
Diplodocus - 90 ft long 11 tons
III. Mesozoic Era
B. Jurassic (200-146 mya)
- Carnivores:
1. three-toed foot2. digits IV and V lost on hand3. long arms4. semilunate carpal5. fused pelvis6. large hole in lacrimal bone in skull7. ?no unique derived characters?8. giant, hook-like claw on digit II of pes9. flight feathers
III. Mesozoic Era
B. Jurassic (200-146 mya)
- Carnivores:
- Avialae Archaeopteryx
First fossil - 1860 - a flight feather (asymmetrical)
10th specimen described in 2005 - shows intermediately rotated halux and hyperextended 2nd digit (like Deinonychosaurs - their sister clade)
10th specimen described in 2005 - shows intermediately rotated halux and hyperextended 2nd digit (like Deinonychosaurs - their sister clade)
A. Herrerasaurus- five digits are present, Digit V shaded yellow and hidden on other side of hand.
B. Coelophysis. Note that digit V is gone.
C. Deinonychus. Note loss of both digits V and IV
D. Archaeopteryx. Note very close correspondence in proportions and relative lengths of bones to Deinonychus.
E. Hoatzin embryo. Number of bones reduced in digit III.
F. Hoatzin adult. Most of the bones of the hand fused
Hand Morphology
Ornitholestes(theropod dinosaur)
Archaeopteryx
Sinornis(a Cretaceous bird)
Modern chicken
Another Set of Examples
Archaeopteryx
Chicken
III. Mesozoic Era
B. Jurassic (200-146 mya)
- Pterosaurs
They were present in the Triassic, but reached their greatest diversity in the Jurassic, with over 80 species recorded.
However, they would attain their greatest size in the Cretaceous.
III. Mesozoic Era
B. Jurassic (200-146 mya)
- Pterosaurs
They were present in the Triassic, but reached their greatest diversity in the Jurassic, with over 80 species recorded.
However, they would attain their greatest size in the Cretaceous.
III. Mesozoic Era
B. Jurassic (200-146 mya)
- Mammals:
Docodonts.... a group of beaver-like animals... the most impressive fossil of the group was found in Feb 2006
- oldest animal with fur
- demonstrates that mammals were radiating into a variety of habitats
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
B. Jurassic (205 - 146 mya)
C. Cretaceous (145 - 65 mya)
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
B. Jurassic (205 - 146 mya)
C. Cretaceous (146 - 65 mya)
- the warming trend of the Jurassic continues, and results in very high sea levels and the expanse of shallow seas over significant portions of continents
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
B. Jurassic (205 - 146 mya)
C. Cretaceous (146 - 65 mya)
- Plants:
Evolution of Angiosperms
Initially in low abundance
Come to dominate by end of Cretaceous
Gymnosperms
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
B. Jurassic (205 - 146 mya)
C. Cretaceous (146 - 65 mya)
- Plants:
Evolution of Angiosperms
Initially in low abundance
Come to dominate by end of Cretaceous
Gymnosperms
Angiosperms
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
B. Jurassic (205 - 146 mya)
C. Cretaceous (146 - 65 mya)
- Plants:
Evolution of Angiosperms
Initially in low abundance
Come to dominate by end of Cretaceous
Gymnosperms
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
B. Jurassic (205 - 146 mya)
C. Cretaceous (146 - 65 mya)
- Plants:
Evolution of Angiosperms
Initially in low abundance
Come to dominate by end of Cretaceous
Gymnosperms
III. Mesozoic Era
A. Triassic Period (250 - 205 mya)
B. Jurassic (205 - 146 mya)
C. Cretaceous (146 - 65 mya)
- Inverts:
radiation of pollinators
radiation of pollinators and herbivores
ground beetles do not
C. Cretaceous (146 - 65 mya)
- Inverts:
- Verts:
Ornithischians:
Stegosaurs give way to a variety of new
Ornithischian groups:
C. Cretaceous (146 - 65 mya)
- Inverts:
- Verts:
Ornithischians:
Saurischians - Sauropods
The Titanosaurs (and they were still big)
The Titanosaurs
Argentinasaurus
Largest one known with confidence, but there are bigger single bones....
35m 80-100 tons
incomplete skeleton but a hip girdle, vertebrae, and tibia
C. Cretaceous
- Theropods: carnivores get big!!
Carnosaurs
- Giant Allosaur cousins like:
Giganotosaurus
Longer than the largest Tyrannosaurus rex by 2m
40-45 ft... from Argentina (1995)
C. Cretaceous
Carnosaurs
- Giant Allosaur cousins like:
Carcharodontosaurus
40 ft - slightly smaller than T. rex
from Niger (1927)
C. Cretaceous
Carnosaurs
- Tyrannosaurs:
- Tyrannosaurus (3 sp.)
Soft tissue from a femur? Yup!
http://www.livescience.com/41537-t-rex-soft-tissue.html
C. Cretaceous
Carnosaurs
- Tyrannosaurs:
- Spinosaurs
- Spinosaurus – largest land carnivore? 40-60 ft?
C. Cretaceous
- non-bird feathered dinosaurs: Sinosauropteryx prima (1996)
first non-bird dinosaur with feathers... a Cretaceous contemporary of birds