Natural History of Reptiles

What kind of reptiles are modern day reptiles descended from?

Synapsids

What were the developments in the synapsid lineage?

-Larger head

-Advanced jaw musculature

-Heterodont dentition

-Ability to chew

What was a key innovations that led to reptiles?

1. Development of scales, derived from the epidermis (prevented water loss)

2. 3 chamber heart

3. Amniotic Egg

What are the parts of the amniotic egg?

1. Leathery shell

2. Chorion (assists in gas exchange)

3. Amnion (protective environment)

4. Yolk sac (early circulatory system)

5. Allantois (respiratory structure)

When did reptiliomorphs emerge?

Carboniferous period (350 mya)

When did modern reptiles emerge?

Triassic period (225 mya)

What are temporal fenestra?

opening above and/or below postorbital and sqamosal bones

What are the 3 types of classification for reptiles?

Anapsid (no opening), Synapsid (one opening), and diapsid (two openings)

What is the cloaca?

outlet for intestinal, urinary, and genital tracts

Contains the hemipenes- paired; squamates

OR penes- unpaired; turtles, crocodilians

What are the 2 ways sex can be determined?

temperature and chromosomes (ZW system)

What is ectothermy versus endothermy?

Endothermy is generates heat from within, ectothermy requires outside source (ex: sun)

What is Homeothermy vs. Poikilothermy?

Homeothermy is body temp is constant, poikilothermy is that it fluctuates with environment

What is the difference between hibernation and brumation?

hibernation is for mainly mammals (endotherms), is a deep sleep, relies on fat deposits (glycogen stores in brumation), and the animal doesn’t eat or drink during hibernation (unlike brumation)

Characteristics of testudines

an Anapsid, most are ectothermic and poikilothermic, are oviparous,, have a beak

What is the shell of a testudines made up of?

carapce and plastron, covered by keratinous scutes

What are lepidosauria?

“scaled reptiles”

Characteristics of order Rhynchocephalia

Includes only the tuatara

Diapsid

Ectothermy/poikilothermic

acrodont

parietal eye

Characteristics of Order squamata

monophyletic

paired copulatory organs

Jacobson’s organ

Egg tooth

some are oviparous and viviparous

What kind of group is lacertilia?

is the lizards and are paraphyletic

What is pleurodont dentition and who mostly has it?

teeth fused to side of jaw bone

some lizards and snakes

Most homodont (single tooth morphology) except venomous snakes

What is proteroglyphous?

front-fanged

What is solenoglyphous?

hinged fangs

What is Opistoglyphous?

rear-fanged

Definition of venom

highly modified saliva containing peptide-based toxins

what are neurotoxins?

disrupt signal transduction which results in muscle paralysis and tetanus

What are hemotoxins?

attack red blood cells and induce coagulation