Topic 32 Reptiles Flashcards
two groups of reptiles
diapsids (turtles, crocs, and birds) and synapsids (mammals)
Non-avian reptiles’ characteristics
- Skin is protected by thick, dry keratinous scales that create a waterproof barrier (desiccation resistant)
- Leathery eggshell
- reptiles are oviparous; they bury their shelled eggs on land
- Most reptiles are ectothermic
Two main lineages of diapsids
lepidosaurs (tuataras, lizards,
snakes, and extinct mosasaurs) and archosaur (crocodilians, pterosaurs, and
dinosaurs)
Turtles
- Box-like bony or cartilaginous shell made of dorsal and ventral shields that are fused to the vertebrae, clavicles, and ribs.
- Teeth lost: toothless beaks.
− Males have a single intromittent organ.
Lepidosaurs
- reptiles with teeth fused to the jaw
- a body covering of overlapping scales
- Male lepidosaurs have a hemipenis
Two clades of lepidosaurs
Tuataras and Squamates (lizards and snakes)
Tuataras
- Tuataras look like lizards but lack the modified jaw structure and male genitalia present in squadmates
- Internal fertilization via copulation, but lack an intromittent organ
the major extant lineage of lepidosaurs consists of
squamates, lizards and snakes.
Squamates are characterized by:
Loosely jointed jaws and skull.
Hemipenis in males.
Archosaurs
reptiles with socketed teeth
two extant lineages of Archosaurs
crocodilians and birds
Crocodilians
(alligators and crocodiles), Males have a single intromittent organ, exhibit maternal care
aquatic diapsids
Ichthyosaurs and Plesiosaurs
Birds are
archosaurs
Birds evolved from
theropods
Similarities between theropods and birds
Hollow, thin-walled bones
Egg laying and brooding
Feathers are homologous with theropod scales
SHared&derived traits of birds
Wings with keratin feathers (Wings are evolved tetrapod forelimbs), Horny beaks that lack teeth, Birds have digestive systems adapted for flight (crop and gizzard), reduced organs, endothermy, high metabolic rate supported by 4-chambered heart and complex respiratory system
Plumage
arrangement of feathers
Cloaca
a common opening for the
digestive, urinary, and reproductive tracts
oviparous
lay shelled eggs on land
