Paleozoic Invasion of Land (midterm 2) Flashcards
Plants initially evolved in _______, then moved into ________, then ________
seawater
freshwater
onto land
With plants’ transition from water to land, what were some of the problems they had to solve?
- had to avoid desiccation (drying out)
- had to develop support (deal with gravity)
- had to develop a reproduction method for land
What are the 2 types of major plant divisions? (+ examples)
Vascular:
- majority of modern land plants
- tissue system of specialized cells for transporting water and nutrients within them
- vascular tissue also provides support (also strength in lignin and cellulose in cell walls)
- examples: flowers, trees, ferns
Nonvascular:
- no specialized cells for water and nutrient transport
- live in moist areas
- examples: liverworts, hornworts, mosses
What was the time period with the most major events in land plant evolution? (some examples?)
Devonian > rapid evolution for plants
ex. development of weeds, heterospory, secondary growth, seeds
What were the likely first land plants?
Hepatica
- nonvascular
- have gemma cups > rainfall splashes in them and splashes the gemma out which causes the reproduction
What are 3 adaptations of Vascular plants to help them survive on land?
Cutin (in outer wall layers):
- prevents desiccation, entry of parasites, oxidation, UV damage
Roots:
- allows greater access to water and nutrients and provides support
Leaves:
- provide light gathering system for photosynthesis
Vascular plants likely evolved from _________
green algae
(evolved before the Silurian)
What was the earliest seedless vascular land plant? characteristics?
Cooksonia:
- during the Silurian
- resistant cuticle, spores, rhizome
- have spores in their cups (reproductive structures)
Explain how vascular plants evolved during the early Devonian
- evolved leaves, roots and secondary growth through Silurian and into the Devonian
*not simultaneous evolutions
Explain the steps of the life cycle of a fern which is a *seedless vascular plant
What is the most important thing to note about this cycle?
- Ferns have sporangia’s which hold spores in them
- Plant releases spores into the environment
- Spores germinate in *moist soil
- grows into larger structure and eventually a gametophyte plant (bears both gametes - eggs and sperm)
- young growing fern is still attached to gametophyte plant
- continuing to grow and eggs and sperm combining
- eventually a mature fern sporophyte
**it is a water dependent life cycle - needs a moist environment
What is the significance of Heterospory and what is a Progymnosperm
Heterospory = production of two different size of spores by a single plant
Progymnosperm = an intermediate plant - between plants with all same spore sizes and plants that have seeds - *has two size of spores
Explain the important notes about a Gymnosperm plant’s life cycle (vascular plant with seeds)
- Pollen gets released to hopefully enter cones and fertilize the embryonic egg → forming a seed
- female part is the giant cone > male part is the small little bits
- Pollen can be distributed by wind (much more effective) - *doesn’t need water
What are the barriers that animals faced while transitioning to land
- desiccation
- gravity
- reproduction
- respiration
What were the first animals to transition to land? what followed them?
*Arthropods came onto land after plants in the Silurian
> Eurypterids. “sea scorpions” and millipedes (first creatures on land)
Amphibians followed plants and arthropods
What is the oldest fossil of a land animal?
a Millipede-like creature (resembles modern millipedes)
- fully terrestrial and freshwater
What were the first vertebrates to live on land? First kind of evidence of this?
Amphibians
Earliest tetrapod (four footed) tracks were about 395 million years ago in a lagoon environment
Explain the link between the lobe finned fish and amphibian
Traditional thought is that the evolutionary progress was from crossopterygian (lobe finned fish) to the Labyrinthodont (amphibian)
Because they have similar morphologies > similar limbs, tooth structure, and overall structure
What is the significance of the Tiktaalik roseae? (amphibian)
- intermediate creature between lobe-finned fish and tetrapods
- first critter that would’ve walked on land
- still very reliant on water and not efficient at maneuvering on land
What are some characteristics of late Devonian amphibians that suggest both suitability to life on land and life on water
Land suitability:
- backbone
- ribcage
- pelvic and pectoral girdles
Water suitability:
- streamlined body
- long tails
- fins on back
What is the significance of the Ichthyostega amphibian
- believed to be fully reliant on land
- had features that suggested they were most suited for land but still features suggesting water suitability as well
- still kind of an in between stage
Explain the Carboniferous coal swamp environment that led to reptile invasion on land
- ferns formed undergrowth
- giant dragonflies
- Lycopsids: tree like things but not actual trees - up to 30m tall - branches and leaves like palms
- Sphenopsids: 5-6m tall - joined
When did reptiles evolve? How do they differ from amphibians?
evolved in lat Mississippian (*also late Carboniferous)
differ from amphibians:
- skull structure
- jawbones
- ear location
- limb and vertebral construction
How were reptiles able to diversify and begin displacing amphibians in the Permian?
Because of several advancements:
- method of reproduction
- jaws and teeth
- tough skin and scales
- faster movement on land (and more efficient movement)
What is each part that makes up an Amniote (reptile) egg? What did this egg evolution allow for?
Amnion - Embryo surrounded by liquid-filled sac
Yolk - food sac
Allantois - waste sac
Shell - protection from desiccation
*reptile emerges from egg a miniature adult
* did not need to return to water at any stage in life cycle
What is the significance of the Joggins Fossil cliff in Nova Scotia
- Fossil cliffs from this time period - preserved the tree like structures (Lycopsids)
- and they found fossil reptiles living inside the tree like plants
Explain how reptiles evolved from the late carboniferous to the permian period?
Late Carboniferous:
- small and agile reptiles eating grubs and insects
- grouped together with the name protorothyrids
Permian:
- reptiles diversified and began displacing many amphibians
- advanced method of reproduction
- more advanced jaws and teeth
- tough skin and scales to prevent desiccation
- ability to move rapidly on land
