III. Mesozoic Era A. Triassic Period (250 - 205 mya)

III. Mesozoic Era

A. Triassic Period (250 - 205 mya)

III. Mesozoic Era


- climate:

Dry; low sea levels; one large supercontinent

beginning to break up

III. Mesozoic Era


- 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


- 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


- Verts:

- Medium sized therapsids dominate early... like Lystrosaurus

Triassic survivors

Mammals

Gorgonopsids

Therapsids

Pelycosaurs

Dicynodonts

Cynodonts

III. Mesozoic Era


- Verts:

- Medium sized therapsids dominate early... like Lystrosaurus

- Temnospondyls resurgent (Mastodonosaurus - 6m)

III. Mesozoic Era


- 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


- 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


- Verts:

- marine reptiles:

Ichthyosaurs

Placodonts

Archeosaurs:

Tanystropheus

Lepidosaurs:

Nothosaurus

III. Mesozoic Era


- Verts:

- marine reptiles:

Lepidosaurs:

Nothosaurus

Shonisaurus - 21m

(Blue Whale = 33m, 110 ft)

III. Mesozoic Era


- Verts:

- As the Triassic proceeds, the Archosaurs displace the Therapsids.

Crocodylomorphs

(Ornithosuchans and Phytosaurs)

Pterosaurs

Dinosaurs

crucrotarsi

Ornithodira

(Marasuchas)

III. Mesozoic Era


- Verts:


- Crocodylomorphs:

III. Mesozoic Era


- Verts:


- In the late Triassic, the first Dinosaur radiations occur.

Ornithichians

Prosauropods

Sauropods

Theropods

Saurichians

III. Mesozoic Era


- Verts:



Ornithichians

Prosauropods

Sauropods

Theropods

Ornithischians

III. Mesozoic Era


- Verts:



Ornithichians

Prosauropods

Sauropods

Theropods

Saurischians

III. Mesozoic Era


- Verts:



Oldest Dinosaurs are the Theropod-like Eoraptor

III. Mesozoic Era


- Verts:



The first radiation of large dinosaurs were the herbivorous Prosauropods

By the late Triassic, all large herbivores were Sauropodomorphs.

III. Mesozoic Era


- 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


- Marine Reptiles:

Ichthyosaurs still present...

III. Mesozoic Era


- Marine Reptiles:

but now joined by Plesiosaurs and Pliosaurs (both Lepidosaurs)

III. Mesozoic Era


- Marine Reptiles:

and marine crocodylians....

III. Mesozoic Era


- Herbivores:

Ornithichian Stegosaurs

III. Mesozoic Era


- 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


- Herbivores:


Ultrasaurus (maybe a Brachiosaurus) stood 98 ft long, 140 tons

III. Mesozoic Era


- Herbivores:


Diplodocus - 90 ft long 11 tons

III. Mesozoic Era


- 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


- Carnivores:

- Ceratosaurs

Ceratosaurus

III. Mesozoic Era


- Carnivores:

- Carnosaurs Allosaurus

III. Mesozoic Era


- Carnivores:

- Avialae Archaeopteryx

III. Mesozoic Era


- Carnivores:

- Avialae Archaeopteryx

First fossil - 1860 - a flight feather (asymmetrical)

The 'London' Specimen - 1861 The 'Berlin' Specimen - 1877

10th specimen described in 2005 - shows intermediately rotated halux

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


- 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


- 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


- 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


B. Jurassic (205 - 146 mya)

C. Cretaceous (145 - 65 mya)

III. Mesozoic Era




- 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




- Plants:

Evolution of Angiosperms

Initially in low abundance

Come to dominate by end of Cretaceous

Gymnosperms

III. Mesozoic Era




- Plants:




Gymnosperms

Angiosperms

Archaefructus sinensis

Science 2002

III. Mesozoic Era




- Plants:




Gymnosperms

III. Mesozoic Era




- Plants:




Gymnosperms

III. Mesozoic Era




- Inverts:

radiation of pollinators

radiation of pollinators and herbivores

ground beetles do not

C. Cretaceous

- Verts:

-Crocodylians

Sarcosuchus

11m


- Inverts:

- Verts:

Ornithischians:

Stegosaurs give way to a variety of new

Ornithischian groups:

Ornithischians:

Ankylosaurs

Ornithischians:

Ceratopsians

Ornithischians:

Iguanodonts

Ornithischians:

Hadrosaurs

Ornithischians:

Pachycephalosaurs


- Inverts:

- Verts:

Ornithischians:

Saurischians - Sauropods

The Titanosaurs (and they were still big)

The Titanosaurs

Andesaurus

40m (?) 80 tons (?)

incomplete skeleton

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:

- Albertosaurus

C. Cretaceous

Carnosaurs

- Tyrannosaurs:

- Gorgosaurus

C. Cretaceous

Carnosaurs

- Tyrannosaurs:

- Tyrannosaurus (3 sp.)

C. Cretaceous

Carnosaurs

- Tyrannosaurs:


C. Cretaceous

Carnosaurs

- Tyrannosaurs:


Soft tissue from a femur? Yup!

http://www.livescience.com/41537-t-rex-soft-tissue.html

C. Cretaceous

Carnosaurs

- Tyrannosaurs:

- Dilong paradoxicus

Feathered

C. Cretaceous

Carnosaurs

- Tyrannosaurs:

- Spinosaurs

- Spinosaurus – largest land carnivore? 40-60 ft?

C. Cretaceous

- Deinonychians

Deinonychus

Velaciraptor

III. Mesozoic

C. Cretaceous

- theropods (still)

- Deinonychians

Velociraptor

C. Cretaceous

- non-bird feathered dinosaurs: Sinosauropteryx prima (1996)

first non-bird dinosaur with feathers... a Cretaceous contemporary of birds

- Protobirds

- Protobirds: Sinornithosaurus (Jurassic)

- Protobirds: Microraptor (Cretaceous)

Protobirds:

- Deinonychians

Velociraptor

- Protobirds: Unenlagia (Cretaceous)

- Protobirds: Caudipterxy (Cretaceous)

- Protobirds: Protarchaeopteryx (Cretaceous)

- Protobirds: Eoalulavis (Cretaceous)

- Pterosaurs:

- Pterosaurs:

Pteranodon - wingspan 7.5 m

- Pterosaurs:

Quetzalcoatlus - largest ptersaur; 40 ft wingspan....

- Quetzalcoatlus - largest flying animal

Quetzalcoatlus - largest ptersaur; 40 ft wingspan....

- Mammals...

- Mammals...

- Multituberculates Dominate in Cretaceous

- over 200 species

The K-T Boundary

The K-T Boundary

hmm... a new star in the constellation of Orion...

THAT'S weird...

The K-T Boundary

The K-T Boundary

WHAT THE HELL!!!

It's the Ceratopsians... they're attacking...!!!

The K-T Boundary

The K-T Boundary

The K-T Boundary

The K-T Boundary

Documents

III. Mesozoic Era A. Triassic Period (250 - 205 mya)