Exam I Flashcards
Lissamphibia
modern amphibians belong to this group
-caecilians
-salamanders
-frogs and toads
Caecilians
-gymnophiona
Gymnophiona Characteristics
-lack limbs
-resemble earthworms
-burrow
-has body rings (annulations)
-thick skull (like shark)
Salamanders
Urodela
Urodela Characteristics
-4 limbs (reduced)
-long tail
-distinct head and neck
Frogs and Toads
Anura
Anura Characteristics
-robust, tail-less bodies
-no real neck
-well developed limbs
-reduced mobility in back
Amphibians Vs Reptiles
Amphibians= wet skin, breathe through skin, moist environment, metamorphosis, simple wet eggs, part aquatic, more glands
Reptiles= dry skin, full terrestrial, less glands, no metamorphosis, complex dry amniotic eggs
Reptile Groups
-turtles
-crocodilians
-tuataras
-lizards, snakes, etc
Turtles
Belong to Testudines
(include both turtles and tortoises)
Testudines Characteristics
-encased in a bony shell
-toothless beak
-can be fully terrestrial to fully aquatic
-need diff way to breath bc can’t expand chest
Crocodilians
Belong to crocodylia
(include crocodiles, caimen, and gavials)
Crocodylia Characteristics
-semiaquatic river and lake predators
-short limbs
-long tail
-strong, powerful skull
-covered in bony osteoderms
Tuataras
Belong to Rhynchocephalian
(not lizards)
Rhynchocephalian Characteristics
-lizard-like body
-2 species that live in New Zealand
-specialized beak like teeth and skull
-teeth fused to skull
Lizards, Snakes, etc
Belong to Squamata
Squamata Characteristics
-lightly built skull with reduced bones
-hemipenes
-specialized scent organs (jacobsons organ)
-many groups lost their legs
Lizards
Lacertilian
Lacertilian Characteristics
-all four legged squamates
Snakes
Serpents
Serpent Characteristics
-exclusive predators
-elongate body with lots of ribs and vertebrae
-no legs
-reduced skull for swallowing food whole (flexible jaw)
-chemosensory tougue
Worm Lizards
Amphisbaenia
Amphisbaenia Characteristics
-burrowing and worm-like
-legless or with forelimbs
-rudimentary eyes
-head and tail difficult to tell apart
Tetrapods are an offshoot group of what
Sarcopterygii
Sarcopterygii have two species left
-lungfish
-coelacanth
Sarcopterygii Ancestors
(direct ancestors of tetrapods)
-prob had lungs (evolved as an accessory respiratory structure)
-used fins for support and movement
-eventually became bottom walking
-bony and robust skull
-powerful jaws
-shifting eyes to top of head to feed above water
-skull flattened
-skull detached from pectoral girdle (forming true neck)
Key Fossils
-eusthenopteron
-panderichthys
-tiktaalik
-acanthostegg
-ichthypstegg
-tulerpeton
Eusthenopteron
-shallow water predator with flat, elongated snout
-large pectoral fins
-very fish like (is a fish)
-lobbed fin (couldn’t support its weight)
-lots of fins going out its side
-swam fast, was a predator
Panderichthys
-predatory fish with flat head
-long snout
-dorsal eyes, strong, flat humerous
-no longer had tail fin bc wasn’t propelling itself
-fins more elongates
-could prob walk in water, not land
-had something like an elbow
-does not have a neck
Tiktaalik
-flat head and body
-raised dorsal eyes
-mobile neck
-robust forlimbs and girdle
-has elbow
-has hand that looks more like paddle
-could stick head above water
-could not leave water
Acanthostegg
-similar to tikaalik but with 8 digits on each limb
-cant walk on land
-powerful swimmer and predator
-first guy to have something like a hand
-more like a paddle with three bones
-don’t have a wrist
Ichthypstegg
-7 digits and sturdy
-stout limbs
-could prob move short distances on land
-longer and stronger paddle
-some fingers may have actually been fingers
-was not fast
Tulerpeton
-6 digits now
-recognizable vert limb
-least aquatic and could move well on land
-wrist and elbow
The First Tetrapods and what they are apart of
acanthostega, ichthyostega, tulerpton all part of paraphyletic group: ichthyostegalia
(now fully extinct)
(when on land, were top and largest predator)
Offshoot of ichthyosteglia
temnospodyli
(lead to all other tetrapods)
(large sized, semiaquatic predators resembling crocs)
(strong skull, stout limbs, powerful tail, bred in water)
Only survivor of temnospodyli
Lissamphibia
(owed the land not far from water, evolved true limbs, fingers, toes, claws, shoulders, neck, strong skull)
(still laid eggs in water like modern amphibians)
(direct ancestors of amphibians)
(extinctions chopped these guys down)
After temnospodyli, two amphibian groups branched off…
-anthracosauria
-lepospondyli
Subset of anthroacosaurs
Amniota
Amniota
-defined by having amniotic egg
-laid on land
-represents all reptiles, birds, and mammals
-results in group called amniotes
-key to getting away from water
-all reptiles are amniotes, but not all amniotes are reptiles
Amniotes aside from mammal line known as…
Sauropsida
(birds and dinos are also these)
(mammals branched off and did their own thing)
What is a reptile?
any amniote that is not a modern bird or mammal
Sauropsids
early sauropods branched into two groups:
-parareptilla
-eureptilla
Parareptilla
Having a solid skull with no openings
Eureptillia
developed two openings in the skull known as diapsid condition (forming the group diapsida)
Diapsid surviving sister groups
-lepidosauria
-archosauria
Rhychocephalian (history)
-first representative that looked similar to modern tuatara
-strong beak-like head
-multiple rows of teeth fused to jaw
-hard and strong bite
-sawing motion with jaw
-only the tuatara survives today
Lepidosaurs (groups)
-rhychocephalians
-squamates
-archosaurs
Squamates (history)
-snakes, lizards, amphibians
-most species living reptile group (they are doing great rn)
Archosaurs (history)
-socketed teeth
-added openings in their snout and jaw (lighten)
-complex parental care
-diverse group
-bad ass
-first flying verts (pterosaurs)
Branch of archosaurs gave rise to…
Crocodylian Lineage
Crocodylian Lineage
-defined by compact skull
-earliest representatives were small and bipedal
-more modern looking crocs came along about 100 million years ago
-still around today and are a dominant species
Turtles
-how turtles are related to everything else is till debatable
-they have no openings in their skull, so originally thought to be parareptiles
-genetic evidence put them as a sister group to archosaurs
-most recent research shows them to be derived from diapsids
Under Temnospondyli
Anura, Urodela, Gymnophionia
Under Tetrapoda
Temnospondyli and Amniota
Under Amniota
Sauropsida
Under Sauropsida
Parareptillia and Eureptilia
Under Parareptillia
Testudines? Nah
Under Eurereptillia
Diapsida
Under Diapsida
Testudines?, Archosauria, Lepidosauria
Under Archosauria
Crocodylia
Under Lepidosauria
Rhynocephalia and Squamata
Embryogenesis
Cleavage is the division of embryonic cells
-zygote divides, but does not increase in size
Blastomeres
when zygote start to divide but not increase in size
Morula
Formed an 8 cell ball
Blastula
Forms a hollow ball of cells
(the hollow part changes in size based on the amount of yolk needed)
Blastocoel
The hollow center of the blastula
Yolk
Needed to give nutrients to the embryo, this increases or decreases in size depending on how large/developed the embryo will be or how long it is stored for
-tadpoles hold yolk in their swimming bodies to give them a head start
Amount of yolk conditions
-isolecithal
-mesolecithal
-marcolecithal
Isolecithal
Yolk amount is small and evenly distributed, found in placental mammals
Mesolecithal
Modern amount of yolk, found in most amphibians, young must start feeing before fully developed (amphibians)
Macrolecithal
Amount of yolk, found in reptiles, birds, and egg laying mammals (lots)
Morphogenesis
The unfolding of form and structure
(transition of undifferentiated cells into differential cells, tissues, organs, and eventually an organism)
(amphibians become free living a lot earlier than reptiles, but they undergo metamorphosis)
Larvae
Free living embryo as opposed to one that fully develops in the egg/parent
-allows for them to feed on their own
-they have some yolk to give head start
-can grow larger and develop at the same time
Lissamphibian larvae
-mostly aquatic
-fish-like characteristics
-think skin (2-3 epidermal layers)
-highly vascularized
-pharyngeal slits and external gills
-lidless eyes and large external nares
-muscular trunks and long tails with dorsal/ventral fins
-lateral line system to detect current flow
(start fishy looking and as mature they get their normal look)
Salamander and Caecilian larvae
-they have anatomy similar to adults
-they look like mini adults as kids
Anuran Larvae
-have very different anatomy than adults
-they are tadpoles, so they need to undergo metamorphosis
(have oral disk for a mouth, external gills replaced by internal gills, spherical body, coiled intestine, tail)
Heterochrony
Changes in timing/rate of growth
paedomorphic
if you decelerate the development of a trait
(more common in amphibians)
Peramorphic
if you accelerate the development of a trait
(adopted characters are adopted early)