presumably ral to us and all otures, knoetrapods.
Most animals are tetrapods, and all living tetrapods end in a maximum of five fingers or toes. Dinosaurs, rapods, or. to tor, it 400 millionyears ago. Before t time noter t time lots of team found just sucure, a t-long animal called an Icega. to Jarvik, at it for tforty-eigunately, Jarvik refused to let anyone study etrapod. tologists o be content cerim papers in ture s ancestral importance.
Jarvik died in 1998. After ologists eagerly examined t Jarvik ed toes—tually eigo observe t t possibly ructure of t it do a great deal to advance our understanding of t land animals. todaytetrapods are kno knoe wherewe came from.
But come state of eminence of course alraig ed of four megadynasties, as times called. t consisted of primitive, plodding but sometimes fairly yampiles. t-knorodon, a sail-backed creature t is commonly confused e, in a picturecaption in t). trodon a synapsid. So, onceupon a time, ilian life,to tion of small o be found in temples; diapsids wo; euryapsids had a single hole higher up.
Over time, eac into furtered. Anapsids gave rise to turtles, e as t’s most advanced and deadlyspecies, before an evolutionary lurc ttle for durability rato four streams, only one of whe Permian.
ream o, and it evolved into a family of protomammalsknoy 2.
Unfortunately for tively evolving,in to dinosaurs (among otoo muco compete o ures, to small,furry, burro bided time for a very long of t, and most han mice.
Eventually, tion, but to nearly 150 millionyears for Megadynasty 3, to come to an abrupt end and make room forMegadynasty 4 and our own Age of Mammals.
Eacransformations, as on t paradoxically important motor of progress: extinction. It is a curiousfact t on Eart literal sense, a y billion is a commonly citedfigure, but t as ever tual total, 99.99percent of all species t o a first approximation,” asDavid Raup of ty of Co say, “all species are extinct.” For c