Getting Animals from Here to There
The world is a big place, and most animals are small. Yet many animals are found far from where their presumed ancestors lived. Most birds, naturally, can fly long distances, and some sea creatures can cross the oceans with the help of currents. That cannot explain all the cases, however. Here are some attempts by evolutionists to explain how animals got from here to there:
- Land-locked reptiles: In the evolutionary saga, the first tetrapods invaded the land close to shore. According to Live Science, though, scientists at the University of London found “ancient reptile tracks” in the Bay of Fundy at a location thought to be 500 kilometers inland at the time they were formed. New Scientist said that the first land colonizers, frogs and amphibians, had to stay near the water. Howard Falcon-Lang gave his speculation on how the reptile track-makers got so far into the dry interior: “Perhaps the coastal swampy forests were becoming overcrowded and the continental interior were empty spaces just waiting to be filled by pioneers.”
- Aussie gloss: One would think that the unique marsupials characteristic of Australia would have evolved down unda. A new theory by a team at the University of Munster, Germany, believes, instead, that they evolved in South America (see Live Science and PhysOrg, “A hop from South America”). There’s a big ocean in between those locations – at least today. The supercontinent Gondwana is thought to have broken apart 80 million years ago. No wonder that PhysOrg said, “Debates have raged for decades about how to arrange the Australian and South American branches of the marsupial family tree.”
According to the new theory, a common ancestor of all the Australian marsupials hopped over before the land bridge became inundated (they based this on measures of retrotransposons in the genes of Australian and South American marsupials, not on fossil evidence). As usual, though, new solutions create new problems. “It is still a mystery how the two distinct Australian and South American branches of marsupials separated so cleanly, but perhaps future studies can shed light on how this occurred.” The BBC News coverage complicated the story by invoking a kind of circular migration pattern over unknown epochs. They envisioned the first marsupial ancestor in China moving across Gondwana South America, then into Australia, and back to Indonesia. It would seem this would allow for quite of bit of genetic mixing during the long periods of migration. One of the scientists is not sure when the genetic signature got locked into the Aussie groups. “It’s now up to other people, maybe from the palaeontology field, to find out when exactly it happened.”
For a related story on Australian marsupials, see this Science Daily article about a cave near New South Wales that was found loaded with marsupial bones said to be 15 million years old.
- One-way birds: Not all birds are capable of long-distance migration. It’s long been unclear how certain species of birds arrived in North and South America. There’s a land bridge now (the Isthmus of Panama), but for a long time before South America bumped into the North American continent, a vast ocean separated the two. Science Daily reported on the thinking of researchers at the University of Nevada that suggests there was one-way traffic: “Avian lineages from the northern Nearctic regions have repeatedly invaded the tropics and radiated throughout South America,” said Brian Tilston Smith (U of Nevada). “In contract [sic, contrast] species with South American tropical origins remain largely restricted to the confines of the tropical regions.” He based his ideas on phylogeny and the “molecular clock” hypothesis, because “the relatively poor fossil record has prevented us from understanding how the land bridge shaped New World bird communities.” Smith said, “Our study suggests the formation of the Panama land bridge was crucial for allowing cross continental bird migration.” But it doesn’t explain the one-way traffic, unless for some reason South America had better marketing. Some 50% of species in the South have Northern origins, the article said, but it’s only 10% the other direction.
- Brazilian elephant: PhysOrg reported the discovery of a 12 cm tooth shows elephants made it to Brazil. They were previously known only as far south as Costa Rica. Maybe it was on vacation.
Charles Darwin spent two chapters in the Origin invoking geographical distribution as evidence for his theory of evolution. Modern evolutionists continue the tradition, with ample use of special pleading (see 08/07/2001, 01/01/2004, 01/22/2010, and 05/27/2010).
Biogeography – is it incontrovertible evidence for evolution? Only if one allows plenty of leeway for storytelling. Creationists have stories for how animals got distributed after the Flood, too. Any position is going to have questions and problems. Do a little research on alternative explanations at TrueOrigin. The reader can decide which story he or she likes better. One, remember, has eyewitness testimony for at least the general picture.