posted on May, 23 2010 @ 08:54 AM
Humans have hardy prehistoric fish ancestors to thank for paving the way to their eventual evolution, a new study suggests.
A Gladbachus shark fossil used in the research, pictured in the scientists' lab.
About 360 million years ago a mass extinction event hit the reset button on Earth's life, wiping out most of the fish that existed then near the
time when the first vertebrates (all animals with backbones) crawled from water towards land. The species fortunate enough to survive set the stage
for modern vertebrate biodiversity. "Everything was hit; the extinction was global," said study leader Lauren Sallan of the University of Chicago.
"It reset vertebrate diversity in every single environment, both freshwater and marine, and created a completely different world."
extinction hit near the end of the Age of Fishes (more commonly known as the Devonian Period, from 416 to 359 million years ago) for the broad array
of species present in Earth's aquatic environments. Armored prehistoric fish called placoderms and lobe-finned fishes — similar to the modern
lungfish — dominated the waters, while ray-finned fishes, sharks and tetrapods — vertebrate animals with four feet — were in the minority. But
between the Devonian Period and the following Carboniferous period, placoderms disappeared and ray-finned fishes rapidly replaced lobe-finned fishes
as the dominant group, a demographic shift that persists today.
The researchers analyzed the vertebrate fossil record and pinpointed a
critical shift in diversity to the Hangenberg extinction event. The Hangenberg event hit 15 million years after another extinction event — the Late
Devonian Kellwasser event, considered to be one of the Big Five extinctions in Earth's history — that scientists have long theorized that was
responsible for a marine invertebrate species shake-up. Prior to the extinction, lobe-finned forms such as Tiktaalik and the earliest limbed tetrapods
such as Ichthyostega had made the first moves toward a land-dwelling existence.
But after the extinction, a long stretch of the fossil record
known as "Romer's Gap," is almost barren of tetrapods, a puzzle that had confused paleontologists for many years. The 15-million-year gap was the
hangover after the traumatic Hangenberg event, said the study's authors. When tetrapods finally recovered, those survivors were likely the
great-great-grandfathers to the vast majority of land vertebrates present today, including humans.
Well, taking the UFO/Aliens factor out of this, this explaination is about the best I have heard on how we came from water to land. But I am not an
expert, or even novice, in this field. Sounds plausable.
As much plausable as life was brought to earth via a satelite of some type. Yes? Or even us being put here by Aliens. But, I will say that I do
think some form of human was here but it was either genetically altered on purpose or natually over time as the Aliens stayed and expanded.