CHAPTER 5 Flashcards
amniotic egg
-have encapsulating membranes that are water tight
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amniotes
animals that lay amniotic eggs
what does holding their own water allow?
it allows for amniotic eggs to be laid on dry land.
how did eggs look before tetrapods laid eggs
similar to modern frog and salamander eggs, being laid in a wet or humid place.
why can’t Dino eggs be larger
cube-square law. eggs larger then half a meter wouldn’t be receiving enough oxygen for the entire volume proportional tho the large surface area.
osteons
bone cells
how do osteons grow
they ass osteons ti their bones outer walls. but the rate is not always the same and varies. according to seasons and resource availability
what happens to osteons when facing seasonal periods of scares resources.
it creates rings inside the bones,
what are the wrings created in the bones through irregular osteon formation called?
lines of arrested growth
how are the bones of younger dinosaurs characterized
by having higher vascularity (many blood vessels) and a texture called lamellar bone.
what do mature dinosaurs go through
remodelling. where the old bones cells are replaced by newer bone cells
what is the bone that is created through remodelling called
Haversian or secondary bone
external fundamental system (EFS)
Indicates that a dinosaur is skeletally mature and has stopped growing.
ontogenetic changes
changes in the form of an organism that occur as it matures
non-isometric ontogenetic changes
changes in the relative proportions of an animal as it grows, that are not simply resulting from a general increase in size.
sexual dimorphism
males and female of the same species each have differing characteristics, some are subtle other can be extreme.
medullary bone
a bone females who are preparing for egg laying develop this bone which contains concentrations of calcium the are stored prior to eggshell development.
why is using the medullary bone method limited to sexing a dinosaur
cuz only females who are preparing to lay eggs can have those bone.
predator satiation
a produce a new generations, only tiny fractions of the eggs laid needed to hatch and grow to adults, this is why they lay as many eggs as possible to increase the odds.
Lameller bone
LAGs formed later, as a dinosaur grows.
