Untitled Flashcards Set

Linean classification (outdated and bad) 

  • Class aves = birds

  • Class reptilia = reptiles 

Terrestrial dinosaurs coexisted 



What is a dinosaur? 


Dinosaurs are archosaurian diapsid reptiles 

  • Can find on a cladogram, Diapsid, Reptilia and archosaurian are all nodes on the cladogram. 

  • Amniotes have 3 major skull types, Anapsid (fully roofed and modern reptiles), Synapsid (1 temporal opening on the side = mammals), Diapsid (Upper openings, side opening and opening infront of eye) DINOSAURS 

 


They Have 5 Identifying features 

  1. Hip structure

  • Hole in pelvis articulating with thigh bone 

  1. Upright posture 

  • Legs held underneath body 

  1. Fused Vertebrate

  • Fuse into a block, allows animal to run more efficiently 

  1. Backward facing shoulder joint 

  • Humerus projects backwards from coracoid 

  1. Hinge-like ankle 

  • AM joint that only moves forward and backward, no side to side or pivot 

   Dinosaurs are defined by this unique combination, and need all of these features to be considered a dinosaur.



They have ancestors not yet known 

  • Look in the group of dinosauromorphs, Any animal more closely related to dinosaurs than pterosaurs. Includes dinosaurs and non dinosaur basal dinosauromorphs.  


Pterosaurs 

  • Mesozoic flying reptiles 

  • Membranous wings stretched across modified forelimbs and himblims 

  • Orinthodirans, but not dinosaurs 


In which time period do we search for the ancestors 

  • Look in middle Triassic rocks, dinosaurs live in the late triassic so any time before that is when we can look. 



Meteor strikes -> Dust polutes air -> Dust covers sun and kills plants -> Dinosaurs cant eat plants and die. 


An asteroid hit the earth 66.1 million years ago and killed many organisms including avian dinosaurs. 


All of this happened 66 my ago 

  • A 10km asteroid collided with earth 

  • Nutrient cycle were partly shut down 

  • Many marine & terrestrial animals, & many plants were extinct 

  • Landscapes were deforested 

  • Tsunamis rolled across oceans 


List of things that went extinct 

  • Many angiosperms and there pollen 

  • All terrestrial dinosaurs 

  • All water reptiles 


Aquatic, ectothermic, small sized, non amniotic were the combination of things that made a surviving vertebrate. 


Who survived? 

  • Turtles 


Hypothesis for extinction 

  • Impact from meteor/asteroid 

  • Volcanic 

  • disease , predation, competition and mammals eating eggs 

How long is the recovery 

  • took a few thousands of year in the oceans 

  • And it took 1.5 million years for the land to recover 


Mammal domination after dinosaurs 


Mammals were super small 


Dinosaurs and mammals existed at the same time, but dinosaurs dominated. 


Characteristics of animals 

  • 4 chambered heart 

  • Endothermic, with sweat glands to cool body 

  • Single replacement of teeth 

  • Mammary glands to nourish young 

  • One bone in lower jaw; 3 bones in ear 


Mammalian limbs were modified for specialization: allows them to dig, run, swim and climb 


Modern mammals reproduction

  • Monotremes - egg laying mammals 

  • Placentals 

  • Marsupials 

All mammals have the amniotic egg