lesson 15 - Lepidisaurs Flashcards
lepidisaurs
- sister groups is the archopedomorpha
- some are secondarily aquatic – the marine iguana
- have a transverse clocal slit
- exctrete, urinate, ,pass feces out of the same hole, the slit is transverse instead
tuatara
- Date back to mezozocic
- Lot of diversity
-Now you only have terresterial - Most have a thing where the tooth is fused to top jaw bone (not embedded)
- Nocturnal
- Primary source of food is bugs → lots of bugs are nocturnal
- Colorchanges
squamates
- Sister to tuararea
- Dictate present of determinate growth
- Meaning that at a certain stage of their lives they stop growing (humans also have this )
- Crocodiles don’t have derermiate growth → you can age a croc based on size
-Male squamates have bilateral penis
—- usually only use 1
lizards
- Can be quite large
- Found in a number of habitats
- Zigadactly
- Some engage in long runs to catch prey
- Limbless lizards (not snakes0
^^ limb reduction has evolved a lot
snakes
- Can range from 10 cm to 10 m
- May have evolved from subterranian legless lizards with reduced eyes
- ^^ complicated by presence of well known crutaceous fossils that show derived skulls from extant snakes
- Also had well developed hinglimbs
- From skulls, they look like snakes
- Found in marine areas
^^^ suggest they did not evolve in this way
Suggests they evolved from marine, leg having origin
wide variety of snake body forms
- many stout
- thick long fangs
- many long and skinny
- Large eyes on nocturnal is not uncommon
- Very shiny scales that can reduce friction
- Varies in locomotion
- Lateral undulation
- Rectilinear (found in larger ?
- Concertina (found in snakes that need to pass through narrow passages)
- Sidewinding
left lung is often reduced or absent
feeding forging ecology in squamates
- Lost lower temporal bar
- Are diapsids
- Enables snakes to take really big bites
- Also lost the second temporal bar
more on snakes
- Can move apart and stretch
- Jaws were never really jointed together so they don’t really dislocated them – they just their jaws to eat
- Constriction
———–Very short vertebrae allow for a very tight bend to be made
————Not usually as mobile
venom delivery for snakes
——Fangs that are located in the rear of the maxilla
—Fangs that are permanently erect
—Muscles - protract in jaw push jaw outward
squamata that have venom
venom clade of squamate reptiles
—- Sequenced the amino acids that combine to form various compunds – including non venomous compounds
sit and wait foraging
- lower risk of predation - not moving around a lot
- almost all iguanas
widely foraging
- More mobile
- Have higher hematocrit levels
- Only possible due to a direct cause and effect hypothesis
- Correlation does not imply causation ^^^^
risk about assuming cause and effect
When speciation happens – there is going to be a difference between the 2 groups due to reproductive isolation
–As they diverge over time, Traits continue to diverge
– But this entire iguanids group maintains the traits as the group diverges
– Sit and wait is one of those traits
- Could be associated for no reason tho
Ex: parents reproduced and you might just happen to be tall because both your parents are tall, and you might have large earlobes because your parents have large earlobes
– but that doesn’t mean that you have large earlobes in order to be tall
Can use phylogeny to infer caue and effect ties between traits
autotomization – part of tail being lost – lizard being caught by a snake
- Occurs between weak links in caudal vertebra
- Differs de[ending on temperature
- More caudal or less caudal
————They lose more tail (point is less causal ) on colder days
————Think that the lizard is slower
————-Not moving so tail breaks up
————On a warmer day it breaks off more caudally
what makes a signal different from any other trait
-A signal elictis a response to the receiver that on average is adaptive for the individuals producing that signal
——Can be olfactory ….
——-Receiver must provide the majority of that energy
