Folch and his collaborators are repeating their attempt this year and Fernández-Arias said they hope that if all goes well, a kid, or kids, could be born in August.

In Australia researcher Michael Archer is attempting to clone the Tasmanian tiger, also known as a thylacine or Tasmanian wolf. This was a unique carnivore that carried its young in a pouch and was hunted to extinction by 1936. Archer, who is based at the University of New South Wales, is also working to bring back the gastric brooding frog. Discovered in 1972, it turned its stomach into a uterus where it gestated its tadpoles, then birthed the baby frogs through its mouth. (In most frogs, females and males excrete eggs and sperm, and fertilization occurs in the water).

“It’s the first time we’ve seen an animal change one organ in the body into another,” said Archer. “The medical world was excited at the frog’s discovery. They wondered, could they use this in human health, not to have babies in our stomachs but to manage gastric secretions in the gut?”

The frog was extinct by 1983, likely wiped out by chytrid fungus, a disease spread by peoples’ shoes that is decimating frog populations around the world.

Breeding: In the Netherlands entrepreneurs at an organization called Rewilding Europe are working to create large wildlife parks in parts of the continent where farmland has been abandoned, such as along Croatian mountain ranges on the Adriatic coast, emptied out during the 1990s wars in the former Yugoslavia. They envision parks teeming with wildlife like bears and wolves, and the aurochs, the ancestor to all breeds of modern cattle. Aurochs were hunted, domesticated, and bred out of existence by 1627. They would have been the only cattle big enough to put up a fight with predators like wolves, said Ronald Goderie of the Holland-based Taurus Foundation, which is working in close collaboration with the Rewilding Europe project.

“They want to create something like the game parks in Africa or the national parks in America that will also realize some economic activity,” said Goderie. The idea would be that visitors could go on a European safari.

The Taurus Foundation is focused on bringing back the aurochs by working with researchers in Holland, Spain, and Portugal to breed “primitive” types of cattle: breeds that have survived in poorer parts of Europe where modern breeds of cattle aren’t as available. The process of breeding these cattle to make them more like their ancestors is called “back breeding.” The foundation has already produced 150 crossbred cattle, said Goderie.

The first of these crossbred animals, a bull named Manolo Uno, was created by performing in vitro fertilization using eggs from a Maremmana Primitivo cow from the Maremma region of Tuscany, Italy, and sperm from a Pajuna bull, from Andalucía, Spain. Researchers using genetic analysis have traced both breeds back to aurochs. Maremmanas are similar to aurochs in their thick horns, large size, and coloration (black males and brown females). Pajunas have long faces, like their ancestors. And both breeds live in natural herds and can subsist in harsh conditions. To create Manolo Uno, sperm and egg were joined in a lab by Hurkmans ET, a Dutch company, and the resulting fertilized egg was carried by a surrogate dairy cow.

Genome Editing: At the University of California-Santa Cruz, biologists Ben Novak and Beth Shapiro are piecing together the genome of the extinct passenger pigeon. Three to five billion of these pigeons existed in the United States in the 19th century. They are believed to have been the most abundant birds in the world, but they were hunted for food and went extinct in 1914. Novak’s work to bring the bird back is being funded by Revive & Restore, a nonprofit group based in Sausalito, California, co-founded by environmentalist Stewart Brand, creator of the Whole Earth Catalog, and entrepreneur Ryan Phelan, former CEO of DNA Direct, one of the first companies to offer genetic testing online.

Using DNA extracted from passenger pigeon specimens stored in facilities like Canada’s Royal Ontario Museum, Novak and Shapiro are putting together as much of the passenger pigeon’s genome as possible. Then they’ll compare it to the genome of its closest living relative, the band-tailed pigeon, which is found on the West Coast, in the Southwest, and all the way down to Argentina. By comparing the two genomes scientists hope to figure out what genes gave the passenger pigeon its physical characteristics, like the long tail and swift wings that allowed it to fly at 60 miles per hour.

Once researchers have identified these genes and built them in the lab using chemical compounds, they’ll insert them into the band-tailed pigeon’s genome using new genome-editing technology.

“It’s like very precise scissors that allow you to cut and splice with unprecedented accuracy and ease of use,” said Harvard Medical School geneticist George Church, one of the scientists who pioneered the technology, known as CRISPR, in the past year.

In his lab, Church is editing elephant cells to try to make those animals more closely resemble woolly mammoths, with a fatty layer and thick fur to better withstand the cold. Teams in Russia and South Korea hope to clone a woolly mammoth using blood found in fossilized remains. And although it may be years before mammoths roam the Earth or passenger pigeons take to the skies, it probably isn’t too early to start considering the implications.

KQED Science associate producer Arwen Curry contributed to this story.