SOES2011 Dinosaurs Flashcards
What 2 structures allowed marine organisms to become terrestrial?
amniotic egg, water-proof skin
What’s an amniota?
the reptile-synapsid clade
Define seymouria
classic Permian seymouriamorphs
What did amniotes first diverge into?
Synapsida (mammals and their relatives) and diapsida
Describe disapsid?
diapsid = two holes in skull; eloginated limbs
Describe the characteristics of reptiles
- skills covered by reptiles
- eggs are laid in ground, developing embryonary membranes and apergaminate (soft) or calcareous (hard) calcium carbonate shells. Some groups can develop embryo retention and viviparity.
Define reptile
all members of the amniote clade that includes living turtles, lizards, crocs
Define diapsid
reptiles with two skull openings behind orbit: the lizards
Define neodiapsid
diapsid clade that includes Youniniformes + Sauria
Define lepidosaur
tuatara and kin (rhynchocephalians) and squamates. Incredibly mobile skull
Define squamate
snakes, lizards, amphinsbaenians (= ‘worm-lizard’. Include large fossilised marine organisms.
Define archosauromorph
archosaurs and close relatives (like protosaurs & rynchosaurs)
Define archosaur
crocodiles and kin, pterosaurs, dinosaurs and kin (including birds)
Why doesn’t the term ‘reptile’ mean anything?
Not all the descendants of ‘reptiles’ are ‘reptiles’ - Reptilia are not monophyletic.
Describe synapsida
Mammal-like reptiles, existed before the divergence of amniota into dinosaurs. BUT they are more closely related to humans than dinosaurs.
Why were turtles and tortoises originally put basally?
The have an anapsid skull
Name and describe the two holes in a diapsid skull
The supratemporal fenestra and the laterotemporal fenestra - allow muscle to go through skull and move jaw.
Where do turtles go on the phylogenetic tree and why?
in the diapsida (from molecular evidence), despite having an anapsid condition (secondarily evolved)
Describe Ichthyosaurs
dolphin-looking, jurassic period
Give the six adaptations a reptile must make to transition back to water
- efficient movement through water
- effective feeding in water
- ability to regulate salt concentrations.
- buoyancy
- reproduction
- heat loss
What is discontinuous locomotion
where propulsion is only generated during the power stroke, e.g. paddling, rowing
Give the two categories of continuous locomotion
axial locomotion and paraxial locomotion
Give the two types of axial continuous locomotion
axial undulatory swimming and axial oscillatory swimming
Define axial locomotion
strokes powered by body and/or tail
Define axial undulatory swimming
using wave-like sweeps of the tail
define axial oscillatory swimming
using swivelling of a propulsive structure, like a tail fin.
define paraxial locomotion
using lift or drag-based limbs
Where are the salt glands in marine iguanas?
in the nasal cavity
Where are croc salt glands?
tongue
Where are sea snake salt glands?
under the tongue
What are placodonts?
triassic sauropterygians, famous for crushing dentition.
What are pachypleurosaurs?
small amphibious triassic sauropterygians. some suction-feeding features, viviparity
Give a key feature of nothosauroids
interesting teeth
Which organism is likely to have been first to use the ‘underwater flight’ movement?
pistosaurs (anscestors of plesiosaurs)
What are Rhynchocephalians?
the living tuatara and their fossil relatives; enlarged back teeth, shearing/sawing motion to break up prey.
