Paleo test 1

• The 5 characteristics of Chordata is:

  • Notochord
  • Pharyngeal slits
  • Hollow, dorsal nerve cord
  • Postanal tail
  • Endostyle or Thyroid
• Radiata is having radial symmetry while bilateral is having bilateral symmetry
• Homology is similar traits in organisms with a common ancestor

  analogy is similar traits with no common ancestor
• Coelocanth is a bony fish with fleshy pectoral fins
• Phytosaur is a crocodilian like reptile with many teeth that are indepentent
• Charcaradon megalodon was a large shark that was the ancestor of great white
• law of superposition is the idea that rock layers are laid down in a sequence, oldest being at the bottom
• cladistics is used to infer evolutionary relationships, where Linnaean is ordering the biodiversity
• The Devonian is known as the age of fished
• paraphyletic fish are bony fish and consist of the groups osteichthyans and sarcopterygians
• Myllokunmingia and Haikuichtyes have v shaped myomeres, dorsal and ventral fins, notochord heart and a broad gut
• legendrelepis links fossils to lamprey
• conodonts are earliest vertebrates with hard tissue
• pikaea is the earliest chordate fossil
• jamoytius is most closely related to lampreys and lacks bony armour
• Astrapsis are early fish who uses a tail fin that goes side to side
• sacabambilla is similar to astrapsis
• heterostracans are fish with head covered in shields and large ventral shield, is grouped with astrapsids
• Thelodonts had flexible bodies and swam like sharks
• osteostracans had massive body armor headpieces and paired fins covered in small scales.
• Hemicyclaspis, apart of the osteostracans has a half circle head piece and is flattened. thought to live on the ocean floor with eyes facing upwards.
• Pituraspida is a swordfish looking like thats related to osteostraci
• placoderms are fish during the devDevoniannian age with a jointed neck
• Acanthodii are early gnastothomes known as spiny sharks
• There are 6 examples of placoderms:

  1. Acanthothoraci- heavy hed shield in australia
  2. Rhennanida- small scaly ray like body
  3. Antiarchi- (bothreolepis) pectoral fin encased with bone
  4. Petalicthyids- ray like- arms to side
  5. Ptycodonts- less armor, whip like tail and concentric scales
  6. Arthrodire- Dunkleosteus- overlaping bone plates
• Psarolepis is missing link between sarcopterygian and actinopterygian
• actinopterygian are ray finned fished while sarcopterygian are lobed finnes fish
• paleonisciformes-polypterus- bichir
• chondrostreans- acipenser- sturgeon
• polydon- paddlefish
• Neopterygians have greater jaw motility, symmetrical homocercal tails include:

  Lepisosteiformes-gars

  Amiiformes- bowfin (eye on tail)
• Acanthostega are amphibian like and looked like large salamanders. earliest tetrapods
• greererpeton looks crocodilia

  crassigyrians- eel like
• capitosaur- long anrrow skull

  divinosauria- broad skull
• trematosauria- lower triasic, long thin snout

  Archegosauroidea- lower permian, long snout
• Lepospondyls- diverse body forms and may have long "horns" (Nectridean)