Life on earth has achived on walking on land.
But were fosusing on the vertabrates,not the arthropods who already reached land over 400 mya.
This is the devonian period 419.2-358.9 mya named after devon,england where it's rock formation from this time period were discovered...
A tiktaalik took it's first steps to land 375 mya.
This is belived to be the earliest known fish to walk on land & also the first to possess lungs to help them breath in the air.
But one of tiktaalik's relatives did opting to return to the open waters instead of venturing onto land.
This is qikiqtania wakei (illustration by alex boersma) found in the fram formation of nunavut,canada.
This large dunkleosteus was the largest predator of it's time.prehistoric armoured fish called placoderms have articulated bony armoured plates and the rest are just smooth of scaled skin. depending on what species it is
Placoderm jaws are likely evolved from the first of their gill arches. there also the earliest fish to evolved pelvic fins, the precursors to hindlimbs in tetrapods.as well as "true-teeth"
A dunkleosteus is swimming across some frightened acanthostegas who reached land to rest. when a stethacanthus hunts it down. the creature is about 1.5 meters while other stethacanthus species like S.productus is about 3 meters long being 2 times larger than S.altonensis the dorsal fins help to stablilize the holocephalian preventing it from rolling over or to scare other fish with its tooth brushes hence, he's nicknamed the anvil shark or ironing board snark
But even holocephalians like the stethacanthus are no-match for other flesh-eating fish...
(artist's illustrations of hyneria lindae)
Hyneria is about 2.3-3 meters long .
She's a freshwater predatory lode-finned fish lurking in the murky waters below. with sensory canals to aid in detection of prey.
Since 360 million years ago, the first trees evolved covered the landscape forming forest pumping oxygen into the air.
Fast forward a little few million years into 358.9 and we witnessed the late devonian extinction.
Triggering the extinction were low temperature stress and oxygen deprivation. the devonian saw oceans getting choked killing 70-80% of species that lived during that time into extinction but there still survivors,
Like our early tetrapod ancestors, bony fish and a few trilobites reaching to the next time period of the paleozoic: the carboniferous
