Tuesday, December 6, 11. Mesozoic Life

Transcription

1 Mesozoic Life

2 Review of Paleozoic Transgression/regressions and Mountain building events during the paleoozoic act as driving force of evolution. regression of seas and continental uplift create variety of environments which, in turn, require great deal of diversification-- especially in marine fauna

3 Review of Paleozoic By end of Paleozoic 90% of the marine fauna is extinct and 70% of land animals are extinct Permian extinction may have both terrestrial and extraterrestrial causes Terrestrial: formation of Pangea causes loss of shallow marine habitat and arid cool climates causes shift in vegetation Siberian Traps (flood basalt) release huge amount of greenhouse gases Extraterrestrial: Many Permian sediment contain fullerenes (soccerball shaped carbon molecules) inside the fullerens is He-3 (a cosmic helium isotope Large impact may have set off Siberian Traps

4 Post Permian Survivors of the Permian extinction would go on to repopulate Mesozoic Earth. Amphibians: one group of tetrapods known as Temnospondyls survive the extinction 17 families live during the triassic, only two survive into the Jurassic and one into the Cretaceous (these would become frogs, newts and salamanders)

5 Synapsid Evolution During Permian Synapsids continue to diversify and evolve into Therapsids Therapsids: small to moderate in size Cheek teeth evolved for slicing Bony palette allows breathing while chewing A bone on snout shows evidence of whiskers hair.

6 Synapsid Evolution During Permian Synapsids continue to diversify and evolve into Therapsids Therapsids: small to moderate in size Cheek teeth evolved for slicing Bony palette allows breathing while chewing A bone on snout shows evidence of whiskers hair.

7 Synapsid Evolution During Permian Synapsids continue to diversify and evolve into Therapsids Therapsids: small to moderate in size Cheek teeth evolved for slicing Bony palette allows breathing while chewing A bone on snout shows evidence of whiskers hair.

8 Reptiles-Diapsids The word Diapsid refers to the two openings behind the eye orbits (di-two, apsis-opening) Diapsids divided into two groups: Lepidosaurs: lizards, snakes Archosaurs: Dinosaurs, Pterosaurs, crocodilians, and birds

9 Basal Archosaurs The term basal refers to the fact that these fossils are found at the base of the Triassic. making basal archosaurs the starting point of dino evolution. exemplified by Hersporosuchus

10 Small (4ft) Hersperosuchus Agile with long tails ability to walk upright

11 Small (4ft) Hersperosuchus Agile with long tails ability to walk upright

12 Though some archosaurs were bipedal some reverted back to four-footed stance and would evolve into heavily armored carnivores or large crocodile-like reptiles called phytosaurs Arcosaurs Phytosaurs were among the largest of land animals in the triassic. Some reached length up to 11ft

13 Divided into two groups Dinosaurs Distinguished by the arrangement of the ilium, ischium, and the pubis bones in the hip Saurichia-lizard hipped: Ilium, ischium, and pubis are in a triradiate arrangment Ornithisicia- Bird hipped: Pubis is downward and parallel to ischium (like modern birds)

14 Divided into two groups Dinosaurs Distinguished by the arrangement of the ilium, ischium, and the pubis bones in the hip Saurichia-lizard hipped: Ilium, ischium, and pubis are in a triradiate arrangment Ornithisicia- Bird hipped: Pubis is downward and parallel to ischium (like modern birds)

15 Divided into two groups Dinosaurs Distinguished by the arrangement of the ilium, ischium, and the pubis bones in the hip Saurichia-lizard hipped: Ilium, ischium, and pubis are in a triradiate arrangment Ornithisicia- Bird hipped: Pubis is downward and parallel to ischium (like modern birds)

16 Divided into two groups Dinosaurs Distinguished by the arrangement of the ilium, ischium, and the pubis bones in the hip Saurichia-lizard hipped: Ilium, ischium, and pubis are in a triradiate arrangment Ornithisicia- Bird hipped: Pubis is downward and parallel to ischium (like modern birds)

17 Dinosaurs Ornithiscians also lacked teeth in the front of both upper and lower jaws Sauriscians teeth extended around the entire jaw

18 Saurischian Saurischians are further divided into two groups Therapods: typically bipedal carnivores Sauropodomorphs: quadrupedal herbivores

19 Therapods Earliest Therapods (eoraptor and herrersaurus) date to 225mya

20 Therapods Earliest Therapods (eoraptor and herrersaurus) date to 225mya

21 More familiar Therapods Jurassic- Allosaurus Text

22 More familiar Therapods Cretaceous- Tyrannosaurus Text

23 Sauropodomorphs Divided into two groups: Prosauropods: most likely ancestors of sauropods. Lived from late Triassic to early Jurassic. quadropeds, front limbs shorter than rear legs Sauropods: replaced prosauropods in early Jurassic

24 Sauropodomorphs

25 Sauropodomorphs

26 Bipedal Ornithiscians known as Ornithopods Evolved near the end of the Triassic Ornithiscians Known to travel in huge herds Camptosaurus

27 Quadrapedal ornithiscians Ornithiscians Stegasaurs (plated quadrapedal ornithiscians) Ceratopsians (horn-faced quadrapedal ornithiscians)

28 Quadrapedal ornithiscians Ornithiscians Stegasaurs (plated quadrapedal ornithiscians) Ceratopsians (horn-faced quadrapedal ornithiscians)

29 Flying Reptiles During the triassic some reptiles developed the ability to glide (much like modern reptilian, amphibian, and mammal gliders).

30 Flying Reptiles During the triassic some reptiles developed the ability to glide (much like modern reptilian, amphibian, and mammal gliders).

31 Flying Reptiles During the triassic some reptiles developed the ability to glide (much like modern reptilian, amphibian, and mammal gliders).

32 Pterasaurs Quetzacoatlus Cretaceous pterasaur 40ft wingspan

33 Marine Dinosaurs Just as some reptiles were adapting to life on land and in the air, others returned to the water and developed traits needed for a marine environment.

34 Marine Dinosaurs Just as some reptiles were adapting to life on land and in the air, others returned to the water and developed traits needed for a marine environment.

35 Marine Dinosaurs Just as some reptiles were adapting to life on land and in the air, others returned to the water and developed traits needed for a marine environment.

36 Marine Dinosaurs Just as some reptiles were adapting to life on land and in the air, others returned to the water and developed traits needed for a marine environment.