From Sea to Land

• buoyancy (gravity)
• dessication (drying out)
• gases behave differently in air
• temperature
• no nutrients in air (filter feeding not so good)

• animals only: vision (light behaves differently on land)
• sounds travels differently (adjust hearing)

• gravity: need a sturdy structure to stand upright
• solution: rigid cuticle/wood (cellulose)

• evaporation: must retain moisture
• solution: water resistant cuticle

• nutrients: no nutrients in air
• solution: roots

• more CO2: easier to extract
• light more intense: photosynthesis easier
• nothing to eat you on land (yet)

a vascular system

(However, first land plants would have lacked hard supportive tissues and would not be preserved.)

green algae

• transport of nutrients and water between roots and leaves
• Most plants utilize this today.

• carries water through the plant
• developed in first land plants
• found in simple mosses
• (Since mosses do not have leaves, stems, or roots, they are not true vascular plants.)

• waxy cuticle
• roots
• leaves
• stomata
• xylem
• phloem

• helps prevent desiccation
• structural support
• protection
• (cannot absorb nutrients)

absorption of water and minerals from soil

gas exchange via stomata; photosynthesis

pores on leaf surface which regulate gas exchange

• xylem
• phloem

• tubes lined by dead cells in vascular plants
• Evaporation creates negative pressure which carries/pumps water/nutrients up the plant from the roots to stems and leaves

carries soluble organic materials made during photosynthesis down the plant from the leaves to stem and roots

Ordovician spores

• can withstand harsh weather (heat and dessication)
• require water for growth and fertilization
• restricted to moist environments
• designed for dispersal (small and light)

• Silurian Sporophytes (similar to club mosses)
• ex. Cooksonia

• embryonic plants (already fertilized) that contain nutrients in a protective cuticle
• doesn't need to be in moist environments
• what allowed plants to truly colonize land

late Devonian

angiosperms (flowers and fruits)

• dominant low latitude "forest" builders of the late Paleozoic
• spore bearing fern-like plants
• oldest surviving leneage of vascular plants

• tree-like habit
• late Devonian
• major shift from Devonian landscape to Carboniferous

herbaceous plants, single story

• high latitude coal swamps
• Gymnosperms more common

Lycopod

• arthropods
• Late Silurian

• nearly waterproof cover
• very strong for their size
• sturdy walking legs

• "sea scorpions" (Chelicerata)
• among the first on land

• limbs (helped maneuver in shallow water)
• lungs (derived from gas bladder that regulated buoyancy: became permeable to gases)
• nostrils (helped breathe air while remaining submerged.. possibly for ambush predation or hiding in shallow stagnant water)
• ancestor to all tetrapods
• evolved in the Devonian

• basking (thermoregulation)
• reproduction (safer for activity and eggs)
• dried up pools/puddles (became isolated on land, Devonian was Arid, continents were closing water ways)
• unexploited resources (plants and arthropods: fit for all diets)

• includes amphibians, reptiles, birds, and mammals
• 4 limbs
• known from the late Devonian
• 1st terrestrial vertebrates

• 4 limbs
• digits on limbs
• hinge-like wrist and knee joints
• pelvic girdle attached to sacral vertebrae

• earliest tetrapods
• aquatic larval stage
• terrestrial adults
• gills as babies, lungs as adults
• reproduction requires moisture

• oldest known tetrapod (amphibian)
• known from 4 bones
• evidence of limb joints
• jawbone = tetrapod
• Devonian

• early amphibian
• broad limbs
• well developed ribs
• lacked nuchal gap. i.e. couldn't move its head
• pelvic girdle not well developed

• early amphibian
• has ankle joint
• weak ribs
• agile and aquatic
• probably lived in shallow water for refuge from large predators

Humerus, radius, and ulna are stable, but digits vary dramatically.

• medial-lateral undulation
• no major change in locomotion
• head held still while body moves back and forth
• derived from early fish

• dessication (not too important initially; epidermis would toughen)
• gravity and locomotion (had stout limbs, ribs, pelvic and pectoral girdles)
• respiration in air (already had lungs)
• vision and hearing (vision probably already adapted; nostril bearing lobe fins)
• reproduction: the amniotic egg

The amniotic egg

• protective outer shell is semi-permeable to gases, but impermeable to water
• membranes provide nutrients, water, protection and takes care of waste

• group of tetrapods including all reptiles, birds, and mammals
• i.e. Synapsida (mammals and mammal-like reptiles) and Sauropsida (reptiles, dinosaurs, and birds)

temporal fenestrae (holes in the head behind the eyes)

• amniotes with 0 holes behind eyes
• primitive reptiles
• i.e. turtles

• amniote with 1 hole behind eyes
• i.e. mammals

• amniote with 2 holes behind eyes
• i.e. dinosaurs, pterosaurs and all other living amniotes