New Zealand is definitely known as a location for the birdsquite literally. Before people arrived 700 years back, the archipelago hosted an idiosyncratic ecosystem, nearly free from mammals. A lot more than 200 bird species filled a food web almost all their own. Instead of cows or antelopes, there is a family group of flightless birds referred to as moa. And instead of apex predators like tigers, New Zealand had Haasts eagle.
Since several farm workers drained a swamp in the late 1860s and uncovered its buried bones, this eagle has captivated researchers. Julius Haast, the explorer and geologist who published the initial notes on the species, described it as a raptorial bird of enormous dimensions. Today, biologists estimate that the eagles weighed around 33 poundsroughly 50 percent a lot more than any raptor known today. But with a wingspan of only 2-3 metersjust beyond the number of a bald eaglethis was an oddly proportioned bird.
The form of Haasts eagle was among the many puzzles that scientists faced because they studied this long-extinct species, preserved in only several skeletons, plus scattered equipment. For nearly a hundred years, there is a debate over whether this type of large bird could fly; even with that feud was settled, questions remained about if the bird was with the capacity of killing moa, which in some instances could have been a lot more than 15 times bigger than the eagle itself. Now, new scientific techniques, coupled with a clearer knowledge of New Zealands geological history, has placed the Haasts eagle amid a much bigger ecological discussion: how species involves invade new territories.
Scientists now think that this superlative bird was one in a wave of feathered invaders that conquered New Zealand over a comparatively short period. Which was not the only real wave of invasions. Haasts eagledespite being gone for centurieshas revealed that people live in a more connected world than we once thought, says biologist Michael Knapp of the University of Otago, who has studied the eagle. If such seemingly isolated islands have repeatedly attracted so many incoming species, he says, then natural invasions should be a significant force in ecosystems around the world.
Digging for answers
New Zealand has always held a significant invest scientists knowledge of extinction. When Western scientists first encountered moa, the theory that species could go extinct was just a couple of decades old. Their skeletons soon became a hot commodity. You can virtually name your price, says paleobiologist Paul Scofield, senior curator at the Canterbury Museum in Christchurch. It had been really what enabled our museum. Haast himself launched the museum and assembled its initial collection by exchanging moa fossils for many other archeological and zoological curiosities.
New Zealand retained unusual speciesincluding, famously, the flightless kiwi. Coupled with these extant oddballs, the moa fossils helped to determine the theory that New Zealand was a lost world, a location where ancient creatures, sheltered by distance from all of those other world, were able to survive mass extinction events. Later geologists confirmed these rocky islands had once been part of a supercontinent they called Gondwana, but split away about 80 million years back. In 1990, a television series described New Zealands islands as Moas Ark, popularizing the catchy name of the long-held style of how its bird-filled ecosystem had become.
By the finish of the 1990s, though, scientists realized that there is a period through the Oligocene, about 25 million years back, when geologic and climatic changes may have put most of New Zealand underwater. This type of flood could have destroyed mostif not allof the hawaiian islands species. The idea, which became referred to as the Oligocene drowning, met resistance from some scientists, launching a heated debate over the amount of land was covered.
Fortunately, new technologies were emerging to answer that question. Scientists started to extract and sequence DNA from fossils; this meant researchers could compare ancient DNA to modern genomes and createfamily trees of the evolutionary relationshipsbetween living and extinct species. Such phylogenies could roughly pinpoint when two species split aside from their common ancestordata useful in settling the fight over New Zealands geological history.
In 2005, a team of scientists published a paper that compared DNA sequences extracted from two Haasts eagle fossils to the genomes of 16 modern eagles. The scientists ascertained that thegreat lost birds closest living relativesincluded Australian species, needlessly to say. The genomic data suggested that the household tree had split within recent million years. Subsequent analysis has put the divergence time around 2.2 million years back.
Score one for the Oligocene drowning hypothesis: The eagle seemed to have arrived following the time of the proposed submergence. But later analyses ofother New Zealand speciesshowed divergence times on the order of tens of an incredible number of years. Some species had persisted through the Oligocene, then.
By 2014, geological evidence had convinced most scientists: Yes, a lot of New Zealand had drowned, but small slivers of landperhaps 20 percenthad remained above water. While some of the islands species date far back again to Gondwana, numerous others, including Haasts eagle, were newer arrivals.