Reptiles Flashcards
Were Dinosaurs fluffy or scaled?
Fluffy
2 Lineages of Reptiles
1) Para-reptilia
2) Eu-reptilia
Eureptilia can be devided into two groups + examples
1) Lepidosauromorpha (snakes, lizards, sphenodon)
2) Archosauromorpha (dinos, crocs, birds)
4 orders of reptiles + examples
1) Tetrudines (turtles/tortoises)
2) Rhynsocephilia/Sphenodonta
3) Squamata (lizards, snakes)
4) Crocodilia (crocs, aligators)
What distinguished between the two groups of Tetrudines?
How they retract their necks:
Cryptodira: Contract neck backwards
Pleurodira: Flex neck laterally
Two groups of Tetrudines
1) Cryptodira
2) Pleurodira
Testudines (general information)
Leatherback turtle is largest Unique to turtles: positioning of limbs within shell Marine and saltwater Herbivorous and Carnivorous Lack teeth - have keratinized ridges
Rhyncocephalia/Sphenodanta (general info.)
Lifespan ~100 years (sexually mature ~20yrs and females breed ~4-5yrs
Redevelopment of diapsid skull
Teeth:
Fuse to bone
Double row (maxilla), single row (mandible)
All have stapes, incus, malleus - Reptiles only have stapes between incus(quadrate) and inner ear
What is the difference between the human ear and reptilian ear?
Humans: Eardrum, malleus(articular), Incus(quadrate), stapes, Inner Ear
Reptiles: Eardrum, Stapes, Inner Ear
NO OUTER MEMBRANE, OR TYMPANIC MEMBRANE
Contain Incus and Quadrate as bones of the skull
Squamates (general info.)
Evolution of venom early on
60% of squamates have venom
Movable Quadrate Bone* (back part of the jaws)
Which to lizards have venom?
Gila Monster [heloderma suspectum] (usa)
Mexican beaded lizard [heloderma horridum]
Who are the closest living relatives to birds?
Crocodilia
Crocodilia
Closest living relative to birds
Semi-sprawled posture
Ability to high-walk
Ancestors were bipedal - sprawled gait is a derived trait
Dinosaurs lived during what period?
Triassic Period (~250mya) Dominant is Jurassoc period (210mya)
Main lineages of Dinosaurs (2)
1) Ornithischia
2) Saurichia
*Ischia refers to pelvic region
Ornithischia
“bird-hipped”
Herbivore
Ex) Stegosaurus
Saurischia
"Lizard-Hipped"
Sauropods: Herbivores
Theropods: Carnivores
- Ex: Tyrannosaurus
- BirdsReptiles (General info.)
All must return to lad to lay eggs or live young (except sea snakes)
Thick keratinized stratum corneum
Epidermal scales
Scutes
Distribution limited by being ectothermic
Specialized atlas and axis cervical vertebrae
Thoracic/lumbar vertebrae not clearly different from rest
Many caudal vertebrae (tail)
Endothermic
Body produces heat
Ectothermic
Heat absorbed by the environment
Homeothermic
Body temperature consistent
Holothermic
Body temperature varies
Scutes
Large, plate-like scales
Modified scales form horns, spikes, and crests
Animals that contain Osteoderms
Crocodilians, testudines, and some lizards
Osteoderm
Plates of bone (-osteo)
Developed within the dermis (-derms)
Additional support to epidermis
Carapace
Osteoderm fused with ribs and vertebrae in turtles and tortoises
Dorsal shell ("top")Plastron
Fusion of osteoderms
Ventral shell
Aspects that distinguish reptiles (7)
1) Pectoral girdle
2) Pelvic girdle
3) Limb bones
4) Skull
5) Paired Lungs
6) Heart
7) Sexual dimorphism
Reptile Pectoral girdle
Scapula, coracoid, clavicle, and inter-clavicle
Reptile Pelvic girdle
Ilium, Ischium, and pubis
Arranged differently compared to humans
Reptile Limb bones
5 digits on each of the manus and pes
Very similar to mammals
Reptile Skull
Key feature is the number of temporal fenestrae
Types of reptilian skulls (2)
1) Anapsid
2) Diapsid
Anapsid
Lacks fenestrae
Ancestral reptiles, turtles and tortoises
Diapsid
Two fenestrae
Ancestral: Dinosaurs and crocodiles
Modern: Snakes, lizards, and birds
Reptile Lung
Paired lungs
Many lizards have reduced left lung
Reptiles have unidirectional flow - just like birds
Reptilia Heart
No typical reptilian heart
Separate pulmonary and systemic circulations
Some degree of mixing
Amphibian heart anatomy
2 atriums and 1 ventricle
Allows for complete mixing
Reptilian heart anatomy
2 atriums
Partial septum between ventricles
Allows for partial mixing
Sexual dimorphism in turtles/tortoises
Males have concave plastron
Sexual dimorphism in snakes and lizards
Males have longer tail due to hemipenes
Types of reproduction (3)
1) Viviparous
2) Oviparous
3) Parthenogenesis
Viviparous
Give birth to live young
~20% of extant snakes and lizards
Fertilised eggs retained in oviduct
Greater protection from predators and environment
Oviparous
Oviduct deposits albumin (not in snakes/lizards) in shell membrane and shell
Turtles/crocs: Ca2+ from shell used for calcification of embryonic skeleton
Yolk is the source of food
Parthenogenesis
Production of eggs without fertilization
Embryo derived solely from the fusion of 2 eggs
