Exam 1 Flashcards
Current classification order for herps
1) Kingdom: Animalia
2) Phylum: Chordata
3) Subphylum: Vertebrata
4) Class: Amphibia and Reptilia
Monophyletic lineage (clade)
- composed of an ancestor and all of its descendants
- Amphibians (frogs, salamanders, caecilians)
Paraphyletic group
- includes all of the descendants of a common ancestor minus one or more monophyletic groups
- Reptilia is an example if birds are excluded
-Polyphyletic group
-consists of distantly related taxa whose last common ancestor is not a member of the group
Sister group
-adjacent branches on the cladogram
Outgroup
-outside of the reptile clade
The devonian opportunity
- about 375 mya
- there was a diversity of shallow aquatic habitats which generated a variety of unexploited microhabitats
What was the driving force behind the evolution of the tetrapods
-exploitation of new habitats during the late devonian
Tiktaalik
-missing link between fishes and walking land creatures
how do we know tetrapods are descended from lobe-finned fish
- labyrinthodont teeth (moze or labyrinth pattern of tooth surface)
- this is a characteristic not shared with other fishes
Ichthyostega
- a stem tetrapod
- basically a fish with legs
- tiktaalik
Transitioning from fish to tetrapod
1) Lungs already present for air breathing
2) Passive pump mechanism replaced by buccal-force pump
3) Joints formed (fins to limbs)
4) No more suction feeding
5) Developed elongated jaws, rudimentary ears, nasal passages, thicker skin
Morphology - fins to limbs
- joints formed in “legs” and digits formed from fin rays
- no longer supported by buoyancy in water
How did feeding change from fish to tetrapods
- skull and vertebral column become mobile
- elongated jaws develop
Origin of modern amphibians
-250-300 mya
Primitive amphibians: Lepospondyls
- labyrinthodont teeth
- simple, spool-shaped vertebrae
- primitive amphibians
- similar niches to salamanders, caecillians, lizards
Primitive amphibians: Temnospondyls
- labyrinthodont teeth
- resemble large salamanders, crocodiles
- sharp, conical teeth, l
- large fangs suggest they were predators
Carboniferous
- Age of giant amphibians
- increasingly warm, with moist terrestrial env
- this env is highly favorable for amphibians
- 360-286 mya
Gerobatrachus
- earliest fossil that can be clearly assigned to an extant modern amphibian clade
- could be link to modern salamanders
- frogmander
Triadobatrachus
- sister taxon to anura
- early triassic 245 mya
- protofrog
What generated many of the extant amphibian families
=radiation later in the Cretaceous and Paleocene
- many of these familes are essentially unchanged for epochs
- red spotted newt is example
Subclass Lissamphibia
- living amphibians
- extant amphibians fall into one of three orders (anura, caudata, gymophiona)
Traits of Lissamphibia
- smooth skin
- Pedicellate teeth
- containts poison, pheromone, and mucous glands
- shell-less eggs
- three chambered heart
- ability to elevate the eye
Anuran traits
- fore and hind limbs usually of unequal size
- usually no parental care
- external fertilization
- fused bones (tibiofibula, raidioulna)