Scientific Answer
The first bacterial life to appear on Earth was 3.46 billion years ago in the Precambian supereon. The first complex life appeared around 600 million years ago just preceding the Cambrian Explosion of life 530 million years ago.
dinosaurs
Many people would argue that no one species was on the Earth before another species. These people believe in creationism.
Zoegrass
The human species that appeared first on Earth is Homo habilis, followed by Homo erectus, then Homo sapiens (modern humans).
Coelophysis,Pterosaure and Technosaures.
Porpoises are not actually dolphins, they are both different branches of sea mammals known as ceteceans but they are not the same so in answer to your question porpoises were not the first dolphin species on earth because they are not a dolphin.
about 18,492,002 species consists on earth
The dinosaurs are one of the species that has disappeared from the earth.
It was celophysys a small dinosaur that hunted in groups and ate fish.
The first known species to appear on Earth were single-celled microorganisms like bacteria and archaea. These simple life forms emerged around 3.5 billion years ago.
the first person to live on earth was adem and eve
God made Man !st (Adam0 Then made woman(eve).