t i m e l i n e

mya = million years ago

• precambrian
  • 4600-545 mya
• palaeozoic era ("ancient life")
  • cambrian period (545-490 mya)
    • cambrian explosion of life
  • ordovician period (490-445 mya)
  • silurian period (445-415 mya)
  • devonian period (415-355 mya)
  • carboniferious period (355-390 mya)
  • permian period (290-250 mya)
• mesozoic era ("middle life") - age of the dinosaurs!
  • triassic period (250-200 mya)
    • super-continent pangaea
    • climate: hot and dry, no ice caps
    • dinosaurs are the underdogs
    • at the end: mass extinction
  • jurassic period (200-145 mya)
    • pangea splits into two (atlentic ocean is created)
    • climate: slightly less hot, more rain
    • dinosaurs rule the earth
  • cretaceous period (145-65 mya)
    • today's continents start to form
    • that means more diverse dinosaurs
    • at the end: mass extinction
• cenozoic era ("recent life")
  • tertiary period (65-1.64 mya)
  • quaternary period (1.54 mya - present day)

the 'big five' mass extinctions:

• ordovician–silurian extinction events (445-444 mya)
  • ✞ 85% of all species
• late devonian extinctions (372–359 mya)
  • ✞ 70% of all species
• permian-triassic extinction event (252 mya)
  • ✞ 90-96% of all species
• triassic-jurassic extinction event (201.3 mya)
  • ✞ 70-75% of all species
  • leaves dinosaurs the dominating species
  • probably because of global warming due to carbon dioxide from vulcanic eruptions
• cretaceous-paleogene ('K-Pg', 'K-T') extinction event (66 mya)
  • ✞ 75% of all species
  • all non-avian dinosaurs become extinct
  • probably because of the impact winter of an asteroid hitting today's mexico

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o r n i t h o d i r a

dinosauria: terrestrial

saurischia:

• theropods
  • meat-eaters
  • all famous dinos with sharp teeth are theropods
  • evolved into birds
  • tyrannosaurus, carnotaurus, deinocheirus, ...
• sauropods
  • the largest animals to walk the earth
  • plateosaurus, brontosaurus, diplodocus, brachiosaurus, ...

ornithischia:

‍ ‍ ‍‍ ‍ ‍ ‍ ‍ ‍ ‍ thyreophora:

• amored dinosaurs
• stegosaurs
  • bony back plates
• ankylosaurs
  • heavily armored, tank-like
  • tail-clubbed or spiky
  • commin in the cretaceous period

‍ ‍ ‍‍ ‍ ‍ ‍ ‍ ‍ ‍ ornithopods:

• almost exclusively plant-based diets
• small bipedal runners
• includes hadrosaurs and duck-billed dinosaurs
• lesothosaurus, heterodontosaur, ...
• ceratopsians
  • horn-faced dinosaurs
  • bony projection from skull to neck
  • triceratops, styracosaurus, ...
• pachycephalosaurs
  • 'thick-headed lizards'
  • bipedal, medium-sized
  • dome heads, spikes
  • pachycepholosaur, ...
• hadrosauridae
  • duck-billed dinosaurs
  • _

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pterosauria: flying

pterodactyloids:

• large
• no teeth
• shorter tails
• elongated hand bones
• extravagant head crests
• archaeopterodactyloidea
  • a 'pterodactyl' does not exist, but a pterodactylus does
  • also includes flamingo-like pterosaurs
  • pterodactylus, pterodaustro, ...
• azhdarchoidea
  • largest pterosaurs
  • largest headgear
  • terrestrial stalkers
  • quetzalcoatlus, tapejara, hatzegopteryx, azhdarcho, ...
• pteranodontia
  • long, toothless beaks
  • pteranodon, nyctosaurus, ...

rhamphorhynchoids (non-pterodactyloid pterosaurs):

• toothy jaws/beaks
• long tails
• sprawling quadrupedal stance
• relatively small
• less extravagant head crests
• eopterosauria
  • includes the most famous pterosaurs
  • caviramus, preondactylus, eudimorphodon, ...
• dimorphodontia
  • have theropod-looking heads
  • therefore look like a mix of dinosaur and pterosaur
  • dimorphodon, caelestiventus, ...
• rhamphorhynchidae
  • long, slender snouths
  • teeth good for catching fish
  • scaphognathus, rhamphorhynchus, ...
• anurognathidae
  • tiny
  • frog-like faces, huge eyes
  • look and behave like bats (insectivorous, nocturnal)
  • anurognathus, ...

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sources: 1, 2, 3

see also