Bones from 20 embryonic sauropods (recreation, above) shed light on the early growth of dinosaurs.
New technologies could make it possible to bring extinct species back to life, concludes a paper published on April 4 in the journal Science. These advances include back-breeding (assembling or reassembling an extinct species' genes), cloning and genetic engineering.
A leading candidate for de-extinction is the woolly mammoth. Russian scientist Semyon Grigoriev, of the Sakha Republic's mammoth museum, plans to replace the nuclei of an elephant egg with nuclei extracted from woolly mammoth bone marrow. The elephant would theoretically become a surrogate mother to a baby mammoth.
Tasmanian tigers died out in 1936, in part because they had little genetic diversity which translates to "bad news for a species," said Katherine Belov, professor of comparative genomics at the University of Sydney. "Species are less able to adapt to change." Even if Tasmanian tigers -- or other animals -- are resurrected, it will take some time to build up diversity again.
Louis Agassiz Fuertes, Wikimedia Commons
Experts believe billions of these birds populated the Americas when Europeans arrived. Loss of habitat and commercial exploitation of the birds for their meat are thought to have killed them all off.
Efforts are now underway to revive the species by extracting DNA fragments from preserved specimens, and later, using band-tailed pigeons as surrogate parents.
Joseph Wolf, Wikimedia Commons
The Pyrenean ibex, a horned mammal once common in Europe, was one of the first subspecies targeted for de-extinction. Scientists began the attempts in late 1990s, when the last female Pyrenean ibex was still alive. Even if researchers could successfully clone that individual, there would be no males for her to breed with. Instead, genetic engineering might be required.
Cicero Moraes, Wikimedia Commons
Since saber-toothed cat bodies are sometimes found frozen, it might be possible to extract preserved DNA and clone the animal. About 5 years ago, scientists did just that with a mouse that was dead and frozen for 16 years. Woolly mammoth remains are also sometimes found in a well-preserved, frozen state.
Oxford Museum of Natural History, Wikimedia Commons
The dodo, a flightless bird, proved to be a tasty meal for humans and other predators. In 2007, scientists found a remarkably well-preserved dodo in a cave. Dodo DNA could be used to resurrect this avian species.
University of Texas at Austin, Wikimedia Commons
Ground sloths, relatively slow, lumbering animals, were easy targets for prehistoric big-game hunters. Scientists have found remains that still bear soft tissue. As with woolly mammoths, there's a chance extracted DNA could be used to back-breed or clone the large sloths.
Charles Knight, Wikimedia Commons
The Irish elk has been extinct for 11,000 years. Like the woolly mammoth, it inhabited colder regions. As a result, bodies are sometimes found frozen and in relatively good condition, making them candidates for DNA extraction.
UNiesert, Wikimedia Commons
Earlier this year, Harvard geneticist George Church -- with tongue in cheek -- said that he was seeing an "adventurous female human" to be a surrogate mother to a cloned Neanderthal. While Church was really just theorizing about what it would take to bring a Neanderthal back to life, the possibility could be a reality, should any scientist undertake such a controversial project.
Paleontologist Jack Horner is leading a project to create a dinosaur out of a chicken -- a "dinochicken." He told Discovery News that birds "are dinosaurs, so technically we're making a dinosaur out of a dinosaur." He and his colleagues have been genetically engineering chickens to reactivate ancestral traits, such as long tails, which are more associated with non-avian dinosaurs.
A site in China contains 190-million-year old organic remains from non-avian dinosaurs and dinosaur embryos, and some of the world’s oldest known eggshells, according to a new study.
The study, published in the journal Nature, reveals for the first time how dinosaur embryos grew, developed and moved around within their eggs. The organic remains -- collagen discovered in bone -- also fuel hopes that many mysteries about dinosaurs may be resolved in the not-too-distant future.
“Our hope is that we may be able to recover collagen from these tissues in the future and do additional analyses,” project leader Robert Reisz told Discovery News. “This would take the study of early dinosaurs to another level.”
“Finding remnants of complex proteins in a 190-million-year-old fossil provides great promise for finding it in other extinct animals, if our targeted method is used,” added Reisz, a University of Mississauga paleontologist.
Reisz and his team recovered all of the remains at the world’s oldest known dinosaur embryo bone-bed, located near the city of Lufeng in Yunnan, China. The study focused on upper hind limb bones from 20 embryonic individuals of the giant herbivorous long-necked dinosaur Lufengosaurus, which was common to the area during the Jurassic period.
The bones showed very rapid growth, doubling in length within the eggs. This indicates that Lufengosaurus had a very short incubation period. The bones were also reshaped, even as they were in the shell, contracting and pulling on the hard bone tissue.
“This suggests that dinosaurs, like modern birds, moved around inside their eggs,” Reisz said. “It represents the first evidence of such movement in a dinosaur.”
Lufengosaurus, like many sauropods and their ancient relatives, grew to enormous sizes and spent their days feasting on large amounts of plant material. Given the new research, it is possible that all such dinosaurs started their growth spurts early, even before emerging into the world, but further analysis is required. No embryos have been found for iconic carnivorous dinosaurs, like T. rex.
While the discovered collagen is not technically “alive,” it was derived from what once were the dinosaur’s living tissues.
As for retrieving DNA, Reisz said, “You never know about what we may be able to find in the fossil record. We are continually breaking new ground.”
“However, resurrecting a dinosaur is out of the question,” he added, reminding that living birds are dinosaurs. Bringing a Jurassic animal into the present could therefore be a disaster, probably worse than what some movies have fictionally predicted. At the very least, such an animal -- if it wound up in the wild -- could wreck havoc on the existing ecosystem.
Paleontologist Martin Sander of the University of Bonn told Discovery News that he agrees with the conclusions of the new paper, and said the tissue results “are great, because no other dinosaur embryo this old has ever been studied histologically.” (Histology is the study of microscopic tissue structures.)
David Evans, curator of vertebrate paleontology at the Royal Ontario Museum’s Department of Natural History, echoed Sander’s view.
“The early life history of most dinosaurs is poorly documented, and the fossil record of dinosaur embryos is particularly scant in the Triassic and Jurassic periods,” Evans said.
He continued, “The study by Reisz and colleagues is certainly the most detailed analysis of embryonic histology and development in an early dinosaur, and it will serve as a baseline for future comparisons with other species, which will deepen our understanding of dinosaur growth and evolution.”