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Drone footage shows volcano's lava reaching sea. Wasted space finds new purpose as China pledges to go carbon neutral. South Africa's last White president has died aged There are a lot of ways to make these groupings. One way—the biological species construct—is to say that to be a member of the same species, you have to be able to reproduce. From that perspective, we would have to say that Denisovans and Neanderthals are also humans, because we know they mated with each other and with Homo sapiens —4 percent of my own genome, for example, is Neanderthal.
One of the long-standing questions paleoanthropologists have been trying to answer is could Neanderthals use language? But then we sequenced their genome, and discovered they have a version of the FOXP2 gene that facilitates speech in present-day humans. From the Middle Pleistocene, we have the archaeological record that tells us humans at that time fairly certainly had tools. If they had tools, they probably had culture, because to make tools you generally need to learn those skills socially and pass those skills on to others.
Dragon Man likely lived in a small band of hunter-gatherers, with a family or with multiple families living together. Were there bonded pairs of mates, or polyamorous groupings? Were they egalitarian? This is actually fairly common—you read about [specimen] caching in a number of cases. We see archaeologists come into an area, collect a bunch of specimens, and then they go into a drawer, waiting for a graduate student or contract archaeologist to catalog and analyze them.
Maybe whoever has them in their possession is interested in something else, and they have lots of specimens to choose from studying, so a lot of times these groundbreaking finds are just waiting for someone to realize what they are. And sometimes a specimen is held back from the public at the will of a researcher. In this case, Dragon Man was hidden at the bottom of a well to keep it from [being taken] by occupying forces, and political instability in that region at the time led to people not picking up on its presence until the family of the discoverer brought it to the attention of researchers.
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This is sooooo fascinating. Tiktaalik's discovery made me reconsider the much later and opposite transition—from land back to the sea—which is documented in the excellent record of fossil whales. For example, Pakicetus is a million-year-old species with whalelike teeth and a whalelike skull. Its skull possesses neither the anatomical adaptations for deep diving nor those for hearing underwater as well as modern whales do, suggesting Pakicetus used both land and shallow water environments.
Most of its skeleton is still unknown, but the part of its pelvis that is known shows aquatic adaptations. Whether or not its limbs and feet were adapted for land or sea won't be known until a more complete specimen is found. Phil Gingerich of the Museum of Paleontology at the University of Michigan has found remains of Pakicetus and many other spectacular whale fossils.
Slightly younger Rodhocetus was better adapted to the water, with ankles like land mammals' that were connected to enlarged hind feet specialized for swimming. Its front feet retained land-adapted hooves.
From 45 million years ago, the fossil whale Dorudon had a less mobile more fishlike neck, front legs modified into flippers, vestigial hind legs and a powerful whale tail. Dorudon shows that foot-propelled swimming had been superseded by the tail-propelled swimming that characterizes modern whales.
The features of these three species—plus those of a dozen other related species—can be used to sketch out the way in which land species returned to the sea and reevolved their aquatic adaptations, eventually evolving into whales. Both transitions, water-to-land and land-back-to-water, occurred in a mosaic fashion and quite possibly used those intermediate habitats to which Tiktaalik is adapted.
In fish and in whales, first the shape and design of the head evolved, then the forelimbs and finally the hindlimbs and tail. Are these parallels meaningful or simply coincidental? Did other lineages preserved in the far north evolve from a fishy life to a tetrapodal one in another way?
Only more analysis and more fossils will tell. Finding a missing link is a life's ambition for many paleontologists, often taking years of hard work, travel to remote regions and more than a generous dollop of luck. The aftermath of finding a missing link is more subtle than might be supposed. The paleontological record will always be sparse compared to the total number of creatures that ever lived, because fossilization is a very rare event.
Millions of animals are born and die every day, but only a few of their bodies find habitats suitable for fossilization and preservation. Of those few creatures that die in the right place at the right time, many are preserved in places so thinly inhabited by human beings that no one who could recognize the fossil for what it is will ever see it.
Not only does an organism have to be fossilized, but it must be found and recognized by a trained eye to add to the sum of scientific knowledge. Although the discovery of a missing link is cause for celebration, it is also cause for more and deeper studies. Ironically, even as one link is found, two new missing links are "created"—one the immediate ancestor and one the immediate descendent of the newly found creature.
But slowly, as discoveries proceed, paleontologists are able to compile an ever-clearer record of the evolution of life on Earth.
The lack of vegetation of Ellesmere Island in the Canadian Arctic produces a barren-looking landscape where fossils are relatively easy to see. This is the valley that yielded the Tiktaalik specimens. The discovery of Tiktaalik will encourage paleontologists to continue their intrepid searches in far-flung areas.
With luck, its existence may spark others to rethink their position, too. Intelligent design advocates and creationists claim that too many links are missing for evolution to be credible; they see only the abrupt appearance of new forms created by an Intelligent Designer.
Stephen Meyer, director of the Center for Science and Culture of the Discovery Institute, asserts that "the transitional life forms that ostensibly occupy the nodes of Darwin's branching tree of life are unobservable The highly observable Tiktaalik is exactly the sort of transitional form that Meyer maintains does not exist.
The fossils are real and solid evidence that you can hold in your hand.
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