Lecture 32 Amniotes - Reptiles Flashcards
what are the two major clades of amniotes?
- reptilia : includes birds
- synapsida: mammals and extinct taxa
what are amniotes?
- group of tetrapods whose living members are the reptiles, including birds and mammals
- many adaptions for terrestrial life
- amniotes are tetrapods that have a terrestrially adapted egg
what is the key unifying feature of amniotes
amniotic egg
what are the four extraembryonic membranes that surround and protect the developing embryo
- allantois, chorion, amnion, yolk sac
- no need for water to reproduce – fully adapted to life on land
what is the allantois?
waste disposal sac and gas exchange organ
what is the chorion?
gas exchange of O2 and Co2 between embryo and air across shell
what is the amnion?
protects embryo from mechanical shock
what is the yolk sac
contains yolk stores nutrients
what kind of eggs are there?
- porous calcareous or leathery shell impervious to water loss
what kind of eggs are there?
- porous calcareous or leathery shell impervious to water loss
if amniotes don’t lay their eggs on land what do they do with the eggs?
- retain the fertilized egg within the mother
how do amniotes develop?
direct development
what are other terrestrial adaptations in addition to the amniotic egg?
- thick, stratified, and relatively impermeable skin
- ability to use muscles associated with rib cage to ventilate lungs
what are the classification of amniotes?
- anapsid: zero holes in post jaw area: turtles
- synapsid: one : turtles
- diapsid: two holes per side behind eye socket : reptilia
what are the two major clades of amniotes?
- reptilia
- synapsida – mammals and numerous extinct taxa
what does class reptilia include?
- tuataras, lizards, snakes, turtles, crocs, birds, dinos
what are characteristics of non-avian reptilia?
- skin protected by thick, dry, keratinous scales that create a waterproof of barrier; skin shed in sections, as in turtles, or all at once
- leathery eggshell - protects from dessication, some are viviparous, with e
what are characteristics of non-avian reptilia?
- skin protected by thick, dry, keratinous scales that create a waterproof of barrier; skin shed in sections, as in turtles, or all at once
- leathery eggshell - protects from dessication, some are viviparous, with extraparous
- most reptiles are ectothermic
- 3 chambered hearts
- little or parental care of young
what are characteristics of non-avian reptilia?
- skin protected by thick, dry, keratinous scales that create a waterproof of barrier; skin shed in sections, as in turtles, or all at once
- leathery eggshell - protects from dessication, some are viviparous, with extraparous
- most reptiles are ectothermic
- 3 chambered hearts
- little or parental care of young
what was the first major group of reptiles?
- parareptiles, which were mostly large, stocky quadrupedal herbivores
- as they were dwinding, diapsids were diversifying
what are the main lineages of diapsids?
- lepidosaurs
- archosaurs
what are the main lineages of diapsids?
- lepidosaurs
- archosaurs
what are lepidosaurs?
tuataras, lizards, snakes, and extinct mososaurs
what are archosaurs?
crocodilians, pterosaurs, and dinosaurs
what are pterosaurs?
were first tetrapods to exhibit flight
what did dinosaurs include?
- bipedal carnivores, theropods from which birds descended
what are the major groups of extant non-avian reptiles?
-turtles, crocodilians, tuataras, lizards, snakes
what is order testudines?
amniotes - reptiles - turtles
- have a boxlike bony or cartilaginous shell made of dorsal and ventral shield
- anapsids
- intromittent organ
- herbivores and carnivores
what are lepidosaura: order tuataras?
- lizard-like
- look like lizards, but lack the modified jaw structure and male genitalia present in squamates
what are lepidosaura: order tuataras?
- lizard-like
- look like lizards, but lack the modified jaw structure and male genitalia present in squamates
- teeth fused to jaw bones
- copulate but lack intromittant organ
what are lepidosaura: order squamata?
- lizards and snakes
- characterized by: loosely jointed jaws and skull
- paired hemipenes in male
- external ear openings
- lizards: well developed limbs
- snakes: no external limbs
what are archosaurs - order crocodilia?
- crocodilians (alligators and crocodiles)
- belong to an archosaur lineage that dates back to the late Triassic
- can’t chew
- extant species can walk on land
- males have a single intromittent organ
- exhibit maternal care
what are extinct reptiles?
parareptiles and numerous diapsids
what are parareptiles?
anapsid reptiles that may or may not have left any descendants
what are the extinct aquatic diapsids?
- ichthysaurs - dolphin like, short necks, fish-like tails
- plesiosaurs - near lizards, flippered marine reptiles
what are archosauria?
- extinct
- include pterosaurs and non-avian dinosaurs
- only extant members: crocodilians and birds
- represent one of 3 independent origns of flapping flight among vertebrates
what are theropods?
bipedal saurischian dinos
- may have been the ancestors of birds
- many had feathers
